Browse Prior Art Database

Laser Beam Intensity Tester

IP.com Disclosure Number: IPCOM000053155D
Original Publication Date: 1981-Sep-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Lawton, J: AUTHOR [+2]

Abstract

This article describes a simple electrical circuit for monitoring the alignment of an expanded laser beam. One use of the device is in the manufacture of holographic optical elements.

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Laser Beam Intensity Tester

This article describes a simple electrical circuit for monitoring the alignment of an expanded laser beam. One use of the device is in the manufacture of holographic optical elements.

In making or copying holographic optical elements, a segment of holographic recording material is exposed using an expanded laser beam. If the intensity of the beam is not uniform over the area of the exposed segment, the resulting holographic optical element will have non-uniform characteristics.

The uniformity of illumination provided by an expanded laser beam is primarily a function of the physical alignment of the laser. A laser beam can be aligned by visual observation of the expanded beam. There are drawbacks to this approach. It is subjective and may be inaccurate since it depends entirely on a given operator's perception of beam intensity at certain points. It may also be time consuming and inefficient. The laser beam may have to be realigned repeatedly during the manufacturing cycle since thermal expansion or contraction may cause the beam to "wander".

The drawing shows a simple system for providing objective measurements of the intensity of an expanded laser beam over a limited area. A plurality of solar cells 10 are arranged in a cruciform configuration on a circular fixture 12. The solar cells 10 are connected to the negative input of an operational amplifier 14 through individual switches in a switch bank 16. The positive input to the operati...