| 摘要 |
A real time image is created of blood circulation deep (e.g. a plurality of millimeters) below the surface of living tissue to aid in evaluating a patient. A first beam ( 26 ) of circularly polarized light is directed forwardly (F) against an outer surface ( 14 ) of the tissue, the circularly polarized beam penetrating into a deep region ( 12 ) of the tissue. Along shallow depths ( 42 ), light of the first beam is scattered a minimum amount from tissue and a portion of such light that passes rearwardly and out of the tissue remains polarized. Along greater depths ( 12 ), light of the first beam is scattered much more and becomes depolarized, and a portion of that deep light travels rearwardly (R) and back illuminates the overlying tissue. Light emerging from the outer surface of the tissue and traveling rearwardly, which constitutes a second beam ( 36 ), is passed through a depolarizing filter ( 24 ) that passes primarily only unpolarized light, so light from a shallow depth is largely blocked. The unpolarized light of the filtered second beam is focused on a photodetector ( 48 ) that creates electrical signals representing a real time image. Light spots ( 54 ) on the image that move, represent spaces between blood platelets ( 52 ) that are moving through a capillary, and indicates the velocity of blood through the capillary.
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