Reverberation multiphoton microscopy for volumetric imaging in scattering media

Multiphoton microscopy has become an extremely valuable tool for peering deeply into thick, scattering media such as biological tissue. However, the traditional multiphoton beam-scanning approach is held back because only one thin plane is observed at a time. The reverberation loop elegantly overcomes this limitation by generating an infinite series of foci at depths spanning the sample, all sampled individually but near-simultaneously. With the inclusion of some additional interleave steps, it is possible to quickly scan a sample at video rates – allowing volumetric imaging at or near the rate one would traditionally image planes. In neural imaging, this enables a reverberation multiphoton microscope to simultaneously monitor relationships in neuronal activity not only horizontally across samples, but vertically across many layers of the brain. In imaging of engineered cardiac tissues, this enables high resolution observation of three-dimensional structures in a live sample, even as it actively beats and moves

Simultaneous multiplane imaging with reverberation multiphoton microscopy

Multiphoton microscopy (MPM) has gained enormous popularity over the years for its capacity to provide high resolution images from deep within scattering samples1. However, MPM is generally based on single-point laser-focus scanning, which is intrinsically slow. While imaging speeds as fast as video rate have become routine for 2D planar imaging, such speeds have so far been unattainable for 3D volumetric imaging without severely compromising microscope performance. We demonstrate here 3D volumetric (multiplane) imaging at the same speed as 2D planar (single plane) imaging, with minimal compromise in performance. Specifically, multiple planes are acquired by near-instantaneous axial scanning while maintaining 3D micron-scale resolution. Our technique, called reverberation MPM, is well adapted for large-scale imaging in scattering media with low repetition-rate lasers, and can be implemented with conventional MPM as a simple add-on.Accepted manuscrip

The Galactic Center with Roman

We advocate for a Galactic center (GC) field to be added to the Galactic Bulge Time Domain Survey (GBTDS). The new field would yield high-cadence photometric and astrometric measurements of an unprecedented ${\sim}$3.3 million stars toward the GC. This would enable a wide range of science cases, such as finding star-compact object binaries that may ultimately merge as LISA-detectable gravitational wave sources, constraining the mass function of stars and compact objects in different environments, detecting populations of microlensing and transiting exoplanets, studying stellar flares and variability in young and old stars, and monitoring accretion onto the central supermassive black hole. In addition, high-precision proper motions and parallaxes would open a new window into the large-scale dynamics of stellar populations at the GC, yielding insights into the formation and evolution of galactic nuclei and their co-evolution with the growth of the supermassive black hole. We discuss the possible trade-offs between the notional GBTDS and the addition of a GC field with either an optimal or minimal cadence. Ultimately, the addition of a GC field to the GBTDS would dramatically increase the science return of Roman and provide a legacy dataset to study the mid-plane and innermost regions of our Galaxy.Comment: 19 pages, 3 figures. Submitted to the NASA Roman Core Community Surveys White Paper Cal

Visualization 1: Conjugate adaptive optics in widefield microscopy with an extended-source wavefront sensor

System demonstration video showing real-time AO while sample and aberrations are sporadically translated. Originally published in Optica on 20 August 2015 (optica-2-8-682