Analog light scattering experiment of hexagonal icelike particles. Part I: Experimental apparatus and test measurements

摘要

An experimental apparatus to measure the scattering properties of hexagonal icelike particles in the analog manner at the helium neon laser wavelength of 0.633 µm has been designed and built. The instrument consists of an array of 36 highly sensitive and linear photodiode detectors that are positioned to measure the light between the scattering angles of 2.8° and 177.2° in approximately 2.5° increments and at any desired azimuthal angle. This array is calibrated such that the retrieved light signals are corrected to the actual light seen by the detectors to within approximately 6% at all applicable scattering and azimuthal angles. A system of electro-mechanical positioners places the sample at the desired and known position. A glass sphere and a glass fiber configured to scatter light like an infinite cylinder was used to test the operational effectiveness and calibration 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.