Phase sensitive parametric optical metrology: exploring the limits of three-dimensional optical metrology

2012 ◽  
Author(s):  
Richard M. Silver ◽  
Jing Qin ◽  
Bryan M. Barnes ◽  
Hui Zhou ◽  
Ronald Dixson ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Optical Metrology ◽  
Phase Sensitive

Holographic and Video Techniques Applied to Engineering Measurement

1971 ◽  
Vol 4 (12) ◽  
pp. 349-354 ◽  
Author(s):  
J N Butters ◽  
J A Leendertz
Keyword(s):  
Process Control ◽  
Holographic Interferometry ◽  
Speckle Pattern ◽  
Three Dimensional ◽  
Sampling Technique ◽  
Closed Circuit ◽  
Optical Metrology ◽  
Photographic Recording ◽  
Closed Circuit Television ◽  
Convenient Means

In a brief period, lasers have developed from curiosities of the physics laboratory to tools suited to incorporation in complex instrumentation systems. One line of progress has been through the applications of holography and holographic interferometry to engineering metrology where the potential of a precision comparator is realized without a convenient means of using it. The process, however, has formed a basis for development and the progress of holographic metrology is reviewed leading to more general concepts better described as “Coherent Optical Metrology”. The authors' latest developments in this area are described where, by means of a coherent optical sampling technique, three dimensional data is coded onto an electronic video waveform. The method is based on speckle pattern interferometry with optical to electronic interfacing by means of a modified closed-circuit television arrangement. With this instrumentation, most of the measurement facilities of holography are retained without many of the inconveniences arising from photographic recording. The data is processed electronically and displayed or presented in a form suitable for viewing or to actuate a stage of process control.

Automated High-Dynamic-Range Three-Dimensional Optical Metrology Technique

2014 ◽  
Author(s):  
Laura Ekstrand ◽  
Song Zhang
Keyword(s):  
Exposure Time ◽  
Measurement System ◽  
High Speed ◽  
Manufacturing Industry ◽  
Dynamic Range ◽  
Three Dimensional ◽  
Optical Metrology ◽  
High Contrast ◽  
Accuracy Measurement ◽  
3D Surfaces

Measuring three-dimensional (3D) surfaces with extremely high contrast (e.g., partially shiny surfaces) is extremely difficult with optical metrology methods. Conventional techniques, which involve measurement from multiple angles or camera aperture adjustments, pose issues for high accuracy measurement in the manufacturing industry because they are difficult to automate and often induce undesirable vibrations in the calibrated measurement system. This paper presents a framework for optically capturing high-contrast 3D surfaces via flexible exposure time variation. This technique leverages the binary defocusing technique that was recently developed at Iowa State University to allow digital fringe projection with a camera exposure time far shorter than the projector’s projection period. Since the camera exposure time can be rapidly adjusted in software, the proposed technique could be automated without mechanical adjustments to the measurement system. Moreover, the exposure times are sufficiently short as to be efficiently packed into a projection period, giving this technique the potential for high speed applications. Experimental results will be presented to demonstrate the success of the proposed method.

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