English summary

the point of incidence in a refractive process
obey the expression nsinI=n'sinI’ The incident ray, the refracted ray, and the surface normal are all coplanar.
Axial magnification (longitudinal magnification) is defined as the ratio of a short length, or depth, in the image measured along the axis, to the conjugate length in the object. In the air, it is equal to the square of the transverse magnification. Angular magnification (magnifying power)
Example: Shadows
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3. The Law of Reflection
A light ray striking a reflecting surface and reflected from it makes equal angles with the normal to the surface at the point of incidence, and the incoming ray, the outgoing ray, and the
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2. Law of Rectilinear propagation
Light as it advances through free space or
through homogeneous, isotropic matter
follows a beeline. (a direct straight course).
2. Principal points are the points where the
optical axis intersects principal planes. 3. Focal points (the first~, the second ~ / the object-side ~, the image-side ~)
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7. Key words and concept Image space extends from infinity on one side to infinity on the other. The same holds for the object space; both completely overlap. Whether a given point is in the object space or the image space depends on whether it is part of a ray before or after refraction. If a given point is in the object space, it is a point object, otherwise it is a point image.
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Homework
1. The object is a transparent cube, 4mm across, placed 60cm in front of a lens of 20cm focal length. Calculate the transverse and axial magnification and describe what the image looks like? P36-3&4 (P37-3&4)
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Keywords and concept 2. Theory of stops (This theory is discussing
about light limitation and proper diameter of optical elements in an optical system.
The total magnification of a combination of lenses is the product of the magnification of the individual lenses.
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Keywords and concept
5. Nodal points are where no refraction occurs. Whenever the refractive indices on either side of the lens are the same, the nodal points coincide with the principal points. If the refractive indices on the two sides of the lens are different, the N points would move away from the principal planes, toward the side of higher index.
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Keywords and concept
1. Lens is a combination of two surfaces
that enclose a medium of a refractive
index different from that outside thቤተ መጻሕፍቲ ባይዱ surfaces.
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Keywords and concept
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4. Focal length is the distance from the principal point to the focal point. 5. An on-axial point object at infinity and the second focal point are conjugate. P36-1 (P37-1)
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Keywords and concept 1. Stops are either the finite size of the lenses or additional diaphragms in optical system which limit the bundle of light passing through in cross section.
The chief ray goes through the principal point without deviation.
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Some Keywords and concept
2. Newton’s lens equation (x, x’ are called Newton’s extrafocal object and image distances, respectively )
3. Gauss’ equation
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Keywords and concept
4. Magnification
Transverse magnification (Lateral magnification) is defined as the ratio of image size, y', to object size, y.
2. Types of lenses
Converging or positive / Diverging or negative lenses Biconvex / Plano-convex / positive meniscus lens Biconcave / Plano-concave / Negative meniscus lens
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Key words and Concept
• The index of refraction, or refractive index, of any optical medium is defined as the ratio between the speed of light in a vacuum and the speed of light in the medium. • Optical path • The principle of Reversibility
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5. Total Internal Reflection
normal Incident ray Denser medium
Surface
Refracted ray
Critical angle
Rarer medium
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6. Fermat’ principle
Light takes the path that requires the least time.
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Some Keywords and concept
1. Principal planes are defined as the loci where
refraction is assumed to occur without
reference as to where it actually does occur.
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Some Keywords and concept
1. Graphical construction
Parallel ray Chief ray F Focal ray H H’ F’
The parallel ray is first parallel to the axis and then, after refraction passes through F’. The focal ray passes through F and then is rendered parallel to the axis.
English Summary
1. The electromagnetic spectrum
short Wave length Gamma Rays XRays Ultra violet V Infrared Micro -waves Radio -waves long
380nm 780nm
violet-blue deep-red
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Homework
1. In ancient times the rectilinear propagation of light was used to measure the height of objects by comparing the length of their shadows with the length of the shadow of an object of known length. A staff 2m long when held erect casts a shadow 3.4 m long, while a building’s shadow is 170 m long. How tall is the building? 2. Light from a water medium with n=1.33 is incident upon a water-glass interface at an angle of 45o . The glass index is 1.50. What angle does the light make with the normal in the glass? P12 4&9 (P13 4&15)
normal to the surface at the point of
intersection all lie in the same plane.
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4. The Law of Refraction
The angle made by the incident ray, that made by the refracted ray, and the surface normal at