Abstract: A system for analysis of specific binding complexes. A reaction surface is treated with a specific receptor chemical (SRC) having specific binding properties and is allowed to bind with an unknown reactant to form specific binding complexes (SRC) on the reaction surface. The output of a laser is directed through the reaction surface to a detection mechanism. Shadows in the detected light may be interpreted to detect the presence of the unknown reactant. The unknown reactant may also be quantified. Preferred embodiments of apparatus, and methods of their use, are disclosed for detecting the presence of the unknown reactant within a system for interpreting the results, including interactive system components by which the bases for interpretation may be updated.