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Inspection Machine

IP.com Disclosure Number: IPCOM000039131D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

Presented in this publication is a machine which makes possible the rapid inspection of many components by comparison with a single template. Flaws or variations from the norm are immediately pinpointed by the machine. The figure illustrates the functioning of the machine. A laser beam is split into three components, two of which are used to pump the Phase Conjugate Mirror (PCM) 1, and the third, called the probe beam, is used to illuminate template 2 through a system of lenses 3 and spatial filters 4. Mirror M1 reflects an image of the template onto PCM 1. The PCM generates a time-reversed wave form which, if allowed to propagate freely, would be reflected by mirror M1 back onto the template, and pass through the filters and lenses to form a collimated beam directed into the laser.

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Inspection Machine

Presented in this publication is a machine which makes possible the rapid inspection of many components by comparison with a single template. Flaws or variations from the norm are immediately pinpointed by the machine. The figure illustrates the functioning of the machine. A laser beam is split into three components, two of which are used to pump the Phase Conjugate Mirror (PCM) 1, and the third, called the probe beam, is used to illuminate template 2 through a system of lenses 3 and spatial filters 4. Mirror M1 reflects an image of the template onto PCM 1. The PCM generates a time-reversed wave form which, if allowed to propagate freely, would be reflected by mirror M1 back onto the template, and pass through the filters and lenses to form a collimated beam directed into the laser. However, beam splitter 5 instead redirects the conjugate beam onto mirror M2, to mirror M3, and onto Piece Under Test (PUT) 6. When PUT 6 is identical to the template, the light is coherently scattered through the second set of lenses 7 and spatial filters 8, and forms an image. By altering the second set of filters, as, for example, by using inverse filters, it can be arranged that the only light emerging in the output image results from differences between the PUT and the template. A video pick-up or detector screen together with computer image processing can analyze the light signal to quantify the differences and pinpoint the places where the PUT and template ha...