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An unprecedented intramolecular [4 + 2] tetrazine-olefin cycloaddition with α,β-unsaturated substrates was discovered. The reaction produces unique coumarin-dihydropyridazine heterocycles that exhibited strong fluorescence with large Stokes shifts and excellent photo- and pH-stability. This property can be used for reaction analysis. The rate of cycloaddition was found to be solvent dependent and was determined using experimental data with a kinetic modeling software (COPASI) as well as DFT calculations ( k 1 = 0.64 ± 0.019 s −1 and 4.1 s −1 , respectively). The effects of steric and electronic properties of both the tetrazine and α,β-unsaturated carbonyl on the reaction were studied and followed the known trends characteristic of the intermolecular reaction. Based on these results, we developed a “release-then-click” strategy for the ROS triggered release of methylselenenic acid (MeSeOH) and a fluorescent tracer. This strategy was demonstrated in HeLa cells via fluorescence imaging. 

Light field cameras have been employed in myriad applications thanks to their 3D imaging capability. By placing a microlens array in front of a conventional camera, one can measure both the spatial and angular information of incoming light rays and reconstruct a depth map. The unique optical architecture of light field cameras poses new challenges on controlling aberrations and vignetting in lens design process. The results of our study show that field curvature can be numerically corrected for by digital refocusing, and vignetting must be minimized because it reduces the depth reconstruction accuracy. To address this unmet need, we herein present an optical design pipeline for light field cameras and demonstrated its implementation in a light field endoscope.

 

Prevalent techniques in label-free linear optical microscopy are either confined to imaging in two dimensions or rely on scanning, both of which restrict their applications in imaging subtle biological dynamics. In this paper, we present the theoretical basis along with demonstrations supporting that full-field spectral-domain interferometry can be used for imaging samples in 3D with no moving parts in a single shot. Consequently, we propose a novel optical imaging modality that combines low-coherence interferometry with hyperspectral imaging using a light-emitting diode and an image mapping spectrometer, called Snapshot optical coherence microscopy (OCM). Having first proved the feasibility of Snapshot OCM through theoretical modeling and a comprehensive simulation, we demonstrate an implementation of the technique using off-the-shelf components capable of capturing an entire volume in 5 ms. The performance of Snapshot OCM, when imaging optical targets, shows its capability to axially localize and section images over an axial range of ±10 µm, while maintaining a transverse resolution of 0.8 µm, an axial resolution of 1.4 µm, and a sensitivity of up to 80 dB. Additionally, its performance in imaging weakly scattering live cells shows its capability to not only localize the cells in a densely populated culture but also to generate detailed phase profiles of the structures at each depth for long durations. Consolidating the advantages of several widespread optical microscopy modalities, Snapshot OCM has the potential to be a versatile imaging technique for a broad range of applications.

 

In this Letter, we present a snapshot hyperspectral light field imaging system using a single camera. By integrating an unfocused light field camera with a snapshot hyperspectral imager, the image mapping spectrometer, we captured a five-dimensional (5D) ($x,y,u,v,\mathrm{\lambda <\#comment/>}$) ($x,y,$spatial coordinates;$u,v,$emittance angles;$\mathrm{\lambda <\#comment/>},$wavelength) datacube in a single camera exposure. The corresponding volumetric image ($x,y,z$) at each wavelength is then computed through a scale-depth space transform. We demonstrated the snapshot advantage of our system by imaging the spectral-volumetric scenes in real time.

 

An image mapping spectrometer (IMS) is a snapshot hyperspectral imager that simultaneously captures both the spatial ($x$,$y$) and spectral ($\mathrm{\lambda <\#comment/>}$) information of incoming light. The IMS maps a three-dimensional (3D) datacube ($x$,$y$,$\mathrm{\lambda <\#comment/>}$) to a two-dimensional (2D) detector array ($x$,$y$) for parallel measurement. To reconstruct the original 3D datacube, one must construct a lookup table that connects voxels in the datacube and pixels in the raw image. Previous calibration methods suffer from either low speed or poor image quality. We herein present a slit-scan calibration method that can significantly reduce the calibration time while maintaining high accuracy. Moreover, we quantitatively analyzed the major artifact in the IMS, the striped image, and developed three numerical methods to correct for it.