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Browse Prior Art Database

Optical Inspection With Fiber Grating

IP.com Disclosure Number: IPCOM000062267D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gupta, A: AUTHOR

Abstract

The ability of a fiber grating to produce a two-dimensional array of light spots when illuminated by a laser finds particular utility in performing fast simultaneous inspection of multiple locations.

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This is the abbreviated version, containing approximately 100% of the total text.

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Optical Inspection With Fiber Grating

The ability of a fiber grating to produce a two-dimensional array of light spots when illuminated by a laser finds particular utility in performing fast simultaneous inspection of multiple locations.

Referring to the Figure, light from laser 1 illuminates grating 2 of crossed optical fibers to generate a two-dimensional array of multiple beams 3 directed via lens 4 to locations 5 at workpiece 6. Workpiece 6 may be a substrate having a plurality of regularly arranged pads 5 each carrying a solder ball. The presence or size of the solder balls can be noted by detecting the uniformity of reflected light at each pad with a microscope 7 or lens 8 to focus the reflected light beams onto an array of photodetectors 9.

An alternate application for the fiber grating setup is as part of a thickness monitor for large areas when depositing transparent coatings. In such arrangements the interference fringe pattern between light reflected from the top and bottom surfaces of a transparent film being deposited can be monitored concurrently at many locations on a work area. In this case either a one- or two- dimensional fiber grating can be used.

Distance between adjacent light spots produced by the grating is a function of the diameter of the grating fibers, laser wavelength and focal length of the lens.

Disclosed anonymously.

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