Abstract: The present invention relates to a supporting structure for a movable mirror of an interferometer, the supporting structure comprising a fixed frame (11), a movable frame (12) to which the movable mirror (42) is arranged to be attachable, and at least two flexible members (13), first ends of said members (13) being fastened to the fixed frame (11) and second ends of said members (13) being fastened to the movable frame (12) in such a way that the distance between fixing points of each flexible member (13) is essentially the same and the distance between the fixing points of the first ends essentially equals the distance between the fixing points of the second ends. The supporting structure comprises support members (16) attached to at least one side of at least two flexible members (13). The invention also relates to an interferometer and a method for reducing the tilting of a movable mirror of an interferometer.

Abstract: The present invention relates to an arrangement for measuring relative movement. The measuring arrangement comprises a light source (110, 210) for emitting a light beam, a moving element (120, 220) having a reflective surface (121, 221) adapted to reflect a first wavefront portion of the light beam, and a reference element (130, 230) having a reflective surface (131, 231) adapted to reflect a second wavefront portion of the light beam. The arrangement further comprises detecting means (140, 240) for detecting changes in a spatial interference pattern produced by the light reflected from the moving element and the reference element, and processing means (150, 160, 250, 260) for calculating the relative movement between the moving element and the reference element from the phase change in the detected spatial interference pattern. The invention also relates to a method for measuring relative movement.

Abstract: The present invention relates to a supporting structure for a movable mirror of an interferometer, the supporting structure comprising a fixed frame (11), a movable frame (12) to which the movable mirror (42) is arranged to be attachable, and at least two flexible members (13), first ends of said members (13) being fastened to the fixed frame (11) and second ends of said members (13) being fastened to the movable frame (12) in such a way that the distance between fixing points of each flexible member (13) is essentially the same and the distance between the fixing points of the first ends essentially equals the distance between the fixing points of the second ends. The supporting structure comprises support members (16) attached to at least one side of at least two flexible members (13). The invention also relates to an interferometer and a method for reducing the tilting of a movable mirror of an interferometer.

Abstract: The present invention relates to an arrangement for measuring relative movement. The measuring arrangement comprises a light source (110, 210) for emitting a light beam, a moving element (120, 220) having a reflective surface (121, 221) adapted to reflect a first wavefront portion of the light beam, and a reference element (130, 230) having a reflective surface (131, 231) adapted to reflect a second wavefront portion of the light beam. The arrangement further comprises detecting means (140, 240) for detecting changes in a spatial interference pattern produced by the light reflected from the moving element and the reference element, and processing means (150, 160, 250, 260) for calculating the relative movement between the moving element and the reference element from the phase change in the detected spatial interference pattern. The invention also relates to a method for measuring relative movement.

Abstract: The invention relates to a system and method for detecting one or more gases or gas mixtures and/or for measuring the concentration of one or more gases or gas mixtures, said system comprising at least a light source, a sample space, a reference chamber, and a measuring chamber. The measuring chamber is supplied with a gas to be detected or measured. In addition, the measuring chamber is provided with a pressure sensor for detecting a photoacoustic signal generated in the measuring chamber. The pressure sensor comprises either a door, whose movement is measured without contact, or a sensor, whose movement is measured optically.

Abstract: The present invention relates to an interferometer, comprising at least a beamsplitter (10), at least one end reflector (11) for returning beams (S2, S3), and a set of reflectors (14, 15) for reflecting the beams (S2, S3) between the beamsplitter (10) and the end reflector (11) or the end reflectors, at least some of said set of reflectors (14, 15) being adapted to be rotatable around an axis (?). Said set of reflectors comprises two angle reflectors (14, 15), constituted by plane reflectors, and the said end reflector (11) is or the end reflectors are an angle reflector constituted by plane reflectors (11?, 11?). An angle line of the end reflector (11) is or the angle lines of end reflectors are arranged perpendicular to an angle line of both of the angle reflectors (14, 15).

Abstract: The invention relates to a photoacoustic detector, comprising at least a first chamber (V0) suppliable with a gas to be analyzed, a window for letting modulated and/or pulsed infrared radiation and/or light in the first chamber (V0), and means for detecting pressure variations created in the first chamber by absorbed infrared radiation and/or light. The means for detecting pressure variations created in the first chamber by absorbed infrared radiation and/or light comprise at least an aperture provided in the wall of the first chamber (V0), in communication with which is provided a door arranged to be movable in response to the movement of a gas, and means for a contactless measurement of the door movement. The invention relates also to a sensor for a photoacoustic detector and to a method in the optimization of a door used as a sensor for a photoacoustic detector.

Abstract: A detector arrangement for electromagnetic radiation has at least an absorbing element and a cantilever sensor which are in operational connection with each other, so that the sensor is bendable in response to electromagnetic radiation absorbed by the absorbing element. The arrangement further includes an interferometer for measuring bending of the cantilever sensor. In a method for measuring electromagnetic radiation, electromagnetic radiation is directed on to the absorbing element and thereby bending of the cantilever sensor is caused. Bending of the cantilever sensor is measured with an interferometer. The cantilever sensor can be a door-like flap made of silicon, attached to one side of a frame of silicon.

Abstract: A detector arrangement for electromagnetic radiation has at least an absorbing element and a cantilever sensor which are in operational connection with each other, so that the sensor is bendable in response to electromagnetic radiation absorbed by the absorbing element. The arrangement further includes an interferometer for measuring bending of the cantilever sensor. In a method for measuring electromagnetic radiation, electromagnetic radiation is directed on to the absorbing element and thereby bending of the cantilever sensor is caused. Bending of the cantilever sensor is measured with an interferometer. The cantilever sensor can be a door-like flap made of silicon, attached to one side of a frame of silicon.

Abstract: The invention relates to an interferometer, comprising at least a beam splitter (10), an end mirror (11) for returning beams (S2, S3), and a set of mirrors (12, 13, 14, 15) for reflecting the beams (S2, S3) between the beam splitter (10) and the end mirror (11), at least some of said mirrors (12, 13, 14, 15) being mounted on a rigid structure (17) which is arranged to be rotatable around an axis (A). Said set of mirrors comprises at least one pair of planar mirrors, constituted by two plane mirrors (12, 13), and two angular mirrors (14, 15), constituted by plane mirrors and arranged to deflect a course of the beam (S2, S3) hitting the angular mirror (14, 15) and to direct the beams (S2, S3), guided from the beam splitter (10) by way of at least one pair of plane mirrors (12, 13) to the angular mirrors (14, 15), to the end mirror (11) and back to the beam splitter (10).

Abstract: The invention relates to a system and method for detecting one or more gases or gas mixtures and/or for measuring the concentration of one or more gases or gas mixtures, said system comprising at least a light source, a sample space, a reference chamber, and a measuring chamber. The measuring chamber is supplied with a gas to be detected or measured. In addition, the measuring chamber is provided with a pressure sensor for detecting a photoacoustic signal generated in the measuring chamber. The pressure sensor comprises either a door, whose movement is measured without contact, or a sensor, whose movement is measured optically.

Abstract: The present invention relates to an interferometer, comprising at least a beamsplitter (10), at least one end reflector (11) for returning beams (S2, S3), and a set of reflectors (14, 15) for reflecting the beams (S2, S3) between the beamsplitter (10) and the end reflector (11) or the end reflectors, at least some of said set of reflectors (14, 15) being adapted to be rotatable around an axis (?). Said set of reflectors comprises two angle reflectors (14, 15), constituted by plane reflectors, and the said end reflector (11) is or the end reflectors are an angle reflector constituted by plane reflectors (11?, 11?). An angle line of the end reflector (11) is or the angle lines of end reflectors are arranged perpendicular to an angle line of both of the angle reflectors (14, 15).

Abstract: The invention relates to a photoacoustic detector, comprising at least a first chamber (V0) suppliable with a gas to be analyzed, a window for letting modulated and/or pulsed infrared radiation and/or light in the first chamber (V0), a second chamber (V), which constitutes a measuring space with a volume V and which is in communication with the first chamber by way of an aperture provided in a wall of the first chamber, at least one sensor, which is arranged in the wall aperture of the first chamber and arranged to be movable in response to pressure variations produced in the first chamber by absorbed infrared radiation and/or light, and means for measuring the sensor movement. The means for measuring the sensor movement include at least one or more light sources for illuminating the sensor or a part thereof and one or more multi-detector detectors for the reception of light reflected from the sensor and for measuring the sensor movement as optical angular and/or translatory measurement.

Abstract: The invention relates to a photoacoustic detector, comprising at least a first chamber (V0) suppliable with a gas to be analyzed, a window for letting modulated and/or pulsed infrared radiation and/or light in the first chamber (V0), a second chamber (V), which constitutes a measuring space with a volume V and which is in communication with the first chamber by way of an aperture provided in a wall of the first chamber, at least one sensor, which is arranged in the wall aperture of the first chamber and arranged to be movable in response to pressure variations produced in the first chamber by absorbed infrared radiation and/or light, and means for measuring the sensor movement. The means for measuring the sensor movement include at least one or more light sources for illuminating the sensor or a part thereof and one or more multi-detector detectors for the reception of light reflected from the sensor and for measuring the sensor movement as optical angular and/or translatory measurement.

Abstract: The invention relates to a photoacoustic detector, comprising at least a first chamber (V0) suppliable with a gas to be analyzed, a window for letting modulated and/or pulsed infrared radiation and/or light in the first chamber (V0), and means for detecting pressure variations created in the first chamber by absorbed infrared radiation and/or light. The means for detecting pressure variations created in the first chamber by absorbed infrared radiation and/or light comprise at least an aperture provided in the wall of the first chamber (V0), in communication with which is provided a door arranged to be movable in response to the movement of a gas, and means for a contactless measurement of the door movement. The invention relates also to a sensor for a photoacoustic detector and to a method in the optimization of a door used as a sensor for a photoacoustic detector.

Abstract: The invention relates to an interferometer, comprising at least a beam splitter (10), an end mirror (11) for returning beams (S2, S3), and a set of mirrors (12, 13, 14, 15) for reflecting the beams (S2, S3) between the beam splitter (10) and the end mirror (11), at least some of said mirrors (12, 13, 14, 15) being mounted on a rigid structure (17) which is arranged to be rotatable around an axis (A). Said set of mirrors comprises at least one pair of planar mirrors, constituted by two plane mirrors (12, 13), and two angular mirrors (14, 15), constituted by plane mirrors and arranged to deflect a course of the beam (S2, S3) hitting the angular mirror (14, 15) and to direct the beams (S2, S3), guided from the beam splitter (10) by way of at least one pair of plane mirrors (12, 13) to the angular mirrors (14, 15), to the end mirror (11) and back to the beam splitter (10).

Abstract: The invention relates to an interferometer comprising a beamsplitter (10), a mirror (11) for retroreflecting beams (S1, S2), at least one pair of mirrors (12, 13) made up of two plane mirrors for reflecting the beams (S1, S2). The pair of mirrors (12, 13) is fitted in a rigid structure (15), which is arranged to rotate around an axis (A). It is characteristic that the beamsplitter (10) is attached to a body (20) supported on the mount and that the axis (A) passes through the body (20). According to a recommended embodiment, the retroreflecting mirror (11) is also attached to the body (20).

Abstract: A focusing interferometer, wherein the focusing and orientation of the different mirrors of the interferometer have been successfully facilitated by combining the focusing mirror and the collimating mirror to provide a single spherical mirror surface and by reversing the paths of light that start from the beam splitter by assembly of mirrors which are arranged back-to-back to reflect to opposite directions such that their optical axes join, each of the mirrors including three flat mirror surfaces that are perpendicular to one another and are arranged to reflect to the direction of the point where the normals of the mirror surfaces intersect.

Abstract: A procedure for enhancing the resolution of spectral data, in which the Fourier self-deconvolution method FSD is used to produce from the input spectrum a data set in an interval 0-L.sub.t, the maximum entropy method MEM is used to compute prediction error filter coefficients {a.sub.k } from this data, and by the linear prediction method LP, using coefficients {a.sub.k } and data points 0 to M. Data are predicted in the interferogram I(x) beyond L.sub.t, whereby output spectrum maximum line narrowing with minimum distortion is achieved.

Abstract: Procedures are provided for analyzing multicomponent FT-IR spectra for unknown mixtures of gases. In the analysis, the FT-IR spectrum is measured for the particular unknown mixture of gases to be analyzed. The operations of the multicomponent analysis are divided into three different levels so that the most laborious operations, which have to be performed very seldom or only once, are on the highest level. Rapid calculation operations to be performed in connection with each spectrum analysis are on the lowest level. The levels are as follows: 1) Forming a spectrum library; 2) Introducing a new basis and adding a new vector to the old basis; and 3) Individual analysis. Variances, error limits, and residual spectrums are calculated in the analysis. A windowing procedure is followed to reject spectrum portions where the transmittance approaches zero or which do not contain real information for some other reason.