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Optical Alignment Apparatus

IP.com Disclosure Number: IPCOM000083764D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Smith, JF: AUTHOR [+3]

Abstract

A subject 2 is to be positioned by apparatus 3 at a selected height. Dashed line 4 represents the upper surface of subject 2 at a different height. A helium-neon laser 5 produces a beam of light along a line 6 and a system of lenses 7 focuses the light at a point 8, which lies on the surface of subject 2 when the subject is at the selected height. A strong portion of the beam is reflected along a line 9, but the reflection of the beam from the surface of subject 2 can be viewed from other angles also.

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Optical Alignment Apparatus

A subject 2 is to be positioned by apparatus 3 at a selected height. Dashed line 4 represents the upper surface of subject 2 at a different height. A helium- neon laser 5 produces a beam of light along a line 6 and a system of lenses 7 focuses the light at a point 8, which lies on the surface of subject 2 when the subject is at the selected height. A strong portion of the beam is reflected along a line 9, but the reflection of the beam from the surface of subject 2 can be viewed from other angles also.

A pair of light-sensitive semiconductor devices 10 and 11 are mounted on a support 12 to face point 8 along a line 13, and to receive light from subject 2 through a lens system 14. Line 13 is at right angles to line 6, and lines 9 and 13 differ sufficiently that devices 10 and 11 are not illuminated by the strongly reflected portion of the laser beam.

Devices 10 and 11 are spaced apart on either side of line 13 on a surface of support 12 that is at right angles to line 13 and is parallel to line 6. A differential amplifier 15 produces an output according to the difference in illumination of devices 10 and 11.

When subject 2 is at the selected height, light from point 8 is focused between devices 10 and 12 so that they produce equal outputs and amplifier 15 produces a zero amplitude signal. When subject 2 is at a height represented by line 4, the light is reflected differently as dashed lines 16 represent, so that device 10 receives more...