Optical correlator

• US 4,206,365 A
• Filed: 05/26/1978
• Issued: 06/03/1980
• Est. Priority Date: 01/17/1976
• Status: Expired due to Term

• Current Assignee: Ernst Leitz Wetzlar GmbH (ACM Project Development Co.)
• Original Assignee: Ernst Leitz Wetzlar GmbH (ACM Project Development Co.)
• Inventors: Leitz, Ludwig
• Primary Examiner(s): Mullins, James B.
• Application Number:
  US05/909,764
• Time in Patent Office: 739 Days
• Field of Search: 250/237 G, 250/550, 350/162 SF, 356/28, 356/28.5
• US Class Current: 250/550
• CPC Class Codes: G01P 13/00 Indicating or recording presence, absence, or direction, of movement electric switches H01H; counting moving objects G06M7/00
• CPC Class Codes: G01P 3/36 Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: G01P 3/806 in devices of the type to be classified in G01P3/68
• CPC Class Codes: G02B 27/0012 Optical design, e.g. procedures, algorithms, optimisation routines
• CPC Class Codes: G02B 27/46 Systems using spatial filters

Abstract

The invention relates to an optical correlator comprising an optical system for imaging an object space, a spatial frequency filter disposed in or close by the image plane, and at least one photoelectric detector assigned to said spatial frequency filter. According to the invention the spatial frequency filter is a raster, the structures of which extend in the direction of the perspective vanishing lines of the image of the object space and/or perpendicularly to at least one of said vanishing lines. The size of the structure elements and/or the distance between the elements constituting the raster structure are chosen according to the distortion of the perspective image.

Claims

1. An optical correlator having an imaging optic for imaging an object space having lines vanishing in the direction of the horizon into an image plane and a spatial frequency filter arranged substantially in said image plane and at least one photoelectric detector assigned to said spatial frequency filter, wherein the improvement comprises:

said spatial frequency filter in the form of a raster having structure elements which extend in said direction of the vanishing lines of the image of the object space.

2. An optical correlator as claimed in claim 1, wherein the raster structure elements extend in the direction of the vanishing lines of a central perspective.

3. An optical correlator as claimed in claim 2, wherein the spatial frequency filter is pivotable about an axis which extends substantially normal to the image plane and substantially intersects the vanishing point of the central perspective.

4. An optical correlator as claimed in claim 1, wherein at least portions of the structure elements are photoelectric detectors.

5. An optical correlator having an imaging optic for imaging an object space having lines vanishing in the direction of the horizon into an image plane and a spatial frequency filter arranged substantially in said image plane and at least one photoelectric detector assigned to said spatial frequency filter, wherein the improvement comprises:

said spatial frequency filter in the form of a raster having structure elements which extend in a direction perpendicular to at least one of said vanishing lines of the image of the object space.

6. An optical correlator as claimed in claim 5, wherein at least portions of the structure elements are photoelectric detectors.

7. An optical correlator as claimed in claim 5, wherein the vanishing lines to which the structure elements extend in a perpendicular direction are the vanishing lines of a central perspective.

8. An optical correlator as claimed in claim 7, wherein the spatial frequency filter is pivotable about an axis which extends substantially normal to the image plane and substantially intersects the vanishing point of the central perspective.

9. An optical correlator having an imaging optic for imaging an object space having lines vanishing in the direction of the horizon into an image plane and a spatial frequency filter arranged substantially in said image plane and at least one photoelectric detector assigned to said spatial frequency filter, wherein the improvement comprises:

said spatial frequency filter in the form of a single raster having structure elements with a first part of said structure elements which extends in the direction of said vanishing lines of the image of the object space and a second part of said structure elements which extends in a direction perpendicularly to at least one of said vanishing lines.

10. An optical correlator as claimed in claim 9, wherein the raster structure elements extend in the direction of the vanishing lines of a central perspective.

11. An optical correlator as claimed in claim 10, wherein the spatial frequency filter is pivotable about an axis which extends substantially normal to the image plane and substantially intersects the vanishing point of the central perspective.

12. An optical correlator as claimed in claim 9, wherein at least portions of the structure elements are photoelectric detectors.