CPC G01S 7/499 (2013.01) [G01S 7/484 (2013.01); G01S 7/4812 (2013.01); G01S 7/4863 (2013.01); G01S 17/10 (2013.01); G01S 7/4817 (2013.01)] | 9 Claims |
1. A photodetector, comprising:
a light detection portion;
a storage unit;
a control unit; and
a selection portion,
wherein the photodetector measures flight time by detecting reflected light from an illumination region of an object illuminated by pulse light, and the illumination region is imaged on the light detection portion as a projection region by an imaging optical element,
wherein the light detection portion is formed to be larger than the projection region,
wherein the light detection portion has photon detection elements configured of single photon avalanche diodes (SPADs) laid out as an array that has multiple rows and multiple columns,
wherein the control unit identifies a part of the photon detection elements that overlays the projection region,
wherein the storage unit stores a light-detection region configured of the part of the photon detection elements,
wherein the selection portion activates only the part of the photon detection elements to configure the light-detection region, and
wherein the control unit further:
identifies, of the multiple columns, abnormal columns where a dark count is greater than a specification value, the dark count being a cumulative count of a part of the photon detection elements that output pulse when dark,
performs a first test that illuminates a test piece by the pulse light in a state where all of the multiple rows are activated and only normal columns other than the abnormal columns in the multiple columns are activated, and identifies, of the normal columns, light-detection columns where a photon detection count from the reflected light is equal to or larger than a specification value in the first test,
performs a second test that illuminates the test piece by the pulse light in a state where all of the multiple rows are activated and only the light-detection columns in the multiple columns are activated, and identifies, of the normal rows, light-detection rows where a photon detection count from the reflected light is equal to or larger than a specification value in the second test, and
stores the light-detection region configured of the light-detection columns and the light-detection rows in the storage unit.
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