EDoF-Miniscope: pupil engineering for extended depth-of-field imaging in a fluorescence miniscope

Abstract

Extended depth of field (EDoF) microscopy has emerged as a powerful solution to greatly increase the access into neuronal populations in table-top imaging platforms. Here, we present EDoF-Miniscope, which integrates an optimized thin and lightweight binary diffractive optical element (DOE) onto the gradient refractive index (GRIN) lens of a head-mounted fluorescence miniature microscope, i.e. "miniscope". We achieve an alignment accuracy of 70 μm to allow a 2.8X depth-of-field extension between the twin foci. We optimize the phase profile across the whole back aperture through a genetic algorithm that considers the primary GRIN lens aberrations, optical property of the submersion media, and axial intensity loss from tissue scattering in a Fourier optics forward model. Compared to other computational miniscopes, our EDoF-Miniscope produces high-contrast signals that can be recovered by a simple algorithm and can successfully capture volumetrically distributed neuronal signals without significantly compromising the speed, signal-to-noise, signal-to-background, and maintain a comparable 0.9-μm lateral spatial resolution and the size and weight of the miniature platform. We demonstrate the robustness of EDoF-Miniscope against scattering by characterizing its performance in 5-μm and 10-μm beads embedded in scattering phantoms. We demonstrate that EDoF-Miniscope facilitates deeper interrogations of neuronal populations in a 100-μm thick mouse brain sample, as well as vessels in a mouse brain. Built from off-the-shelf components augmented by a customizable DOE, we expect that this low-cost EDoF-Miniscope may find utility in a wide range of neural recording applications.

Point spread function engineering based on wavefront phase modulation

“…Lensless imaging systems enable large DOF extension 138 , broadband achromatic imaging 139 , 3D imaging 140 , and microscopy 141 . Planar optics can also be used as phase modulation devices in super resolution microscopy 142 or wavefront coding systems 81,[143][144][145] . Similarly, with the addition of deep optics, the speed and quality of lensless imaging can be enhanced 146,147 .…”

A Systematically Optimized Miniaturized Mesoscope (SOMM) for large-scale calcium imaging in freely moving mice

“…These changes are enabled by shifting some of the complexity into the computational realm (via an image retrieval algorithm) which allows for an improvement in overall performance. While initial implementations of this approach have been demonstrated, they either remain limited to small sub-millimeter FOVs offered by gradient-index objectives [27-29], or they offer larger FOV access at the cost of reduced resolution and signal-to-noise ratio (SNR) [30, 31]. Approaches based on microlens arrays as the sole imaging component offer near-cellular resolution across a ∼7 mm FOV, but they are not optimized for freely-moving applications due to their inadequate form factors, weight, and lack of demonstrated practical functionality in freely moving animals [32, 33].…”

E2E-BPF microscope: Extended depth-of-field microscopy using learning-based implementation of binary phase filter and image deconvolution

“…The DoF de nes the depth range of an object that can be sharply imaged by a given optical imaging system, and is determined by the operating wavelength, effective focal length and aperture size of the imaging lens. In many biomedical imaging applications, such as in cytometry 1,2 , histology 3 , and endoscopy [4][5][6] , high-resolution imaging over a large spatial scale is often desired; for instance, a pathological examination is typically performed with a high numerical-aperture (NA) objective to visualize cellular and subcellular features of tissue specimens, but it is accompanied by limited eldof-view (FoV) and DoF. Therefore, to image large-area pathological/cytology slides, either objects or imaging optics should be scanned and refocused repetitively, which is costly and labor-intensive.…”