Experimental Studies Of Spatial-resolved Diffuse Reflectance Close To Source

Measurement of optical properties of biological tissues is important for medical therapy and diagnosis. For example, the light beam can be controlled according to tissue optical properties in order to get a good effect in photodynamic therapy. Measurement of optical properties performed in vivo could also be used as a diagnostic tool. Additional focus will be put on it increasingly for its non-invasion or micro-invasion. The visible and near-infrared optical parameters of many different kinds of biological tissues have been obtained by different measuring methods so far. However, the most of these values were measured in vitro. Because of unavoidable alterations in excised samples, such as blood drainage, structural alterations, and temperature changes, these values are questionable, therefore, the techniques of measuring in vivo are demanded.Diffuse reflectance method can be used to measure in vivo. In the way of improving spatial resolution, this paper discussed the two-fiber method performed to measure spatial-resolved diffuse reflectance close to source.The improvements in the experiment are as follows: (1) Twenty points from 0.3mm to 2.67mm are measured in the region close to the source and the spacing is 0.125mm. The number of measuring points and the spatial resolution are all increased. (2) Experimental data are acquired and stored in computer automatically by Data acquisition card that is programmed by Labview. (3) The step motor can move micro-distance continuously programmed by Labview (4) A high stability semiconductor-laser with a optical fiber is selected as source, which reduce the influence of source fluctuation on experimental results. Observation-comparison method is adopted to ensure the deepness of fiber in the sample to be identical. (5) Fiber-array experiment system is set up and a fiber probe is designed. The different channels of optical switch can be switched orderly which is programmed by Labview. So the stable measurement of spatial-resolved diffuse reflectance close to source can be finished.