Optical system designed by third order aberration theory is significantly improved by placing it into a ray deviation design program composed of two distinct computer programs. Tests were conducted on telescope systems, an ultraviolet relay lens, and a four lens corrector system

Howell, B. J.

English

NASA Technical Reports Server

September 1969
	 Brief 69-10405 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public .at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Improved Method of Optical Design 
.
An improved method of optical design has been 
developed through the combination of two separate 
and distinct computer program techniques to resolve 
several long standing optical design problems. 
There is in rather wide use today a class of design 
programs known as ray deviation programs. In these 
programs rays are traced through the optical system, 
and the imagery is evaluated by calculating the rms 
radius of the spot formed by the entire bundle of rays 
which go through the system, and the average position 
of the spot in two dimensions. The spot sizes and 
positions relative to desired positions are weighted 
and added into an "error function" which the auto-
matic features of the program minimize by changing 
optical system parameters. 
Another class of programs in wide use employ cer-
tain traced rays to compute aberration coefficients 
which characterize the quality of the imagery in a 
completely different way. The third order (found by 
truncating infinite series) aberrations are called 
spherical, coma, astigmatism, distortion, and Petzval. 
There are derived aberration characteristics, such as 
offense against the sine condition, which are also 
used to characterize the quality of the imagery. 
Some programs in this class, called aberration pro-
grams, use higher order terms to characterize the 
quality, but these terms become so numerous that it 
is difficult to name them. These aberration programs 
are not as independent of each other as the third 
order terms. 
The principle which has been discovered, and 
which represents the new technology, is that an 
optical system prepared or designed by third order 
aberration theory can be significantly improved by 
placing it into a ray deviation design program. This 
improvement is measured by the criteria used by the 
ray deviation program and also by the criteria used by
aberration theory. Thus, the improvement is real and 
not just a theoretical improvement according to a 
particular set of criteria. Efforts to obtain still 
greater improvements by cascading the operations 
(alternating repeatedly between aberration design 
and ray deviation design) result in marginal im-
provement. The sequence of the two-step operation 
is important. The preferred order is aberration design 
followed by ray deviation design. 
Notes: 
1. The new principle has been tested on a number 
of systems, all with positive results. Ritchey-
Chrétien and Dall-Kirkham telescope systems, 
which have unique solutions in terms of third 
order theory, have been designed. An ultraviolet 
relay lens, having greatly improved performance, 
has been designed with the new technique in a 
small fraction of the time used in a previous 
effort. A four-lens corrector system to remove 
residual aberrations in a Ritchey-Chrëtien tele-
scope was designed with the new technique, re-
sulting in a 300 cm focal length f/lO diffraction-
limited 1.2° flat-field system for white light. 
2. Requests for further information may be directed to: 
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland 20771 
Reference: TSP69- 10405 
Patent status: 
No patent action is contemplated by NASA. 
Source: Barton J. Howell of 
Sperry Rand Corporation 
under contract to 
Goddard Space Flight Center 
(GSC- 10743) 
Category 02 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000398 2020-03-16T18:16:35+00:00Z


Improved method of optical design

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