Method and apparatus for recording three-dimensional distribution of light backscattering potential in transparent and semi-transparent structures

A method for generating data representative of a three-dimensional distribution of the light backscattering potential of an object defining at least one reference surface and plural measurement sites, comprising:

• directing a reference beam from a reference arm of an interferometer against the reference surface;
• directing a measurement beam from a measurement arm of the interferomneter against the measurement site;
• shifting the frequency of at least one beam by at least ten million Hertz;
• combining reflections of the beams from the surfaces;
• and
• detecting the combined reflections.

A method for detecting a distributional profile of a light backscattering potential, comprising:

• (a) generating light beams with short coherence length;
• (b) scanning at least one of the light beams in at least one dimension with at least one scan mirror;
• (c) shifting the optical frequency of at least one of the light beams with at least one non-moving frequency shifter;
• (d) directing the light beams towards the object, such that at least one of the light beam is directed at a reference site of the object, and at least one of the light beams is directed at a measurement site of the object;
• and
• (e) directing the reflected light beams from the object to a receiver and generating a signal representative thereof, the signal being usable for determining a multidimensional distribution of light backscattering potential in the object, wherein the plural light beams include at least one reference beam directed at the reference site and at least one measurement beam directed at the measurement site, such that axial motion of the object relative to the incident direction of the light beams to the object equally affects the reference beam and the measurement beam.

An apparatus for matching an object path difference with an interferometer path difference and identifying the matching by heterodyne detection of a reference beam and a measurement beam, comprising:

• a single interferometer through which the reference beam and measurement beam propagate;
• and
• means in the interferometer for shifting the frequency of at least one of:
• the reference beam, and the measurement beam, by at least ten megaHertz, to thereby generate a beat frequency when the object path difference bears a predetermined relationship to an interferometer path difference.