Resolution improvement in laser diode-based pump-probe microscopy with an annular pupil filter.

We experimentally demonstrate the use of annular beams to improve lateral resolution in laser-diode-based pump-probe microscopy. We found that the width of the point-spreading function in the case of the annular pump-probe beams is 162 nm, which is 30% smaller than that of the circular beams (232 nm). Furthermore, side lobes were efficiently suppressed at the focal plane since the pump-probe signal is proportional to the product of the two beam intensities. This scheme is demonstrated for the photothermal signal of nonfluorescent gold nanoparticles and the stimulated emission signal of fluorescence beads.

[1]  Hiroshi Ishikawa,et al.  Green-to-Yellow Continuous-Wave Operation of BeZnCdSe Quantum-Well Laser Diodes at Room Temperature , 2011 .

[2]  Wei Min,et al.  Imaging chromophores with undetectable fluorescence by stimulated emission microscopy , 2009, Nature.

[3]  S. Lutgen,et al.  True Green Laser Diodes at 524 nm with 50 mW Continuous Wave Output Power on c-Plane GaN , 2010 .

[4]  Dan Fu,et al.  Nonlinear Absorption Microscopy † , 2009, Photochemistry and photobiology.

[5]  S. Hell,et al.  Annular aperture two-photon excitation microscopy , 1995 .

[6]  C. Saloma,et al.  Advantages of two-color excitation fluorescence microscopy with two confocal excitation beams , 2000 .

[7]  Ji-Xin Cheng,et al.  Label-free imaging of semiconducting and metallic carbon nanotubes in cells and mice using transient absorption microscopy. , 2011, Nature nanotechnology.

[8]  Warren S Warren,et al.  High-resolution in vivo imaging of blood vessels without labeling. , 2007, Optics letters.

[9]  V. Mahajan.  Uniform versus Gaussian beams: a comparison of the effects of diffraction, obscuration, and aberrations , 1986 .

[10]  Warren S Warren,et al.  Pump-Probe Imaging Differentiates Melanoma from Melanocytic Nevi , 2011, Science Translational Medicine.

[11]  Novotny,et al.  Orientational imaging of single molecules by annular illumination , 2000, Physical review letters.

[12]  E. Ramsay,et al.  70 nm resolution in subsurface optical imaging of silicon integrated-circuits using pupil-function engineering , 2009 .

[13]  Susumu Noda,et al.  Sub-wavelength focal spot with long depth of focus generated by radially polarized, narrow-width annular beam. , 2010, Optics express.

[14]  Tana Elizabeth Villafana,et al.  Femtosecond pump-probe microscopy generates virtual cross-sections in historic artwork , 2014, Proceedings of the National Academy of Sciences.

[15]  F. Cichos,et al.  Photothermal single particle Rutherford scattering microscopy. , 2013, Physical review letters.

[16]  Wei Min,et al.  Ground-State Depletion Microscopy: Detection Sensitivity of Single-Molecule Optical Absorption at Room Temperature , 2010 .

[17]  Warren S Warren,et al.  Probing skin pigmentation changes with transient absorption imaging of eumelanin and pheomelanin. , 2008, Journal of biomedical optics.

[18]  J. Simon,et al.  Pump-Probe Microscopic Imaging of Jurassic-Aged Eumelanin. , 2013, The journal of physical chemistry letters.

[19]  G. J. Brakenhoff,et al.  Confocal scanning light microscopy with high aperture immersion lenses , 1979 .

[20]  Alberto Diaspro,et al.  Lateral resolution improvement in two-photon excitation microscopy by aperture engineering , 2008 .

[21]  Haruo Kasai,et al.  Sub-diffraction resolution pump-probe microscopy with shot-noise limited sensitivity using laser diodes. , 2014, Optics express.

[22]  Y. de Koninck,et al.  Two-photon excitation fluorescence microscopy with a high depth of field using an axicon. , 2006, Applied optics.

[23]  T. Wilson,et al.  Scanning two photon fluorescence microscopy with extended depth of field , 2006 .

[24]  Partha Pratim Mondal,et al.  Spatial Filter Based Bessel-Like Beam for Improved Penetration Depth Imaging in Fluorescence Microscopy , 2012, Scientific Reports.