Abstract: A device for determining the position of a medical instrument that is introduced into an object to be examined is also used for imaging the vicinity of the medical instrument. In order to enable the acquisition of instantaneous position information and image information from the vicinity of the medical instrument for all kinds of medical instruments, a localization device that is arranged in the end zone of the medical instrument that is to be introduced determines the position of the medical instrument within the object to be examined; at the same time image information is acquired in the vicinity of the medical instrument by an image acquisition device that is arranged on the medical instrument and on the basis of the position thus determined the position of the medical instrument (3) is reproduced in a survey image of the object to be examined and images of the vicinity of the object to be examined are displayed on the basis of the image information acquired.

Abstract: The invention relates to a method and a device for determining the position of a medical instrument (3) that is introduced into an object (1) to be examined and for imaging the vicinity of the medical instrument (3).

Abstract: Heterodyne optical time domain reflectometer (OTDR) for determining the attenuation behavior of a monomode waveguide (test waveguide) by measurement of the backscattered parts of light pulses transmitted in said waveguide. An acousto-optic modulator (AOM) which deflects the transmission beam from a laser into the waveguide to be tested at a light frequency which is modulated with the acoustic frequency when the AOM is acoustically energized in a pulse mode. The light pulses backscattered from the test waveguide are superimposed on a local oscillator beam (LO) constituted by the laser beam which traverses the AOM when the AOM is not energized. The optical system losses are reduced in that the superposition is realized in a passive coupler, particularly a fibre coupler (10, 26).

Abstract: The invention relates to an optical time domain reflectometer (OTDR) with heterodyne reception for determining the attentuation of an optical waveguide (measuring waveguide) by measuring the back-scattered portion of light pulses sent into the measuring waveguide. This structure is comprised of a modulated laser light source sending a send beam into the measuring waveguide and a laser light source which constitutes a local oscillator and transmits continuous light, on whose light of a wavelength differing by an intermediate-frequency from the back-scattered light from the transmission light source is superposed and is applied to a photodetector having an intermediate-frequency electric output signal which is filtered and evaluated. To improve the signal-to-noise ratio it is provided that the transmission light source is a transmission laser 1 whose light is influenced in consecutive time intervals (t.sub.1 to t.sub.2) such that the light frequency varies between two cut-off frequencies f.sub.L1 and f.sub.

Abstract: The invention relates to an optical time-domain reflectometer (OTDR) using heterodyne reception for determining the attenuation of an optical fiber guide by measuring the backscattered portion of light pulses launched into the fiber. The reflectometer comprises a light source whose light is split into a local-oscillator beam and a measuring beam. The measuring beam is pulsed by an acousto-optical modulator (AOM) and is then launched into the optical fiber to be tested. The measuring beam thus has a frequency which is offset from the optical frequency by an acoustic frequency. The local-oscillator beam and the back-scattered portion of the measuring beam are both directed to an optical receiver producing an electric output signal. A component of the output signal has a frequency corresponding to the acoustic frequency. The time-dependent amplitude of this component is a measure of the length-dependent attenuation of the optical fiber.