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Electro Optic Mask Selection

IP.com Disclosure Number: IPCOM000090610D
Original Publication Date: 1969-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Pfitzer, WA: AUTHOR

Abstract

Wherever photographic techniques are used for phototracing, artwork generation, photocomposing etc., a more or less great variety of masks is necessary to shape the light beam according to the requirements of the individual process stages. Selection of masks required in individual process stages usually is made by mechanical devices. For fast operation, an electro-optic light deflector is used to select the desired mask which is recentered, i.e., imaged, in a reference point common to all masks by a second light deflector.

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Electro Optic Mask Selection

Wherever photographic techniques are used for phototracing, artwork generation, photocomposing etc., a more or less great variety of masks is necessary to shape the light beam according to the requirements of the individual process stages. Selection of masks required in individual process stages usually is made by mechanical devices. For fast operation, an electro-optic light deflector is used to select the desired mask which is recentered, i.e., imaged, in a reference point common to all masks by a second light deflector.

An arrangement for mask selection and recentering comprises laser 6. Its radiation is passed through a beam expander consisting of lenses 7 and 8, electro-optic rotators 1...5, reflecting elements 31...35 lambda/4 plates 41...45 and 51...55, reflecting masks 21...25, common mirror 9 and lens 10. Each rotator
1...5 consists of a KDP crystal sandwiched between two transparent electrodes. If no voltage is applied to the electrodes, a linearly polarized beam of light passes the rotator without any rotation of its plane of polarization. If an adequate voltage is applied to the electrodes, the plane of polarization of a light beam passing the rotator is rotated by 90 degrees. Elements 31...33 are arranged to include the Brewster angle with the optical axis of the system.

Light, polarized parallel to the plane of the drawing, passes the elements
31...35 without being influenced. If the plane of polarization is perpendicula...