INTERFEROMETRIC DEVICE FOR CONTACTLESS MEASUREMENT OF THICKNESS Russian patent published in 2000 - IPC

FIELD: measurement technology, optical interferometry. SUBSTANCE: invention can be used for uninterrupted contactless measurement of geometric thickness of transparent and opaque objects, for instance, sheet materials ( metal rolled products, polymer films ), parts of complex shape made from soft materials that do not allow contact measurement ( for instance, piston inserts of internal combustion engines ), reference plates and substrates in optical and semiconductor industries, etc. Proposed interferometric device includes light source 1 with small length of coherence, measurement interferometer 2, beam splitter 3, photodetector 9 and first light guide 4 and first semi-transparent mirror 5 arranged in series, coupled optically and positioned between beam splitter 3 and first surface of measured layer 6, second light guide 7 and second semi-transparent mirror 8 arranged in series, coupled optically and positioned between beam splitter 3 and second surface of measured layer 6. In this case second light guide 7 is optically coupled to first light guide 4 via beam splitter 3. First light guide 4 and first semi-transparent mirror 5 are oriented so that light reflected from first semi-transparent mirror 5 and from first surface of measured layer 6 return into first light guide 4. Similar to this second light guide 7 and second semi-transparent mirror 8 are oriented so that light reflected from second semi-transparent mirror 8 and from second surface of measured layer 6 return into second light guide 7. EFFECT: increased precision of measurement of thickness of opaque objects up to fractions of wave length of used light, increased precision of measurements under conditions of vibrations and acoustic noises. 8 cl, 8 dwg