Patent ID: 6724489
Filing Date: 2004-04-20
Classification: G01B

Abstract:
A system for measuring the spatial dimensions of a three-dimensional object, comprising:a source of light for illuminating said object; a lens and a sensor, the combination thereof defining an optical axis, said sensor including at least a first photodetector and a second photodetector; said object to be measured being aligned with an object plane substantially normal to said optical axis; said first photodetector being spaced a first distance from said lens and said second photodetector being spaced a second distance from said lens wherein said first distance is greater than said second distance, such that said first photodetector images at best focus a point in the object plane at some distance from said lens and determined by the focal length of said lens, and such that said second photodetector images at best focus a point further in said object plane from said lens, again determined by the focal length of said lens; separate electrical outputs being generated by said first photodetector and by said second photodetector wherein intensities of said separate electrical outputs are proportional light collected from said object by said lens; and an electronic processing module effective to capture and store said separate electrical outputs from at least said first and second photodetectors to determine distance along said optical axis from said lens to a point on said object by contrast comparison of at least said first and second photodetectors.