Lab visit to Palczewski Lab

P. Ciąćka and J. Bogusławski of prof. Wojtkowski's group visited the University of California Irvine. Their research visit involved working for two and a half weeks at Palczewski Lab (part of the Center of translational Vision Research). During that time researchers aimed to implement a photon-counting-based detection scheme into their custom-built two-photon-excited-fluorescence scanning light ophthalmoscope (SLO) for murine eyes, obtain images of mouse retina and test the feasibility of replacing the MIIPS dispersion control device with a dedicated pulse compressor.

On their previous visit, it was decided that a detection scheme based on photon counting is optimal and necessary for improving the signal-to-noise ratio to aid imaging using minimal light doses. A custom implementation of photon counting was done in Warsaw in preparation for the visit. Employing National Instruments card-based counters for easy interfacing with custom Lab-View software, the scheme was carefully tested, characterized, and benchmarked against the alternatives. Upon installing the detector and Software at UCI, all the components interfaced without any problems. Crucially, the improvement in sensitivity of the device was readily evident.

Piotr and Jakub proceeded to obtain images of murine retinas in vivo. After a couple of unsuccessful trials where no retina features could be discerned, it was discovered that an additional high optical power element inserted before the relay telescope is needed to aid the focusing of light on the retina. Despite some aberrations limiting the resolution, the first two-photon excited fluorescence retinal images were duly obtained from their setup.

Additionally, a MIIPS device present in their setup for group-velocity dispersion compensation was replaced with a prototype of a pulse compressor. Tests benchmarking the laser pulse width at the sample were performed for both devices, with satisfactory results. The murine retina in vivo images was also collected with the compressor present in the system.

Visitors

Piotr Ciąćka, Jakub Bogusławski,

Dates

Aug.23 – Sep. 12, 2019

Location

The University of California Irvine, Irvine, CA, USA