Measurement of surface bidirectional reflectance distribution based on optical fiber array in hemispheric space

A novel approach and system for measurement of bidirectional reflectance distribution function (BRDF) based on optical fiber array in hemispheric space are proposed. With a fiber array composed of numerous multimode fibers located uniformly in a hemisphere, the angular distribution of surface optical reflectance in tri-dimensional space is transformed into a two-dimensional planar image. By collecting the image using a CCD camera and going though a corresponding data processing, a fast measurement of BRDF can be realized. Furthermore, the laser beam is transmitted and guided by fibers to irradiate the sample surface in various incidence angles. Primary measurements and analysis of surface reflectance of varied substance along with various machining process are carried out with this system. The results indicate that, comparing with conventional measurement systems, this novel one can avoid the measuring errors generated by the fluctuation of laser power and the sensitivity of the detector, as well as dramatically shorten the acquisition time. In addition, a compact configuration eases the measurement procedure consumedly.