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.