Scatterometer at Korea Research Institute of Standards and Science (KRISS) for bidirectional reflectance distribution function (BRDF)

A description is given of the scatterometer which has been developed at KRISS for BRDF and diffraction pattern measurement. Light source, goniometer, and receiver is described. As a light source, the collimated HeNe and argon ion laser is used, with which the: wavelengths of 632.8, 514.5, and 488.0 nm are available. The goniometer has 6 degrees of freedom. The precision of scattering polar angle is enhanced by choosing long rotating arm( length : 1.2 meter) placed on the stepmotor-controlled rotary table whose angle is read by the angle encoder with the resolution of 0.0001 degrees and accuracy 0.001 degrees. The receiver has a wide dynamic range greater than 10(14) in intensity without intenisty attenuation and receiver aperture change, which is made by cascading three kinds of detectors : photodiode(PD), photo-multiplier in direct current mode(DC), and photo-multiplier in pulse counting mode(Pe). The measured instrument signature and the sinusoidal grating BRDF at the wavelength of 488 nm is presented.