A new imaging method for gold-surface adsorbates based on anomalous reflection

A new imaging method is proposed for ultrathin films with a thickness of a few nanometers, based on the anomalous reflection (AR) of gold. In the AR effect, the reflectivity fairly decreases for blue or purple light (380 nm < λ < 480 nm) with the existence of a transparent dielectric layer at a gold surface. Thus, a thin gold film can be used as an imaging platform. Clear AR images are obtained for a microarray of protein (avidin) spots of diameter 120 μm with gaps of size 50 μm between the spots (36 spots/mm2). The resolution of the AR imaging is governed solely by the illumination spot size. AR imaging is a promising technique for high throughput analysis of biomolecular detection in a microarray format.