Importance

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Abstract

A method and apparatus are provided for testing a photodetector (20) that has a narrow field of view (A) and an alignment surface (50), to determine whether the field of view and the axis (52) of the field of view are precisely what is expected or deviates therefrom. While the photodetector views a region or zone (102), a narrow spot of light (82) is moved into and out of the zone and across the zone, while the output of the photodetector is monitored. The narrow spot of light is generated by focusing a small spot of light onto a surface. The small spot of light can be a spot of light on an oscilloscope monitor (80) which scans the spot back and forth in a raster pattern. To create a very small spot, the image on the oscilloscope monitor is focused to a greatly reduced size spot image (124) onto the surface that the photodetector views.

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First Claim