Spectrometer system for optical reflectance measurements
First Claim
1. A spectrometer system comprising:
- a thermal light source for illuminating a sample, wherein the thermal light source comprises a filament that emits light when heated;
a spectrograph for measuring a light spectrum from the sample;
an electrical circuit for supplying electrical current to the filament to heat the filament and for controlling a resistance of the filament, the electrical circuit comprising;
a power supply that supplies current to the filament;
first electrical components that sense a current through the filament;
second electrical components that sense a voltage drop across the filament;
third electrical components that compare a ratio of the sensed voltage drop and the sensed current with a predetermined value; and
fourth electrical components that control the current through the filament or the voltage drop across the filament to cause the ratio to equal substantially the predetermined value.
6 Assignments
0 Petitions
Accused Products
Abstract
A spectrometer system includes a thermal light source for illuminating a sample, where the thermal light source includes a filament that emits light when heated. The system additionally includes a spectrograph for measuring a light spectrum from the sample and an electrical circuit for supplying electrical current to the filament to heat the filament and for controlling a resistance of the filament. The electrical circuit includes a power supply that supplies current to the filament, first electrical components that sense a current through the filament, second electrical components that sense a voltage drop across the filament, third electrical components that compare a ratio of the sensed voltage drop and the sensed current with a predetermined value, and fourth electrical components that control the current through the filament or the voltage drop across the filament to cause the ratio to equal substantially the predetermined value.
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Citations
24 Claims
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1. A spectrometer system comprising:
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a thermal light source for illuminating a sample, wherein the thermal light source comprises a filament that emits light when heated; a spectrograph for measuring a light spectrum from the sample; an electrical circuit for supplying electrical current to the filament to heat the filament and for controlling a resistance of the filament, the electrical circuit comprising; a power supply that supplies current to the filament; first electrical components that sense a current through the filament; second electrical components that sense a voltage drop across the filament; third electrical components that compare a ratio of the sensed voltage drop and the sensed current with a predetermined value; and fourth electrical components that control the current through the filament or the voltage drop across the filament to cause the ratio to equal substantially the predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of controlling a spectrum of light emitted from a heated filament, the method comprising:
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supplying electrical current from a power supply to heat the filament; sensing a current flowing through the filament; sensing a voltage drop across the filament; comparing a ratio of the sensed voltage drop and the sensed current with a predetermined value; and controlling the current or the voltage drop to cause the ratio to equal the predetermined value. - View Dependent Claims (11, 12, 13, 14)
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15. A spectrometer system comprising:
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a light source; a spectrograph; an first optical beam path for guiding light from the light source to a sample; a second optical beam path for guiding light from the light source to the spectrograph; a third optical beam path for guiding light reflected from the sample to the spectrograph; a shutter for blocking and unblocking the light in the first beam path from the sample and for blocking and unblocking light in the second beam path from the spectrograph; and a processor adapted for analyzing light spectra from light guided into the spectrograph and adapted for correcting the spectra for a dark current in the system based on spectra recorded when both the first and second optical beam paths are blocked and adapted for correcting the spectra for temporal changes in the spectrum of the light source based on a plurality of spectra recorded at different times when light is guided into the spectrograph along the second beam path. - View Dependent Claims (16, 17, 18, 19)
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20. A method for correcting a spectrum measured by a spectrometer system having a spectrograph and a light source for illuminating a sample with light output from the light source, the method comprising:
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recording a reference spectrum, Ro(λ
), from a reference sample having a known reflectivity spectrum when light from the light source is shined on the reference sample;recording an initial lamp spectrum, Lo(λ
), of the light output from the light source at an initial time when light from the light source is shined into the spectrograph;recording a subsequent lamp spectrum, Lt(λ
), of the light output from the light source at a time later than the initial time when light from the light source is shined into the spectrograph;recording a spectrum from a test sample, S(λ
);correcting the spectrum from the test sample using data from the reference spectrum, the initial lamp spectrum, and the subsequent lamp spectrum, to produce a corrected spectrum; and outputting the corrected spectrum. - View Dependent Claims (21, 22, 23, 24)
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Specification