Algorithms for analyzing laser interferometry
signals were developed and adopted to the computer based
processing of small displacement measurements. These
methods, matrix operation approach and fixed parameters
approach, are based on signal phase calculation and are
able to replace complex fringe counting electronic
circuits. The matrix operation provides an approach for
instantaneously displaying the results. The computer
fixed parameters analysis allows the laser intensity to
vary arbitrarily during a measurement. Displacement
caused by a piezoelectric crystal was measured. Second
order polynomial curve fitting was performed. The root
mean square error is found to be 0.0086 μm in this 8-bit
data acquisition system. CTEs of a fused silica plate
and a tube were measured by an interferometry system.
Signals were analyzed by both manual chart approach and
computer based fixed parameters approach. Results agree
well with published data. The accuracy of the CTE
measurement system was 4 μ€, one third of the reference
NBS SRM 739 suggested standard deviation. Out-of-plane
and in-plane displacements can be measured independently
from speckle interferometry. Their resolutions are
0.3164 μm/cycle for the out-of-plane configuration and
0.224 μm/cycle for the in-plane configuration with light
incident angle of 45°. Optical systems with Fast Fourier
Transform data analysis showed that the minimum
detectable vibration amplitudes were 0.0065 μm, 0.0038
μm, and 0.0010 μm for the out-of-plane speckle, the in-plane
speckle, and Michelson interferometry systems
respectively. Resonance frequency of a steel rod was
found by the optical non-contact sensing system. The
modulus of elasticity calculated from the resonance
frequency was close to the literature data, 182 GPa vs.
200 GPa. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36539 |
| Date | 21 January 1992 |
| Creators | Peng, Gwo-sheng |
| Contributors | Wolff, Ernest G. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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