Hologram is constructed by taking number of digitized sample points and blending them together to form ''continuous'' picture. New system selects better set of sample points resulting in improved hologram from same amount of information

Hopper, W. A.

English

NASA Technical Reports Server

Figure 1. A Square Lattice Of Sampling Points
I.
February 1973	 B7340101 
NASA TECH BRIEF 
•	 Marshall Space Flight Center 
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 National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
A Generalized Approach To Computer Synthesis
of Digital Holograms 
The problem: 
When a digital computer is used to construct a holo-
gram, the resulting image is not as good as that obtained 
by conventional methods. 
The solution: 
The hologram is constructed by taking a number of 
digitized sample points and blending them together to 
form a "continuous" picture. However, this new system 
selects a better set of sample points from which the 
hologram is constructed. The result is an improved holo-
gram from the same amount of information.
How it's done: 
The holographic field is constructed by the com-
puterized application of a modified fast Fourier trans-
form to a set of digitally encoded data. Previously, the 
field was constructed from a set of sample points form-
ing a square lattice as shown in Figure 1. The square 
lattice of sampling points is not optimal in the sense 
that some other set of lattice points may represent the 
image equally well, but require fewer sample points for 
a given image size. A set of lattice points, with a basic 
cell in the shape of a 1200 rhombus, as shown in Figure 
2, forms a lattice closer to the optimum. This rhombus 
allows fewer sample points to be used for a given image 
size. 
In general, the optimal locations for the sampling 
points may be determined by the use of generalized, 
multi-dimensional sampling techniques. in this way, 
computer generated holograms can be made to be as 
good as conventional holograms and may be applied 
to optical information processing systems, optical data 
storage, testing of optical equipment, and other areas 
in which holograms might be used. 
Notes: 
1. Information concerning this innovation may be of 
interest to the designers and users of optical data 
storage and processing systems. 
2. Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&PS-TU 
Marshall Space Flight Center, Alabama 35812 
Reference: B73-10101 
(continued overleaf) 
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 Stales 	 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.
https://ntrs.nasa.gov/search.jsp?R=19730000101 2020-03-17T06:46:39+00:00Z
. 
Figure 2. A Sampling Lattice Of Which The Basic Cell 
Is A 1200 Rhombus 
Patent status: 
Inquiries concerning rights for the commercial use 
of this invention should be addressed to: 
Patent Counsel 
Marshall Space Flight Center 
Code A&PS-PAT 
Marshall Space Flight Center, Alabama 35812 
Source: W. A. Hopper of

Sperry Rand Corp. 
under contract to

Marshall Space Flight Center

(MFS.2 1973)
S 
B73-10101	 Category O9,03
	 0


A generalized approach to computer synthesis of digital holograms

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