Abstract: An apparatus is proposed for making absolute, two-dimensional measurements of the position of an object (10) with reference to a measuring arrangement (11), with the surface of the object (10) being configured as a hologram. The information contained in the hologram is red out by means of a measuring wave (13) that is directed onto the hologram (18), is diffracted there and interferes with a reference wave (14). The interfered-with waves (13, 14) are picked up by an optical sensor arrangement (20) including at least two sensors (21, 22). In a signal processing arrangement (23), the absolute position is determined either from the radiation intensities picked up by the sensors (21, 22) or from the phase relationship between the signals emitted by the sensors (21, 22), in each case by a comparison with a value stored in a memory.

Abstract: A device for interferometric detection of surface structures by measurement of the phase difference in laser speckle pairs in the measuring points of this surface is proposed. This device comprises at least two laser sources (10-12), the frequency or wavelength of which is modulated, a splitter device (16) splitting the respectively generated laser beam into two partial beams, means for frequency shifting of the two partial beams in relation to each other, and a beam guide device, by means of which one of the partial beams can be supplied as a reference beam and the other as a measuring beam, guided to the measuring point and reflected there, both interferometrically superimposed, to a photodetector device (25), downstream of which an evaluating device (27) for determining the phase shift is placed.

Abstract: A method for optoelectronically measuring distances and/or angles is suggested. A first and second beam (13, 14 and 61, 63) are directed onto the surface 12 of an object 10 to be measured at pregiven angles (.alpha. and (.beta.) which are diffracted at a common point of incidence on the surface 12. In one embodiment, the two beams (13, 14 and 61, 63) have different frequencies. In another embodiment, the frequency of the two beams (13, 14 and 61, 63) changes simultaneously and one of the two beams (13, 61; 14, 63) has a phase modulation. The phase change of the signal supplied by the sensor 18 is evaluated with reference to a reference signal.