A differential-imaging polarimeter for high-contrast exoplanet imaging

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宏观傅里叶叠层技术远距离成像实验研究

航天返回与遥感第44卷第6期38 SPACECRAFT RECOVERY & REMOTE SENSING2023年12月宏观傅里叶叠层技术远距离成像实验研究田芷铭赵明王森李剑（大连海事大学，大连116026）摘要傅里叶叠层是一新型的宽视场高分辨成像技术，但是其在宏观成像领域的应用中，成像模型在米级成像距离下通常仅有2 cm左右的成像视场，难以满足使用要求。

为了提高宏观傅里叶叠层技术的成像距离和视场，文章开展了远距离宏观反射式傅里叶叠层成像模型的理论研究，提出了一种新的宏观傅里叶叠层成像模型，该模型使用发散光束照明，通过球面波移位对目标傅里叶谱进行扫描重建高分辨率目标图像；此外，还分析了宏观相干成像机理和傅里叶成像模型近似条件，由此推导出模型的近似范围，为模型推广提供了理论基础；最后，利用搭建的实验系统对10 m外目标成像，使目标分辨率从1.4 mm提升到0.35 mm，分辨率提升4倍以上，验证了模型具有通过合成孔径技术提升目标成像分辨率的能力。

关键词宏观成像傅里叶叠层成像模型远距离成像超分辨技术傅里叶叠层实验中图分类号: TP391.41文献标志码: A 文章编号: 1009-8518(2023)06-0038-07 DOI: 10.3969/j.issn.1009-8518.2023.06.004Experimental Research on Long-Range Imaging Using MacroscopicFourier Ptychographic TechnologyTIAN Zhiming ZHAO Ming WANG Sen LI Jian（Dalian Maritime University, Dalian 116026, China）Abstract Fourier ptychography is a promising high-resolution imaging technique that has been gradually applied in the field of macroscopic imaging. However, its imaging model typically provides a limited field-of-view of around 2 cm at meter-level imaging distances, which often falls short of practical requirements. To enhance the imaging distance and field-of-view of macroscopic Fourier ptychography, this article conducted theoretical research on the long-distance macro reflection Fourier stack imaging model. The proposed model utilizes diverging light beams for illumination, scans the target Fourier spectrum using spherical wavefront shifting, and reconstructs high-resolution target images. The article analyzes the mechanism of macroscopic coherent imaging and the approximation conditions of the Fourier imaging model, deriving the approximate range of the model and establishing a theoretical foundation for its extension. Finally, the built experimental system was used to image a target 10 meters away, increasing the target resolution from 1.4 mm to 0.35 mm, a resolution increase of more than 4 times, verifying the model’s capability to improve target imaging resolution through the synthetic aperture technology.收稿日期：2023-06-20引用格式：田芷铭, 赵明, 王森, 等. 宏观傅里叶叠层技术远距离成像实验研究[J]. 航天返回与遥感, 2023, 44(6): 38-44.TIAN Zhiming, ZHAO Ming, WANG Sen, et al. Experimental Research on Long-Range Imaging Using Macroscopic Fourier Ptychographic Technology[J]. Spacecraft Recovery & Remote Sensing, 2023, 44(6): 38-44. (in Chinese)第6期田芷铭等: 宏观傅里叶叠层技术远距离成像实验研究 39Keywords macroscopic imaging; Fourier ptychographic model; long-range imaging; super-resolution technology; Fourier ptychographic experiment0 引言目前，在监视、遥感等领域，高分辨率成像问题面临着重要挑战。

分焦平面偏振成像关键技术

分焦平面偏振成像关键技术罗海波;刘燕德;兰乐佳;叶双辉【摘要】偏振成像是一项具有巨大应用价值的前沿技术,近年得到了业内人士的广泛关注.文章介绍了偏振成像的原理、特点、应用以及国内外研究现状,还介绍了几种常用的实现方法及其优缺点,最后对当前偏振成像的主流方法——分焦平面法的关键技术进行了讨论.%Polarization imaging is an advanced technology with increasing applications and it has attracted wide atlention in recent years. In this paper, theories, characteristics, applications and the research status of polarization imaging are introduced. The implementation of several common methods and their advantages and disadvan-tages are also explored. Finally, the key technologies of division of focal plane polarimeters which is the current mainstream method of polarization imaging are analyzed.【期刊名称】《华东交通大学学报》【年(卷),期】2017(034)001【总页数】6页(P8-13)【关键词】成像;偏振成像;分焦平面法;插值;非均匀性校正【作者】罗海波;刘燕德;兰乐佳;叶双辉【作者单位】中国科学院沈阳自动化研究所,辽宁沈阳 110016;华东交通大学机电与车辆工程学院,江西南昌 330013;华东交通大学机电与车辆工程学院,江西南昌330013;华东交通大学机电与车辆工程学院,江西南昌 330013【正文语种】中文【中图分类】TP391偏振是光波的基本属性之一,其中蕴含着被测物的众多特征信息。

专业英语

Definition of polymers A simple understanding of polymers can be gained by imaging them to be like a chain or, perhaps, a string of pearls, where the individual pearl represent small molecules that are chemically bonded together. Therefore, a polymer is a molecule made up of smaller molecules that are joined together by chemical bonds. The word polymer means „many parts or units.‟ The parts or units are the small molecules that combine. The result of the combination is, of course, a chainlike molecule (polymer). Usually the polymer chains are long, often consisting of hundreds of units, but polymers consisting of only a few units linked together are also known and can be commercially valuable.
Figure 1.1 Diagram illustrating the definition of plastics.
As Figure 1.1 shows, all materials can be classified as gases, simple liquids, or solids, with the understanding that most materials can be converted from one state to another through heating or cooling. If only materials that are structural solids at normal temperatures are examined, three major types of materials are encountered: metals, polymers, and ceramics. The polymer materials can be further divided into synthetic polymers and natural polymers. Most synthetic polymers are those that do not occur naturally and are represented by materials such as nylon, polyethylene, and polyester. Some synthetic polymers could be manufactured copies of naturally occurring materials (such as

成像技术英文作文

成像技术英文作文Imaging technology has revolutionized the way we seeand understand the world around us. It allows us to capture and visualize images of objects, people, and places thatare beyond the reach of our naked eyes.The use of imaging technology has become increasingly widespread in various fields, including medicine, astronomy, and security. In medicine, imaging technology enables doctors to diagnose and treat diseases by providingdetailed images of the inside of the body. In astronomy, it allows scientists to capture images of distant galaxies and stars, helping us to better understand the universe. In security, imaging technology is used for surveillance and screening purposes, helping to keep people and places safe.One of the most common imaging technologies is photography, which has evolved significantly with the advancement of digital cameras and smartphones. These devices allow us to capture high-quality images and sharethem instantly with others, making photography more accessible and widespread than ever before.Another important imaging technology is medical imaging, which includes techniques such as X-rays, CT scans, and MRI. These techniques provide detailed images of the inside ofthe body, helping doctors to diagnose and treat various medical conditions.In addition to photography and medical imaging, there are other emerging imaging technologies that are changingthe way we see the world. For example, 3D imagingtechnology allows us to capture and visualize three-dimensional images, providing a more immersive andrealistic viewing experience.Overall, imaging technology has had a profound impacton our lives, allowing us to see and understand the worldin new and exciting ways. As technology continues to advance, we can expect even more innovative imaging techniques to emerge, further expanding our ability to capture and visualize the world around us.。

AWG5000系列混合信号伪随机波形生成器说明书

Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)The AWG5000 Series of Arbitrary Waveform Generators Delivers the Industry’s Best Mixed Signal Stimulus Solution for Today’s Complex Measurement ChallengesThe AWG5000 Series of Arbitrary Waveform Generators delivers theoptimal combination of industry leading sample rate, vertical resolution, signal fidelity and waveform memory length,all in an easy-to-use self-contained package.The series offers the industry’s best solution to the challenging signal stim-ulus issues faced by designers verifying,characterizing and debugging sophisti-cated electronic designs.Meeting the needs of today’s design engineers, the series provides excellent signal dynamic range and integrity.AWG5000 Series models, with a 14bits DA converter based sample rate from 600MS/s to 1.2GS/s, two to four output channels, synchronized four to eight digital marker outputs, and 28-channels of digital data outputs, easily solve the toughest measurement chal-lenges in wireless base band I/Q communications, digital consumer product design such as imaging devices, data conversion equipment and semiconductor design and test. The open Windows (Windows XP)-based instruments are easy and convenient to use and connect easily with peripherals and third-party software.AWG5000 Series.Features & Benefits1.2Gs/s and 600MS/s Models 14 bit Vertical Resolution 2 or 4Arbitrary WaveformDifferential/Single-ended Outputs –Up to 4.5V p-p Single-ended and 9V p-p at Differential Output into 50Ω–0.95ns Tr/Tf (10 to 90%) at 0.6V p-p–+/– 5ns Range (50ps Resolution) Inter Channel Skew Control–SFDR: 80dBc (1MHz),64dBc (10MHz)4 or 8Variable Level Marker Outputs–Up to 3.7V p-p Single-ended Output into 50Ω–300ps Tr/Tf (20 to 80%)at 0 to 1V–Up to 1ns Range (50ps Resolution) Delay Control28 Bits Ch 1/Ch 2Variable Level Digital Data Output–Up to 3.7V p-p Single-ended Output into 50Ω–300ps Tr/Tf (20 to 80%)at 0 to 1VUp to 32M Point Record Length For Longer Data Streams Down to 800ps Resolution Edge Timing Shift Control Real-time Sequencing Creates Infinite Waveform Loops, Jumps,and Conditional BranchesEasy to Use and Learn Shortens Test TimeIntuitive User Interface Based on Windows 2000 XP Convenient Bench Top Form FactorIntegrated PC Supports Network Integration and Provides a Built-in DVD, Removable Hard Drive,LAN and USB portsApplicationsDesigning, Testing and Deploying Wireless Communications: –High Fidelity QuadratureModulation I and Q Base-band Signals (Polar Modulation:I/Q + Magnitude Control, Two Pair of I/Q for MIMO)Imaging–Stimulus Signals for Imaging Display and Recording Devices (CCD, LCD)Data Conversion–Stimulus Signals for DataConversion Devices (ADC, DAC)Mixed Signal Design and Test –2/4Ch Analog + 4/8Ch Marker Outputs + 28 Bit Digital Data OutputsReal-world, Ideal or Distorted Signal Generation – Including All the Glitches, Anomalies and ImpairmentsEnhanced/Corrupted Playback of DSO Captured SignalsWaveform Vectors Imported from Third-party T ools such as MathCAD,MATLAB, Excel and OthersArbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)AWG5000 Series • /signal_sources2EVM/Constellation measurement.Typical Signal Injection.Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002) RTSA Spectrum view.9-PAM with 250 Mbps.Mixed signal test by TDS/TLA iView.™AWG5000 Series • /signal_sources3Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)4AWG5000 Series • /signal_sourcesArbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)AWG5014AWG5012AWG5004AWG5002Arbitrary WaveformsWaveform Length 1 to 16,200,000 points (or 1 to 32,400,000 points,option 01)Number of Waveforms 1 to 16,000Sequence Length 1 to 4,000stepsSequence Repeat Counter 1 to 65,536 or infiniteSequence Control Repeat count,Trigger,Go-to-N and JumpJump Mode Synchronous and AsynchronousRun ModesContinuous Waveform is iteratively output.If a sequence is defined,the sequence order and repeat functions are appliedTriggered Waveform is output only once when an external,internal,GPIB,LAN or manual trigger is receivedGated Waveform begins output when gate is true and resets to beginning when falseSequence Waveform is output as defined by the sequenceClock GeneratorSampling Frequency10 MS/s to 1.2GS/s10 MS/s to 600 MS/sResolution8digitsInternal ClockAccuracy Within ±(1 ppm + Aging),Aging:within ±1 ppm/yearClock Phase Noise Less than –90dBc/Hz at 100kHz offsetInternal Trigger GeneratorInternal Trigger RateRange 1.0μs to 10.0sResolution3digits,0.1μs minimumSkew Control Between OutputsRange– 5 ns to + 5nsResolution5psAWG5000 Series • /signal_sources5Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)AWG5000 Series • /signal_sources6AWG5014AWG5012AWG5004AWG5002Main Arbitrary Waveform Output Resolution14 bitsAnalog OutputOutput StyleDifferential Output Impedance 50ΩConnectorBNC FrontAmplitude Output Voltage Normal:–4.5 V to + 4.5V,Direct –0.3V to +0.3V Amplitude Normal:20mV p-p to 4.5V p-p ,Direct; 20mV p-p to 0.6V p-pResolution 1mVDC Accuracy±(2.0% of Amplitude + 2mV) at offset = 0V Offset (into 50Ω) Range Normal:–2.25V to +2.25V,Direct:N/A Resolution 1mVAccuracy±(2% of offset +10mV at minimum amplitudePulse Response Rise/Fall time:(10% to 90%).Normal:1.4ns (2.0V p-p ),Direct:0.95ns (0.6V p-p )Bandwidth (–3dB)Normal:250MHz (2.0V p-p ),Direct:370MHz (0.6V p-p )Ringing Normal:750mV p-p (4.5V p-p filter through),80mV p-p (2.0V p-p filter through),Direct:60mV p-p (0.6V p-p )Low Pass Filter High range:100MHz,20MHz,Low range:through,100MHz,20MHz,Direct:N/ADelay from Marker Normal:17.5ns to 19.4ns (20MHz filter),3.8ns to 5.7ns (100MHz filter),0 to 1.9ns (Through),Direct:–1.5ns to 0.4nsSine Wave Characteristics (1.2GS/s clock,32 waveform points,37.5MHz signal frequency)(600MS/s clock,32 waveform points,18.75MHz signal frequency)Harmonics Normal:≤–40dBc (2.0V p-p ),Direct ≤=–49dBc (0.6V p-p )Normal:≤–46dBc (2.0V p-p ),Direct ≤=–55dBc (0.6V p-p )Non Harmonics Normal:≤–60dBc (2.0V p-p ,DC to 600MHz)Normal:≤–60dBc (2.0V p-p ,DC to 300MHz)Phase noise ≤–85dBc/Hz (2.0V p-p ,10kHz offset) –85dBc/Hz (2.0V p-p ,10kHz offset) SFDR 50dBc (Normal,37.5MHz,1.2GS/s,2.0V p-p )56dBc (Normal,18.75MHz,600MS/s,2.0V p-p )60dBc (Normal,10MHz,600MS/s,1.0V p-p )60dBc (Normal,10MHz,600MS/s,1.0V p-p )80dBc (Normal,1MHz,600MS/s,1.0V p-p )80dBc (Normal,1MHz,600MS/s,1.0V p-p )64dBc (Direct,10MHz,600 MS/s,0.6V p-p )64dBc (Direct,10MHz,600MS/s,0.6V p-p )80dBc (Direct,1MHz,600 MS/s,0.6V p-p )80dBc (Direct,1MHz,600MS/s,0.6V p-p )Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002) Auxiliary OutputsOutput Style Single-endedOutput Impedance50ΩConnector BNC FrontLevel (into 50Ω)(Twice for Hi_Z input)Output Windows–1.00 V to + 2.7VAmplitude0.10 Vp-p to 3.7 Vp-pResolution10mVDC Accuracy±(10% of setting +120mV) Maximum Output Current±54mA /chRise/Fall Time (20% to 80%)300 ps(1.0 Vp-p,Hi +1.0V,Lo 0V) Skew Adjust Between MarkersRange0 to 1000ps Resolution50psRandom Jitter (Typical)1010 clock patternRMS5psrmsTotal Jitter (Typical)2^15–1PN data patternPeak to Peak (p-p)80psp-pClock (VCO) OutRange600MHz to 1.2GHzAmplitude0.4 Vp-pinto 50Ωto GND Impedance:50Ω,AC coupling Connector BNC Rear10MHz Reference OutAmplitude 1.2 Vp-p into 50Ω.Max 2.5 Vp-popenImpedance50Ω,AC couplingConnector BNC RearDC OutputsNumber of Outputs4:independently controlled outputsRange–3.0 to +5.0VResolution10mVMax.Current±100mAConnector2x4 pin header on front panelAWG5000 Series • /signal_sources7Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)AWG5000 Series • /signal_sources8Trigger In Impedance 1 k Ωor 50ΩPolarity POS or NEG ConnectorBNC FrontInput Voltage Range1 k Ω:±10V.50 Ω:±5V Threshold Level –5.0 V to 5.0VResolution 0.1VTrigger Jitter2.0ns to 4.5ns (Typical) Trigger Mode Minimum Pulse Width 20nsTrigger Hold-off 832* sampling_period – 100ns Delay to Analog Out128* sampling_period + 250ns Gate Mode Minimum Pulse Width 1024* sampling_period + 10ns Delay to Analog Out640* sampling_period + 260ns Event Input Impedance 1 k Ωor 50ΩPolarity POS or NEG ConnectorBNC FrontInput Voltage Range 1 k Ω:±10V.50 Ω:±5V Threshold –5.0 V to 5.0VResolution0.1VSequence Mode Mode Minimum Pulse Width 20nsEvent Hold Off 1024* Sampling Period + 10nsDelay to Analog Out640* Sampling Period + 280 ns (Jump timing:Asynchronous jump)External Clock IN Input Voltage Range 0.2 V p-p to 0.8 V p-p Impedance50Ω,AC coupledConnectorBNC RearReference Clock IN Input Voltage Range 0.2 V p-p to 3.0 V p-p Impedance50Ω,AC coupledFrequency Range 10MHz,20MHz,100MHz (with ±0.1%)ConnectorBNC RearPhase Lock IN Input Ranges5MHz to 600MHz (acceptable frequency drift is ±0.5%)Input Voltage Range 0.2 V p-p to 3 V p-pConnectorBNC RearAdd IN For each analog channel Impedance 50Ω,DC coupledDC Gain 1BandwidthDC to 100MHz at –3 dBInput Voltage Range ±1.0V ConnectorBNC RearArbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)(Third party software creation waveform data:MATLAB,MathCad,Excel)S/W driver for 3rd party S/W IVI-com driver and MATLAB libraryInstrument Control/Data Transfer PortsGPIB Remote control and data transfer.(Conforms to IEEE-Std 488.1,compatible with IEEE 488.2 and SCPI-1999.0)Ethernet (10/100/1000Base-T)Remote control and data transfer.(Conforms to IEEE 802.3).RJ-45Computer System & Peripherals Windows XP Professional,512 MB SDRAM,80 GB removable Hard Drive at rear (available front mount kit),CD-RW/DVD drive at front,included USB compact keyboard and mousePC I/O Ports USB 2.0 compliant ports (6 total,2 front,4 rear),PS/2mouse and keyboard connectors (rear panel),RJ-45 Ethernet connector (rear panel) supports 10/100/1000BASE-T,XGA outDisplay Characteristics10.4inch,LCD color display with touch screen,1024 (H)x768 (V) (XGA)Power Supply100 to 240VAC,47 to 63HzPower Consumption450WSafety UL61010-1,CAN/CSA-22.2,No.61010-1-04,EN61010-1,IEC61010-1Emissions EN 55011 (Class A),IEC61000-3-2,IEC61000-3-3Immunity IEC61326,IEC61000-4-2/3/4/5/6/8/11Regional CertificationsEurope EN61326Australia/New Zealand AS/NZS 2064AWG5000 Series • /signal_sources9Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)Ordering Information Arbitrary WaveformGenerator MainframeAWG50141.2GS/s,4-channel,14bits,16M point/channel Arbitrary Waveform Generator.AWG50121.2GS/s,2-channel,14bits,16M point/channel Arbitrary Waveform Generator.AWG5004600MS/s,4-channel,14bits,16M point/channel Arbitrary Waveform Generator.AWG5002600MS/s,2-channel,14bits,16M point/channel Arbitrary Waveform Generator.All Models Include:Accessory pouch,front cover, USB mouse,compact USB key board,lead set for DC output,stylus for touch screen 2 each, Windows®XP operating system restore DVD and instructions,AWG5000 Series product software CD and instructions,Document CD with Browser,Quick Start User Manual,registration card,Certificate of Calibration,power cable.Note:Please specify power cord and language option when ordering.Instrument OptionsAWG5014/AWG5012,AWG5004/AWG5002Opt.01 – Waveform Length Expansion (from 16 M to 32 M).AWG5012/AWG5002Opt. 03 –28 bits digital data outputs (digital data of ch 1 and ch 2).Common OptionsInternational Power PlugsOpt. A0 – North America power.Opt. A1 –Universal EURO power.Opt. A2 – United Kingdom power.Opt. A3 – Australia power.Opt. A5 – Switzerland power.Opt.A6 –Japan power.Opt.A10 – China power.Opt.A99 – No power cord or AC adapter.Language OptionsOpt. L0 – English.Opt. L5 – Japanese.Opt. L7 –Simplified Chinese.Opt. L8 – Traditional Chinese.ServiceOpt. CA1 – A single calibration event.Opt. C3 – Calibration service 3 years.Opt. C5 – Calibration service 5 years.Opt. D1 –Calibration data report.Opt. D3 – Calibration data report 3 years (withoption C3).Opt. D5 – Calibration data report 5 years (withoption C5).Opt. R3 –Repair service 3 years.Opt. R5 –Repair service 5 years.Post-sales Service Options:(e.g.,AWG5012-CA1).CA1 – A single calibration event.R3DW – Repair service coverage 3 years.R5DW – Repair service coverage 5 years.R2PW –Repair service coverage 2 yearspost warranty.R1PW –Repair service coverage 1 yearpost warranty.Product UpgradeAWG5014, AWG50UPOpt.M14 – Waveform Length Expansionfrom 16 M point to 32 M point.Product UpgradeAWG5012, AWG50UPOpt. M12 – Waveform Length Expansionfrom 16 M point to 32 M point.Opt.D13 –Digital Data Outputs.Product UpgradeAWG5004, AWG50UPOpt. M04 – Waveform Length Expansionfrom 16 M point to 32 M point.Product UpgradeAWG5002, AWG50UPOpt.M02 – Waveform Length Expansionfrom 16 M point to 32 M point.Opt.D03 –Digital Data Outputs.AWG5000 Series • /signal_sources 10Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)WarrantyOne-year parts and labor.AWG5000 Series • /signal_sources11Arbitrary Waveform GeneratorAWG5000 Series (AWG5014 • AWG5012 • AWG5004 • AWG5002)For Further InformationTektronix maintains a comprehensive, constantly expanding collection of application notes, technical briefs and other resources to help engineers working on the cutting edge of technology. Please visit Copyright © 2008, Tektronix. All rights reserved. Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supersedes that in all previously published material.Specification and price change privileges reserved. TEKTRONIX and TEK are registered trademarks of Tektronix, Inc. All other trade names referenced are the service marks, trademarks or registered trademarks of their respective companies. 07/08 JS/WOW 76W-20381-3Contact Tektronix:ASEAN/Australasia (65) 6356 3900Austria +41 52 675 3777Balkans, Israel, South Africa and other ISE Countries +41 52 675 3777Belgium 07 81 60166Brazil & South America (11) 40669400Canada 1 (800) 661-5625Central East Europe, Ukraine and the Baltics +41 52 675 3777Central Europe & Greece +41 52 675 3777Denmark +45 80 88 1401Finland +41 52 675 3777France +33 (0) 1 69 86 81 81Germany +49 (221) 94 77 400Hong Kong (852) 2585-6688India (91) 80-22275577Italy +39 (02) 25086 1Japan 81 (3) 6714-3010Luxembourg +44 (0) 1344 392400Mexico, Central America & Caribbean 52 (55) 5424700Middle East, Asia and North Africa +41 52 675 3777The Netherlands ***********Norway 800 16098People’s Republic of China 86 (10) 6235 1230Poland +41 52 675 3777Portugal 80 08 12370Republic of Korea 82 (2) 6917-5000Russia & CIS +7 (495) 7484900South Africa +27 11 206 8360Spain (+34) 901 988 054Sweden 020 08 80371Switzerland +41 52 675 3777Taiwan 886 (2) 2722-9622United Kingdom & Eire +44 (0) 1344 392400USA 1 (800) 426-2200For other areas contact Tektronix, Inc. at: 1 (503) 627-7111Updated 12 November 2007roduct(s) are manufactured in ISO registered facilitie Product(s) complies with IEEE Standard 488.1-1987,RS-232-C,and with Tektronix Standard Codes and Formats.。

科学作文医学影像与人工智能

科学作文医学影像与人工智能英文回答：Medical imaging plays a crucial role in the field of medicine as it allows healthcare professionals to visualize and diagnose various medical conditions. With the advancements in technology, particularly in the field of artificial intelligence (AI), the integration of medical imaging and AI has the potential to revolutionize healthcare.One of the main benefits of combining medical imaging and AI is the improvement in accuracy and efficiency of diagnoses. AI algorithms can analyze medical images and detect abnormalities or patterns that may be missed by human radiologists. This can lead to earlier detection of diseases and more accurate diagnoses, ultimately improving patient outcomes.For example, AI-powered algorithms can analyzemammograms and identify early signs of breast cancer. This can help in detecting breast cancer at an early stage when it is more treatable. Similarly, AI algorithms can analyze brain scans and identify signs of stroke or other neurological conditions, allowing for prompt intervention and treatment.Another advantage of using AI in medical imaging is the ability to automate repetitive tasks. Radiologists often spend a significant amount of time reviewing and analyzing medical images. AI algorithms can automate these tasks, allowing radiologists to focus on more complex cases and providing faster results to patients.Furthermore, AI can assist in the development of personalized treatment plans. By analyzing medical images and patient data, AI algorithms can predict how a patient may respond to a particular treatment. This can help healthcare professionals in making informed decisions about the most effective treatment options for individual patients.In addition to diagnosis and treatment, AI can also be utilized in medical imaging for research purposes. AI algorithms can analyze large datasets of medical images, identifying patterns or correlations that may not be apparent to human researchers. This can lead to new discoveries and advancements in the understanding ofvarious diseases.Overall, the integration of medical imaging and AI has the potential to greatly enhance healthcare. By improving accuracy and efficiency in diagnoses, automating repetitive tasks, assisting in personalized treatment plans, andaiding in research, AI can revolutionize the field of medicine and improve patient outcomes.中文回答：医学影像在医学领域中起着至关重要的作用，它使医护人员能够可视化和诊断各种疾病。

毕业设计论文塑料注射成型

Modeling of morphology evolution in the injection moldingprocess of thermoplastic polymersR.Pantani,I.Coccorullo,V.Speranza,G.Titomanlio* Department of Chemical and Food Engineering,University of Salerno,via Ponte don Melillo,I-84084Fisciano(Salerno),Italy Received13May2005;received in revised form30August2005;accepted12September2005AbstractA thorough analysis of the effect of operative conditions of injection molding process on the morphology distribution inside the obtained moldings is performed,with particular reference to semi-crystalline polymers.The paper is divided into two parts:in the ﬁrst part,the state of the art on the subject is outlined and discussed;in the second part,an example of the characterization required for a satisfactorily understanding and description of the phenomena is presented,starting from material characterization,passing through the monitoring of the process cycle and arriving to a deep analysis of morphology distribution inside the moldings.In particular,fully characterized injection molding tests are presented using an isotactic polypropylene,previously carefully characterized as far as most of properties of interest.The effects of both injectionﬂow rate and mold temperature are analyzed.The resulting moldings morphology(in terms of distribution of crystallinity degree,molecular orientation and crystals structure and dimensions)are analyzed by adopting different experimental techniques(optical,electronic and atomic force microscopy,IR and WAXS analysis).Final morphological characteristics of the samples are compared with the predictions of a simulation code developed at University of Salerno for the simulation of the injection molding process.q2005Elsevier Ltd.All rights reserved.Keywords:Injection molding;Crystallization kinetics;Morphology;Modeling;Isotactic polypropyleneContents1.Introduction (1186)1.1.Morphology distribution in injection molded iPP parts:state of the art (1189)1.1.1.Modeling of the injection molding process (1190)1.1.2.Modeling of the crystallization kinetics (1190)1.1.3.Modeling of the morphology evolution (1191)1.1.4.Modeling of the effect of crystallinity on rheology (1192)1.1.5.Modeling of the molecular orientation (1193)1.1.6.Modeling of theﬂow-induced crystallization (1195)ments on the state of the art (1197)2.Material and characterization (1198)2.1.PVT description (1198)*Corresponding author.Tel.:C39089964152;fax:C39089964057.E-mail address:gtitomanlio@unisa.it(G.Titomanlio).2.2.Quiescent crystallization kinetics (1198)2.3.Viscosity (1199)2.4.Viscoelastic behavior (1200)3.Injection molding tests and analysis of the moldings (1200)3.1.Injection molding tests and sample preparation (1200)3.2.Microscopy (1202)3.2.1.Optical microscopy (1202)3.2.2.SEM and AFM analysis (1202)3.3.Distribution of crystallinity (1202)3.3.1.IR analysis (1202)3.3.2.X-ray analysis (1203)3.4.Distribution of molecular orientation (1203)4.Analysis of experimental results (1203)4.1.Injection molding tests (1203)4.2.Morphology distribution along thickness direction (1204)4.2.1.Optical microscopy (1204)4.2.2.SEM and AFM analysis (1204)4.3.Morphology distribution alongﬂow direction (1208)4.4.Distribution of crystallinity (1210)4.4.1.Distribution of crystallinity along thickness direction (1210)4.4.2.Crystallinity distribution alongﬂow direction (1212)4.5.Distribution of molecular orientation (1212)4.5.1.Orientation along thickness direction (1212)4.5.2.Orientation alongﬂow direction (1213)4.5.3.Direction of orientation (1214)5.Simulation (1214)5.1.Pressure curves (1215)5.2.Morphology distribution (1215)5.3.Molecular orientation (1216)5.3.1.Molecular orientation distribution along thickness direction (1216)5.3.2.Molecular orientation distribution alongﬂow direction (1216)5.3.3.Direction of orientation (1217)5.4.Crystallinity distribution (1217)6.Conclusions (1217)References (1219)1.IntroductionInjection molding is one of the most widely employed methods for manufacturing polymeric products.Three main steps are recognized in the molding:ﬁlling,packing/holding and cooling.During theﬁlling stage,a hot polymer melt rapidlyﬁlls a cold mold reproducing a cavity of the desired product shape. During the packing/holding stage,the pressure is raised and extra material is forced into the mold to compensate for the effects that both temperature decrease and crystallinity development determine on density during solidiﬁcation.The cooling stage starts at the solidiﬁcation of a thin section at cavity entrance (gate),starting from that instant no more material can enter or exit from the mold impression and holding pressure can be released.When the solid layer on the mold surface reaches a thickness sufﬁcient to assure required rigidity,the product is ejected from the mold.Due to the thermomechanical history experienced by the polymer during processing,macromolecules in injection-molded objects present a local order.This order is referred to as‘morphology’which literally means‘the study of the form’where form stands for the shape and arrangement of parts of the object.When referred to polymers,the word morphology is adopted to indicate:–crystallinity,which is the relative volume occupied by each of the crystalline phases,including mesophases;–dimensions,shape,distribution and orientation of the crystallites;–orientation of amorphous phase.R.Pantani et al./Prog.Polym.Sci.30(2005)1185–1222 1186R.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221187Apart from the scientiﬁc interest in understandingthe mechanisms leading to different order levels inside a polymer,the great technological importance of morphology relies on the fact that polymer character-istics (above all mechanical,but also optical,electrical,transport and chemical)are to a great extent affected by morphology.For instance,crystallinity has a pro-nounced effect on the mechanical properties of the bulk material since crystals are generally stiffer than amorphous material,and also orientation induces anisotropy and other changes in mechanical properties.In this work,a thorough analysis of the effect of injection molding operative conditions on morphology distribution in moldings with particular reference to crystalline materials is performed.The aim of the paper is twofold:ﬁrst,to outline the state of the art on the subject;second,to present an example of the characterization required for asatisfactorilyR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221188understanding and description of the phenomena, starting from material description,passing through the monitoring of the process cycle and arriving to a deep analysis of morphology distribution inside the mold-ings.To these purposes,fully characterized injection molding tests were performed using an isotactic polypropylene,previously carefully characterized as far as most of properties of interest,in particular quiescent nucleation density,spherulitic growth rate and rheological properties(viscosity and relaxation time)were determined.The resulting moldings mor-phology(in terms of distribution of crystallinity degree, molecular orientation and crystals structure and dimensions)was analyzed by adopting different experimental techniques(optical,electronic and atomic force microscopy,IR and WAXS analysis).Final morphological characteristics of the samples were compared with the predictions of a simulation code developed at University of Salerno for the simulation of the injection molding process.The effects of both injectionﬂow rate and mold temperature were analyzed.1.1.Morphology distribution in injection molded iPP parts:state of the artFrom many experimental observations,it is shown that a highly oriented lamellar crystallite microstructure, usually referred to as‘skin layer’forms close to the surface of injection molded articles of semi-crystalline polymers.Far from the wall,the melt is allowed to crystallize three dimensionally to form spherulitic structures.Relative dimensions and morphology of both skin and core layers are dependent on local thermo-mechanical history,which is characterized on the surface by high stress levels,decreasing to very small values toward the core region.As a result,the skin and the core reveal distinct characteristics across the thickness and also along theﬂow path[1].Structural and morphological characterization of the injection molded polypropylene has attracted the interest of researchers in the past three decades.In the early seventies,Kantz et al.[2]studied the morphology of injection molded iPP tensile bars by using optical microscopy and X-ray diffraction.The microscopic results revealed the presence of three distinct crystalline zones on the cross-section:a highly oriented non-spherulitic skin;a shear zone with molecular chains oriented essentially parallel to the injection direction;a spherulitic core with essentially no preferred orientation.The X-ray diffraction studies indicated that the skin layer contains biaxially oriented crystallites due to the biaxial extensionalﬂow at theﬂow front.A similar multilayered morphology was also reported by Menges et al.[3].Later on,Fujiyama et al.[4] investigated the skin–core morphology of injection molded iPP samples using X-ray Small and Wide Angle Scattering techniques,and suggested that the shear region contains shish–kebab structures.The same shish–kebab structure was observed by Wenig and Herzog in the shear region of their molded samples[5].A similar investigation was conducted by Titomanlio and co-workers[6],who analyzed the morphology distribution in injection moldings of iPP. They observed a skin–core morphology distribution with an isotropic spherulitic core,a skin layer characterized by aﬁne crystalline structure and an intermediate layer appearing as a dark band in crossed polarized light,this layer being characterized by high crystallinity.Kalay and Bevis[7]pointed out that,although iPP crystallizes essentially in the a-form,a small amount of b-form can be found in the skin layer and in the shear region.The amount of b-form was found to increase by effect of high shear rates[8].A wide analysis on the effect of processing conditions on the morphology of injection molded iPP was conducted by Viana et al.[9]and,more recently, by Mendoza et al.[10].In particular,Mendoza et al. report that the highest level of crystallinity orientation is found inside the shear zone and that a high level of orientation was also found in the skin layer,with an orientation angle tilted toward the core.It is rather difﬁcult to theoretically establish the relationship between the observed microstructure and processing conditions.Indeed,a model of the injection molding process able to predict morphology distribution in theﬁnal samples is not yet available,even if it would be of enormous strategic importance.This is mainly because a complete understanding of crystallization kinetics in processing conditions(high cooling rates and pressures,strong and complexﬂowﬁelds)has not yet been reached.In this section,the most relevant aspects for process modeling and morphology development are identiﬁed. In particular,a successful path leading to a reliable description of morphology evolution during polymer processing should necessarily pass through:–a good description of morphology evolution under quiescent conditions(accounting all competing crystallization processes),including the range of cooling rates characteristic of processing operations (from1to10008C/s);R.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221189–a description capturing the main features of melt morphology(orientation and stretch)evolution under processing conditions;–a good coupling of the two(quiescent crystallization and orientation)in order to capture the effect of crystallinity on viscosity and the effect ofﬂow on crystallization kinetics.The points listed above outline the strategy to be followed in order to achieve the basic understanding for a satisfactory description of morphology evolution during all polymer processing operations.In the following,the state of art for each of those points will be analyzed in a dedicated section.1.1.1.Modeling of the injection molding processTheﬁrst step in the prediction of the morphology distribution within injection moldings is obviously the thermo-mechanical simulation of the process.Much of the efforts in the past were focused on the prediction of pressure and temperature evolution during the process and on the prediction of the melt front advancement [11–15].The simulation of injection molding involves the simultaneous solution of the mass,energy and momentum balance equations.Theﬂuid is non-New-tonian(and viscoelastic)with all parameters dependent upon temperature,pressure,crystallinity,which are all function of pressibility cannot be neglected as theﬂow during the packing/holding step is determined by density changes due to temperature, pressure and crystallinity evolution.Indeed,apart from some attempts to introduce a full 3D approach[16–19],the analysis is currently still often restricted to the Hele–Shaw(or thinﬁlm) approximation,which is warranted by the fact that most injection molded parts have the characteristic of being thin.Furthermore,it is recognized that the viscoelastic behavior of the polymer only marginally inﬂuences theﬂow kinematics[20–22]thus the melt is normally considered as a non-Newtonian viscousﬂuid for the description of pressure and velocity gradients evolution.Some examples of adopting a viscoelastic constitutive equation in the momentum balance equations are found in the literature[23],but the improvements in accuracy do not justify a considerable extension of computational effort.It has to be mentioned that the analysis of some features of kinematics and temperature gradients affecting the description of morphology need a more accurate description with respect to the analysis of pressure distributions.Some aspects of the process which were often neglected and may have a critical importance are the description of the heat transfer at polymer–mold interface[24–26]and of the effect of mold deformation[24,27,28].Another aspect of particular interest to the develop-ment of morphology is the fountainﬂow[29–32], which is often neglected being restricted to a rather small region at theﬂow front and close to the mold walls.1.1.2.Modeling of the crystallization kineticsIt is obvious that the description of crystallization kinetics is necessary if theﬁnal morphology of the molded object wants to be described.Also,the development of a crystalline degree during the process inﬂuences the evolution of all material properties like density and,above all,viscosity(see below).Further-more,crystallization kinetics enters explicitly in the generation term of the energy balance,through the latent heat of crystallization[26,33].It is therefore clear that the crystallinity degree is not only a result of simulation but also(and above all)a phenomenon to be kept into account in each step of process modeling.In spite of its dramatic inﬂuence on the process,the efforts to simulate the injection molding of semi-crystalline polymers are crude in most of the commercial software for processing simulation and rather scarce in the ﬂeur and Kamal[34],Papatanasiu[35], Titomanlio et al.[15],Han and Wang[36],Ito et al.[37],Manzione[38],Guo and Isayev[26],and Hieber [25]adopted the following equation(Kolmogoroff–Avrami–Evans,KAE)to predict the development of crystallinityd xd tZð1K xÞd d cd t(1)where x is the relative degree of crystallization;d c is the undisturbed volume fraction of the crystals(if no impingement would occur).A signiﬁcant improvement in the prediction of crystallinity development was introduced by Titoman-lio and co-workers[39]who kept into account the possibility of the formation of different crystalline phases.This was done by assuming a parallel of several non-interacting kinetic processes competing for the available amorphous volume.The evolution of each phase can thus be described byd x id tZð1K xÞd d c id t(2)where the subscript i stands for a particular phase,x i is the relative degree of crystallization,x ZPix i and d c iR.Pantani et al./Prog.Polym.Sci.30(2005)1185–1222 1190is the expectancy of volume fraction of each phase if no impingement would occur.Eq.(2)assumes that,for each phase,the probability of the fraction increase of a single crystalline phase is simply the product of the rate of growth of the corresponding undisturbed volume fraction and of the amount of available amorphous fraction.By summing up the phase evolution equations of all phases(Eq.(2))over the index i,and solving the resulting differential equation,one simply obtainsxðtÞZ1K exp½K d cðtÞ (3)where d c Z Pid c i and Eq.(1)is recovered.It was shown by Coccorullo et al.[40]with reference to an iPP,that the description of the kinetic competition between phases is crucial to a reliable prediction of solidiﬁed structures:indeed,it is not possible to describe iPP crystallization kinetics in the range of cooling rates of interest for processing(i.e.up to several hundreds of8C/s)if the mesomorphic phase is neglected:in the cooling rate range10–1008C/s, spherulite crystals in the a-phase are overcome by the formation of the mesophase.Furthermore,it has been found that in some conditions(mainly at pressures higher than100MPa,and low cooling rates),the g-phase can also form[41].In spite of this,the presence of different crystalline phases is usually neglected in the literature,essentially because the range of cooling rates investigated for characterization falls in the DSC range (well lower than typical cooling rates of interest for the process)and only one crystalline phase is formed for iPP at low cooling rates.It has to be noticed that for iPP,which presents a T g well lower than ambient temperature,high values of crystallinity degree are always found in solids which passed through ambient temperature,and the cooling rate can only determine which crystalline phase forms, roughly a-phase at low cooling rates(below about 508C/s)and mesomorphic phase at higher cooling rates.The most widespread approach to the description of kinetic constant is the isokinetic approach introduced by Nakamura et al.According to this model,d c in Eq.(1)is calculated asd cðtÞZ ln2ðt0KðTðsÞÞd s2 435n(4)where K is the kinetic constant and n is the so-called Avrami index.When introduced as in Eq.(4),the reciprocal of the kinetic constant is a characteristic time for crystallization,namely the crystallization half-time, t05.If a polymer is cooled through the crystallization temperature,crystallization takes place at the tempera-ture at which crystallization half-time is of the order of characteristic cooling time t q deﬁned ast q Z D T=q(5) where q is the cooling rate and D T is a temperature interval over which the crystallization kinetic constant changes of at least one order of magnitude.The temperature dependence of the kinetic constant is modeled using some analytical function which,in the simplest approach,is described by a Gaussian shaped curve:KðTÞZ K0exp K4ln2ðT K T maxÞ2D2(6)The following Hoffman–Lauritzen expression[42] is also commonly adopted:K½TðtÞ Z K0exp KUÃR$ðTðtÞK T NÞ!exp KKÃ$ðTðtÞC T mÞ2TðtÞ2$ðT m K TðtÞÞð7ÞBoth equations describe a bell shaped curve with a maximum which for Eq.(6)is located at T Z T max and for Eq.(7)lies at a temperature between T m(the melting temperature)and T N(which is classically assumed to be 308C below the glass transition temperature).Accord-ing to Eq.(7),the kinetic constant is exactly zero at T Z T m and at T Z T N,whereas Eq.(6)describes a reduction of several orders of magnitude when the temperature departs from T max of a value higher than2D.It is worth mentioning that only three parameters are needed for Eq.(6),whereas Eq.(7)needs the deﬁnition ofﬁve parameters.Some authors[43,44]couple the above equations with the so-called‘induction time’,which can be deﬁned as the time the crystallization process starts, when the temperature is below the equilibrium melting temperature.It is normally described as[45]Dt indDtZðT0m K TÞat m(8)where t m,T0m and a are material constants.It should be mentioned that it has been found[46,47]that there is no need to explicitly incorporate an induction time when the modeling is based upon the KAE equation(Eq.(1)).1.1.3.Modeling of the morphology evolutionDespite of the fact that the approaches based on Eq.(4)do represent a signiﬁcant step toward the descriptionR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221191of morphology,it has often been pointed out in the literature that the isokinetic approach on which Nakamura’s equation (Eq.(4))is based does not describe details of structure formation [48].For instance,the well-known experience that,with many polymers,the number of spherulites in the ﬁnal solid sample increases strongly with increasing cooling rate,is indeed not taken into account by this approach.Furthermore,Eq.(4)describes an increase of crystal-linity (at constant temperature)depending only on the current value of crystallinity degree itself,whereas it is expected that the crystallization rate should depend also on the number of crystalline entities present in the material.These limits are overcome by considering the crystallization phenomenon as the consequence of nucleation and growth.Kolmogoroff’s model [49],which describes crystallinity evolution accounting of the number of nuclei per unit volume and spherulitic growth rate can then be applied.In this case,d c in Eq.(1)is described asd ðt ÞZ C m ðt 0d N ðs Þd s$ðt sG ðu Þd u 2435nd s (9)where C m is a shape factor (C 3Z 4/3p ,for spherical growth),G (T (t ))is the linear growth rate,and N (T (t ))is the nucleation density.The following Hoffman–Lauritzen expression is normally adopted for the growth rateG ½T ðt Þ Z G 0exp KUR $ðT ðt ÞK T N Þ!exp K K g $ðT ðt ÞC T m Þ2T ðt Þ2$ðT m K T ðt ÞÞð10ÞEqs.(7)and (10)have the same form,however the values of the constants are different.The nucleation mechanism can be either homo-geneous or heterogeneous.In the case of heterogeneous nucleation,two equations are reported in the literature,both describing the nucleation density as a function of temperature [37,50]:N ðT ðt ÞÞZ N 0exp ½j $ðT m K T ðt ÞÞ (11)N ðT ðt ÞÞZ N 0exp K 3$T mT ðt ÞðT m K T ðt ÞÞ(12)In the case of homogeneous nucleation,the nucleation rate rather than the nucleation density is function of temperature,and a Hoffman–Lauritzen expression isadoptedd N ðT ðt ÞÞd t Z N 0exp K C 1ðT ðt ÞK T N Þ!exp KC 2$ðT ðt ÞC T m ÞT ðt Þ$ðT m K T ðt ÞÞð13ÞConcentration of nucleating particles is usually quite signiﬁcant in commercial polymers,and thus hetero-geneous nucleation becomes the dominant mechanism.When Kolmogoroff’s approach is followed,the number N a of active nuclei at the end of the crystal-lization process can be calculated as [48]N a ;final Zðt final 0d N ½T ðs Þd sð1K x ðs ÞÞd s (14)and the average dimension of crystalline structures can be attained by geometrical considerations.Pantani et al.[51]and Zuidema et al.[22]exploited this method to describe the distribution of crystallinity and the ﬁnal average radius of the spherulites in injection moldings of polypropylene;in particular,they adopted the following equationR Z ﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃ3x a ;final 4p N a ;final 3s (15)A different approach is also present in the literature,somehow halfway between Nakamura’s and Kolmo-goroff’s models:the growth rate (G )and the kinetic constant (K )are described independently,and the number of active nuclei (and consequently the average dimensions of crystalline entities)can be obtained by coupling Eqs.(4)and (9)asN a ðT ÞZ 3ln 24p K ðT ÞG ðT Þ 3(16)where heterogeneous nucleation and spherical growth is assumed (Avrami’s index Z 3).Guo et al.[43]adopted this approach to describe the dimensions of spherulites in injection moldings of polypropylene.1.1.4.Modeling of the effect of crystallinity on rheology As mentioned above,crystallization has a dramatic inﬂuence on material viscosity.This phenomenon must obviously be taken into account and,indeed,the solidiﬁcation of a semi-crystalline material is essen-tially caused by crystallization rather than by tempera-ture in normal processing conditions.Despite of the importance of the subject,the relevant literature on the effect of crystallinity on viscosity isR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221192rather scarce.This might be due to the difﬁculties in measuring simultaneously rheological properties and crystallinity evolution during the same tests.Apart from some attempts to obtain simultaneous measure-ments of crystallinity and viscosity by special setups [52,53],more often viscosity and crystallinity are measured during separate tests having the same thermal history,thus greatly simplifying the experimental approach.Nevertheless,very few works can be retrieved in the literature in which(shear or complex) viscosity can be somehow linked to a crystallinity development.This is the case of Winter and co-workers [54],Vleeshouwers and Meijer[55](crystallinity evolution can be drawn from Swartjes[56]),Boutahar et al.[57],Titomanlio et al.[15],Han and Wang[36], Floudas et al.[58],Wassner and Maier[59],Pantani et al.[60],Pogodina et al.[61],Acierno and Grizzuti[62].All the authors essentially agree that melt viscosity experiences an abrupt increase when crystallinity degree reaches a certain‘critical’value,x c[15]. However,little agreement is found in the literature on the value of this critical crystallinity degree:assuming that x c is reached when the viscosity increases of one order of magnitude with respect to the molten state,it is found in the literature that,for iPP,x c ranges from a value of a few percent[15,62,60,58]up to values of20–30%[58,61]or even higher than40%[59,54,57].Some studies are also reported on the secondary effects of relevant variables such as temperature or shear rate(or frequency)on the dependence of crystallinity on viscosity.As for the effect of temperature,Titomanlio[15]found for an iPP that the increase of viscosity for the same crystallinity degree was higher at lower temperatures,whereas Winter[63] reports the opposite trend for a thermoplastic elasto-meric polypropylene.As for the effect of shear rate,a general agreement is found in the literature that the increase of viscosity for the same crystallinity degree is lower at higher deformation rates[62,61,57].Essentially,the equations adopted to describe the effect of crystallinity on viscosity of polymers can be grouped into two main categories:–equations based on suspensions theories(for a review,see[64]or[65]);–empirical equations.Some of the equations adopted in the literature with regard to polymer processing are summarized in Table1.Apart from Eq.(17)adopted by Katayama and Yoon [66],all equations predict a sharp increase of viscosity on increasing crystallinity,sometimes reaching inﬁnite (Eqs.(18)and(21)).All authors consider that the relevant variable is the volume occupied by crystalline entities(i.e.x),even if the dimensions of the crystals should reasonably have an effect.1.1.5.Modeling of the molecular orientationOne of the most challenging problems to present day polymer science regards the reliable prediction of molecular orientation during transformation processes. Indeed,although pressure and velocity distribution during injection molding can be satisfactorily described by viscous models,details of the viscoelastic nature of the polymer need to be accounted for in the descriptionTable1List of the most used equations to describe the effect of crystallinity on viscosityEquation Author Derivation Parameters h=h0Z1C a0x(17)Katayama[66]Suspensions a Z99h=h0Z1=ðx K x cÞa0(18)Ziabicki[67]Empirical x c Z0.1h=h0Z1C a1expðK a2=x a3Þ(19)Titomanlio[15],also adopted byGuo[68]and Hieber[25]Empiricalh=h0Z expða1x a2Þ(20)Shimizu[69],also adopted byZuidema[22]and Hieber[25]Empiricalh=h0Z1Cðx=a1Þa2=ð1Kðx=a1Þa2Þ(21)Tanner[70]Empirical,basedon suspensionsa1Z0.44for compact crystallitesa1Z0.68for spherical crystallitesh=h0Z expða1x C a2x2Þ(22)Han[36]Empiricalh=h0Z1C a1x C a2x2(23)Tanner[71]Empirical a1Z0.54,a2Z4,x!0.4h=h0Zð1K x=a0ÞK2(24)Metzner[65],also adopted byTanner[70]Suspensions a Z0.68for smooth spheresR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221193。

水下偏振成像技术英文文章

水下偏振成像技术英文文章Underwater Polarized Imaging TechnologyPolarized imaging is a powerful technique that has gained significant attention in the field of underwater imaging and sensing. This technology leverages the unique properties of light to extract valuable information about the underwater environment, enabling a wide range of applications, from marine biology and oceanography to underwater navigation and object detection.At its core, polarized imaging relies on the fact that light interacts differently with various materials and surfaces, depending on its polarization state. When light travels through water, it can become partially polarized due to scattering and other optical phenomena. By analyzing the polarization characteristics of the reflected or transmitted light, researchers and engineers can gain insights into the properties of the underwater objects or environments.One of the primary advantages of polarized imaging in the underwater domain is its ability to enhance contrast and visibility. In turbid or murky waters, the scattering of light can significantly degrade the quality of traditional imaging systems, making it difficultto distinguish between objects and the background. Polarized imaging, however, can effectively reduce the effects of this scattering, allowing for clearer and more detailed images to be captured.This is achieved by exploiting the fact that the scattered light tendsto have a different polarization state than the light reflected from the objects of interest. By using specialized optical filters or polarizers, the imaging system can selectively capture the light with the desired polarization, effectively suppressing the scattered light and enhancing the contrast of the target objects.Another key application of polarized imaging in the underwater environment is the detection and identification of submerged objects. The unique polarization signatures of different materials and surfaces can be used as a fingerprint to distinguish between various objects, such as mines, shipwrecks, or marine life. This information can be valuable for a wide range of applications, from military and security operations to marine conservation and exploration.In addition to object detection, polarized imaging has also found applications in the field of underwater navigation and guidance. By analyzing the polarization patterns of the light reflected from the seafloor or other underwater features, autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) can navigate more effectively, even in low-visibility conditions.The development of polarized imaging technology for underwater applications has been an active area of research and innovation. Researchers have explored various techniques, such as the use of liquid crystal variable retarders, Stokes polarimeters, and Mueller matrix imaging, to capture and analyze the polarization state of the light in the underwater environment.One particularly promising area of research is the integration of polarized imaging with other sensing modalities, such as sonar or laser imaging. By combining these technologies, researchers can create more comprehensive and robust underwater imaging and sensing systems, capable of providing a more complete understanding of the underwater environment.Despite the significant progress made in this field, there are still several challenges that need to be addressed. For example, the development of compact, cost-effective, and reliable polarized imaging systems that can withstand the harsh underwater conditions is an ongoing area of research. Additionally, the interpretation and analysis of the complex polarization data collected by these systems require advanced signal processing and machine learning algorithms, which continue to be an active area of investigation.In conclusion, underwater polarized imaging technology is apowerful tool that has the potential to revolutionize the way we interact with and explore the underwater world. By leveraging the unique properties of light, researchers and engineers can develop innovative solutions for a wide range of applications, from marine biology and oceanography to underwater navigation and object detection. As the field continues to evolve, we can expect to see even more exciting advancements in this technology, paving the way for a deeper understanding and better stewardship of our aquatic environments.。

全息照相的原理英语作文

全息照相的原理英语作文The principle of holographic photography is based on the interference pattern created by the interaction oflight waves. This pattern captures the three-dimensional information of an object, allowing us to reproduce a realistic and detailed image.Holographic photography uses a laser beam to illuminate the object and a photosensitive material to record the interference pattern. The laser light is coherent, meaning that all the light waves have the same frequency and phase, which is essential for creating a clear and sharp hologram.When the laser light reflects off the object, it combines with the reference beam to create an interference pattern on the photosensitive material. This pattern contains information about the object's shape, size, and texture, allowing us to reconstruct a lifelike image when the hologram is illuminated with laser light.Unlike traditional photography, holographic photography captures the complete wavefront of light, preserving both the intensity and phase information. This allows us to reproduce not only the appearance of the object but alsoits depth and spatial relationships, creating a truly realistic representation.One of the key advantages of holographic photography is its ability to capture and display three-dimensional images without the need for special glasses or viewing devices. This makes holograms an ideal tool for scientific research, medical imaging, and artistic expression, opening up new possibilities for visual communication and storytelling.In conclusion, holographic photography offers a unique and powerful way to capture and reproduce three-dimensional images with unparalleled realism and detail. By harnessing the principles of interference and wavefront reconstruction, holograms enable us to experience the world in a new and immersive way, pushing the boundaries of visual representation and storytelling.。

Polarization-difference imaging a biologically inspired technique for observation through scattering

608OPTICS LETTERS/Vol.20,No.6/March15,1995Polarization-difference imaging:a biologically inspired technique for observation through scattering mediaM.P.Rowe and E.N.Pugh,Jr.Institute of Neurological Sciences,University of Pennsylvania,Philadelphia,Pennsylvania19104J.S.Tyo and N.EnghetaMoore School of Electrical Engineering,University of Pennsylvania,Philadelphia,Pennsylvania19104Received August17,1994Many animals have visual systems that exploit the polarization of light,and some of these systems are thought tocompute difference signals in parallel from arrays of photoreceptors optimally tuned to orthogonal polarizations.We hypothesize that such polarization–difference systems can improve the visibility of objects in scattering mediaby serving as common-mode rejection amplifiers that reduce the effects of background scattering and amplifythe signal from targets whose polarization-difference magnitude is distinct from the background.We presentexperimental results obtained with a target in a highly scattering medium,demonstrating that a manmadepolarization-difference system can render readily visible surface features invisible to conventional imaging.Optical scattering by suspended particles(e.g.,fog,rain,plankton)diminishes the visual contrast ofobjects.1–3Although polarization-sensitive vision iswell documented as serving in navigation,1,4,5sometypes of polarization-sensitive vision also may serveto enhance the visibility of targets in scatteringmedia.6,7The goal of this Letter is to demonstratethat a manmade polarization-difference imaging(PDI)system,similar to that hypothesized to functionin some biological visual systems,7,8can enhance thevisibility of target features in a scattering medium.Our PDI system captures images of a scene at twoorthogonal linear polarizations,computes the differ-ence of the images pixel by pixel,and rescales theresultant difference image for optimum use of themonochrome display range.Symbolizing the two im-age intensity distributions as I k͑x,y͒and IЌ͑x,y͒,where͑x,y͒identifies the pixel position in the imageand k andЌindicate two orthogonal linear polar-izations,the PDI system generates the polarization-difference(PD)and polarization-sum(PS)images:PDI͑x,y͒෇I k͑x,y͒2IЌ͑x,y͒,(1a)PSI͑x,y͒෇I k͑x,y͒1IЌ͑x,y͒.(1b)If an ideal linear polarizer is used to measure I k andIЌ,then the PS image is equivalent to a polarization-blind image obtained by a conventional imaging sys-tem.In general,PD I depends on the choice of polar-ization axes,whereasPS I does not.The choice of theorthogonal axes will be discussed shortly.The experimental layout is shown in Fig.1.Two incandescent tungsten filament slide projectors backilluminate a sheet of0.64-cm-thick white Plex-iglas attached to a glass tank.The tank is filled with water to which milk is added.The Plexiglas acts as an initial diffuser and the milk as a strong scattering agent.The tank is viewed with a CCD camera(Hamamatsu Model XC-77)equipped with a macro lens(Vivitar Y/C55mm,f2.8).Images are digitized and processed by an image analysis system that has a16-bit frame buffer(accumulator) (Imaging Technology Series151).In the absence of a target,the region viewed by the camera has an average apparent radiance ofϳ7.2W͞(m2sr) uniform to within15%,and its light is essentially unpolarized.The target is an aluminum disk sus-pended in the middle of the tank by means of a rod attached to the back face of the disk,i.e.,the face hidden from the camera.The end of the rod not attached to the target disk is inserted into a clear Plexiglas mount suspended from above;the surface of this mount is perpendicular to the incident light, and both it and the rod are completely invisible to both PDI and conventional imaging.Except for two 1-cm2patches,the disk surface facing the camerais Fig.1.Top:the top view of the experimental setup. A,polarization analyzer;TNLC,twisted nematic liquid crystal;F,narrow-band filter.Bottom:the front view of the tank(drawn to scale)with inside dimensions of 30cm330cm315cm.This tank is filled with water to which5mL of whole milk is added.The measured beam attenuation coefficient for a632.8-nm laser beam is19.7m21.Thus the tank depth isϳ2.9attenuation lengths at this milk concentration.The sensitivity of the imaging system at610nm isϳ4.431027display units͞(quanta s21)(in8-bit display).0146-9592/95/060608-03$6.00/0©1995Optical Society of AmericaMarch15,1995/Vol.20,No.6/OPTICS LETTERS609sandblasted,rendering it nearly Lambertian.These patches,whose relative locations are shown in Fig.1, are a few thousandths of an inch higher than the sandblasted background and have been abraded with emory paper lightly in orthogonal directions—on one patch vertically,and on the other horizontally.The image-forming light from the target surface results from multiple scattering:photons scatter off milk particles to the target surface,and some of these are scattered again toward the camera.Before reaching the camera,the light from the tank passes through a twisted nematic liquid crystal(TNLC;Liquid Crystal Institute,Kent State University.)In its off state, the TNLC rotates the plane of polarization of inci-dent light by90±;when driven,the TNLC passes the incident light with no rotation.After the TNLC,the light passes through a linear polarization analyzer.A narrow-band filter(10nm FWHM,centered at 610nm)eliminates light outside the operating wave-band of the TNLC.When the TNLC is driven,the TNLC͞analyzer passes only light polarized parallel to the analyzer axis,yielding the image I k;when the TNLC is off,the TNLC͞analyzer combination passes light polarized perpendicular to the analyzer axis,yielding IЌ.For the results reported here,the analyzer axis was oriented vertically.Figure2illustrates the application of the PDI sys-tem to the imaging of the aluminum target suspended in diluted milk.Figures2A and2B present the im-ages,I k and IЌ,convolved with a two-dimensional (low-pass)filter.To generate Figs.2A and2B,we summed128consecutive33-ms frames and then di-vided by8.Figures2C and2D presentPSI andPDI, respectively,the sum and difference images.Fig-ures2E and2F re-present the data in images in Figs.2C and2D transformed with affine transfor-mations to use the full intensity range of the dis-play.The abraded patches,which are not visible in Figs.2A–2D,are clearly visible in the transformed PD image(Fig.2F)but practically invisible in the transformed PS image(Fig.2E).Figures2A0–2F0 present numerical plots of average pixel intensities in the pixel region y1#y#y2,as illustrated by the ar-rows shown in Figs.2B,2D,and2F;these plots pro-vide quantitative evidence that supports the qualita-tive conclusion drawn from inspection of the images. The principal factor underlying the enhanced visibility of the two patches in Panel F isthe Fig.2.Application of the PDI system to an aluminum target suspended in diluted milk as illustrated in Fig.1.A,B,The images I k͑x,y͒and IЌ͑x,y͒convolved digitally with a two-dimensional low-pass spatial filter.This filter is roughly a truncated Gaussian,with maximal linear extentϳ5pixel widths;the images of the abraded patches are ഠ80392pixels.The filter removes a periodic high-spatial-frequency artifact produced by the imaging system.Image intensities(ordinates)are expressed in the units of the8-bit display.C,D,PS I͑x,y͒͞2and PD I͑x,y͒1128,respectively [cf.Eqs.(1a)and(1b)];an offset of128was used,because most pixel values of PD I͑x,y͒are near zero and can be positive or negative.E,F,The data of C and D,respectively,but transformed with affine transformations.The transformed values are given by PS I͑x,y͒trans෇a PS͓PS I͑x,y͒2PS I͑x,y͒min͔and by PD I͑x,y͒trans෇a PD͓PD I͑x,y͒2PD I͑x,y͒min͔,where a PS෇255͓͞PS I͑x,y͒max2PS I͑x,y͒min͔,and similarly for a PD.In E,PS I͑x,y͒max and PS I͑x,y͒min were obtained from the disk region only;the resultant scale factor,a PSഠ6.4,is such that the intensity variation of the disk region occupies the full display range.In F,PD I͑x,y͒max and PD I͑x,y͒min were obtained from the entire image,yielding a PDഠ38.4. Abraded patches,not visible in A–D,are clearly visible in F but practically invisible in E.The vertical bands of pixels in the pixel regions y1#y#y2,as shown by the arrows at the right of panels B,D,and F,were averaged over y to generate numerical plots(as a function of x)shown in A0–F0.610OPTICS LETTERS /Vol.20,No.6/March 15,1995common-mode rejection feature intrinsic to PDI.Given that a target feature may produce a nonzero value of PD I in some region of the image,the system permits extraction of this feature by rejecting intensity common to both polarization axes.This common-mode rejection feature of the PDI system is exhibited in two ways in the images of Fig.2.First,the relatively intense halo of unpolarized light surrounding the disk is eliminated from the PD im-age (cf.Figs.2C 0and 2D 0).Second,the effect of the relatively modest variation (ϳ20%of total display range)across the disk surface is also minimized.This modest intensity variation masks the visibility of the target features in the PS image,and its rejection allows a higher gain to be applied to the PD image than to the PS image (cf.Figs.2E 0and 2F 0).On the basis of the results shown in Fig.2and other data we have obtained,PDI has a gen-eral applicability.First,PDI is quite sensitive to intrinsically small signals.For a particular region of an image,the observed degree of lin-ear polarization (ODLP),defined as ͗ODLP ͘region ෇͗PD I ͑x ,y ͒͘region ͗͞PS I ͑x ,y ͒͘region ,serves as a dimension-less measure of the PD signal magnitude.For the left patch,͗ODLP ͘෇10.0164;for the right patch,͗ODLP ͘෇20.0138.Moreover,in experiments in which we have systematically raised the milk con-centration to degrade the images until the target patches are undetectable,target patches having ͗ODLP ͘&0.01still could be readily seen on in-spection of the PD image (data not shown).The images of many object surfaces in natural environ-ments predictably will have ODLP’s of considerably higher magnitude.9Second,PDI can be generalized readily to scattering environments in which the back-ground itself has nonzero PD I ͑x ,y ͒for a given set of orthogonal polarization axes.Judicious orientation of the analyzer in the PDI system can enhance the PD I of target regions relative to that of the background in the image plane.10Finally,PDI possesses the generally useful qualities of being passive,simple,and potentially very fast.PDI can operate passively in any region of the electromagnetic spectrum in which natural radiation exists.PDI is simple,in that it does not require the use of sophisticated im-age processing techniques;nevertheless,any image processing techniques can be added to,or used in par-allel with,PDI to make it even more effective.PDI is also potentially very fast.In our current setup,it takes 4–5s to obtain each of I k and I Ќ,but this rate limitation is imposed by the low light levels achiev-able with monochromatic light and by the frame rate (30Hz)and limited sensitivity of our imaging sys-tem.With a more-sophisticated system,a higher speed could be achieved with a successive-frame dif-ferencing technique.Furthermore,PDI also can be made very much faster by implementation in a mas-sively parallel system,as nature appears to have done in the retinas of many animals.7,8Other optical imaging techniques also employ po-larization information.3,11–17However,in some of this work,the state of polarization of the illumi-nating light has been known and is typically un-der the experimenters’control.3,11,12In contrast,in PDI the light incident on the target does not have to be polarized,nor need its state of polarization be known or under the control of the imaging system.In other related work 13–17in which there is no con-trol over the polarization of illuminating light either the Stokes parameters have been mapped onto col-orimetric coordinates 13,17or PD I ͑x ,y ͒͞PS I ͑x ,y ͒14–16or some form of percent polarization and polarization angle 16,17has been mapped onto the z axis of a mono-chrome display.Mapping PD I ͑x ,y ͒͞PS I ͑x ,y ͒onto in-tensity confounds the common mode with the signal.In contrast,our technique removes the common mode and allows us to maximize the display of informa-tion that survives the common-mode rejection.The variation and magnitude of PD I are usually less than the variation and magnitude of PS I across the scene.Thus,to use the full dynamic range of a display,higher amplification can be applied to PD I and thus some of the target features not visible to polarization-blind imaging can be observed with PDI.This work is supported by U.S.Department of the Navy Office of Naval Research grant N00014-93-1-0935and,in part,by the University of Pennsylvania Research Foundation.References1.J.N.Lythgoe,The Ecology of Vision (Oxford U.Press,London,1979),pp.112–127.2.S.Q.Duntley,J.Opt.Soc.Am.53,214(1963).3.S.Q.Duntley,in Optical Aspects of Oceanography,N.G.Jerlov and E.Steemann Nielsen,eds.(Academic,New York,1974),pp.135–149.4.K.von Frisch,Experientia 5,142(1949).5.T.H.Waterman,in Vision in Invertebrates,H.Autrum,ed.,Vol.VII/6B of the Handbook of Sen-sory Physiology (Springer-Verlag,New York,1981),pp.281–469.6.J.N.Lythgoe and C.C.Hemmings,Nature (London)213,893(1967).7.D.A.Cameron and E.N.Pugh,Jr.,Nature (London)353,161(1991).8.M.P.Rowe,N.Engheta,S.S.Easter,Jr.,and E.N.Pugh,Jr.,J.Opt.Soc.Am.A 11,55(1994).9.G.P.K¨o nnen,Polarized Light in Nature (Cambridge U.Press,London,1985),pp.74–99.10.J.S.Tyo,University of Pennsylvania,Philadelphia,Pa.(undergraduate senior design project,1994).11.G. D.Gilbert and J. C.Pernicka,in Underwa-ter Photo-Optics,Seminar Proceedings (Society of Photo-Optical Instrumentation Engineers,Belling-ham,Wash.,1966),p.AIII-1.12.B.A.Swartz and J.D.Cummings,Proc.Soc.Photo-Opt.Instrum.Eng.1537,42(1991).13.J.E.Solomon,Appl.Opt.,20,1537(1981).14.G.F.J.Garlick,G.A.Steigmann,and mb,U.S.patent 3,992,571(November 16,1976).15.W.G.Egan,W.R.Johnson,and V.S.Whitehead,Appl.Opt.30,435(1991).16.J.Halajian and H.Hallock,in Proceedings of 8th Sym-posium on Remote Sensing and Environment 1(Envi-ronmental Research Institute of Michigan,Ann Arbor,Mich.,1972),p.523.17.R.Walraven,Proc.Soc.Photo-Opt.Instrum.Eng.112,164(1977).。

冷原子光谱法英语

冷原子光谱法英语Okay, here's a piece of writing on cold atom spectroscopy in an informal, conversational, and varied English style:Hey, you know what's fascinating? Cold atom spectroscopy! It's this crazy technique where you chill atoms down to near absolute zero and study their light emissions. It's like you're looking at the universe in a whole new way.Just imagine, you've got these tiny particles, frozen in place almost, and they're still putting out this beautiful light. It's kind of like looking at a fireworks display in a snow globe. The colors and patterns are incredible.The thing about cold atoms is that they're so slow-moving, it's easier to measure their properties. You can get really precise data on things like energy levels andtransitions. It's like having a super-high-resolution microscope for the quantum world.So, why do we bother with all this? Well, it turns out that cold atom spectroscopy has tons of applications. From building better sensors to understanding the fundamental laws of nature, it's a powerful tool. It's like having a key that unlocks secrets of the universe.And the coolest part? It's just so darn cool! I mean, chilling atoms to near absolute zero? That's crazy science fiction stuff, right?。

成像技术英文作文

成像技术英文作文英文：Imaging technology has revolutionized the way we see and understand the world around us. From medical imaging to satellite imagery, there are a wide range of applications for imaging technology. In this essay, I will discuss the different types of imaging technology and their uses.One of the most common types of imaging technology is X-ray imaging. This technology is used in medical imaging to see inside the human body. X-rays are able to penetrate soft tissue and bone, allowing doctors to see inside the body and diagnose medical conditions. Another type of medical imaging is magnetic resonance imaging (MRI). This technology uses magnetic fields to create detailed images of the body's internal structures. MRIs are often used to diagnose conditions such as tumors, infections, and injuries.In addition to medical imaging, there are also manyother applications for imaging technology. For example, satellite imagery is used to monitor weather patterns and track natural disasters. This technology is also used in agriculture to monitor crop growth and identify areas that need more water or fertilizer. Another application of imaging technology is in the field of art conservation. Imaging technology can be used to analyze paintings and identify areas of damage or deterioration.Overall, imaging technology has had a significantimpact on many different fields. From medicine toagriculture to art conservation, there are a wide range of applications for this technology.中文：成像技术已经彻底改变了我们看待和理解周围世界的方式。

光的衍射英语作文

光的衍射英语作文如下：Title: The Phenomenon of Light DiffractionLight diffraction is a fascinating optical phenomenon that has captivated scientists and laypeople alike for centuries. At its core, diffraction refers to the bending of light waves around an obstacle or through an aperture, resulting in a deviation from the expected straight-line path. This intriguing behavior of light not only challenges our intuitive understanding of how light should behave but also plays a crucial role in various applications, from fiber optics to medical imaging.To delve into the world of light diffraction, it's essential to grasp the basic principles of wave optics. Light, as described by the wave theory, consists of oscillating electromagnetic fields that travel in waves. When these waves encounter an obstacle or aperture whose dimensions are comparable to the wavelength of light, they cannot maintain their original direction of propagation. Instead, they spread out and interfere with one another, leading to the characteristic patterns associated with diffraction, such as the bright and dark bands observed in diffraction gratings.One classic experiment that demonstrates light diffraction is the double-slit experiment. Here, a beam of light is directed towards a screen with two closely spaced slits. Rather than producing two distinct lines on the screen, corresponding to each slit, the result is a series of alternating light and dark bands. This pattern arises because the waves passing through each slit interfere with one another, constructively in the bright bands and destructively in the dark ones.The mathematical description of diffraction involves complex wave equations, which can be solved using techniques from physics and mathematics. These solutions allow us to predict the intensity distribution of light after diffraction and have been instrumental in the design of optical instruments such as telescopes and microscopes. Moreover, the principles of diffraction have found application in technologies like holography, where interference patterns are used to reconstruct three-dimensional images.Despite its utility, light diffraction also presents challenges in certain contexts, such as in the resolution limits of optical systems. The diffractive spreading of light can blur images, making it difficult to achieve high resolution in imaging devices. However, by understanding and manipulating diffraction effects, scientists have developed methods to enhance image quality, such as phase-contrast microscopy and adaptive optics.In conclusion, light diffraction is a profound natural phenomenon that reveals the wave-like nature of light and has significant implications for both pure science and technological innovation. Its study has led to a deeper understanding of the behavior of light and has inspired countless advancements in optics and photonics. As we continue to explore the properties of light and its interaction with matter, the concept of diffraction remains a cornerstone of modern physics, offering endless opportunities for discovery and application.。

离轴三反同时偏振成像仪光机设计

195 Hz,结构能够承受发射时严苛的力学环境，具备良好的强度和刚度。整机性能满足实际使用需
求。
关键词：离轴三反；偏振；光机设计；同时
中图分类号：V447+.1
文献标志码：A
DOI： 10.3788/IRLA201948.0518001
Optical design for simultaneous polarization imager based on off-axis three-mirror
Ling Mingchun1,2,3, Song Maoxin1,2*, Hong Jin1-2, Sun Xiaobing1,2, Tao Fei1,2,3
(1. Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; 2. University of Science and Technology of China, Hefei 230026, China;
3.中国科学院通用光学定标与表征技术重点研究室，安徽合肥230031)
摘要：基于离轴三反的前置望远系统，结合分振幅同时偏振成像技术，设计了一种运用于卫星平
台环境的高空间分辨率的同时偏振成像仪，能同时获取目标的斯托克斯偏振参数，为抑制海面耀
光、海雾、大气辐射等干扰，提升探测目标对比度提供了一种有效手段，在进行动态目标探测方面具
Email: hongjin@
0518001-1
第5期
红外与ห้องสมุดไป่ตู้光工程

第48卷
resolution was 5 m@500 km, the optical MTF was more than 0.4@71.4 lp/mm, and under the condition of an elevation angle of 30° and a reflectivity of 0.2, the noise ratio was better than 38 dB, the polarization measurement accuracy is better than l%(PW0.3), the first -order mode of the whole machine was 195 Hz, and it had good strength and stiffness. The overall performance meets the actual use requirements. Key words: off-axis three-mirror; polarization; optical design; simultaneous

Olympus dotSlide 在偏光模式下的使用说明书

Using Olympus dotSlide for polarising microscopyBackgroundBecause the dotSlide system is built using a conventional microscope frame it lends itself to acquiring scans in different imaging modes whose components can be added to the frame. Polarising microscopy can be performed by adding polarising filters below and above the sample.However, because the polarising image has a dark background, there can be are problems with camera exposure, with using automatic tissue content recognition and with generation of the focus map, especially if the crystalline features are rare events within the sample.The following is a generic approach which should work for most samples. It relies on setting a manual exposure time, acquiring the overview in bright field and then generating the focus map and scan in polarising modeMethod:Startup and initial setup∙Start system∙Start dotSlide software∙Perform the usual calibration of stage limits (XY and Z) and overview area∙Remove filter holder from nosepiece and replace with the analyser (with tint plate retracted (out))∙Place polariser (U-POT) on field diaphragm with lettering and notch to front∙Retract ND6 filter from stand (button out – only button in should be LBD (colour correction))∙Place sample on stage and focus using eyepieces∙Rotate polariser clockwise to extinction point (crossed polars) or whatever degree of polarisation you want –I suggest that the polariser isn’t set to full extinction so that the non tissue background is a bluey grey and non refractile tissue can still be seen.Calculate exposure∙Start live view∙Change to objective required for higher power scan∙Focus live view using wheel on joystick box∙Toggle camera exposure to manual exposure mode and adjust exposure to desired image intensity∙Rough guide for exposure (exact exposure will depend on how crossed the polars are): o x4 = 30-50 mso x10 = 30-50 mso x20 = 70-100 mso x40 = 250-400 ms∙Stop live view – leave exposure set on manual with desired exposure timeOverview scan∙Start expert mode∙Remove analyser by retracting it to click stop but leave polariser in place∙Do overview (in BF mode) –this won’t look perfect as the polariser gives a slight unevenness to the illuminationHigh power scan∙Select magnification∙Check “More Options” settings∙Select scan area – hopefully the tissue content algorithm will be able to see the stain and identify the tissue. Modify scan area options as required∙Check and edit focus map as required*∙Reinsert analyser (with tint plate out)∙Change to desired objective for high power scan∙In Stage Navigator window, click on an area of the sample within and near the bottom of your defined scan area∙Focus on the sample down the eyepieces using wheel on joystick box∙Autofocus∙Scan now – the scan will then be performed using the preset, manual exposure time* Generation of the focus map will only work if the camera can see sample content within each field of view being sampled - i.e. when there is a significant amount of refractile material within each field and /or when the polariser isn’t set to full extinction so that the non tissue background is a bluey grey and non refractile material can still be seen. If this isn’t the case then you will need to adopt the following strategy at the focus map stage:∙Keep the analyser out∙Set focus map to semi-automatic focussing∙Edit the focus map as desired∙Change to desired objective for high power scan∙In Stage Navigator window, click on an area of the sample within and near the bottom of your defined scan area∙Focus down the eyepieces∙Autofocus –if you get an “Images are too bright” message appear at bottom RHS of screen, reinsert one or both neutral density filters and try again.∙Then scan focus map with the ND filters in∙Once the focus map has been generated, the Review Focus Map window will appear and the interface will look like this:∙The top LH window is a live view. Check the proposed focus of this field of view. If you are happy with the focus, simply click the rightward blue arrow to accept the proposed focus and review the next position∙If unhappy with the focus, refine it using the focus wheel on the RHS of the joystick box, then click the rightward blue arrow to accept the refined focus and review the next position∙Once all of the focus positions have been reviewed, the rightward arrow is greyed out∙VERY IMPORTANT – (1) remove any inserted ND filters (2) Reinsert the analyser with the tint plate out∙Scan Now – the scan will proceed immediatelyAt end of sessionPlease return system to its normal, brightfield setup so as not to confuse the next user:∙reinsert ND8 filter∙remove polariser and analyser and return them to storage∙replace standard filter holder above the nosepiece。

脑炎影像表现英文版护理问答

Diffuse swelling
Diffuse swelling of the brain is also a common imaging finding in encephalitis. It manifests as increased signal intensity on MRI scans and can lead to brain herniation.
Focal lesions
Focal lesions are common in encephalitis and can occur in any part of the brain. They appear as areas of increased or decreased density on CT or MRI scans.
Differential diagnosis: A list of possible explanations for the observed imaging findings, considering various possible causes such as infection, inflammation, tumor, or trauma.
Imaging manifestations can provide valuable information on the prognosis of encephalitis. For example, the presence of cerebral edema or hydrocephalus can indicate a poor prognosis.
Fluid-attenuated inversion recovery (FLAIR)
A MRI sequence that is used to enhance the visualization of cerebrospinal fluid and brain parenchyma. It is particularly useful in the detection of small hemorrhages and microbleeds.

利用偏振特性因子的偏振成像目标探测实验

利用偏振特性因子的偏振成像目标探测实验曾恒亮;张孟伟;刘征;谢宗良【摘要】In order to enhance target-background contrast in target detection, we use micropolarizer camera providing a division of focal plane to obtain four polarization status images. Based on the polarization status images, the Stokes vectors, degree of linear polarization, angle of polarization and polarization parameterF are calculated. The result shows that, the degree of linear polarization enhances target-background contrast by a large margin, comparing with the origin intensity image, and the polarization parameter enhances the clearness and expands information content of the image, meanwhile keeps the advantage of the degree of linear polarization image.%为了提高目标探测中目标背景对比度，本文利用分焦平面的微偏振元相机同时获取目标四幅偏振状态图像，解算得到斯托克斯矢量，提取目标的偏振度和偏振角成像图像，并结合偏振特性因子F对偏振图像效果进行了改进。

结果表明：目标偏振度成像图像在原光强图像基础上能够增强目标背景对比度，偏振特性因子成像图像在保留偏振度成像图像增强目标背景对比度的优点的同时，能够提高图像清晰度，扩展图像信息。

太阳散射偏振研究进展

太阳散射偏振研究进展李昊;屈中权【摘要】太阳磁场的诊断对研究太阳物理有着重要的意义。

近几十年，许多科学家利用汉勒效应(Hanle effect)进行诊断弱磁场的研究。

而利用汉勒效应诊断弱磁场，需要对偏振的产生机制有一个完整的理解。

直到近年来，随着技术的发展，对偏振的测量精度达到10−5的ZIMPOL (Zurich Imaging Polarimeter)获得以斯托克斯参量Q/I 为表征的第二太阳光谱(second solar spectrum)，展现丰富的散射偏振特征，促进了偏振研究的蓬勃发展。

通过对第二太阳光谱的研究，使我们对偏振产生机制理解得更为透彻，从而使利用汉勒效应诊断弱磁场逐渐成为可能。

主要介绍了用量子电动力学为基础的密度矩阵来研究偏振光谱产生的物理过程，并简要介绍了近年有关在第二太阳光谱和汉勒效应研究的一些进展。

%The magnetic field plays a very important role in solar atmosphere. The diag-nostic of the strong magnetic field is usually based on Zeeman effect. When the magnetic field is so weak that Zeeman effect becomes less eﬃcient, Hanle effect can provide another diagnostic tool to diagnose the weak magnetic field. However this needs a complete un-derstanding of the polarization mechanisms. A series of International Solar Polarization Workshops (SPWs) which focus on probing the magnetic field have been held every three years since the first one in St.Petersberg, Russia, in 1995. As the high polarimetric precision <br> technology was applied by the ZIMPOL (Zurich Imaging Polarimeter), the so-called Second Solar Spectrum was observed and it shows a great amount of rich and complicated struc-tures of the linear polarization profiles. The linear polarized spectrum is a playgroundfor Hanle effect application in solar atmosphere. Through the efforts by a lot of scientists, the theories to treat the Hanle effect were developed, like the statistical equilibrium equations and radiative transfer equation in form of the density matrix. These theories have made great successes and solved many problems in the polarization profile formation, but they still face some diﬃculties. Here we review the basic theories in the scattering polarization to deal with the Second Solar Spectrum and Hanle effect, and describe the progressing in this area.【期刊名称】《天文学进展》【年(卷),期】2014(000)004【总页数】18页(P423-440)【关键词】太阳磁场;汉勒效应;偏振;谱线轮廓【作者】李昊;屈中权【作者单位】中国科学院云南天文台，昆明 650011; 中国科学院大学，北京100049;中国科学院云南天文台，昆明 650011【正文语种】中文【中图分类】P182.71 引言我们只能通过获取太阳发出的光子和粒子信息对其进行研究，其中光谱观测给我们提供了大量的信息，可以用来确定太阳中的元素丰度、密度、温度等。

热红外偏振成像技术在目标识别中的实验研究

第33卷第2期2007年3月光学技术OPT ICAL T ECHN IQU EVol.33No.2M ar. 2007文章编号:1002-1582(2007)02-0196-03热红外偏振成像技术在目标识别中的实验研究汪震,洪津,乔延利,王峰,杨伟锋(中国科学院安徽光学精密机械研究所遥感研究室,合肥 230031)摘要:简要分析了热红外偏振探测与热红外强度探测在物理含义方面的区别,由此提出了一种利用偏振信息在红外图像中识别目标的新方法。

通过热红外偏振成像系统获得了目标的偏振图像,并由计算机提取出了图像中的偏振信息。

由于目标与自然背景的热红外偏振特性有较大的差异,所以通过分析这些信息,可以更好的识别目标。

实验结果表明,该方法不仅可以很好地识别自然背景中的人造目标,而且对热红外伪装目标的识别也很有效。

关键词:光学测量;偏振;红外图像;成像偏振仪;目标识别中图分类号:O436.3;T N219 文献标识码:AStudy of thermal polarization imaging measurement in target recognitionWAN G Zhen,H ON G Jing,QIAO Yan _li,WAN G Feng,YAN G Wei_feng(Remote Sensing Laborator y,Anhui I nstitute of O ptics and Fine M echanics,Chinese Academy o f Science,Hefei 230031,China)Abstract:T he differences in physics between r emote sensing using t hermal polar ization of radiat ion and using intensity of radiatio n are analyzed.A nov el method that is applied to recog nize manmade targets with their polarization information in ther -mal images is presented.Polarizatio n images of targets ar e obtained by the thermal imaging polarimeter,and the polarizatio n in -for matio n of tar gets is ex tracted by computer.Because of the difference bet ween the polarization char acters of natural back -ground and manmade targets,these targets can be w ell recognized by means of analy zing the polarization information.T he ex -periments show that this method is effective in r ecognizing manmade targets and camouflaged targets from natur al background.Key words:optical measurement;polarization;thermal image;imag ing polarimeter;tar get recognition1 引言由传统的遥感方法获取的信息主要是电磁强度特征和几何特征。

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脑炎影像表现英文版护理问答

利用偏振特性因子的偏振成像目标探测实验

太阳散射偏振研究进展

热红外偏振成像技术在目标识别中的实验研究

冷原子光谱法英语