Method for optically distorting readout reticles

• US 4,166,694 A
• Filed: 03/28/1978
• Issued: 09/04/1979
• Est. Priority Date: 03/28/1978
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Hagstrom, John R., Horning, John E., Radzai, Roy R.
• Primary Examiner(s): Wintercorn, Richard A.
• Application Number:
  US05/890,891
• Time in Patent Office: 525 Days
• Field of Search: 355/52, 355/46, 355/47, 355/77, 353/34, 353/25, 353/74, 353/94, 354/292, 340/378.2
• US Class Current: 355/77
• CPC Class Codes: G03B 21/00 Projectors or projection-type viewers; Accessories therefor devices for changing pictures G03B23/00
• CPC Class Codes: G03B 27/68 Introducing or correcting distortion, e.g. in connection with oblique projection

Abstract

A method for preparing distortion-compensated images on film reticles for e in a plural optical projector readout unit. An oversized matrix of the images is prepared with each legend proportionately positioned in the field of view corresponding to one of the plural optical projectors. A very short focal length lens having one surface flat and the other convex is placed over the matrix with the flat surface adjacent thereto. The images, distorted through the lens, is photographed to produce a film reticle in a size suitable for use in the readout unit. The spherical aberration induced by the lens closely approximates the barrel distortion from the off-axis projection and magnification in the readout unit. In this manner, the image projected on the screen from the film reticle proportionately corresponds to the images in the matrix.

Claims

1. A method of preparing a film reticle having a plurality of legends thereon for a readout unit having a corresponding plurality of optical projectors and a flat screen therefor, comprising the steps of:

preparing an undistorted flat layout of a plurality of legends arranged according to the corresponding position of the optical projectors of the readout unit;

exposing the layout on a photosensitive film through a very short focal length lens having a flat side adjacent to the layout; and

developing the photograhic image on said film into a film reticle of a size and configuration acceptable in the readout unit;

whereby the resulting film bears distorted images of the legends equal to the barrel distortion of the readout unit.

2. A method according to claim 1 wherein the lens is selected with a focal length and diameter sufficient to induce spherical aberrations closely approximating the barrel distortion.

3. A method of preparing a barrel distortion compensated film reticle having a plurality of legends thereon for a readout unit having a corresponding plurality of optical projectors and a flat screen therefor, comprising:

exposing a photosensitive film through a very short focal length lens to an undistorted flat layout of legends arranged according to the corresponding area projected by the respective projectors of the readout unit; and

developing the photographic image on said film into a film reticle in size and configuration acceptable to the readout unit.

4. A method according to claim 3 wherein the lens is selected with a focal length and diameter sufficient to induce spherical aberrations closely approximating the barrel distortion.