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Achromatized Compressor Prisms

IP.com Disclosure Number: IPCOM000037683D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Herring, FA: AUTHOR [+2]

Abstract

Compressor prisms 1 and 2 used in laser delete equipment were achromatized to facilitate accurate prealignment of the He-Ne laser 3 to assure that the working visible Ruby laser 4 struck a target precisely. Due to the wavelength difference of Ruby (6943A) and He-Ne (6328A) alignment laser, the two lasers beams did not track each other at refracting surfaces. Due to refraction at the prisms it was found that the He-Ne beam deviated from the Ruby beam in excess of eight minutes of arc which, over a distance of greater than 21 inches, produced a considerable beam displacement error. The solution was to achromatize the compressor prism 1, and provide an achromatic compensator block 5 so that the He-Ne alignment laser 3 would track parallel to the Ruby cutting laser 4 and no further optical alignments of the Ruby were required.

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Achromatized Compressor Prisms

Compressor prisms 1 and 2 used in laser delete equipment were achromatized to facilitate accurate prealignment of the He-Ne laser 3 to assure that the working visible Ruby laser 4 struck a target precisely. Due to the wavelength difference of Ruby (6943A) and He-Ne (6328A) alignment laser, the two lasers beams did not track each other at refracting surfaces. Due to refraction at the prisms it was found that the He-Ne beam deviated from the Ruby beam in excess of eight minutes of arc which, over a distance of greater than 21 inches, produced a considerable beam displacement error. The solution was to achromatize the compressor prism 1, and provide an achromatic compensator block 5 so that the He-Ne alignment laser 3 would track parallel to the Ruby cutting laser 4 and no further optical alignments of the Ruby were required.

Two glasses (P1,P2) of widely different dispersions, with approximately the same refraction characteristics for Ruby wavelength were selected to minimize Ruby deviatio within the prism 1 and compensator block 5. The He-Ne laser beam has a pronounced refraction within the interfaces to bring the He-Ne beam parallel to the Ruby beam. This provides a means of aligning a high power pulsed laser with a low power continuous wave laser.

The parallel displacement of the respective laser beams, while not negligible, would be difficult to measure, being on the order of less than 60 microns. This displacement will not affect...