Fourier transform infrared spectrometer

• US 5,416,325 A
• Filed: 04/29/1993
• Issued: 05/16/1995
• Est. Priority Date: 04/29/1993
• Status: Expired due to Fees

• Current Assignee: ARCH Development Corporation (University of Chicago)
• Original Assignee: ARCH Development Corporation (University of Chicago)
• Inventors: Rice, Stuart A., Buontempo, Joseph T., Winston, Roland
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US08/055,696
• Time in Patent Office: 747 Days
• Field of Search: 250/353, 250/339, 250/339.08
• US Class Current: 250/339.08
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0216 using light concentrators or collectors or condensers
• CPC Class Codes: G01J 3/453 by correlation of the amplitudes

Abstract

A Fourier transform infrared spectrometer. A system includes a non-imaging concentrator coupled to an infrared detector enabling optimized detection of a signal in the Fourier transform infrared spectrometer.

Claims

1. A fourier transform infrared spectrometer, comprising:

means for providing an infrared beam;

means for detecting an infrared beam; and

a dielectric concentrator coupled to said means for detecting by means consisting of a good optical coupling, said concentrator being a non-imaging concentrator comprising a convergent concentrator having an output aperture with an output aperture diameter and further having reflecting surface providing a light output angle θ

₁ between 45° and

90°

as seen by said means for detecting and said concentrator and said means for detecting having a spacing therebetween of less than 0.1 times the output aperture diameter of said concentrator, thereby minimizing the amount of the light which leaves the output aperture and misses the detector.

2. The Fourier transform infrared spectrometer as defined in claim 1 wherein said concentrator comprises a compound parabolic concentrator.

3. The Fourier transform infrared spectrometer as defined in claim 1 wherein said concentrator comprises a compound elliptical concentrator.

4. The Fourier transform infrared spectrometer as defined in claim 1 wherein said means for providing the infrared beam generates an output beam having an etendue of at least 0.002 mm².

5. The Fourier transform infrared spectrometer as defined in claim 4 wherein said means for detecting has an active detector area less than or equal to the etendue of said output beam.

6. The Fourier transform infrared spectrometer as defined in claim 1 wherein said good optical coupling has an index of refraction 0.9 times the index of said concentrator.

7. The Fourier transform infrared spectrometer as defined in claim 1 wherein said concentrator and said means for detecting are constructed of the same material.

8. A method of performing Fourier transform spectrometry on a specimen, comprising the steps of:

providing an infrared spectrometer for generating an infrared beam and outputting said infrared beam;

providing a specimen and impinging said infrared beam on said specimen;

providing means for detecting said infrared beam after interacting with said specimen;

providing a dielectric concentrator coupled to said means for detecting by forming a good optical coupling therebetween, said concentrator being a non-imaging concentrator comprised of a convergent concentrator having an output aperture with an output aperture diameter and further having a reflecting surface providing a light output angle θ

₁ between 45° and

90°

as seen by said means for detecting and said concentrator and said means for detecting having a spacing therebetween of less than 0.1 times the output aperture diameter of said concentrator, thereby minimizing the amount of the light which leaves the output aperture and misses the detector; and

detecting said infrared beam output from said concentrator using said means for detecting to generate a signal for processing to perform said Fourier transform spectrometry.