TUNABLE OPTICAL INSTRUMENTS

摘要

An optical instrument may include a tunable free-space filter as a wavelength selector. The tunable free-space filter may be a tunable thin film filter (TTFF). The TTFF may be thermo-optically tunable. The tunable filter may be a multi-layer film structure incorporating thin film semiconductor materials. The temperature, and hence the wavelength, of the TTFF may be controlled by various heating and cooling structures. Various TTFF structures are also possible. The TTFF may have a single-cavity Fabry-Perot structure or may have a multi-cavity structure. Calibration aids can be included, such as an external source of one or more known wavelength signals, or an internal source of one or more known wavelength signals. The instrument may further comprise a passive interferometric wavelength reference, a device that measures temperature of the thermo-optically tunable TTFF to determine wavelength and a photodetector.