OPTICAL FILTER AND OPTICAL VARIABLE WAVELENGTH FILTER DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optical variable wavelength filter capable of sweeping a central transmission wavelength at a high speed and with high precision without any mechanical disturbance and realizing an optical wavelength separation with high precision and high resolution, and an optical variable wavelength filter device using the same. SOLUTION: The optical filter is an optical variable wavelength filer exhibiting a disk like appearance, in which its cavity (a resonator part) is integrally constructed with a disk like transparent parallel planar substrate 4 and a spacer layer 2 composed of a dielectric film of which the film thickness varies corresponding to an observation angle around an axis of rotation of the disk and which has the same refractive index as the substrate and further an etalon type resonator is constructed with high reflectance mirrors 3 composed of multilayer coatings arranged on both sides of the substrate 4 and the layer 2. Thereby, it is no more necessary to directly move the mirrors to control a resonator length and any mechanical disturbance is excluded. Preferably a rotary encoder mark to detect an absolute position is arranged on an outer peripheral part of the optical filter.