Patent ID: 8610897

Claim:
A high-resolution scanning surface-plasmon microscope including: a source (LG) of coherent light; a medium for coupling and confining a surface plasmon including an objective (O, O M ) with a large numerical aperture, immersion oil (H i ), and a glass cover slip (G s ); a metal layer (M s ) covering a surface of the glass cover slip (G s ) of the coupling medium that is not in contact with the immersion oil thereof, the metal layer being adapted to be brought into contact with an observation medium (D) containing a sample to be observed and to emit a surface plasmon generated by excitation of at least one light beam (L) coming from the light source (LG); a heterodyne-mode Twyman-Green interferometer adapted to split a light beam emitted by the light source into at least one reference beam (L Ref ) and at least one measurement beam (L Mes ) directed toward the coupling medium and the metal layer (M s ) to generate a surface plasmon, the interferometer being positioned between the light source and the objective of the coupling medium to form an interferometric beam (L v ) between a reference beam and a measurement beam after reflection of each of them by a mirror (M) and by the metal layer (M s ), respectively; at least one beam enlarger (BE) placed between the light source (LG) and the interferometer and between the interferometer and the coupling medium (O, O M , H i , M s ); means (PL 1 , PL 2 , EC) for scanning the metal layer with the measurement light beam, including piezoelectric means (PL 1 , PL 2 ) for relative movement in translation between the cover slip (G S ) and the objective (O, O M ) of the coupling medium in two mutually-orthogonal directions X, Y in the same plane and piezoelectric means for moving the objective (O, O M ) in translation in a direction Z normal to the plane of each of the surfaces of the glass cover slip (G s ) and the metal layer (M s ) covering one of them; means (PD) for detecting the interferometric beam from the interferometer; and processing means (S, F, D Tec , COMP) for forming an image from the interferometric beam and being disposed between the light source and the interferometer, at least one polarization converter (CP) for converting the light beams (L) emitted by the light source (LG) from linear polarization to radial polarization in pure p mode in which all the electric field vectors E 0 relative to the propagation axis of the beam L are all oriented radially relative to the propagation axis and from the linear polarization to azimuth polarization in pure s mode in which all the electric field vectors E 0 relative to the propagation axis of the beam L are all oriented in azimuth direction relative to the propagation axis, thereby enabling detection of dielectric or metal objects with a diameter less than 10 nm without marking, the piezoelectric means (PL 1 , PL 2 , EC) for scanning the metal layer alternately with beams polarized in radial polarization in pure p mode and in azimuth polarization in pure s mode.