Optics: measuring and testing – For light transmission or absorption – By comparison
Patent
1997-06-10
2000-03-21
Rosenberger, Richard A.
Optics: measuring and testing
For light transmission or absorption
By comparison
250345, G01N 2131, G01N 2139
Patent
active
060409142
ABSTRACT:
A laser absorption sensor system for performing optical measurements on a sample is described. The sensor system includes a tunable laser, capable of being tuned at rates exceeding 1 KHZ, and with a tuning range approaching 1 GHz. The laser beam is modulated at a modulation frequency between 1 and 100 KHz. Modulation in this frequency range is termed wavelength modulation. The beam is split into two beams, a signal beam and a reference beam. The signal beam traverses the sample where characteristic absorption takes place and is incident on a signal photodetector. The reference beam is incident directly on a reference photodetector. A noise cancellation circuit combines signal and reference photo-currents from signal and reference photodetectors reducing signal noise and increasing system sensitivity. The combination of wavelength modulation and the noise cancellation scheme provide a highly sensitive simple, rugged, low cost laser absorption sensor system.
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Bortz Michael L.
Godil Asif A.
New Focus Inc.
Rosenberger Richard A.
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