Radiant energy – Luminophor irradiation – With ultraviolet source
Patent
1987-05-15
1989-06-20
Fields, Carolyn E.
Radiant energy
Luminophor irradiation
With ultraviolet source
2504591, 356381, G01N 2164
Patent
active
048411566
ABSTRACT:
An ultraviolet source (14) directs selected ultraviolet radiation onto a thin film (10) to excite it. The thin film fluoresces, either naturally or as a result of adding fluorescing material. The amount of light fluoresced is proportional to the film thickness. An optical filter (16) selectively transmits fluoresced wavelengths, excluding exciting wavelengths. A photodetector (18) converts the light to an electrical signal which is processed by signal processing circuits (20) and displayed on a readout (26). The output is compensated for variations in the intensity of the exciting ultraviolet radiation by generating a second electrical signal (13', 18') proportional to the intensity of the exciting radiation and dividing the first electrical signal by a function of said second electrical signal. The compensated output is then calibrated to assure precision and accurate measurements.
Various materials may be selectively measured, individually in the presence of others by choosing appropriate excitation and emission wavelengths. The amount of fluoresced light is linear with respect to the amount of material present as long as the layer is quite thin. As the layer thickness increases, the amount of light to thickness relationship becomes non-linear.
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A. Smart et al., "Measurement of Thin Liquid Films by a Fluorescence Technique", INSPEC, vol. 29(1), pp. 41-47, 7/74.
Casacia Edward A.
May Joe T.
Electronic Instrumentation and Technology Inc.
Fields Carolyn E.
Miller John A.
Whitham C. Lamont
Whitham Michael E.
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