Abstract

We demonstrate an imaging spectrometer with 30nm resolution that utilizes a novel time-domain filtering architecture. The architecture is based on a pixel by pixel integration of the interferogram signal mixed with reference waveforms. The system can be adapted in real time to discriminate between LED sources of different wavelengths, perform signal processing on the spectra, as well as discriminate between highly overlapping, broadband spectral features in a scene illuminated by a tungsten lamp. Unlike a conventional spectral signature discrimination system, which needs a dedicated computation subsystem running a discrimination algorithm, the time-domain filtering architecture embeds much of the computation in the filtering, which will aid the design of integrated miniaturized spectral signature discrimination systems.

© 2003 Optical Society of America

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References

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Anal. Chem. (1)

A. S. Banalore, G. W. Small, R. J. Combs, R. B. Knapp, R. T. Kroutil, C. A. Traynor, J. D. Ko �??Automated detection of trichloroethylene by Fourier transform infrared remote sensing measurements�?? Anal. Chem. 69, 118-129 (1997).
[CrossRef]

Appl. Spectrosc. (4)

IEE J. Sel. Top. Quantum Electron (1)

H. L. Kung, S. R. Bhalotra, J. D. Mansell, D. A. B. Miller, and J. S. Harris, Jr. "Standing-wave transform spectrometer based on integrated MEMS mirror and thin-film photodetector" IEE J. Sel. Top. Quantum Electron. 8, 98-105 (2002).
[CrossRef]

J. Biomed. Opt. (1)

R.J. McNichols, G.L. Coté, �??Optical glucose sensing in biological fluids�?? J. Biomed. Opt. 5, 5 (2000).
[CrossRef] [PubMed]

Opt. Lett. (1)

Proc. SPIE (1)

N. Gupta, R. Dahmani �??Multispectral and hyperspectral imaging with AOTF for object recognition�?? Proc. SPIE 3584, 128 (1999).
[CrossRef]

Other (1)

J. Proakis and M. Salehi, Communication Systems Engineering (Prentice Hall, New York, 1994).

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Figures (5)

Fig. 1.
Fig. 1.

Time-domain filtering setup.

Fig. 2.
Fig. 2.

Example reference interferograms. (a) is the reference interferogram recorded with a yellow LED, and (b) is the interferogram formed by taking the difference of the interferograms of the red and green LEDs

Fig. 3.
Fig. 3.

40×40 pixel images of the object. a) shows the conventional color camera image. b), c) and d) show the overlap integral of each pixel’s interferogram with the reference waveforms red, green, and yellow respectively. White areas indicate the presence of a spectral signature. e) shows the overlap integral with the reference “not red&green”. Areas that only contain a green component are white; red is dark, gray areas contain either both or none of the spectral signatures. The incomplete mixing of the light from the two LEDs within each two-color LED causes the in-homogeneity of the two-color LED image.

Fig. 4.
Fig. 4.

Discrimination of broadband features by TDF-ML.

Fig. 5.
Fig. 5.

Experimental measurement of source spectra.

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