CHARACTERISTICS OF A GUIDED-WAVE DISPLACEMENT SENSOR-BASED ON WAVE-FRONT DETECTION

The characteristics of a guided-wave displacement sensor based on the wavefront detection are obtained. The displacement is measured by dete cting the wavefront gradient of the light reflected from the measured object. The wavefront gradient is determined using the mode interferen ce of the even and odd modes in the double-mode waveguide which is fab ricated of silica glass on a Si substrate. The measuring range is 3 mu m and the resolution is determined to be less than 1 nm. The object t ilting dependence and the stability of the sensor are also measured. F urthermore, sample surfaces are observed and very fine images are obta ined using this sensor. The optical system is very simple and the sens or is very compact, hence it will be useful as a built-in component fo r various kinds of industrial equipment.