Friends Specially Joan Mule

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Sergio Gonzalez
07/24/00 Evaluation of Bispectral Spectrophotometry for Accurate Colorimetry of Printing Materials
II. Background
Definition of Terminology
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Sergio Gonzalez
07/24/00 Evaluation of Bispectral Spectrophotometry for Accurate Colorimetry of Printing Materials
Fluorescence introduces challenges and difficulty in creating color matches and formulations. Among the motivation of the present work is to gain a better understanding of the behavior of fluorescent samples.
Optical brightneners, which are used to increase whiteness in paper and natural pigments within the inks which are employed to reproduce color in different printing technologies; are examples in hardcopy materials that exhibit fluorescence. Most of these fluorescent components come in very small amounts that are not overtly detectable to the eye, but can be significant enough to affect colorimetric values in practice.
I. Introduction
The concern for accurate measurements has been a defining impetus in the field of color science. However, when dealing with fluorescence, the accuracy of measurements can be questionable. There have been many studies to improve fluorescence measurements in the past, but there has not been a commercial instrument available that can achieve the accuracy needed to give adequate results. Through the years, several methods have been developed to try to overcome this problem.
One aspect of fluorescence is that conventional spectrophotmetric instruments might lead to the wrong colorimetric values, which eventually can lead to incorrect color matching, color rendering, and incorrect overall color management.
Luminescence is the emission of light that does not derive energy from the temperature of the emitting body, as in phosphorescence, fluorescence, and bioluminescence. Luminescence is caused by chemical, biochemical, or crystallographic changes in the motions of subatomic particles, or the radiation-induced excitation of an atomic system1. The energy conversion of interest here usually occurs in the visible or near-visible range, under light excitation. Luminescence can be divided into the following three main categories: Fluorescence: The emission of electromagnetic radiation, especially of visible light, stimulated in a substance by the absorption of incident radiation, that persist only as long as the stimulating radiation continues. Fluorescence is the emission of light from a luminescent sample under some form of excitation. Commonly, fluorescent ink is used in the manufacturing of highlighter pens.7
The main goal of the present work is to determine colorimetric errors created by conventional spectrophotometry compared to bispectral measurements on a collection of printed materials. Another objective is to evaluate the significance of these errors in color reproduction applications. Among other considerations in the present work is demonstrating the precision and accuracy of the bi-spectrophotometer employed to take measurements.
And to everybody who must be in this list but I forgot.
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Sergio Gonzalez
07/24/00 Evaluation of Bispectral Spectrophotometry for Accurate Colorimetry of Printing Materials
When dealing with hardcopy materials (paper and inks) that contain fluorescent components, the color measurements become questionable. Conventional
spectrophotometers measure total radiance factors of fluorescent materials for the light source within the instrument. Such measurements cannot be used to obtain accurate colorimetry for other light sources.
Sergio Gonzalez
07/24/00 Evaluation of Bispectral Spectrophotometry for Accurate Colorimetry of Printing Materials
Thesis Title: Evaluation of Bispectral Spectrophotometry for Accurate Colorimetry of Printing Materials
In order to give a better understanding of this research, time is taken to introduce and describe some of the terminology associated with fluorescence. First, it should be mentioned that fluorescence is a phenomenon associated with luminescence that affects the instruments used in the measurement of color.
Every day new improvements in printed materials (substrates and inks) enter the market. Most of these improvements are oriented to enhance the appearance and appeal of products such as magazines, posters, etc. to grab the attention of potential clients.