Dual beam fourier spectrometer
AssigneeLaser Precision Corporation
InventorWalter M. Doyle
Life of this patent
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Abstract
A dual beam Fourier-type spectrometer is disclosed in which the collimated output beam of a Michelson type interferometer is divided (post-interferometer) by a reflector which (a) reflects the bulk of said beam to the sample and thereafter a first detector, but (b) transmits part of said beam (preferably through apertures in the reflector) directly to a second detector. The relatively small portion of said beam which is transmitted to the second detector preferably passes through a substantial number of very small apertures in the reflector which are spaced in such a way as to maximize the spatial identity of the beams reaching the first and second detectors.
Claims17
A dual beam spectrometer comprising:
- a radiation source propagating its beam from a single location;
- an interferometer which receives the beam and which outputs a spectrally-scanned beam;
- a beam interceptor which receives the output beam from the interferometer and divides its energy into two components;
- a first detector adapted to receive one such energy component after it has illuminated a sample and convert it into an electronic signal;
- a second detector adapted to receive the other such energy component without attenuation by a sample and convert it into an electronic signal;
- and
- means for co-adding the signals generated by the two detectors to provide an electronic spectrometer output.
In a spectrometer which includes a beam splitter interferometer providing two radiation "arms" which are recombined and exit from the interferometer as a collimated beam, a dual beam optical system for comparing sample-illuminating radiation with non-sample-illuminating radiation, comprising:
- a beam interceptor which receives the collimated exit beam from the interferometer and divides its energy into two components;
- a first detector adapted to receive one such energy component after it has illuminated a sample and convert it into an electronic signal;
- a second detector adapted to receive the other such energy component without attenuation by a sample and convert it into an electronic signal;
- and
- means for co-adding the signals generated by the two detectors to provide an electronic spectrometer output.
For use in a spectrometer which includes a beam splitter interferometer providing two radiation "arms" which are recombined and exit from the interferometer as a collimated beam, a method of analyzing the collimated exit beam from the interferometer comprising the following steps:
- dividing said collimated exit beam into two portions, one of which has much larger radiation energy than the other;
- causing the relatively large energy portion of divided radiation to illuminate the sample;
- causing the post-sample radiation to be measured by a first photodetector;
- causing the relatively small energy portion of divided radiation to be measured by a second photodetector without illuminating the sample;
- and
- combining the electrical signals output by the first and second photodetectors.
Dependencies are inferred from the claim text.