Graduate Thesis Or Dissertation
 

Processing of laser interferometric signals for small displacement measurements

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/2v23vx611

Descriptions

Attribute NameValues
Creator
Abstract
  • 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.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details PengGwoShen1992.pdf 2017-08-15 Public Download