Stellar classification is accomplished by correlating holograms of classified spectra with the Fourier transform of the spectral images to be classified

Reid, J. H.

English

NASA Technical Reports Server

June 1970	 Brief 70-10319 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Stellar Spectrum Classifier 
Laser
Expander 
Collimating Lens 
Plate with Objective Prism 
Spectra in Holder with 
x, y Coordinate Readout 
Lens (Fourier Transform) 
Holograms of Classified 
Spectra on Film with 
Coded Edge 
Lens (Inverse Transform) 
Video 
Camera	 Monitor 
Classifier of Objective Prism Spectra of Stars 
An apparatus has been designed to assist in clas-
sifying the spectra of stars photographed through 
an objective prism. With this apparatus, classification 
of the stars is made easier and more accurate. As 
shown in the figure, a photographic plate is placed in a 
holder which has an x-y coordinate readout to measure 
the relative positions of the spectra of stars on the 
plate. Collimated light from a laser passes through
a spectrum on the plate, through a Fourier-transform 
lens, and then through an edge-coded film strip which 
contains complex-conjugate holograms of classified, 
representative stellar spectra. The film strip is moved 
until a hologram is reached which correlates with the 
Fourier transform of the spectral image. When this 
occurs, maximum energy passes through the holo-
gram, through the inverse-transform lens, and into the 
video camera, causing a spot to appear on the monitor. 
Notes: 
1. Used in conjunction with wide-field telescopes, 
stellar classification will be accelerated by the 
proposed system, since holograms are required 
only of the relatively few classified spectra, a small 
number in comparison to the large number of prints 
on file. 
2. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Manned Spacecraft Center, Code BM7 
Houston, Texas 77058 
Reference: B70-10319 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: J. H. Reid of
Lockheed Electronics Company 
Houston Aerospace Systems
under contract to
Manned Spacecraft Center
(MSC-13450) 
Category 03 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned.rights.
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Stellar spectrum classifier

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