Project Title:

On-Line Sensing of Aircraft Vibration

94-1	03.06	8736

On-Line Sensing of Aircraft Vibration

Abstract:

A scanning CW coherent lidar system will be used to make proof-of-
principle measurements of spatially-resolved images of vibration of 
aircraft. A recently developed CW 2 mm lidar transceiver system 
will be used to evaluate the capability of a coherent lidar to 
collect useful vibrational data on operational aircraft. Concepts 
for both ground-based measurements and flight measurements will be 
evaluated. In Phase I of the proposed program a scanning system 
will be developed and integrated with 
the transceiver for transport to a suitable observation site. A 
demonstration measurement program will be carried out to acquire 
spatial maps of the vibrational characteristics of operating 
aircraft during ground testing and to compare the results with 
those from conventional instrumentation. Concepts for an 
operational sensing system will be developed. A plan for 
implementation and demonstration of a fieldable prototype in 
Phase II and its commercialization in Phase III will be defined.

A scanning coherent laser system can acquire quantitative 
vibration spectra from a remote location in a very short time 
and at many spatial locations on a scanned target area. Many 
Applications exist for such remote measurements at moderate 
ranges ( 1 kilometer) that monitor vibration by observation of 
the motion of accessible surface elements. On-line remote 
monitoring of moving or stationary vehicles, including aircraft 
and autos during ground test, railroad wheel bearings on passing 
trains or municiple transit systems are some applications. The 
ability of the laser to operate in a strobe mode allows remote 
scanning and measurement of vibration and flexing of rotating 
elements, such as turbine, helicopter, and propeller blades.

KEY WORDS

Coherent Technologies, Inc.
P. O. Box 7844
Boulder, CO  80306