Fourier light field microscopy (FLFM) captures a sample 3D volume in a single snapshot, providing game-changing imaging speed for various bio-imaging applications. Existing FLFM platforms have often been designed as single-purpose implementations, with a fixed performance in resolution and field of view, restricting widespread applications. Here, to democratize FLFM toward broader adoption for biomedical research, we describe a multi-purpose implementation of FLFM that enables synchronous volumetric imaging across a wide range of resolution and field of view. With our single instrument, we demonstrate a variety of bio-imaging applications across scales, including sub-cellular dynamics, tissue cellular dynamics, and whole-brain neural activity.
The breaking of bilateral symmetry in most vertebrates is critically dependent upon the motile cilia of
the embryonic left-right organizer (LRO), which generate a directional fluid flow; however, it remains
unclear how this flow is sensed. Here, we demonstrated that immotile LRO cilia are mechanosensors for
shear force using a methodological pipeline that combines optical tweezers, light sheet microscopy, and
deep learning to permit in vivo analyses in zebrafish. Mechanical manipulation of immotile LRO cilia
activated intraciliary calcium transients that required the cation channel Polycystin-2. Furthermore,
mechanical force applied to LRO cilia was sufficient to rescue and reverse cardiac situs in zebrafish that lack
motile cilia. Thus, LRO cilia are mechanosensitive cellular levers that convert biomechanical forces into
calcium signals to instruct left-right asymmetry.
Hyperpsectral fluorescence imaging has been gaining its popularity in life-science field for its simultaneous multiplexing capability of multiple fluorescent labels. Traditional diffraction grating-based hyperspectral acquisition has limited photon-throughput due to the loss at the diffractive optics. The uniform spectral sampling using multiple narrow spectral bands also limits the detectable photons for each channel, which limits the imaging speed as longer exposure is required to achieve sufficient signal to noise ratios. Here we present a Fourier transform-based spectral sampling strategy based on high efficiency dichroic mirrors, enabling video-speed snapshot acquisition with the capability of multiplexing more than five fluorescent signatures.
Molecular rotational dynamics is an old problem that continues to be relevant today. In the continuing search for new optical materials and phenomena, both from an application and scientific standpoint, a detailed understanding of molecular rotational dynamics is often of crucial importance. An example is the so-called Janossy effect, where it was found that the already large optical reorientation of liquid crystals (LC) could be greatly enhanced by doping a small amount of absorbing dye. We report here our recent effort studying the Janossy effect in isotropic-phase LC. The current explanation of the Janossy effect assumes a change in guest-host interaction upon photoexcitation of the guest molecules, which would manifest as a difference in rotational dynamics between solute ground and excited states. While there are many available experimental techniques to selectively probe the solute excited state, probing the solute ground state is often difficult, due to interferences from the excited solute and solvent molecules. We have developed an optical pump/probe technique that employs two successive pump pulses that are adjusted to allow selective measuring of the solute ground state rotational dynamics. Application of the technique to the dye-LC system that exhibits the Janossy effect shows a large difference between rotational diffusion rates of the ground and the excited state of the dye molecules. Combined with results from optical pump/probe of the LC host, information on the rotational dynamics of the dye yields a better understanding of the mechanism of the Janossy effect.
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