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More Non-linear Microscopy. E x = E xo cos(2  ft) = E xo cos (   t) P x = aE xo cos (  t) + dE 2 xo cos 2 (  t) P = aE + dE 2 + d'E 3 +... Nonlinear.

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Presentation on theme: "More Non-linear Microscopy. E x = E xo cos(2  ft) = E xo cos (   t) P x = aE xo cos (  t) + dE 2 xo cos 2 (  t) P = aE + dE 2 + d'E 3 +... Nonlinear."— Presentation transcript:

1 More Non-linear Microscopy

2 E x = E xo cos(2  ft) = E xo cos (   t) P x = aE xo cos (  t) + dE 2 xo cos 2 (  t) P = aE + dE 2 + d'E Nonlinear Polarization

3 First experimental observation of SHG (1962) Right after invention of ruby laser

4 Coherent Anti-Stokes Raman Scattering (CARS)

5 Collect SHG, TPEF Simultaneously Laser scanning Nonlinear optical microscope 850 nm SHG is coherent: Forward propagates Or TPEF

6 Evans and Xie Video Rate epi- CARS for Tissue Imaging

7 Intensity ~ Power 2 Intensity ~ concentration Lifetime ~ ns Stoke shift Intensity ~ Power 2 Intensity ~ concentration 2 Instantaneous No loss of energy TPEF and SHG Photophysics

8

9 Mertz, BJ )SHG “spectrum” mirrors Two-photon spectrum: Resonance enhancement 2) TPEF intensity >> SHG TPEF TPEF and SHG “Spectra”

10 Only forward direction for objects axially longer than wavelength Dipole Emission Patterns for scattering particles Xie J. Phys. Chem Many dipoles aligned: All forward directed

11 Mertz, BJ 2001 Calculations show that SHG emitted in two lobes

12 WT OI/OI Fw Bw Fw Bw Forward/Backward Fractions SHG in Tendon: Wild type vs OI WT larger fibers, also brighter, F/B Ratio?

13 image plane A Percent Scattered Back Thickness (µm) B Thick tissues, initial photon is multiply scatttered Some goes backwards direction Like SHG Backscattered collection Red, Black: experimental and Monte Carlo simulations From intralipid phantom Blue=mouse Real Tissue: Only Scattering Matters

14 100  m 50  m 100  m 20  m 30  m deep 70  m deep 100  m deep 0  m deep ABC D E F 50  m CorneacytesSebaceous glands Adipocytes Evans and Xie PNAS CARS Image of Hairless Mouse Ear


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