Miniscope3D: miniature fluorescence microscope

K. Yanny, N. Antipa, W. Liberti, S. Dehaeck, K. Monakhova, F. L. Liu, K. Shen, Ren Ng, and L. Waller, “Miniscope3D: optimized single-shot miniature 3D fluorescence microscopy,” Light Sci Appl. 9, 171 (2020).

Under the leadership of Laura Waller, researchers from the University of California, Berkeley, have reported a lightfield miniscope that is much smaller and lighter than previous ones, and that provides with 3D images with unprecedent resolution over a very large depth of field.

The 3D miniscope is based in the smart combination of three bright ideas: the Fourier lightfield concept, the use of an optimized multifocal phase mask, and the application of a rendering algorithm based on sparsity-constrained inverse methods

Based on those concepts, authors have built a demonstration prototype composed basically by a GRIN-lens objective, a phase mask inserted at the Fourier plane and a CMOS sensor placed at the mean focal length of the phase mask. With this prototype, authors have demonstrated the capability of render 3D images of sparse fluorescent samples with lateral resolution of  across a depth of 2,76µm across a depth of 390µm.

In this paper the Miniscope3D demonstrates its utility providing 3D images of mouse brain tissue and also of freely moving tardigrades. In summary, the miniscope3D provides single-shot 3D imaging for applications where a compact platform matters, such as volumetric neural imaging in freely moving animals and 3D motion studies of dynamic samples in incubators and lab-on-a-chip devices.

Commented by Dr. Manuel Martínez

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Lightfield microscopy, a technique to study neural activities

Z. Zhang, L. Cong, L. Bai, and K. Wang, “Light-field microscopy for fast volumetric brain imaging,” Journal of Neuroscience Methods 352, 109083 (2021)

Researchers of the Center for Excellence in Brain Science and Intelligence Technology (Shanghai) have published this interesting paper in which a review of techniques for volumetric brain imaging is made.

Recording neural activities over large populations are critical for a better understanding of the functional mechanisms of animal brains. In this sense, the authors review different inspection techniques starting from those based on 3D scannings, like two-photon microscopy, which has the problem of low process speed and high light density. Another possibility, based on parallelizing the imaging process, is light-sheet microscopy which still has the problem requiring axial scanning.

Light-field-3d-microscopy for fast volumetric-brain-imaging

Confocal LFM (Zhang et al., 2020). MIPs over time of representative planes in reconstructed volumes in larval zebrafish brain (HuC: GCaMP6s). Scale bars, 50 μm.

In author’s opinion, lightfield microscopy (LFM) solves these problems elegantly by recording both the direction and location of light rays and achieving scanning-free and instantaneous volumetric imaging with a single camera exposure. However, this is made at the cost of a poor spatial resolution. But this drawback is overcome with the Fourier lightfield (FLFM) configuration, which shows substantially enhanced performance compared to that of conventional LFMs, including a lack of reconstruction artifacts near the focal plane, improved 3D reconstruction performance, and significantly reduced computational cost.

The paper finishes by collecting the results of LFM and FLFM when applied to brain images of different animals, like drosophila, zebrafish, or mouse. These results confirm the great utility of Fourier lightfield microscopy for brain imaging.

Commented by Dr. Manuel Martínez

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