Device recognizes variations in wire size and is being used during computer memory-plane fabrication. Decrease in wire diameter, due to stretching, permits removal of wire from memory-plant mold. Monitoring provides means of detecting imperfect wire and permits fabrication of computer memory plane to be stopped prior to its insertion into mold

Burcher, E. E.

Kelly, W. L., IV

English

NASA Technical Reports Server

October 1973	 B73-10321 
NASA TECH BRIEF 
Langley Research 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. 
Electro-Optical Device for Monitoring Wire Size 
n
A device to monitor and recognize variations in wire 
size has been developed and is being used during compu-
ter memory-plane fabrication. The elctro-optical device 
is simple in operation but provides an accurate means of 
wire-size monitoring. 
Computer memory-plane fabrication relies on a de-
crease in wire diameter, due to stretching, to permit re-
moval of the wire from the memory-plane mold. Wire 
breakage, prior to removal from the mold, is caused by 
localized variations in wire size and results in a useless 
mold. Wire-size monitoring by this system provides a 
means of detecting imperfect wire and permits fabrica-
tion of the computer memory plane to be stopped prior 
to its insertion into the mold. The imperfect wire can be 
removed and the fabrication process continued without 
damage to the memory plane.
The components of this device are shown in the illus-
tration. The photomask has two apertures, reference and 
sample. The reference aperture has a reference wire 
mounted across it and the wire to be monitored is passed 
continuously across the sample aperture in the same geo-
metrical configuration as the reference wire. Diffuse 
light illuminates the identical apertures which are 
mounted over photodiode-preamplifiers. 
The reference photo diode-preamplifier voltage output 
is proportional to the unobscured area of the reference 
aperture. The photodiode-preamplifier outputs are ap-
plied to the inputs of a differential operational amplifier 
where they are subtracted and the difference amplified. 
Monitored wire which is the same size as the reference 
wire will result in zero output voltage. Smaller monitored 
wire will result in a negative voltage indication and larger 
wire will result in a positive voltage indication. 
Sample 
Detector	 Reference 
Photomask
	 Detector
Reference 
Wire 
Sample 
Wire 
Reference 
Diffuser
	 Sample	 Aperture 
(to Insure Identical
	 Aperture 
Illumination for 
Both Apertures)
Light Source 
S	 Wire-Size Monitoring Device
(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 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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System sensitivity is determined by amplifier gain, 
the ratio of the difference in cross-sectional area be-
tween the reference wire and the wire being monitored, 
and the unobscured area of the reference aperture. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
Reference: B73-10321
Patent status: 
Inquiries concerning rights for the commercial use of 
this invention should be addressed to: 
Patent Counsel 
Langley Research Center 
Code 456 
Hampton, Virginia 23665 
Source: Ernest E. Burcher, W. Lane Kelly IV,

and Carroll W. Rowland

Langley Research Center

(LAR-1 1358) 
B73-10321	 Category 02, 08
	 •


Electro-optical device for monitoring wire size

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