Browse Prior Art Database

A COHERENT IMAGE PROCESSOR FOR PHOTORECEPTOR INSPECTION

IP.com Disclosure Number: IPCOM000026153D
Original Publication Date: 1990-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 4 page(s) / 121K

Publishing Venue

Xerox Disclosure Journal

Abstract

Simple Fourier Processor to Detect Physical Defects 8 J 12 10 L Camera Array Fourier Plane FIG. 1 XEROX DISCLOSURE JOURNAL - Vol. 15, No. 4 July/August 1990 233 A COHERENT IMAGE PROCESSOR FOR PHOTORECEPTOR INSPECTION( Cont'd)

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XEROX DISCLOSURE JOURNAL

A COHERENT IMAGE PROCESSOR FOR PHOTORECEPTOR U.S. C1.355/210 INSPECTION Int. C1. G03g 15/00 John R. Andrews

Proposed Classification

Simple Fourier Processor to Detect Physical Defects

8

J

12

10

L

Camera Array

Fourier Plane

FIG. 1

XEROX DISCLOSURE JOURNAL - Vol. 15, No. 4 July/August 1990 233

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A COHERENT IMAGE PROCESSOR FOR PHOTORECEPTOR INSPECTION( Cont'd)

Electrooptic Fourier Processor to Detect Electrical Defects

30

36

II' 34

J

10

L

/ *O

Camera CCD Array

234 XEROX DISCLOSURE JOURNAL - Vol. 15, No. 4 July/August 1990

\ 32 12 '

Fourier Plane

FIG. 2

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A COHERENT IMAGE PROCESSOR FOR PHOTORECEPTOR INSPECTION( Cont'd)

Figure 1 and 2 illustrate the use of a Fourier processor to detect defects in a photoreceptor belt during its manufacture. Both systems utilize the principle that in the focal plane of a lens the spatial characteristics of the input image are Fourier-transformed, i.e., the characteristics of the image are transformed into a spatial frequency spectrum. If one uses a second identical lens at the appropriate spacing one can generate an image of the input plane (in this case, the photoreceptor) at the output plane. Figure 1 shows a fixed system 8 for detecting physical defects (thickness variation, refractive index correction, etc.) in the photoreceptor. A coherent light source 10 is directed through the back of a transparent photoreceptor belt 12. The light passes through the belt and is focused by lens 14 at the focal (Fourier) plane. A filter 16 will block all light except that created by defects in the belt 12, which can have contributions at many non-zero spatial frequencies and over a wide range of the Fourier plane. The light is projected by second lens 18 onto an...