Alignment Verification Using Holographic Correlation

Kevin G. Harding; Mark Michniewicz

doi:10.1117/12.947569

16 January 1989 Alignment Verification Using Holographic Correlation

Kevin G. Harding, Mark Michniewicz

Proceedings Volume 0954, Optical Testing and Metrology II; (1989) https://doi.org/10.1117/12.947569
Event: SPIE International Symposium on Optical Engineering and Industrial Sensing for Advance Manufacturing Technologies, 1988, Dearborn, MI, United States

Abstract

Holographic correlation filters have been used for a variety of recognition tasks, generally related to military applications. In these applications, the holographic correlation filter is made in the Fourier transform plane of some known subject, then compared to an unknown to determine degree of correlation or fit. Correlations of this type have the properties of very high speed, near insensitivity to position of the subject, and tolerance to small variations in the subject. The output from a correlation operation of this type is typically a single point of light, the intensity of which is a measure of the degree of correlation. Classical holographic interferometry, on the other hand, is unique to a particular diffuse subject and very intolerant to any rigid body motions of the subject. When a subject is moved in a holographic interferometry system, the interference fringes quickly decrease in contrast and vanish as the hologram becomes decorrelated. Positioning a subject with a real-time holographic interferometry technique can be very difficult as the fringes, which must be found, are moving very fast and are changing in character and shape as the object is moved through the referenced position. The use of a correlation filter simplifies this registration task by creating a single, unmoving correlation point, which can appear and vanish with the sensitivity of holographic interferometry, yet also be made flexible enough to determine near registration conditions. The use of a single element detector permits the reference position to be determined to a very high accuracy, with the very high speeds associated with optical correlations. Experimental results of using this technique for high accuracy registration of a zero position of a rotational shaft will be presented in this paper.

Citation Download Citation

Kevin G. Harding and Mark Michniewicz "Alignment Verification Using Holographic Correlation", Proc. SPIE 0954, Optical Testing and Metrology II, (16 January 1989); https://doi.org/10.1117/12.947569

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