Abstract: An interferometric probe for measuring the distance to the surface of an object has a light source, for example, a super-luminescent diode, that produces a coherent light beam preferably such as to produce a speckle pattern in light reflected from the object. An interferometer includes a beam splitter that produces a reference beam directed towards a reference diffracting reflector and a measuring beam directed towards the surface of the object to be measured. The diffracting reflector produces a plurality of diffraction orders each of which are combined with portions of the light reflected from the surface to produce interference, which is detected by a detector system having a number of individual detectors equal to the number of diffracted orders of the reference beam that are used. Use of the diffracting reflector enables more of the light reflected from the object to be used in the detector and improves signal-to-noise ratio.

Abstract: A method of determining surface contour of diffusely reflecting objects is realized by interferometric comparison of beams reflected from a reference mirror and from an object (11), by changing the optical path length of the object beam, by focusing the object beam onto a plane corresponding to the zero path length difference between the beams being compared interferometrically, and by measuring said variation of the optical path length from an initial value up to a moment when appears an interference pattern displaying maximum contrast.