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TWO CAMERA FOCUS PROCESS FOR A LASER DIODE RASTER OUTPUT SCANNER

IP.com Disclosure Number: IPCOM000027693D
Original Publication Date: 1998-Oct-31
Included in the Prior Art Database: 2004-Apr-08
Document File: 2 page(s) / 53K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed is a method for measuring best focus of a Laser Diode Raster Output Scanner (LDROS) used in an electrostatographic printing machine. During LDROS verification with a production test fucture, the laser itself needs to be focused at the printer's image plane. Heretofore focusing was accomplished using a single Charge-Coupled Device (CCD) camera placed at the image plane. Upon moving the Iaser and measuring spot size after each move, the laser would be set and tightened after the smallest spot size was achieved. However, valuable time was lost by the trail and error of finding the optimum focus point.

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XEROX DISCLOSURE JOURNAL

TWO CAMERA FOCUS PROCESS FOR A LASER DIODE RASTER OUTPUT SCANNER Andrew J. Maltese
Melvin J. Russell, Jr.

Proposed Classification
U. S. CL 3991118 Int. CL G03g 15/00

Disclosed is a method for measuring best focus of a Laser Diode Raster Output Scanner (LDROS) used in an electrostatographic printing machine. During LDROS verification with a production test fucture, the laser itself needs to be focused at the printer's image plane. Heretofore focusing was accomplished using a single Charge-Coupled Device (CCD) camera placed at the image plane. Upon moving the Iaser and measuring spot size after each move, the laser would be set and tightened after the smallest spot size was achieved. However, valuable time was lost by the trail and error of finding the optimum focus point.

By changing to a two camera system of focus measurement, with continuous operator feedback, focus measurement time is halved. Placing the CCD cameras at spots equal distance in front of and behind the image plane ensures that the spot size at each camera is equaL The laws of optics define the LDROS beam to be at best focus

DP5769

XEROX DISCLOSURE JOURNAL - Vol. 23, No. 5 September/October 1998 253

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254 XEROX DISCLOSURE JOURNAL - Vol. 23, No. 5 September/October 1998

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