A new system for optical displacement measurement

Two known methods of measuring the displacement of a light beam double dagger are discussed and it is shown that while neither is really satisfactory for accurate measurement, except under closely controlled conditions, a combination of the two methods gives greatly improved resolution and linearity, particularly with a light source having an arbitrary intensity distribution. It is shown that a wide variety of transfer functions (electrical output against displacement) could be produced using this method and some possible applications are suggested. A linear system using this method has been constructed providing a displacement range of 15 mm with an ultimate resolution of 5 μm.