Chiroptical Effects in the Second Harmonic Signal of Collagens I and IV

We applied our multimodal nonlinear spectral imaging microscope to the measurement of rat cornea. We successfully obtained multiple nonlinear signals of coherent anti‐Stokes Raman scattering (CARS), third‐order sum frequency generation (TSFG), and second harmonic generation (SHG). Depending on the nonlinear optical processes, the cornea tissue was visualized with different image contrast mechanism simultaneously. Due to white‐light laser excitation, multiplex CARS and TSFG spectra were obtained. Combined multimodal and spectral analysis clearly elucidated the layered structure of rat cornea with molecular structural information. This study indicates that our multimodal nonlinear spectral microscope is a promising bioimaging method for tissue study.

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“…The image corresponds to 25 × 175 μm 2 . [29]. Therefore, SHG signal should be obtained only from the Bowman's layer, not from basement membrane.…”

Section: Resultsmentioning

confidence: 99%

Multimodal and multiplex spectral imaging of rat cornea ex vivo using a white‐light laser source

Segawa

Kaji

Leproux

et al. 2014

Journal of Biophotonics

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“…While second harmonic generation is often used to image biological samples, there is still a lack of understanding of the signal formation. Especially the χ-tensor of the specimen remains elusive [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Molecular orientation sensitive second harmonic microscopy by radially and azimuthally polarized light

Ehmke

Nitzsche

Knebl

et al. 2014

Biomed. Opt. Express

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Abstract:We demonstrate the possibility to switch the z-polarization component of the illumination in the vicinity of the focus of high-NA objective lenses by applying radially and azimuthally polarized incident light. The influence of the field distribution on nonlinear effects was first investigated by the means of simulations. These were performed for high-NA objective lenses commonly used in nonlinear microscopy. Special attention is paid to the influence of the polarization of the incoming field. For linearly, circularly and radially polarized light a considerable polarization component in z-direction is generated by high NA focusing. Azimuthal polarization is an exceptional case: even for strong focusing no z-component arises. Furthermore, the influence of the input polarization on the intensity contributing to the nonlinear signal generation was computed. No distinct difference between comparable input polarization states was found for chosen thresholds of nonlinear signal generation. Differences in signal generation for radially and azimuthally polarized vortex beams were experimentally evaluated in native collagen tissue (porcine cornea). The findings are in good agreement with the theoretical predictions and display the possibility to probe the molecular orientation along the optical axis of samples with known nonlinear properties. The combination of simulations regarding the nonlinear response of materials and experiments with different sample orientations and present or non present z-polarization could help to increase the understanding of nonlinear signal formation in yet unstudied materials.

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“…In order to carry out such investigation, model systems made up of spherical particles in suspension in a host medium have been widely studied [1,2]. Femtosecond lasers are bright enough to go through very thick media with tunable wavelength [3,4], and are used in a wide variety of optical diagnosis and imaging techniques (SHG [5], THG [6], CARS [7], …). Furthermore, thanks to Optical Kerr Gate (OKG) measurements [8] or up-conversion technique [9], it is possible to temporally sample the light going out of the sample with a resolution of approximately 100 fs [10] (i.e.…”

Section: Introductionmentioning

confidence: 99%

Picosecond time scale modification of forward scattered light induced by absorption inside particles

Kervella¹,

d’Abzac²,

Hache³

et al. 2011

Opt. Express

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Abstract:The aim of this work is to evaluate the influence of absorption processes on the Time Of Flight (TOF) of the light scattered out of a thick medium in the forward direction. We use a Monte-Carlo simulation with temporal phase function and Debye modes. The main result of our study is that absorption inside the particle induces a decrease of the TOF on a picosecond time scale, measurable with a femtosecond laser apparatus. This decrease, which exhibits a neat sensitivity to the absorption coefficient of particles, could provide an efficient way to measure this absorption.

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Chiroptical Effects in the Second Harmonic Signal of Collagens I and IV

Cited by 89 publications

References 42 publications

Multimodal and multiplex spectral imaging of rat cornea ex vivo using a white‐light laser source

Multimodal and multiplex spectral imaging of rat cornea ex vivo using a white‐light laser source

Molecular orientation sensitive second harmonic microscopy by radially and azimuthally polarized light

Picosecond time scale modification of forward scattered light induced by absorption inside particles

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