An apparatus detects a target reactant that binds to an immobilized reactant. The apparatus generates a holographic image at a predetermined location when the reactants are present and bound to one another. The immobilized reactant is bound to a support surface at selected locations. The locations are...http://www.google.ca/patents/US5352582?utm_source=gb-gplus-sharePatent US5352582 - Holographic based bio-assay
