An analog light scattering experiment of hexagonal icelike particles. PartI: Experimental apparatus and test measurements

An experimental apparatus to measure the scattering properties of hexagonal icelike panicles in the analog manner at the helium neon laser wavelength of 0.633 mu m has been designed and built. The instrument consists of an ar ray of 36 highly sensitive and linear photodiode detectors that are positio ned to measure the light between the scattering angles of 2.8 degrees and 1 77.2 degrees in approximately 2.5 degrees increments and at any desired azi muthal angle. This array is calibrated such that the retrieved light signal s are corrected to the actual light seen by the detectors to within approxi mately 6% at all applicable scattering and azimuthal angles. A system of el ectro-mechanical positioners places the sample at the desired and known pos ition. A glass sphere and a glass fiber configured to scatter light like an infinite cylinder was used to test the operational effectiveness and calib ration of the experimental apparatus. The phase functions for the parallel and perpendicular components determined from the experimental results match closely with the results computed from Mie theory.