Masters Theses

Date of Award

8-1988

Degree Type

Thesis

Degree Name

Master of Science

Major

Computer Science

Major Professor

Kenneth R. Kimble

Committee Members

Bruce W. Bomar, Wilbur C. Armstrong

Abstract

A customized digital data acquisition system and a comprehensive set of applications programs were developed to provide automatic, high-speed operation of a modified grating spectroradiometer. A 1/2-meter grating spectrograph was rendered a fast scanning device by using a wavelength scanning mirror behind the entrance slit, along with a customized detector assembly on the exit focal plane. The detector assembly consists of eight Indium Antimonide detectors, with each detector having a separate order-sorting filter and exit slit. The concatenated ranges of the eight detectors cover the range from 1.1 to 5.1 microns. Spectral scan times are on the order of 1 second per scan.

Approximately 2100 lines of C programming code were written to acquire raw data, organize and store data, perform wavelength cali brations, perform radiance calibrations, and reduce raw data to absolute radiometric units. The code is executed on a Zenith Z-248 microcomputer. Very high data densities on the wavelength scale were realized. Up to 8,000 data points can be stored per spectral scan, and data run times of 10 minutes or longer are possible. All data are digitized and stored on a Bernoulli disk recorder during the data run. The raw data can be reduced to engineering units within minutes of the completion of the data run. A complete experimental demonstration of the applications software is presented. The performance of the data acquisition and processing system was excellent in all respects. However, several operating deficiencies of the spectroradiometer were discovered, and it was concluded that in a qualitative sense, the performance of the data acquisition and processing system exceeds the performance of the spectroradiometer. Improvements in the spectroradiometer performance are suggested. The most important possible improvement is the use of an evacuable spectrometer to eliminate calibration errors near the atmosphere absorption bands.

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