INTERFERENCE AND POLARIZATION FILTER FOR GAS SPECTROSCOPY Russian patent published in 2007 - IPC G01N21/61 

FIELD: engineering of optical devices meant for gas analysis by studying absorption spectrum of gas being measured, possible use in optical devices (gas analyzers, spectrometers) for selective measurement of concentration of gas component in gas mixture.

SUBSTANCE: interference and polarization filter contains input and output polarizer devices, located serially between which are first two-beam-refracting element, photo-resilient modulator or a different controllable two-beam-refracting element and second two-beam-refracting element, while optical axes of first two-beam-refracting element and modulator are parallel, polarization plane of input polarizer is oriented at an angle of 45° to optical axis of modulator, while polarization plane of outlet polarizer is parallel or perpendicular to polarization plane of input polarizer, and optical axis of second two-beam-refracting element is parallel or perpendicular to optical axis of modulator. Two-beam-refracting elements are made of various materials, having varying dispersion of two-beam refraction, and their thicknesses are selected in such a way that their total spectral dispersion results in difference of working points of modulator in filter by measured and accompanying gas components for π/2, and in appearance of signal of measured gas component on first or second modulation frequency harmonic, and of accompanying gas component signal - on second or first one, respectively, providing for high selectivity of concentration measurements of analyzed gas component in presence of accompanying gas component. Interference and polarization filter composition may additionally include additional elements, capable of optical activity or double beam refraction.

EFFECT: increased selectivity of measurements of concentration of gas component being measured in presence of accompanying gas component with close spectral characteristics.

11 cl, 7 dwg