ISSN:
1741-2765
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract In remote-objective-speckle (ROS) metrology an individual single-mode optical fiber (SMF) is used to illuminate a small surface region with coherent light. The coarse objective-speckle pattern which is reflected from the surface moves when the surface moves, and easily can be transmitted through a flexible multimode image bundle (MMB) back to a remote photoelectronic digitizer/computer system for analysis and correlation. Sensitivity is a function of both the intrinsic gain of the optical system operating between the MMB output and the photoelectronic digitizer and/or monitor, and the geometrical parameters of the illumination and observation system used to input the speckle into the MMB. This investigation is concerned with understanding this latter, geometrical sensitivity,M for a fiber-based system. Results obtained for simple in-plane translations demonstrate the advantages and disadvantages of such an approach, and confirm the theoretical and experimental work of other investigators. For example, when the illumination beam is collimated, the speckle field moves with the surface such thatM=1. This is true regardless of the illumination angle, θ, or the observation distance, Z. However, when the illumination is not collimated (the numerical aperture of the SMF being greater than 0) the speckle field rotates as the surface translates and the geometrical sensitivity varies according to the two-parameter relationship $$M = \frac{{\rho + Z}}{\rho }$$ where ϱ is the radius of curvature of the illumination beam as it falls on the surface.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02321338
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