Abstract: A method and/or arrangement for compensating the dispersion in signals of short-coherence interferometers and/or OCT interferometers, wherein the effect of the dispersion is eliminated by subsequent compensation in that the interferometer signal is correlated with a spatially variant correlation core which corresponds along the measurement axis in z-direction to an interferometer signal of an individual light-reemitting location with the same dispersion which is punctiform in z-direction.

Abstract: An arrangement is provided for optical surface profile measurement and for obtaining optical sectional images of transparent, partially transparent and opaque objects by the spectral interferometric OCT method. In the spectral interferometric OCT method, the depth position of the object locations from which light is diffusely reflected is given by the light diffusely reflected by the object through a Fourier transform. Because of the path difference between the object light and reference light which is required for this purpose, large spatial frequencies occur in the spectrum which impair the resolution capacity of this method. According to the invention, the reference light is used to measure the phase of the wavelength spectrum by use of discrete phase displacements from the measured spectral intensities. This is also possible when the path difference between the object light and reference light is zero and a worsening of resolution therefore does not occur in this case.

Abstract: A dynamic optical path length modulator for optical interferometry, holography and tomography is disclosed. The optical path length in a beam path is changed in that the light beam in question is guided through a double mirror arrangement which is formed of two plane mirrors which are parallel to one another and are rotatable about a common axis. A path length-dependent dispersion of any desired magnitude can be introduced into the beam path by the arrangement of plane plates and prisms.

Abstract: A problem occurring in the acquisition of planar sectional images by means of transverse optical coherence tomography consists in that the frequency of the photoelectric interferometer signal is not constant during the scanning process. The corresponding frequency bandwidth impedes the electronic bandpass filtering required for noise reduction. However, planar tomographic images are particularly important. A beam path which is telecentric on the object side is realized in that the center of rotation of the pair of scanning mirrors which directs the scanning measurement beam onto the object is arranged in the focal plane of the focussing optics. In this way, the frequency of the photoelectric interferometer signal remains constant during the scanning of planar object sections, which enables optimum noise filtering. The invention is best represented by FIG. 2.

Abstract: In coherence tomography, an interferometric measurement light beam scans the measurement object and is focused for improving the transverse resolution. In order to achieve a high transverse resolution over the entire object depth, the focal displacement and the change in path length in the measurement light beam for maintaining the coherence of the focus is achieved by one and the same moving optical element in the measurement light beam. The present invention achieves this by a particularly simple and easily adjustable arrangement which is characterized by especially low light loss in the measurement beam path.

Abstract: In optical coherence tomography, a sectional image I(x,z) of an object is obtained in that a light beam scans the object along a x-line on the surface, and the depth z from which light of intensity I is reflected is measured by means of a partial-coherence interferometer. In so doing, a strong medium intensity can cover and conceal small differences in adjacent object points. The invention renders small differences in adjacent object points visible in that the object is illuminated by a dual beam which simultaneously illuminates the object at two adjacent points and whose two components are in opposite phase after traversing the arrangement, so that they cancel one another in a homogeneous object structure. On the other hand, if changes are brought about in the two light bundles by means of the reflectance at the object structure, they do not cancel one another, but rather produce an image signal.

Abstract: In the application of coherence distance measurement in medical biometry and in medical coherence tomography, an interferometric measurement light path is directed on the object to be measured and is focussed in order to improve the transverse resolution. Since the focus of the measurement light beam is fixed in the axial direction, high transverse resolution cannot be achieved over the entire object depth at all interferometric measurement points along the measurement light beam. This problem is not solved merely by displacing the focus along the measurement beam, since the focus will then lose coherence with respect to the reference light and the actual interferometric measurement location will then lie outside of this focus. In accordance with the invention, a simultaneous displacement of the reference light mirror be effected synchronously with the displacement of the focus by virtue of the optics generating the focus in order to maintain the coherence of the focus.