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Browse Prior Art Database

Spectrophotometric Film and Color Analyzer

IP.com Disclosure Number: IPCOM000041657D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Korth, HE: AUTHOR

Abstract

A small low-cost analyzer for film thicknesses, surface colors, and the like consists of at least three microprocessor-controlled light sources, emitting different wavelengths for sequentially illuminating the sample, and one photodiode, whose readings are fed to the microprocessor for calculating the optical property desired. The figure shows an embodiment with three light-emitting diodes (LEDs) 10a, 10b, 10c having their terminals connected to output lines 14 of the microprocessor 13. A holographic grating 11 acts as an imaging element and a beam combiner for directing the light emitted in the red, green and blue wavelength bands, through window 18, onto a spot on the surface 20. Other light sources and/or imaging elements can also be used for this purpose.

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Spectrophotometric Film and Color Analyzer

A small low-cost analyzer for film thicknesses, surface colors, and the like consists of at least three microprocessor-controlled light sources, emitting different wavelengths for sequentially illuminating the sample, and one photodiode, whose readings are fed to the microprocessor for calculating the optical property desired.

The figure shows an embodiment with three light-emitting diodes (LEDs) 10a, 10b, 10c having their terminals connected to output lines 14 of the microprocessor 13. A holographic grating 11 acts as an imaging element and a beam combiner for directing the light emitted in the red, green and blue wavelength bands, through window 18, onto a spot on the surface 20. Other light sources and/or imaging elements can also be used for this purpose. The light reflected from the surface is received by photodiode 19, the output of which is fed to microprocessor 13 through a series-connected integrator 16 and a threshold switch 15. A display 12 receives the results generated by microprocessor 13. For initiating a measuring sequence, the microprocessor triggers a counter and the first LED until the integrated output signal of the photodiode reaches the threshold of circuit 15; the count then corresponds to the inverse of the surface reflectivity for the first wavelength and is stored in the microprocessor. Subsequently, the same sequence is repeated for the remaining two wavelengths. Finally, the microprocessor evaluates the measured surface reflectivit...