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Browse Prior Art Database

Cylindrical Integrating Cavity as Illumination Device for Scanners

IP.com Disclosure Number: IPCOM000103619D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 3 page(s) / 83K

Publishing Venue

IBM

Related People

Prakash, R: AUTHOR

Abstract

Spherical integrating cavities are used as uniform light sources for a variety of optical meteorological applications. Since the light from the source goes through a number of reflections within the cavity, near uniform distribution of optical energy over the exit port is easily achieved. Several factors influence the uniformity, including the size of the light source, cavity, and the exit port. Lamp orientation also plays a major role.

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Cylindrical Integrating Cavity as Illumination Device for Scanners

       Spherical integrating cavities are used as uniform light
sources for a variety of optical meteorological applications.  Since
the light from the source goes through a number of reflections within
the cavity, near uniform distribution of optical energy over the exit
port is easily achieved.  Several factors influence the uniformity,
including the size of the light source, cavity, and the exit port.
Lamp orientation also plays a major role.

      Disclosed is a method for document illumination in a scanning
device.  The system contains two cylindrical integrating cavities,
each using several incandescent lamps.  The cavity details are shown
in Figs. 1a, 1b, 1c, which are a top view, a cut away front view
and a side view, respectively.  The cavity 5 consists of a
cylindrical section, with the inside painted with a white highly
reflective material.  Three lamps 6 are placed inside the cavity.
The figure also shows two air ports 7 that are used to maintain the
cavity temperature to a reasonable value.

      Fig. 2 illustrates the system layout.  Two integrating cavities
8 are used to illuminate the document 9.  The lens 10 images the
document on a linear CCD (charged coupled device) 11.

      The location of the lamps 6, in combination with the cavity
geometry, provides for desired intensity profiles (Fig. 3).  The
higher peaks at the end illuminate the edges of the document to...