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A Real Time Fourier Transform Synthesizer.

AD653200

Publication Date	1966
Personal Author	Hoffman, J. E.
Page Count	132
Abstract	A study of the relationship between the interferogram F(x) 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.
Keywords	Interferometers Real time Optical scanning Integral transforms Refractive index Spectrum analyzers Spectroscopy Transformations(Mathematics) Synthesis Optical instruments Digital computers Errors Gain Performance(Engineering) Electrical networks Frequency multipliers Detectors
NTIS Subject Category	63F - Optical Detection 46C - Optics & Lasers 94K - Laboratory & Test Facility Design & Operation
Corporate Authors	Utah State Univ Logan Electro-Dynamics Labs
Document Type	Technical Report
NTIS Issue Number	196715
Contract Number	AF 19(628)-3825

A Real Time Fourier Transform Synthesizer.

A Real Time Fourier Transform Synthesizer.
AD653200

Publication Date	1966
Personal Author	Hoffman, J. E.
Page Count	132
Abstract	A study of the relationship between the interferogram F(x) 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.
Keywords	Interferometers Real time Optical scanning Integral transforms Refractive index Spectrum analyzers Spectroscopy Transformations(Mathematics) Synthesis Optical instruments Digital computers Errors Gain Performance(Engineering) Electrical networks Frequency multipliers Detectors
NTIS Subject Category	63F - Optical Detection 46C - Optics & Lasers 94K - Laboratory & Test Facility Design & Operation
Corporate Authors	Utah State Univ Logan Electro-Dynamics Labs
Document Type	Technical Report
NTIS Issue Number	196715
Contract Number	AF 19(628)-3825