| 摘要 |
Interferometer apparatus for measuring the microtopography of surfaces in two dimensions (surface roughness) uses monochromatic light from a laser. A beam splitter divides the light and directs a beam to the surface being measured and another beam to a reflector. The phase of the reflected beam is varied linearly by means which applies a saw tooth wave to an electromechanical transducer on which the reflector is mounted. The beam is focused onto a spot on the surface by a lens which is translated along the surface in two dimensions. The beams from the reflector and the surface are recombined by the beam splitter and the interference fringe detected thus producing an alternating current signal. The waveform is tracked during the rising portion of the waveform and sampled and held during the retrace portion of the saw tooth. Finally, the resulting waveform is filtered to provide an alternating current (AC) output, the phase change of which is a measure of the topography of the surface to a high degree of accuracy, for example, less than one Angstrom (A) vertical resolution and one micron (um) horizontal resolution. The apparatus provides a low cost profile measurement device which is highly accurate.
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