Reflectance measurement of spherical samples

Abstract

A device to measure reflectance has been built by the French Atomic Energy Commission (CEA). It can measure the reflectance of samples even if their shapes are spherical. This device has a good accuracy on flat samples; now, we want to show that it gives the same results whatever the sample shape may be. The measurement accuracy will be studied in another paper. For this matter, we have carried out reflectance measurements on eight ball bearings with different diameters over a spectral range (500–950 nm) to check the authenticity of the measure whatever the size of the ball bearing may be. The results were compared to ascertain the affinity between them. The differences do not depend on the diameter but on the defects on the ball bearings and their roughness. So, the reflectance of a measured sample seems independent of the curvature radius on our measuring system.