Portable fiber optics sensing device which detects surface irregularities in a specific tube flare, permits discrete dimensional measurements to be taken, scanned and read out with only one setup. Capabilities of the instrument can be expanded to include surface inspection of various kinds of tube flares

Zoike, H. M.

English

NASA Technical Reports Server

May 1969	 Brief 69-10152 
NASA TECH BRIEF 
NASA Teàh 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. 
Surface Irregularities Detected by Flare Inspection Instrument 
Reflected Light Rays - 
-'	 J.- I.. - \	 I	 Li ght k - Sensor 
A	 F - _-- k Position Of Part Surface 
/
Fiber Optics 
Transmitting 
Fiber Optics 
.
Light	 I 
Source
	
I	 I Electrical	 i Response	
5f 
ED
r"l, i Peak 
-	 D	 I 
PRINCIPLE OF FIRER OPTICS DISPLACEMENT MeASUREMENTS 
A fiber optics sensing device has been developed to 
detect surface irregularities in a specific tube flare. 
The portable device permits a large number of discrete 
dimensional measurements to be taken, scanned and 
read out with only one setup. High resolution meas-
urement of distances down to minute units of length 
can be achieved. This instrument is intended to inspect 
a specific flare (MSFC Design Standard MC 146); 
however, the capabilities of the device could be ex-
panded to include surface inspection of other kinds of 
tube flares, and surfaces (flat or curved) of other parts
where precise inspection of conditions is required. 
The inspection is accomplished through the use of 
fiber optics associated with a fixture consisting of male 
and female gauge pieces configured to embrace the 
interior and exterior lip portions of the flare to be 
inspected. The fiber optics consist of a number of 
discrete bundles of light pipes with the ends of the 
bundles arranged on the gauge in a pattern of meas-
uring points. Each measuring point is composed of 
transmitting and receiving fibers. The transmitting 
fibers in each bundle lead to a common light source. 
(continued overIcI) 
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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The remaining fibers in the bundle are receiving fibers 
and lead to an independent light sensor, with one light 
sensor for each bundle. Light emitted from the trans-
mitting fibers is reflected to the receiving fibers by the 
surface being inspected. The reflected light is trans-
mitted through the receiving fibers and is emitted to a 
pick-off device. The amount of light being reflected is 
a measure of the distance between the surface being 
measured and the end of the bundle (see note I) and 
is converted into an electrical signal proportional to 
that distance. (Scanning circuitry is provided to sys-
tematically activate and interrogate the fiber optics 
bundles.) Electronics are provided for activating the 
fiber optics, for activating the scanning functions, for 
receiving, amplifying and displaying the scanned data, 
and for determining the distance being sensed and the 
deviation from standard. 
Notes: 
I. Basically, the amount of light which strikes the 
receiving fibers is determined by the distance from 
the surface under inspection to the ends of the 
fibers. if this distance is zero, obviously no light 
will be received because the transmitting fibers are 
prevented from emitting light. As the distance in-
creases, the amount of light increases until a dis-
tance of approximately twice the fiber diameter is 
reached. Beyond this distance the amount of re-
ceived light falls off, becoming proportional to 
the reciprocal of the square of further increase in 
distance.
2. Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69-101 52 
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: H. M. Zoike
of Metro Physics Inc.
under contract to
Marshall Space Flight Center

(MFS-20 157) 
Brief 69-10152	 Category 01


Surface irregularities detected by flare inspection instrument

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