Browse Prior Art Database

Holographic Character Generator

IP.com Disclosure Number: IPCOM000087178D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 65K

Publishing Venue

IBM

Related People

Pole, RV: AUTHOR [+2]

Abstract

A holographic device is described which, when illuminated by a pulsed laser beam, is capable of forming high resolution character images and deflecting them into appropriate positions for nonimpact printing purposes.

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Holographic Character Generator

A holographic device is described which, when illuminated by a pulsed laser beam, is capable of forming high resolution character images and deflecting them into appropriate positions for nonimpact printing purposes.

The holographic device is capable of projecting on the image plane, such as a photoconductor drum, for example, the full image of a desired character. The deflecting properties of the device can position that character anywhere along the printing line, and since one of the characters in the set can always be a single point, this device can also be used as a simple point deflector.

The employment of this device in a nonimpact printing machine or an optically addressable display would not only obviate the need for the electronic circuits associated with character generation, but would also generate characters of much higher quality and less rugged appearance without sacrificing the image- producing capabilities of the machine. A number of different fonts are provided, and these fonts can be accessed by simple rephasing of the laser pulse stream.

The holographic device comprises a cylinder and the information on the cylinder is recorded as holograms formed by the interference of two coherent beams. As shown in the upper figure, a vertically offset divergent beam 10, emanating from a point on the axis of the cylinder, serves as a reference beam. The object beam 12 is now a spatially incoherent image beam formed by an appropriate transparency 14 and back-up scatterer 16. This beam is focused through a vertically limiting aperture into the image plane 18 by the imaging lens
20. This lens is cut into a narrow horizontal strip so as not to obstruct the reference beam, and to form a hologram over the slim rectangle of the holographic segment.

Once such a hologram is developed, the image of the original transparency can be reproduced by illuminating any portion of the segment with a narrow beam of the same divergence as the original reference beam 10. If, conversely, the illumination beam is stationary, and the holographic cylinder is rotated, the image of the character will move across the image plane 18.

The holographic character generator (HCG) is constructed in the form of a cylinder in which there are n holographic bands, with each band consisting of m holographic segments. Different characters can now be recorded in different bands and differ...