Optical focusing system

An optical proximity detection system for detecting the proximity of a reflective surface of a workpiece to an image plane of an imaging lens, said system comprsing:

• source means for directing first and second beams of light through the imaging lens and towards the reflective surface of the workpiece to form first and second input images of portions of the source means at selected distances from the image plane of the imaging lens so that light reflected from the reflective surface of the workpiece is reimaged by the imaging lens to form first and second output images of the first and second input images, respectively, at positions determined by the relative spacing between the reflective surface of the workpiece and the image plane of the imaging lens;
• and
• detector means, responsive to the positions of the first and second output images, for producing a signal having a magnitude and a polarity indicative of the position of the reflective surface of the workpiece relative to the image plane of the imaging lens.

An optical plane detection system for detecting the orientation of a reflective surface of a workpiece relative to an image plane of an imaging lens, said system comprising:

• source means for directing light through the imaging lens and towards three spaced regions of the reflective surface of the workpiece to form at each of said regions first and second input images of portions of the source means at selected distances from the image plane of the imaging lens so that light reflected from each region is reimaged by the imaging lens to form corresponding first and second output images at positions determined by the relative spacing between that region and the image plane of the imaging lens;
• and
• detector means, responsive to the positions of the first and second output images from each of said regions of the reflective surface of the workpiece, for producing a corresponding signal having a magnitude and a polarity indicative of the position of that region relative to the image plane of the imaging lens, the signals for all three of said regions being indicative of the orientation of the reflective surface of the workpiece relative to the image plane of the imaging lens.