Figure 7:

Label-free imaging methods for single bio-NP detection.

(A) (i) Schematic representation of the experimental setup for TIRDFM: ND, neutral density filter; BE, beam expander; FS, field stop; M1, mirror; L1 lens; PM, perforated mirror; L2, objective lens. (ii) Pictorial representation of the detection event. Adapted from Ref. [100]. (B) (i) Schematic representation of the iSCAT optical setup: O, objective; QWP, quarter wave plate; PBS, polarizing beam splitter; AOD, acousto-optic deflector. (ii) Pictorial representation of the sample region, where the incident Einc, reflected by the substrate Eref, and scattered by the biomolecule Esca, are also shown. Adapted from Ref. [101]. (C) (i) Schematic representation of the optical setup for IRIS: XC, x-cube used to combine the beam of three different LED sources; BS, cube beam splitter. (ii) Pictorial representation of the layered substrate and of the optical paths leading to the interference signal. Adapted with permission from Ref. [102]. Copyright (2010) American Chemical Society. (D) Schematic representation of the SPRM experimental setup. Adapted from Ref. [103].

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