Three dimensional imaging device comprising a lens system for

Abstract

A three dimensional imaging device has a converging lens system defining an optical axis, known as the Z direction. The imaging device also includes a position sensitive detector that has a series of pixels extending in at least a selected one of two mutually perpendicular X and Y directions both perpendicular to the Z direction. The lens system will simultaneously image a plurality of distributed points on a target surface onto the detector to generate first data on the coordinate of each point on the target surface in the X and/or Y direction. Also included in the system is a mask having a pair of apertures spaced apart from each other in the selected direction and respectively aligned with portions of the lens system for imaging discrete dots on the detector. The spacing between the dots generates second data on the coordinate of each point on the target surface in the Z direction. The device is modified in such a way as to cause a point on the target surface at a reference plane that would normally appear as a single focussed dot on the detector now to appear as a pair of spaced, substantially fully focussed dots. This modification takes the form of modifying the lens system such that a pair of spherical lens portions are rendered aspherical with respect to each other while each remains spherical with respect to itself. Another component of the system scans the pixels to extract data for all points on the target surface.