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Dual Spot Scanning Technique

IP.com Disclosure Number: IPCOM000097373D
Original Publication Date: 1962-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Gelernter, HL: AUTHOR [+3]

Abstract

This dual spot scanning technique permits a document to be simultaneously scanned at a high resolution and at a low resolution. Such arrangement provides signals which are indicative of the intensity of the recorded data with respect to the document background intensity.

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Dual Spot Scanning Technique

This dual spot scanning technique permits a document to be simultaneously scanned at a high resolution and at a low resolution. Such arrangement provides signals which are indicative of the intensity of the recorded data with respect to the document background intensity.

A scanning beam of light having energy of at least two wavelengths is generated by a cathode ray tube scanner 1. The beam is directed toward a document transparency 2 by a lens 3 and an arrangement of mirrors 4, 5, 6 and
7. Dichroic mirrors 4 and 5 transmit the light energy at one wavelength toward the document 2. The light energy at the second wavelength is reflected by dichroic mirror 4, conventional mirrors 6 and 7 and dichroic mirror 5 toward the document.

Since the two light paths are of different lengths, the light in one path may be focussed on the transparency while the light in the other path is defocussed. The light energy emanating from the document is directed through lens 8 toward another dichroic mirror 9. This transmits the light energy at one wavelength to photomultiplier 10 and reflects the light energy at the second wavelength to another photomultiplier 12. The photomultiplier output signals on leads 11 and 13 are indicative of the intensity of the recorded data with respect to the document background intensity.

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