Tunable narrow band optical filter

摘要: Polarization interference filters are described which can have a pass band ranging from fraction of an angstrom to several hundred angstroms in width. The be shifted any desired region the spectrum. These tunable based on fixed discussed by Lyot and Evans. transmission is formed superposition polarized channel spectra, produced x-cut plates quartz or other birefringent media placed between parallel polarizers. thicknesses ratio 1:2:4 etc. tuning accomplished changing retardation successive elements so that maxima various spectra coincide at wave-length. change made mechanically, for example, stretching supplemental plastic sheets series with filter elements, electrically using Kerr cells crystals high electro-optic coefficients, such as ammonium dihydrogen phosphate. additional never has exceed full wave wave-length peak transmission. measured experimental shown. electrical method particularly adapted cathode-ray oscillograph presentation spectra. also possible application color reproduction colorimetry. With half-angstrom line sight motion solar prominences could determined use Doppler shift prominence radiation.