INFRARED AMPLITUDE-PHASE PLASMON SPECTROMETER Russian patent published in 2016 - IPC G01N21/55 G01N21/35 G01J3/42 

FIELD: physics.

SUBSTANCE: spectrometer comprises a frequency-tuneable source of p-polarised monochromatic radiation, a flat and cylindrical focusing mirror, a solid-state plane-faced conducting sample, an element for converting source radiation into surface plasmons, an opaque screen placed in a non-absorbent medium and directed perpendicular to the track of the surface plasmons, and a photodetector which is interfaced with an information processing device and mounted on a platform which is movable along the track. The edge of the screen directed towards the surface plasmon guiding face of the analysed sample lies at a distance from the said face which is not less than the penetration depth of the surface plasmon field in the medium. The spectrometer also includes a controlled delay line, a rotating polariser, a platform-mounted flat mirror whose reflecting face adjoins the guiding face of the analysed sample, is inclined thereto at an angle of 45° and is directed perpendicular to the track, a focusing lens and an adjustable diaphragm mounted in front of the input opening of the photodetector, a volume radiation beam splitter placed on the path of radiation incident on the sample at the level of the inclined mirror. The end face of the sample which is perpendicular to the plane of incidence of radiation and is adjacent to the guiding face has a cylindrical surface shape, the axis of which is parallel to the guiding face and lies in the plane comprising the interface line of the cylindrical and flat faces, wherein the distance from the said line to the axis is equal to the radius of curvature of the cylindrical surface, and the length of the arc comprising the surface plasmon track on the said surface is less than ten times the propagation length of the surface plasmons.

EFFECT: high measurement accuracy due to a signal-to-noise ratio.

2 dwg