Fiber-optic coupled diffuse reflectance probe

Abstract

The invention relates to a fiber-optic coupled diffuse reflectance probe that is adapted to detachably connect to a bifurcated fiber bundle. The probe includes one or more lenses for imaging the bundle onto a target with more space between the bundle and the target than otherwise possible. The collecting lens adjacent to the bundle preferably has a reflection stop which diverts reflected light away from the bundle to minimize the problem of stray light. The preferred probe also uses an objective lens to increase the distance between the bundle and the target. The rays emerging from the collecting lens will diverge or spread because of the finite diameter of the transmitting fibers in the bundle. Accordingly, the preferred probe also has a lightguide between the collecting lens and the objective lens to remedy such divergence and, just as significantly, to uniquely spread the various rays from a particular transmitting fiber so that they form a first ring on the target, the several points of the first ring being reimaged onto the fiber bundle as a second ring that covers a plurality of receiving fibers rather than only the original transmitting fiber. The radius of the second ring corresponds to the distance between the original transmitting fiber and the system axis so that the image will be spread about the ring but the system still remains in effective focus. The preferred probe is contained in an elongated housing with a protective window at a far end of the housing. The preferred probe further includes a spacer which varies the position of the protective window relative to the objective lens so that the beam may be selectively focused at the window for contact analysis or beyond the protective window for spaced analysis.