Ultra-small angle light scattering: Apparatus design optimization

Ultra-small angle light scattering (USALS) is a technique used to probe large average spatial and temporal structure of soft condensed matter complementary to microscopy. Limited information is available on the design and features of a multi-speckle CCD-based USALS apparatus. The optics of such a setup are described followed by an optimization scheme involving ray tracing that can be used to choose the optimum lenses by taking into account the finite spot size due to lens aberrations, diffraction, and the CCD pixel size. Results of calculations of the optimization scheme are presented for a static light scattering (SLS) setup followed by a few experimental tests of our current apparatus.