Accession Number:

AD0653200

Title:

A REAL TIME FOURIER TRANSFORM SYNTHESIZER

Descriptive Note:

Corporate Author:

UTAH STATE UNIV LOGAN ELECTRO-DYNAMICSLAB

Personal Author(s):

• Hoffman, Joseph E., Jr

Report Date:

1966-11-01

Pagination or Media Count:

133.0

Abstract:

A study of the relationship between the interferogram Fx obtained in Fourier spectroscopy and the corresponding spectral distribution E is made. It is found that the spectral distribution is the Fourier cosine transform of the interferogram. Various computational techniques for performing the required transformation are studied, and a real time Fourier transform synthesizer is described. It has been designed to be compatible with a lamellar grating Michelson interferometer, but could be used just as well with a well-compensated Michelson interferometer. The system used to obtain the point of zero path difference is described in detail. A novel approach is used to obtain the cosine functions required in the synthesis of the cosine transform. All the computations except the summation are done in analog form, while the summation is done digitally. The result of the computation, the spectral distribution, is available as soon as the interferogram is obtained. Errors in the technique are discussed and methods of compensating for them are enumerated.

Descriptors:

• *REAL TIME
• *OPTICAL SCANNING
• *INTERFEROMETERS
• *INTEGRAL TRANSFORMS
• DETECTORS
• SPECTROSCOPY
• SYNTHESIS
• PERFORMANCE(ENGINEERING)
• OPTICAL INSTRUMENTS
• FREQUENCY MULTIPLIERS
• ELECTRICAL NETWORKS
• SPECTRUM ANALYZERS
• DIGITAL COMPUTERS
• REFRACTIVE INDEX
• TRANSFORMATIONS(MATHEMATICS)
• ERRORS
• GAIN

Subject Categories:

• Test Facilities, Equipment and Methods
• Optical Detection and Detectors
• Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE