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Position Detection of an Extended Light Spot

IP.com Disclosure Number: IPCOM000079169D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Korth, HE: AUTHOR [+2]

Abstract

To track the movement of the photometric neutral axis of an extended light spot, i.e., the neutral axis of the area included by the X-axis of a Cartesian coordinate system and the curve representing the intensity distribution of the light spot in the direction of the X-axis, the light beam forming the light spot is directed onto photodiode array 5 consisting of photodiodes 5-1 to 5-40. The resolution of array 5 is improved by cylindrical lens 3 providing an image of light spot 1, magnified in a horizontal direction. To concentrate the energy of light beam 2 on array 5, a second cylindrical lens 4 having its main axis perpendicular to the main axis of lens 3 is arranged in the beam path.

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Position Detection of an Extended Light Spot

To track the movement of the photometric neutral axis of an extended light spot, i.e., the neutral axis of the area included by the X-axis of a Cartesian coordinate system and the curve representing the intensity distribution of the light spot in the direction of the X-axis, the light beam forming the light spot is directed onto photodiode array 5 consisting of photodiodes 5-1 to 5-40. The resolution of array 5 is improved by cylindrical lens 3 providing an image of light spot 1, magnified in a horizontal direction. To concentrate the energy of light beam 2 on array 5, a second cylindrical lens 4 having its main axis perpendicular to the main axis of lens 3 is arranged in the beam path.

Photodiodes 5-1, 5-9, 5-17, 5-25 and 5-33 are connected to impedance converter 6-1, and photodiodes 5-2, 5-10, 5-18, 5-26 and 5-34 are connected to impedance converter 6-2. Photodiodes 5-3 to 5-40 are connected in the same manner to impedance converters 6-3 to 6-8.

Resistors 7-1, 7-16, 8-1 and 8-16 are arranged in two rows 7 and 8 and in four groups A to D. Resistor 7-1 in row 7, group A, and resistors 8-6, 8-10, 8-14 in row 8, groups B C D, are connected to the output of impedance converter 6-1. Resistors 7-4 and 7-6 of row 7, groups B and C, and resistors 8-11 and 8-16 of row 8, groups C and D, are connected to the output of impedance converter 6-2. The remaining impedance converters 6-3 to 6-8 are each connected in the same manner to...