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Proceedings Paper

Fiber-coupled AOTF spectrometers
Author(s): Neelam Gupta
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Paper Abstract

Acousto-optic (AO) technology is used to design compact, vibration-insensitive spectrometers with fairly high sensitivity and resolution. The design of such AO spectrometers (AOS's) is based on the phenomenon of an anisotropic Bragg diffraction in a birefringent crystal, i.e., quartz, lithium niobate, tellurium dioxide (TeO2), etc. The fundamental building block of an AOS is an acousto-optic tunable filter (AOTF) cell used with a sensitive detector. There are two types of AOTF cells - (i) collinear where the incident and diffracted optical beams and the acoustic beam all propagate in the same direction and (ii) noncollinear where all these beams do not travel in the same direction - based on the design of the cell. We have developed a number of AOS's to cover wavelengths from the ultraviolet (UV) to the mid wave infrared (MWIR). Spectrometers using a collinear AOTF cell fabricated in a single crystal of quartz operate in the spectral range from 255 to 430 nm and from 400 to 800 nm and those fabricated in a single crystal of TeO2 with a noncollinear design operate from 1100 to 2700 nm and from 2000 to 4500 nm. We have developed special accessories to couple optical fiber(s) to such spectrometers for efficient light collection. In our laboratory, we are using these AOS's to measure emission, absorption, fluorescence, and Raman spectra. The development of these AOS's is discussed and compact portable fiber-coupled spectrometers based on quartz AOTF operating in the 255 to 800 nm spectral region are described and sample results are presented. Such spectrometers should be useful for medical diagnostics applications.

Paper Details

Date Published: 15 February 2006
PDF: 12 pages
Proc. SPIE 6083, Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications VI, 60830U (15 February 2006); doi: 10.1117/12.663002
Show Author Affiliations
Neelam Gupta, U.S. Army Research Lab. (United States)

Published in SPIE Proceedings Vol. 6083:
Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications VI
Israel Gannot, Editor(s)

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