Polarization control and tomography for nonlinear microscopy

In optical microscopy, the polarization state of the focal field strongly influences formed images due to its interactions with the sample and the effective focal spot size. We demonstrate experimentally that control over the spatial profile of the focal field polarization state improves spatial resolution in laser-scanning third harmonic generation (THG) microscopy. The focal field is manipulated by imaging a spatial light modulator to the focal plane of a moderate-numerical aperture microscope. The resolution enhancement arises from exploiting the suppression, in isotropic media, of THG for circularlypolarized field polarization. By synthesizing a focal field whose polarization state changes from linear at the beam center to circular beyond radius rs, we quench THG beyond rs. A transverse spatial resolution of up to 2 times is demonstrated. Targeted manipulation necessitates measurement techniques that allow us to determine of the focal field polarization state. We develop two such techniques to characterize the field. We use a nano-particle with known third-order susceptibility to localize THG scattering to a small focal volume. Scanning this nano-probe through the focal volume of the microscope allows for complete reconstruction of the vector point spread function. Under moderate focusing conditions, where the recorded THG signal is dominated by the incident paraxial polarization component, the spatial polarization state is determined non-iteratively via three linear-polarization projection THG measurements. Under tight focusing conditions, polarization scrambling occurs such that the input and focal fields are dissimilar, and we introduce an algorithm for focal field retrieval through the collection of far-field THG images.

[1]  T G Brown,et al.  Polarization-vortex-driven second-harmonic generation. , 2003, Optics letters.

[2]  P. Carney,et al.  Robust determination of the anisotropic polarizability of nanoparticles using coherent confocal microscopy. , 2008, Journal of the Optical Society of America. A, Optics, image science, and vision.

[3]  E. Beaurepaire,et al.  Third-harmonic generation microscopy with focus-engineered beams: a numerical study. , 2008, Optics express.

[4]  Kraig E. Sheetz,et al.  Ultrafast optics: Imaging and manipulating biological systems , 2009 .

[5]  M. Hashimoto,et al.  Second-Harmonic-Generation Microscopy Using Excitation Beam with Controlled Polarization Pattern to Determine Three-Dimensional Molecular Orientation , 2005 .

[6]  B. Hecht,et al.  Principles of nano-optics , 2006 .

[7]  Tsutomu Araki,et al.  Second-harmonic-generation microscope using eight-segment polarization-mode converter to observe three-dimensional molecular orientation. , 2007, Optics letters.

[8]  S F Pereira,et al.  Field in focus with a maximum longitudinal electric component. , 2008, Physical review letters.

[9]  Brian Vohnsen,et al.  Polarization structuring for focal volume shaping in high-resolution microscopy , 2007 .

[10]  T G Brown,et al.  Longitudinal field modes probed by single molecules. , 2001, Physical review letters.

[11]  Jeffrey A. Squier,et al.  High resolution nonlinear microscopy: A review of sources and methods for achieving optimal imaging , 2001 .

[12]  Lukas Novotny,et al.  Programmable vector point-spread function engineering. , 2006, Optics express.

[13]  G Leuchs,et al.  Sharper focus for a radially polarized light beam. , 2003, Physical review letters.

[14]  M D Duncan,et al.  Scanning coherent anti-Stokes Raman microscope. , 1982, Optics letters.

[15]  Bahaa E. A. Saleh,et al.  Second- and third-harmonic generation with vector Gaussian beams , 2006 .

[16]  Colin Sheppard,et al.  Effects of axial field components on second harmonic generation microscopy. , 2006, Optics express.

[17]  R. Hellwarth,et al.  Nonlinear optical microscope using second harmonic generation. , 1975, Applied optics.

[18]  Randy A Bartels,et al.  Enhanced spatial resolution in third-harmonic microscopy through polarization switching. , 2009, Optics letters.

[19]  Kimani C Toussaint,et al.  Three-dimensional polarization control in microscopy. , 2006, Physical review letters.

[20]  John C. Schotland.  Inverse Scattering for Near-Field Microscopy , 1999 .

[21]  K. Nugent,et al.  Precision measurement of the electromagnetic fields in the focal region of a high-numerical-aperture lens using a tapered fiber probe. , 2002, Journal of the Optical Society of America. A, Optics, image science, and vision.

[22]  A. Asatryan,et al.  Vector treatment of second-harmonic generation produced by tightly focused vignetted Gaussian beams , 2004 .

[23]  Yaron Silberberg,et al.  Nonlinear scanning laser microscopy by third harmonic generation , 1997 .

[24]  K R Wilson,et al.  Third harmonic generation microscopy. , 1998, Optics express.

[25]  Ji-Xin Cheng,et al.  Green’s function formulation for third-harmonic generation microscopy , 2002 .

[26]  E. Wolf,et al.  Electromagnetic diffraction in optical systems, II. Structure of the image field in an aplanatic system , 1959, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[27]  R. Bartels,et al.  Control and measurement of spatially inhomogeneous polarization distributions in third-harmonic generation microscopy. , 2009, Optics letters.

[28]  Satoshi Kawata,et al.  Detection and characterization of longitudinal field for tip-enhanced Raman spectroscopy , 2004 .

[29]  Daniel L Marks,et al.  Inverse scattering for rotationally scanned optical coherence tomography. , 2006, Journal of the Optical Society of America. A, Optics, image science, and vision.

[30]  E. Potma,et al.  Detecting lateral interfaces with focus-engineered coherent anti-Stokes Raman scattering microscopy , 2008 .