Abstract: An interferometer arrangement includes a beam splitter (8), two retroreflectors (15, 16), a drive (24) that moves at least one of the retroreflectors to alter an optical path difference between interferometer arms (13, 14), a converging element (18) for reference light, and a reference light detector (19) with at least three detector areas (19a-19d). First and second pairs of detector areas are aligned in respective first and second directions, wherein the first direction, the second direction and a central propagation direction of the reference light at the reference light detector are linearly independent. At least two actuators (9, 10) alter a lateral shear between two reference light partial beams (11, 12), which are reflected back from the interferometer arms and superimposed at the beam splitter, in at least two degrees of freedom. Control electronics (38) control the actuators depending on signals (Sa-Sc) at the detector areas, thereby minimizing the shear.

Abstract: An interferometer arrangement includes a beam splitter (8), two retroreflectors (15, 16), a drive (24) that moves at least one of the retroreflectors to alter an optical path difference between interferometer arms (13, 14), a converging element (18) for reference light, and a reference light detector (19) with at least three detector areas (19a-19d). First and second pairs of detector areas are aligned in respective first and second directions, wherein the first direction, the second direction and a central propagation direction of the reference light at the reference light detector are linearly independent. At least two actuators (9, 10) alter a lateral shear between two reference light partial beams (11, 12), which are reflected back from the interferometer arms and superimposed at the beam splitter, in at least two degrees of freedom. Control electronics (38) control the actuators depending on signals (Sa-Sc) at the detector areas, thereby minimizing the shear.

Abstract: A lens arrangement for an optical unit operating in a predetermined spectral range, includes at least two lenses (11-14, 114) of material, which transmits in the spectral range, and a common casing (15), in which the lenses are arranged sequentially. The lenses are at least substantially aligned radially, axially and angularly inclined relative to a common optical axis. Adjacent lenses in the sequence are mounted to allow relative movement therebetween. Abutment faces (2) of the lenses rest against one another. An elastic tensioner (21) pretensions the sequence of lenses in the axial direction. Only one of the lenses (11) in the sequence is axially aligned by way of the common casing. Only a portion of the lenses (11, 114) in the sequence are radially aligned by the common casing; the remaining lenses are aligned with respect to one another by the abutment faces of the respectively adjacent lenses.

Abstract: A lens arrangement for an optical unit operating in a predetermined spectral range, includes at least two lenses (11-14, 114) of material, which transmits in the spectral range, and a common casing (15), in which the lenses are arranged sequentially. The lenses are at least substantially aligned radially, axially and angularly inclined relative to a common optical axis. Adjacent lenses in the sequence are mounted to allow relative movement therebetween. Abutment faces (2) of the lenses rest against one another. An elastic tensioner (21) pretensions the sequence of lenses in the axial direction. Only one of the lenses (11) in the sequence is axially aligned by way of the common casing. Only a portion of the lenses (11, 114) in the sequence are radially aligned by the common casing; the remaining lenses are aligned with respect to one another by the abutment faces of the respectively adjacent lenses.

Abstract: An IR microscope (1) is constituted such that, in an optical viewing mode in a beam path of visible light (VIS-R, VIS-T), a first intermediate focus (ZW1) is imaged onto a flat detector surface (15a) of a camera. The IR microscope (1) is constituted such that, in the beam path of the visible light (VIS-R, VIS-T), the first intermediate focus (ZW1) is imaged onto a second intermediate focus (ZW2), and, in the second intermediate focus (ZW2), a Mangin mirror (11) is disposed that corrects a field curvature of the Cassegrain objective (4). The invention provides an IR microscope in which the field curvature generated by the Cassegrain objective is corrected in a simple manner in the optical viewing mode when detection is performed using a flat detector and without restricting the spectral range of the IR microscope.

Abstract: A method of obtaining an FT spectrum according to Brault is improved in that the compensation filter is determined by recording a broad-band effective interferogram, carrying out complex Fourier transformation, forming a mean value of the phase spectra, converting the abscissa values into electrical frequencies, and establishing the transfer function of the detector and of the further signal processing elements, wherein the free parameters of the transfer function are chosen such that the phase response of the transfer function deviates as little as possible from the mean value of the phase spectrum of the effective recorded interferogram. If necessary, the determined transfer function is then digitized. The compensation filter is then determined as the inverse of the discrete transfer function. In this way, deconvolution of the signal processing elements transfer function from the spectra is facilitated in a particularly simple and effective manner.

Abstract: An optical or Fourier infrared Fourier spectrometer with a two-beam interferometer with which the mirror drive is effected via two retroreflectors which are located on two 180.degree. displaced arms of a double pendulum. Deflecting mirrors are arranged between the beam splitter and the retroreflectors. The otherwise usual retroreflecting mirrors are not present. The beam splitter is displaced with respect to the plane of the pendulum. Thereby, a stable, easily aligned, and compact configuration is effected.

Abstract: An interferogram is formed as in the prior art by dividing a beam of radiation from the source into two beams and interfering these beams so as to form an interferogram on the detector. A Fourier transform is then made of this interferogram. This transform has a signal spectrum above the cutoff frequency of the detector; and because of non-linearities in the detector and in the electronic signal processing circuitry, this transform also has a spectrum below the cutoff frequency of the detector. In accordance with the invention, two correction factors are calculated from this Fourier transform and these correction factors are then used to calculate a corrected interferogram. The first correction factor is evaluated by determining from the portion of the spectrum below the cutoff frequency a valve for the spectral signal at zero frequency.