Signal processing, data encoding andor decoding techniques are applied in a dictionary system. Opposed parallel sets of belts move in synchronism with each other transversely to the direction of movement of the trays along the packaging station. Adjoining surfaces of the two glass members, which are located on the side of the sandwiched polarizing plate, are finished to a high degree of planeness, and at least one of the two glass members is in the form of a resilient glass plate capable of flexural deformation in a lateral direction. The metal nanoparticles can also be linked to chemical andor biochemical moieties which bind specifically to the target tissue.