METHOD DETERMINING SHORT DISTANCES TO DIFFUSION-REFLECTING OBJECTS AND GEAR FOR ITS REALIZATION Russian patent published in 1997 - IPC

FIELD: measurement technology. SUBSTANCE: method is conducted by way of interferometric comparison of beams of light reflected from object and from diffraction reflector, by change of optical path of reference beam and measurement of specified change of optical path from initial value to moment of emergence of interference picture with maximum contrast. Focusing of radiation source to plane of reflecting element is carried out beforehand. Method is realized with the use of gear incorporating source of coherent radiation on which axis there are placed in sequence twin-wave interferometer including beam splitter, modulator of optical path on which membrane reference reflector manufactured in the form of diffraction element is mounted for oscillatory translation. Modulator is connected to unit measuring its position in space. Gear also has photodetector placed across output of interferometer, unit determining contrast of interference bands which input is connected to output of photodetector, unit fixing position of modulator of optical path connected to unit measuring position of modulator in space and to output of unit determining contrast of interference bands. Objective in placed between interferometer and source of coherent radiation. Additional photodetector is mounted in symmetry to basic one relative to beam splitter. EFFECT: increased accuracy of measurements. 6 cl, 2 dwg