Abstract: A method for sensing a spatial coordinate of a point of an article, wherein a main coherent light field is formed in the area of the article and an approximate coordinate of a selected point of the article is found by means of an optical characteristic of this field. Simultaneously, a system of additional coherent light fields is formed in the area of the article, said light fields having periodic spatial and temporal modulation of illumination, and engaged in no interaction with the main coherent light field and between one another. The phase of each additional coherent light field in the selected point of the article is measured. Making use of the already obtained approximate coordinate of the selected point of the object and the measured phases, increasingly accurate coordinates of the selected point of the article are successively found. An apparatus for realizing the proposed method includes transmitting and receiving sections.

Abstract: A phase-metering device comprises first and second input signal sources; N-1 phase-shift circuits at N exceeding two, which are placed in series, a phase shift of each of said circuits being equal to .pi./N radians, the input of the first phase-shifter circuit being connected to the second input signal source; N phase converter units each having two potential (positive and inverted) outputs and two pulse outputs, first inputs of said units being connected to the first input signal source, a second input of the first phase converter unit being connected to the first input signal source, while second inputs of the other phase converter units are coupled to the outputs of the respective phase-shift circuits; the outputs of said phase converter units being connected to inputs of a pulse distributor whose outputs are coupled to inputs of a reversible counter; a digital recorder being connected to the outputs of said reversible counter.

Abstract: Arranged in succession on a common optical axis is a laser, a modulator for shifting the frequency of light produced by the laser, an optical system for forming two light beams, a system of markers formed on the surface of a specimen being tested and a recorder of an interference pattern resulting from the interference of light scattered by the markers.