HIGH-SENSITIVE LIGHT WAVE REFLECTION MEASURING DEVICE AND LIGHT-WAVE ECHO TOMOGRAPHIC DEVICE USING SAME

摘要

PURPOSE: To enable detecting at high sensitivity and high S/N the distribution of the positions of boundary planes within an object to be measured which differ in refractive index by detecting an output position which is produced corresponding to a reflecting position by the combination of a multi-mode laser beam reflected from within the object to be measured and a reference beam which is varied in delay time. CONSTITUTION: A laser beam from a multi-mode laser oscillator 1 is split into two beams by a beam splitter 3, one of the beams reflected by a scanning reflector 6a and Doppler-shifted in frequency to become a reference beam having a delay in position that corresponds to the distance over which the reflector 6a moves; the other beam propagates through an object 4 to be measured which is made of multiple layers of materials with different refractive indexes, and reflections occur at each of the boundaries among the layers so that the phase of the reflected light wave in each of the multiple of modes is delayed in accordance with the boundary positions, and that the beam is combined 3 with the reference beam. In-depth reflecting positions with different refractive indexes can be detected through the detection 7 of the combined beams and the processing of a pulse beam that is produced at a delayed time corresponding to a reflection point produced by the coherent components of the combined components.