Method and apparatus for producing ambient light trapping filters

Claim 1

APPARATUS FOR PRODUCING SIMULTANEOUSLY A PLURALITY OF SUBSTANTIALLY PARALLEL DEPTHWISE SPACED LIGHT TRAPPING FILTER ELEMENTS OF GRID FORM IN A TRANSPARENT SHEET HAVING ALTERNATING LAMINAE OF PHOTO-SENSITIVE AND NON-PHOTO-SENSITIVE MATERIAL; THE GRID PATTERNS OF SAID ELEMENTS BEING IN PREDETERMINED REGISTRY, COMPRISING: AN OPAQUE LIGHT SHIELD HAVING AN ELONGATE LIGHT PASSAGE THERETHROUGH; A POINT-TYPE LIGHT SOURCE SPACED FROM ONE SIDE OF SAID SHIELD; A NARROW ELONGATE COLLIMATING LENS ON THE SAME SIDE OF THE LIGHT SHIELD DIRECTLY OVERLYING SAID LIGHT PASSAGE AND BEING OF SUBSTANTIALLY THE SAME LONGITUDINAL AND LATERAL DIMENSIONS AS SAID LIGHT PASSAGE; A MASK AT THE OPPOSITE SIDE OF SAID SHIELD MOVABLE PAST SAID LIGHT PASSAGE IN AN ARCUATE PATH AND IN A DIRECTION NORMAL TO THE LONGITUDINAL AXIS OF SAID PASSAGE; SAID MASK HAVING ALTERNATING OPAQUE AND TRANSPARENT PORTIONS ARRANGED IN A GRID PATTERN; AND MEANS TO MOVE SAID MASK AND SAID SHEET PAST SAID PASSAGE IN SAID ARCUATE PATH IN CLOSE CONTACT WITH EACH OTHER AND WITH THE MASK BETWEEN THE LIGHT SOURCE AND THE SHEET TO MOMENTARILY SUBJECT PORTIONS OF SAID PHOTO-SENSITIVE LAMINAE TO DEPTHWISE DIRECTED LIGHT RAYS FROM SAID SOURCE PASSING THROUGH THE TRANSPARENT PORTIONS OF SAID MASK.