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Browse Prior Art Database

Analog To Digital Converter

IP.com Disclosure Number: IPCOM000089938D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Pennington, KS: AUTHOR [+2]

Abstract

This high-speed optical analog-to-digital converter, shown in drawing A, includes laser 10 whose beam is deflected, for example, by an analog voltage applied to electro-optic deflection device 12. The deflected beam is incident on a hologram multilens 14. This generates a plurality of diffracted beams 16-1...16-N, each one of which is incident on a separate one of code plates 18-1...18-N. Behind each code plate is a separate one of integrating photodetectors 20-1...20-N. These produce an N-bit digital output code word directly related to the angular direction of propagation of the incident laser beam which, in turn, is directly related to the analog voltage applied to deflection device 12.

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Analog To Digital Converter

This high-speed optical analog-to-digital converter, shown in drawing A, includes laser 10 whose beam is deflected, for example, by an analog voltage applied to electro-optic deflection device 12. The deflected beam is incident on a hologram multilens 14. This generates a plurality of diffracted beams 16-1...16- N, each one of which is incident on a separate one of code plates 18-1...18-N. Behind each code plate is a separate one of integrating photodetectors 20-1...20- N. These produce an N-bit digital output code word directly related to the angular direction of propagation of the incident laser beam which, in turn, is directly related to the analog voltage applied to deflection device 12. If a nonlinear relationship exists between the angle of deflection and the analog voltage, compensation can be made by making the code plates nonlinear by using the device to initially form the code plates.

Another arrangement of the converter can be employed by providing a cylindrical lens system in the path of the deflected beam from deflector 12. The cylindrical lens system images the deflected beam onto a conventional code plate behind which is a plurality of strip photodetectors.

Hologram multilens 14 also produces a zero order beam 22. Most power flows through the zero order beam 22 and it can, therefore, be employed to perform functions such as scanning. This is accomplished by providing a feedback path as in drawing B. A feedback signal is...