A sensor for measuring displacement.
Typical conventional displacement sensors are the capaci-tance
gauges and the differential transformers, and their resolution is about 0.01 μm. In atomic force
microscopes (AFM), displacement of stylus is measured by optical lever method. Conventional
displacement sensors, with their limited spatial resolution and excess load applied to the object by
stylus, are not always applicable for micromachine-related purposes where the objective items are
very small. Some types of displacement sensors that use laser beam have a measurement spot of the