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Photographic Light Meter and Self Powered Exposure Controller

IP.com Disclosure Number: IPCOM000078979D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Hovel, H: AUTHOR [+2]

Abstract

A radiation detector and energy converter for use with visible light applications, such as photography or quantitative monitoring of visible light, is described. Prior art light meter cells have had the undesirable properties of either detecting radiation outside the visible spectrum or only a part of the visible spectrum. The figure shows a radiation detector-energy converter comprising a layer of n-type gallium arsenide 1 on which layers 2, 3 of n- and p-type Ga(0.7)Al(0.3) As, respectively, are deposited. A p-type layer 4 of Ga(1-x)Al(x)As, where 0.7

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Photographic Light Meter and Self Powered Exposure Controller

A radiation detector and energy converter for use with visible light applications, such as photography or quantitative monitoring of visible light, is described. Prior art light meter cells have had the undesirable properties of either detecting radiation outside the visible spectrum or only a part of the visible spectrum. The figure shows a radiation detector-energy converter comprising a layer of n-type gallium arsenide 1 on which layers 2, 3 of n- and p-type Ga(0.7)Al(0.3) As, respectively, are deposited. A p-type layer 4 of Ga(1- x)Al(x)As, where 0.7 </-x </- 1, forms a transparent contact to layer 3. The energy converter formed from layers 2 and 3 provides an output which can be detected by ammeter 5.

The above arrangement can be utilized as a light meter or self-powered exposure controller in photographic or other visible light applications. The advantage of this cell is that it "sees" what the eye sees and what photographic film sees, and nothing else. Thus, on hazy days, when signals of previously used cells dropped too much, thus overexposing film, the present device provides a current reading. Furthermore, it converts light into electrical power, which can be used in a camera to control either the shutter or diaphragm without the need of a battery.

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