A Hadamard-multiplexed spectrometer based on an acousto-optic tunable filter

Author

Mortensen, A. Norman ; Dyer, Stephen A. ; Hammaker, Robert M. ; Fateley, William G.

Author_Institution

Dept. of Electr. & Comput. Eng., Kansas State Univ., Manhattan, KS, USA

Volume

45

Issue

2

fYear

1996

fDate

4/1/1996 12:00:00 AM

Firstpage

394

Lastpage

398

Abstract

This paper presents a Hadamard-multiplexed spectrometer based on an acousto-optic tunable filter (AOTF). The multifrequency capability of the AOTF enables it to be operated in a multiplexed mode. The AOTF can then be operated at lower power to obtain improved passband characteristics without a reduction in the signal-to-noise ratio as compared to a higher-power, nonmultiplexing instrument. An expandable, PC-based spectrometer has been developed to illustrate this technique. The current implementation provides seven-frequency Hadamard multiplexing and collects the spectra in multiplexed blocks. The AOTF is controlled via IEEE-485 bussed VHF synthesizer modules based on a hybrid DDS/PLL technique. The modular design allows convenient system expansion. The design of and specifications for this instrument are discussed

Keywords

Hadamard transforms; acousto-optical filters; digital phase locked loops; direct digital synthesis; photoacoustic spectroscopy; physical instrumentation control; spectrometers; spectroscopy computing; wavelength division multiplexing; Hadamard-multiplexed spectrometer; IEEE-485 bussed VHF synthesizer modules; acousto-optic tunable filter; expandable PC-based spectrometer; hybrid DDS/PLL technique; improved passband characteristics; modular design; multifrequency capability; multiplexed mode; photoacoustic spectroscopy; Acoustic beams; Acoustic diffraction; Acoustic transducers; Acoustic waves; Optical diffraction; Optical filters; Optical noise; Piezoelectric transducers; Spectroscopy; Structural beams;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.492754

Filename

492754