Browse Prior Art Database

Automated Topography Measurement System

IP.com Disclosure Number: IPCOM000047461D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Feliss, NA: AUTHOR

Abstract

The surface topography of an element can be measured by means of the system shown in Fig. 1. The technique of measuring crown and recession makes use of an experimental apparatus employing monochromatic inter ferometry, data acquisition instrumentation, and computer algorithms to calculate the curvature or deformity of the interferometric fringes. Monochromatic fringes using light of wavelength g are projected onto the rail of the element (magnified 30x for crown, twist and camber, and 100x for recession). The fringes are aligned parallel to the rail as observed in Fig. 2 and 3 for measuring both crown and recession. Any slight deviation of the fringes from a straight line indicates surface contour changes.

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Automated Topography Measurement System

The surface topography of an element can be measured by means of the system shown in Fig. 1. The technique of measuring crown and recession makes use of an experimental apparatus employing monochromatic inter ferometry, data acquisition instrumentation, and computer algorithms to calculate the curvature or deformity of the interferometric fringes. Monochromatic fringes using light of wavelength g are projected onto the rail of the element (magnified 30x for crown, twist and camber, and 100x for recession). The fringes are aligned parallel to the rail as observed in Fig. 2 and 3 for measuring both crown and recession. Any slight deviation of the fringes from a straight line indicates surface contour changes. In the vicinity of the trailing edge, the fringes show a slight discontinuity between the trailing edge and the air bearing. A typical example can be observed in Fig. 3. If the fringes are projected along the entire air bearing surface from leading edge to trailing edge, any slight deviation from a straight line indicates a surface deformity. This deformity is characterized as crown, twist, and camber depending on the axis of measurement. The image of the rail and the fringe pattern is captured by a video camera and held "frozen" by means of a video storage device. The frozen image is then scanned by a digitizing cursor, and the output is stored in the memory of a small minicomputer. The computer then processes the scann...