Browse Prior Art Database

Holographic Inspection System

IP.com Disclosure Number: IPCOM000077944D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR [+2]

Abstract

A holographic inspection system is provided for inspecting circuit boards, to determine if the components thereon have been properly positioned and oriented and if there are any missing components. A hologram is made of a master circuit board 10, Fig. 1, having a complete set of components which are correctly placed and oriented. When constructing the hologram, the elements shown in Fig. 1 are placed on a vibration-free table. These elements include laser 15 which projects a beam of coherent light to beam splitter 20. The split beam of light is directed in two different light paths to mirrors 25 and 30. Mirror 25 reflects the impinging split beam of light to mirror 35, which in turn directs the beam to a beam expander 40 and onto firm plate 45.

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Holographic Inspection System

A holographic inspection system is provided for inspecting circuit boards, to determine if the components thereon have been properly positioned and oriented and if there are any missing components. A hologram is made of a master circuit board 10, Fig. 1, having a complete set of components which are correctly placed and oriented. When constructing the hologram, the elements shown in Fig. 1 are placed on a vibration-free table. These elements include laser 15 which projects a beam of coherent light to beam splitter 20. The split beam of light is directed in two different light paths to mirrors 25 and 30. Mirror 25 reflects the impinging split beam of light to mirror 35, which in turn directs the beam to a beam expander 40 and onto firm plate 45. Film Plate 45 becomes the hologram as mirror 30 directs the light impinging thereon to master circuit board 10 via mirror 50 and beam expander 55.

After film plate 45 is developed, the hologram 60 resulting therefrom is placed in the film holder as in Fig. 2. Master board 10 is replaced by test board 10a. The hologram 60 is illuminated by a reference beam of light from laser 15 via beam splitter 20, mirrors 25 and 35, and beam expander 40. Test board 10a is illuminated by the object beam of light from laser 15 via beam splitter 20, mirrors 30 and 50, and beam expander 55. The person inspecting test circuit board 10a adjusts the circuit board position, so that the image seen through hologram 60...