Patent ID: 9175954
Filing Date: 2015-11-03
Classification: G01B,G02F,G03H

Abstract:
1. A method for short-coherence holography of an at least partially light-diffusing object: providing a holographic measuring arrangement comprising: generating a reference bundle of rays and an object bundle of rays using the unbalanced two-beam interferometer, in which a mean optical path difference Xm different from zero exists, and which, at its output, has a surface-like hologram detection area HDB, in which the at least one rasterized detector spectrally integrally detecting at least in spectral sub-ranges is arranged, and which in its surface-like hologram detection area HDB at a point DP of the HDB, for an optically detected object point OP, always has an optical object point-related path difference x_OP_DP different from zero, wherein in the unbalanced two-beam interferometer, short-coherent or quasi short-coherent light having frequency comb characteristic with the frequency interval Δf and in which the inequation is satisfied for at least one integer n1 with n1=1, 2, 3, . . . , and for at least one optically detected, at least partially light-diffusing object point OP - and thus the at least one short-coherence hologram forms in at least one sub-range of the at least one rasterized detector - with lc as the coherence length of the short-coherent or quasi short-coherent comb light, which returns from the light-diffusing object point OP and contributes to hologram formation, and with x_OP_DP as the optical path difference at a point DP of the surface-like hologram detection area HDB for the optically detected, light-diffusing object point OP; performing at least one measurement for determining the distance and the velocity - or a multiple measurement of the distance, also by means of a conducted time measurement suitable for determination of the velocity of the object ( and the magnitude of the distance and the velocity is available as information in measurement real time at least approximately, and is provided for the measurement method for shape detection by means of optical sectioning, and in the holographic sampling process, the spatial pulse interval Y on the basis of the information about the velocity and distance of the object ( the optical path length of this cavity ( so that the ordinal number q of object-sampling short pulses is kept constant for at least the capturing time delta_t_Hol of the at least one short-coherence hologram, by making the first derivative over time of the spatial pulse interval, which results from the delay length of the frequency comb-forming cavity, at least approximately equal to a value of 2/q-times the component of the velocity of the object in the movement direction or the difference velocity between the at least one rasterized detector and the object, wherein the ordinal number q results from the quotient of optical path length so that the phase in the at least one short-coherence hologram changes by less than 2 Pi at least in a sub-range thereof; and capturing the at least one short-coherence hologram using the at least one rasterized detector and performing a numerical reconstruction thereof, whereby at least one sectional plane E or one sectional area is calculated and at least one intensity amplitude of a light-diffusing object point OP from the reconstructed hologram above a threshold value 1S is evaluated as a characteristic of the presence of a light-diffusing object point OP of the object space.