A new type of optical range sensor is being developed which makes use of the shallow depth of field of a type II confocal scanning optical microscope. The range resolution is of the order of 2 μm at a 10-20 cm distance from the lens. We have shown that the system works well on rough surfaces, although with a much decreased output signal. In another set of experiments employing microscope lenses, various versions of the system are being used to measure the thickness of transparent films with a thickness of the order of 100 nm to 5 μm with good accuracy and with transverse resolutions in the 150-500 nm range. We can scan the beam electronically with a Bragg cell, or mechanically, to measure the profiles of objects.
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1987
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