Abstract: An IR microscope includes an IR light source/interferometer (1) generating a collimated IR beam (26), an effectively beam-limiting element (8) in a stop plane (27), a sample position (15), a detector (19) having an IR sensor (19a), a detector stop (19b), a first optical device focusing the collimated IR beam onto the sample position, and a second optical device imaging the sample position onto the IR sensor. The effectively beam-limiting element is situated in the collimated IR beam. The first and second optical devices image the detector stop opening into an input beam plane. For the area A1 of the image of the detector stop opening in the input beam plane and the area A2 of the cross section of the collimated IR beam in the input beam plane: 0<A1/A2?1. Thereby, only collimated IR radiation is picked up, while vignetting and stray radiation are avoided.

Abstract: A method for determining a correcting quantity function kF(x, y) for calibrating an FTIR measurement arrangement with an IR detector. The IR detector includes a plurality of sensor elements, which are each located at a position (x, y), and the method includes: (a) recording interferograms IFGRxy of a reference sample using the sensor elements of the IR detector, (b) calculating spectra Rxy of the reference sample by Fourier transforming the interferograms of the reference sample for at least four sensor elements, (c) calculating correcting quantities kxy by comparing each spectrum Rxy of the reference sample calculated in step b) with a reference data set of the reference sample, and (d) determining the correcting quantity function kF(x, y) using the correcting quantities kxy calculated in step c). This permits frequency shifts that occur in FTIR spectrometers with extensive detectors to be effectively corrected regardless of the position of the sensor element.

Abstract: An IR microscope includes an IR light source (1) generating a collimated IR beam (26), an effectively beam-limiting element (8) in a stop plane (27), a sample position (15), a detector (19) having an IR sensor (19a), a detector stop (19b), a first optical device focusing the collimated IR beam onto the sample position, and a second optical device imaging the sample position onto the IR sensor. The effectively beam-limiting element is situated in the collimated IR beam. The first and second optical devices image the detector stop opening into an input beam plane. For the area A1 of the image of the detector stop opening in the input beam plane and the area A2 of the cross section of the collimated IR beam in the input beam plane: 0<A1/A2?1. Thereby, only collimated IR radiation is picked up, while vignetting and stray radiation are avoided.

Abstract: A method for measuring and determining a THz spectrum of a sample (17) having an improved spectral resolution. Two laser beams (1a, 2a) are superimposed, such that two parts (11, 12) of a superimposed laser radiation are generated, which have a beat frequency in the THz range. The first part (11) is introduced into an emitter (13) for generating a THz radiation (14), which passes through the sample. The characteristic transmission radiation (18) thus obtained is forwarded to a detector (15), which is activated by the second part (12) of the superimposed laser radiation. By repetition with different beat frequencies, a measurement signal I(f) of the form I(f)=A(f)·cos [?(f)] is obtained for the sample. An auxiliary signal ?(f) shifted by 90° is determined from the measurement signal I(f), with ?(f)=A(f)·cos [?(f)±90°]. The THz spectrum S(f) of the sample is determined by the auxiliary signal ?(f), with S(f)=|z(f)|=|I(f)+i?(f)|.

Abstract: The invention relates to a method for measuring and determining a THz spectrum of a sample (17), wherein two laser beams (1a, 2a) are superimposed, such that two parts (11, 12) of a superimposed laser radiation are generated, which have a beat frequency in the THz range, wherein the first part (11) is introduced into an emitter (13) for generating a THz radiation (14), wherein the THz radiation (14) passes through the sample (17) and the characteristic transmission radiation (18) thus obtained is forwarded to a detector (15), wherein the detector (15) is activated by the second part (12) of the superimposed laser radiation, wherein, by repetition with different beat frequencies, a measurement signal I(f) of the form I(f)=A(f)·cos[?(f)] is obtained for the sample (17), wherein an auxiliary signal ?(f) shifted by 90° is determined from the measurement signal I(f), with ?(f)=A(f)·cos[?(f)±90°], and wherein the THz spectrum S(f) of the sample (17) is determined by means of the auxiliary signal ?(f), with S(f)