Two-photon endoscopic imaging using a multi-mode fiber

Project description:

Two-photon fluorescence1 is a popular choice for tissue imaging, owing to its intrinsic optical-sectioning capability when the excitation beam is focused on the sample. The resulting image is that of a well-defined plane inside the sample, which enables the reconstruction of three-dimensional objects with good resolution along the axial (z) direction.

It is necessary to use an ultrashort pulsed laser source to achieve high enough photon density for two-photon absorption. However, pulse broadening effects due to group velocity dispersion (GVD) and modal dispersion in the multi-mode fiber must be addressed to enable nonlinear imaging2–6. In this project, we propose the use of a phase light modulator (PLM) for simultaneous spatial and temporal focusing of the beam, thus enabling two-photon absorption and nonlinear imaging.

Microscope images from: https://doi.org/10.5021/ad.2020.32.3.251

Main activities:

– Optical design and building an experimental setup

– Instrument control (light modulator, camera, motorized stages, etc.)

– Imaging of calibration and biological samples.

We are looking for a motivated student, eager to learn and develop their experimental optics skills. If that sounds like you, please send a CV and motivation letter to Assia Benachir at: [email protected]

 

References

1. Zipfel, W. R., Williams, R. M. & Webb, W. W. Nonlinear magic: multiphoton microscopy in the biosciences. Nat. Biotechnol. 21, 1369–1377 (2003).

2. Cao, H., Čižmár, T., Turtaev, S., Tyc, T. & Rotter, S. Controlling light propagation in multimode fibers for imaging, spectroscopy, and beyond. Adv. Opt. Photonics 15, 524–612 (2023).

3. Morales-Delgado, E. E., Psaltis, D. & Moser, C. Two-photon imaging through a multimode fiber. Opt. Express Vol 23 Issue 25 Pp 32158-32170 https://doi.org/10.1364/OE.23.032158 (2015) doi:10.1364/OE.23.032158.

4. Mounaix, M. et al. Spatiotemporal Coherent Control of Light through a Multiple Scattering Medium with the Multispectral Transmission Matrix. Phys. Rev. Lett. 116, 253901 (2016).

5. Cao, H., Mosk, A. P. & Rotter, S. Shaping the propagation of light in complex media. Nat. Phys. 18, 994–1007 (2022).

6. Boniface, A., Dong, J. & Gigan, S. Non-invasive focusing and imaging in scattering media with a fluorescence-based transmission matrix. Nat. Commun. 11, 6154 (2020).