Pure silicon improves optical mirrors for use in telescopes and high resolution optical systems. Pure silicon is used in both mirror and substrate in environments where large thermal changes occur. It has applicability in astronomical devices

Markle, D. A.

Vrabel, J.

English

NASA Technical Reports Server

October 1969	 Brief 69-10529 
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. 
A New Method for Producing Optical Mirrors 
.
The problem: 
To design an improved optical mirror for use in 
telescopes and high resolution optical systems. 
The solution: 
Use pure silicon both as mirror and substrate in 
environments where large thermal changes occur and 
high optical quality is required. 
How it's done: 
The process consists of forming a mirror blank of 
silicon and grinding the surface to be used as the re-
flector to the desired shape. The surface is then opti-
cally polished and the reflective film deposited (if 
desired). The silicon substrate can be polished directly 
and coated with an aluminum film, as opposed to 
beryllium or aluminum substrates which require a 
chemically deposited nickel or oxide coating before 
they can be polished to optical component tolerances. 
The advantages of using silicon in place of other 
commonly used materials are as follows: 1) Its 
abundance; 2) Its strength, hardness, and greater 
predictability than glass; 3) Its chemical and physical 
stability; 4) Several methods exist to produce high 
purity silicon; 5) It can be inspected for flaws and
strain using optical techniques; and 6) It can be 
brought to a liquid state and molded. 
Notes: 
1. This innovation may be of interest to the optics 
industry and those personnel working in astronomy. 
2. No further documentation is available. Inquiries 
may be directed to: 
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space Administration 
Washington, D.C. 20546 
Reference: B69-10529 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
(42 U.S.C. 2457 (f)), to the Perkin-Elmer Corporation, 
Norwalk, Connecticut 06852. 
Source: David A. Markle and Joseph Vrabel of 
Perkin-Elmer Corporation
under contract to
NASA Headquarters
(H QN -10227) 
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.
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A new method for producing optical mirrors

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