Bubble level sensor with fiber-optic field flattener is simple, rugged, small, and impervious to temperature and vibration effects. Pitch angles from -15 deg to +40 deg and roll angles of +30 deg are determined within 0.5 deg

Mattson, E. J.

Mcnally, P. F.

English

NASA Technical Reports Server

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April 1971	 Brief 71-10085 
NASA TECH BRIEF 
Maimed Spacecraft 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 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 Offi ce, NASA, Code KT, Washington, D. 1C. 20546. 
Modified Bubble Level Senses Pitch and Roll Angles Over Wide Range 
The addition of a fiber-optic field flattener enables 
a simple bubble level to be used as a sensor 
for determining pitch and roll angles over a wide 
range. The bubble level sensor is a desirable an-
Source 
gular position indicator because it is simple, rug-
ged, and small in size, and is impervious to the 
effects of temperature and vibration. 
The sensor (see fig.) consists of a base, a light 
source, a diffuser, a silicone fluid and a coherent 
fiber optic field flattener. The air bubble in the 
silicone fluid indicates pitch and roll angles by its
position on the spherical surface of the field flat-
teners. Indicial marks are placed on the flat sur-
face of the fiber optic bundle to aid in determin-
ing the pitch and roll angles from the location of 
the bundle. The fluid is contained in a spherical 
segment bounded by the diffuser and the spherical 
surface of the fiber optic bundle. Since the fibers 
are coherent, any pattern of light on the spherical 
surface is transmitted to the flat surface; hence, 
the fiber optic bundle serves as a field flattener. 
In the original application, the sensor was placed 
inside the body of a camera, and an image of the 
bubble was directed to the film for the purpose 
of recording the roll and pitch angles at the time 
of exposure. Pitch angles from - 7r/12 to + 7r/4 rad. 
(-15° to +45°) and roll angles of +ir/6 rad. (+30°) 
were determined within ir/360 rad. (0.5°). 
Note: 
No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Manned Spacecraft Center, Code JM7 
Houston, Texas 77058 
Reference: B71-10085 
Patent status: 
No patent action is contemplated by NASA. 
Source: Edward J. Mattson and

Paul F. McNally of

Goerz Optical Co., Inc.
under contract to

Manned Spacecraft Center
(MSC-13506) 
Category 03 
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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Modified bubble level senses pitch and roll angles over wide range

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