Abstract
Laser scanning is used in advanced biological microscopy to deliver superior imaging contrast, resolution and sensitivity. However, it is challenging to scale up the scanning speed required for interrogating a large and heterogeneous population of biological specimens or capturing highly dynamic biological processes at high spatiotemporal resolution. Bypassing the speed limitation of traditional mechanical methods, free-space angular-chirp-enhanced delay (FACED) is an all-optical, passive and reconfigurable laser-scanning approach that has been successfully applied in different microscopy modalities at an ultrafast line-scan rate of 1–80 MHz. Optimal FACED imaging performance requires optimized experimental design and implementation to enable specific high-speed applications. In this protocol, we aim to disseminate information allowing FACED to be applied to a broader range of imaging modalities. We provide (i) a comprehensive guide and design specifications for the FACED hardware; (ii) step-by-step optical implementations of the FACED module including the key custom components; and (iii) the overall image acquisition and reconstruction pipeline. We illustrate two practical imaging configurations: multimodal FACED imaging flow cytometry (bright-field, fluorescence and second-harmonic generation) and kHz 2D two-photon fluorescence microscopy. Users with basic experience in optical microscope operation and software engineering should be able to complete the setup of the FACED imaging hardware and software in ~2–3 months.
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Data availability
The custom codes and data used in this protocol are available in the Supplementary Software and upon request, respectively.
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Acknowledgements
The work is supported by the Research Grants Council of the Hong Kong Special Administrative Region of China (grant nos. 17209017, 17259316, 17207715, C7047-16G and RFS2021-7S06), Innovation and Technology Support Programme (ITS/204/18), NIH BRAIN Initiative grants 1UF1NS107696.
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K.K.T. and the University of Hong Kong have filed a US patent application (14/733,454) that relates to the all-optical laser-scanning imaging methods.
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Peer review information Nature Protocols thanks Pietro Ferraro and the other, anonymous reviewer(s) for their contribution to the peer review of this work.
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Key references associated with this protocol
Wu, J. L. et al. Light Sci. Appl. 6, e16196 (2017): https://doi.org/10.1038/lsa.2016.196
Wu, J. et al. Nat. Methods 17, 287–290 (2020): https://doi.org/10.1038/s41592-020-0762-7
Ren, Y. X. et al. Light Sci. Appl. 9, 8 (2020): https://doi.org/10.1038/s41377-020-0245-8
Supplementary information
Supplementary Information
Supplememtary Manuals 1–3, Supplementary Note 1 and Supplementary Tables 1 and 2.
Supplementary Software
The data acquisition and visualizing program for FPGA system and oscilloscope.
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Lai, Q.T.K., Yip, G.G.K., Wu, J. et al. High-speed laser-scanning biological microscopy using FACED. Nat Protoc 16, 4227–4264 (2021). https://doi.org/10.1038/s41596-021-00576-4
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DOI: https://doi.org/10.1038/s41596-021-00576-4
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