Adjustable bandwidth optical filter

摘要: THE OPTICAL APPARATUS USED IN A TELEVISION SYSTEM, FOR EXAMPLE, INCLUDES SERIES ARRANGEMENT OF THREE BIREFRINGENT ELEMENTS DIFFERENT THICKNESS INTERSPERSED WITH TWO QUARTER WAVE DELAY TO CONSTITUTE AN FILTER. FILTER IS PLACED LIGHT PATH BETWEEN OBJECT AND IMAGE FORMED AT PHOTOSENSITIVE ELEMENT CAMERA TUBE. SPATIAL FREQUENCY BANDWIDTH PASSING THROUGH CONTROLLABLE ONE OR MORE DIRECTIONS SAME AMOUNTS PLURALITY BY SUITABLE DIMENSIONING AND/OR APPROPRIATE ROTATIONAL POSITIONING ENTIRE ABOUT AXIS.