Interferometric measuring device for measuring shape of object surface

摘要

The measuring device includes a beam generator comprising a laser diode (1) for providing short coherent radiation. A beam (ST1) splitter forms two part beams, one (3) of which is directed onto the surface (7) to be measured, the other (4) being directed to a device with a reflecting element for periodically varying the optical path. The radiation from the surface and the radiation from the device are superimposed to cause interference, and a photodetector (11) detects the radiation. The beam generator includes a drive unit (15) for modulating the laser diode frequency to produce short coherent radiation. The modulation may by achieved by modulating the injection current or the geometric length of the resonator or the laser diode.