Laser interferometer with a sharply focused beam as a tool for optical tomography

Vladimir P. Ryabukho; Vladimir L. Khomutov; Valery V. Tuchin; Dmitry V. Lyakin; Kirill V. Konstantinov

doi:10.1117/12.306064

24 April 1998 Laser interferometer with a sharply focused beam as a tool for optical tomography

Vladimir P. Ryabukho, Vladimir L. Khomutov, Valery V. Tuchin, Dmitry V. Lyakin, Kirill V. Konstantinov

Proceedings Volume 3251, Coherence Domain Optical Methods in Biomedical Science and Clinical Applications II; (1998) https://doi.org/10.1117/12.306064
Event: BiOS '98 International Biomedical Optics Symposium, 1998, San Jose, CA, United States

Abstract

On the base of spatial-temporal analogy in properties of the optical fields the equivalence of temporal and spatial photodetector averaging of light interference field is shown. In the low-coherence interferometry the interferential signal is vanished when optical path difference becomes more than light coherence length l_c approximately equals (lambda) ²/(Delta) (lambda) . This value determines the accuracy of the testing of the reflecting layer location. The analogous vanishing of the interferential signal can be realized by a spatial averaging of the interference field in the case of the sufficiently wide receiving photodetector aperture. For such averaging Michelson interferometer with a laser beam focussed on the object surface can be used. In this case interferential signal is vanished when the surface displacement is more than a focussed beam parameter (delta) ((Delta) z) equals (lambda) /(NA)², where NA is a numerical aperture of the objective. With NA approximately equals 1 only a few oscillations of interferential signal is observed. It is corresponding to advanced achievements of the low-coherence interferometry. The experimental results show a high testing accuracy of the position of smooth and rough surfaces, the thickness of transparent coating attached to the rough surface and multilayered scattering objects. Thus, interferometers with a sharply focussed probing beam can be consider as a good alternative for the low-coherence interferometry and can be used in coherent optical tomography.

Citation Download Citation

Vladimir P. Ryabukho, Vladimir L. Khomutov, Valery V. Tuchin, Dmitry V. Lyakin, and Kirill V. Konstantinov "Laser interferometer with a sharply focused beam as a tool for optical tomography", Proc. SPIE 3251, Coherence Domain Optical Methods in Biomedical Science and Clinical Applications II, (24 April 1998); https://doi.org/10.1117/12.306064

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