INTERFEROMETER WITH A WAVELENGTH-TUNED DIODE-LASER FOR SURFACE PROFILOMETRY

An interference profilometer has been developed which uses a diode las er as a non-expensive, compact and wavelength tunable light source. Th e profilometer works like an optical stylus and can be realized at rel atively low expense. Two different methods of interference signal proc essing have been worked out. Both methods take advantage of the wavele ngth tunability of the diode laser. In connection with the development of the profilometer the spectral properties of different types of dio de laser in the wavelength range from 780 nm down to 633 nm have been measured. The performance of the profilometer was proved by comparison measurements with a HeNe laser interferometer and by the measurement of well known surfaces. A measurement range of up to 100 mu m and a me asurement uncertainty of better than 10 nm can be achieved.