Technique individually photographs first the orifice in the transparent object and then a microscopic scale immersed in a liquid having the same index of refraction as the transparent object. Using a scale photograph, the orifice photograph is measured

Mills, S. M.

Salmirs, S.

English

NASA Technical Reports Server

December 1971	 Brief 71-10505 
•	 NASA TECH BRIEF 
Langley Research Center 	 4r 
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 aubscription 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 Oflce, NASA, Code KT, Washington, D.C. 20546. 
Measuring Internal Dimensions of Small Transparent Objects 
The problem: 
Measure the dimensions of an internal orifice or 
other contour in a transparent object. 
The solution: 
Individually photograph first the orifice in the 
transparent object and then a microscopic scale im-
mersed in a liquid having the same index of refrac-
tion as the transparent object. Using the photograph 
of the scale, measure the photograph of the orifice. 
Microscope Gloss Plate 
Objective  
Orifice-.-....	 II	 ...-.	 I I	 Glass Container 
Plane of 
Focus 
7l[	 1___Benzene & 
Methanol 
Solution 
Glass Slide on 
Microscope Stage/ 
Collimator
Figure 1 
How it's done: 
Immerse the transparent object in a liquid having 
the same index of refraction (Fig. I). The bound-
aries of the orifice appear as dark lines and may be 
photo micrographed (Fig. 2). A second photomicro-
graph of a calibrated microscope recticle slide (Fig. 
3) is made using the same lens combination, with 
the slide immersed in the same fluid. It is necessary 
to completely fill the container and to place a thin
glass plate directly on the surface of the liquid in 
order to eliminate vibration resulting from evapora-
tion. 
This technique has been used to measure internal 
dimensions of objects up to one half inch in diam-
eter with an accuracy of 0.00008 inch, using a long 
working distance objective. 
Figure 2. Microscopic View of Orifice 
Note: 
No additional documentation is available. Spe-
cific questions, however, may be directed to: 
Technology Utilization Officer 
Langley Research Center 
Langley Station 
Hampton, Virginia 23365 
Reference: B71-10505 
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=19710000502 2020-03-17T02:26:14+00:00Z
Patent status: 
No patent action is contemplated by NASA. 
Source: S. Salmirs and
S.M. Mills
Langley Research Center 
(LA R-10712) 
Figure 3. Microscopic View of Calibrated
Microscope Reticle Slide
ri 
Brief 71-10505
	
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Measuring internal dimensions of small transparent objects

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