| 摘要 |
PURPOSE: A multi-frequency heterodyne interferometer using an AOTF(Acousto-Optical Tunable Filter) is provided to obtaining a multi-frequency interferometer using an acousto-optical tunable filter, thereby constituting various complex wavelengths by avoiding 2π-ambiguity with an optical system of a simple structure. CONSTITUTION: A multi-frequency heterodyne interferometer using an AOTF comprises a light source(600), a polarization beam splitter(610), an acousto-optical tunable filter(620), an AOTF driving unit(630), a sample stage(640), a second beam route guide unit(650), a quarter wavelength phase-lag plate, a multi-wavelength demodulator(670), and a controlling unit(680). The light source provides multi-wavelength beams. The polarization beam splitter transmits or reflects the beams provided by the light source according to a polarization condition. The acousto-optical tunable filter divides the multi-wavelength beams into first and second beams per wavelengths according to RF frequencies and outputs the second beams by separating the same from the first beams at a different angle according to each frequencies. The AOTF driving unit provides driving RF frequencies to the acousto-optical tunable filter, thereby driving the acousto-optical tunable filter. The sample stage is arranged in a progressive path of the first beams, thereby providing signal beams by reflecting the first beams along an incident route of the first beams. [Reference numerals] (630) AOTF driving unit; (676) Demodulator
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