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Drive Circuit for Electro Optic Crystals

IP.com Disclosure Number: IPCOM000092788D
Original Publication Date: 1967-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Chang, D: AUTHOR [+2]

Abstract

Electro-optic crystals are used as optical shutte rs and light polarization rotators. To accomplish polarization rotation, a voltage that is a multiple of the half wavelength voltage for the crystalline material is impressed across the crystal. Electrolysis of the crystalline material and shortening of the crystal life occur when subjected to the steady application of the half wavelength voltage. By reversing the polarity of the voltage across the crystal within particular time boundaries, as in this circuit, the electrolysis problem is alleviated.

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Drive Circuit for Electro Optic Crystals

Electro-optic crystals are used as optical shutte rs and light polarization rotators. To accomplish polarization rotation, a voltage that is a multiple of the half wavelength voltage for the crystalline material is impressed across the crystal. Electrolysis of the crystalline material and shortening of the crystal life occur when subjected to the steady application of the half wavelength voltage. By reversing the polarity of the voltage across the crystal within particular time boundaries, as in this circuit, the electrolysis problem is alleviated.

Capacitors X1... Xn are electro-optic crystals. Each crystal is connected to an associated channel driver circuit 1... n. Common point 4 for crystals X1... X4 is ordinarily connected to a constant reference potential. However, in this circuit, point 4 is connected to a common reference driver circuit 5. The latter is driven between the same voltage levels as circuits 1... n at a repetitive rate between 1 and 10 cycles per second.

When a particular crystal is selected for operation through its channel driver circuit, the crystal is driven between the negative and positive half wavelength voltages at a rate considerably faster than the rate of operation of circuit 5. The effective voltage ac ross the crystal is either the positive half wavelength voltage or the negative half wavelength voltage. At every polarity reversal of circuit 5, the voltage across the selected crystal is inv...