Abstract: A voltage-tuned optical filter that is low cost and simple to fabricate uses cascaded etalon modules, each module comprising a liquid crystal etalon, such as a Fabry-Perot etalon, having a relatively small Free Spectral Range (FSR). At least two of the modules are provided with a voltage control to enable Vernier tuning control. For a given overall scan, the voltage-tuned optical filter may operate with reduced voltage ranges for each liquid crystal etalon.

Abstract: A temperature-tuned dielectric-slab-etalon scanning spectrometer that is low cost and simple to fabricate uses cascaded etalon modules, each module comprising a Fabry-Perot (FP) etalon having a relatively small Free Spectral Range (FSR), with at least two modules provided with a temperature control. According to the invention, the multiple FP modules produce Vernier tuning control. In these devices, the tuning temperature range is typically less than 10° C., and the required slab thickness may be less than 1 mm. This reduces fabrication and material requirements, and results in lower device cost and improved reliability.