Acousto-optic tunable filter

摘要

In a non-collinear type acousto-optic tunable filter, the incident angle of a source light beam L1 radiated from a light source 6 onto an acoustic medium 1 is set at an equivalence incident angle for which the wavelength lambda i of the diffracted ordinary ray L3 and the wavelength lambda i' of the diffracted extraordinary ray L4 become approximately identical. Further, the diffracted ordinary ray L3 and the diffracted extraordinary ray L4 of the approximately identical wavelength are superposed, and the intensity of the superposed ray is detected. Consequently, spectrometry is performed based on the superposed diffracted ray having twice the intensity and a very sharp waveform, so that accurate spectroscopy can be made possible even if the intensity of the source light beam is low.