Device for the laterally resolved investigation of a laterally

Abstract

A device for the laterally resolved investigation of a laterally heterogeneous ultrathin object layer, especially for the laterally resolved detection of a change in the layer thickness of the object layer which results from a specific binding reaction of a first binding partner bound to the object layer with an unbound second binding partner. The device has a multilayer structure which extends in an investigation region and includes the object layer as first layer and a second layer adjacent to the latter, a coupler arrangement for the coupling in of excitation light into the second layer. The excitation light generates at at least one defined angle of incidence in the second layer a bound, non-radiating electromagnetic wave, from which an evanescent wave extends into the object layer. An optical imaging system is provided for the imaging of the investigation region of the object layer in an image plane at a defined angle of emergence, at which detection light is coupled out from the second layer. The coupler arrangement includes an optical grating structure which extends in the investigation region parallel to the object layer and which is rotatable about an axis extending perpendicular to the grating plane. This allows adjustment of the image contrast, by varying the orientation of the grating lines relative to the plane of incidence.