Optical spatial frequency filter
Abstract
Abstract IN AN OPTICAL SYSTEM FOR FORMING A REPRESENTATION OF A SCENE AT AN IMAGE PLANE, A WEDGE STRUCTURE OF OPTICAL QUALITY MATERIAL IS DISPOSED BETWEEN THE SCENE AND THE IMAGE PLANE. THE LIGHT PASSING THROUGH DIFFERENT SECTIONS OF THE WEDGE STRUCTURE IS DEFLECTED IN DIFFERENT DIRECTIONS, FORMING A PLURALITY OF DISPLACED IMAGES AT THE IMAGE PLANE. THE SUMMATION OF THE VARIOUSLY DISPLACED IMAGES RESULTS IN A MODULATION TRANSFER FUNCTION EXHIBITING SUBSTANTIAL ATTENUATION OF THE SPATIAL FREQUENCY COMPONENTS WITHIN A PREDETERMINED FREQUENCY RANGE. THE WEDGE IS DESIGNED AND ORIENTED TO PRODUCE ANGULAR DEFLECTIONS WHICH YIELD SPECIFIC DISPLACEMENTS OF THE IMAGES AND A CORRESPONDING SPATIAL FREQUENCY REJECTION BAND. THE FILTER MAY BE USED TO AVOID ALIASTING IN COLOR TELEVISION CAMERAS HAVING STRIPED COLOR MODULATING GRATINGS BY UTILIZING THE WEDGE TO INSURE HIGH ATTENUATION IN THE VICINITY OF THE SPATIAL MODULATION FREQUENCY PRODUCED BY THE STRIPED COLOR GRATINGS. D R A W I N G
Inventors
- 👤 A Larsen
Bibliographic Details
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