@article{801f7131e450451586ff10e3aa73499e,
title = "Throughput-Speed Product Augmentation for Scanning Fiber-Optic Two-Photon Endomicroscopy",
abstract = "Compactness, among several others, is one unique and very attractive feature of a scanning fiber-optic two-photon endomicroscope. To increase the scanning area and the total number of resolvable pixels (i.e., the imaging throughput), it typically requires a longer cantilever which, however, leads to a much undesired, reduced scanning speed (and thus imaging frame rate). Herein we introduce a new design strategy for a fiber-optic scanning endomicroscope, where the overall numerical aperture (NA) or beam focusing power is distributed over two stages: 1) a mode-field focuser engineered at the tip of a double-clad fiber (DCF) cantilever to pre-amplify the single-mode core NA, and 2) a micro objective of a lower magnification (i.e., ∼ 2× in this design) to achieve final tight beam focusing. This new design enables either an 9-fold increase in imaging area (throughput) or an 3-fold improvement in imaging frame rate when compared to traditional fiber-optic endomicroscope designs. The performance of an as-designed endomicroscope of an enhanced throughput-speed product was demonstrated by two representative applications: (1) high-resolution imaging of an internal organ (i.e., mouse kidney) in vivo over a large field of view without using any fluorescent contrast agents, and (2) real-time neural imaging by visualizing dendritic calcium dynamics in vivo with sub-second temporal resolution in GCaMP6m-expressing mouse brain. This cascaded NA amplification strategy is universal and can be readily adapted to other types of fiber-optic scanners in compact linear or nonlinear endomicroscopes.",
keywords = "Biomedical optical imaging, biophotonics, endomicroscope, in vivo imaging, nonlinear optics, optical microscopy, two-photon microscopy",
author = "Wenxuan Liang and Park, {Hyeon Cheol} and Kaiyan Li and Ang Li and Defu Chen and Honghua Guan and Yuanlei Yue and Gau, {Yung Tian A.} and Bergles, {Dwight E.} and Li, {Ming Jun} and Hui Lu and Xingde Li",
note = "Funding Information: This work was supported in part by the National Institutes of Health (NIH) under Grant R01 CA153023 and Grant P50 CA103175, in part by the National Science Foundation: Major Research Instrumentation (MRI) under GrantCBET-1430040, in part by the Medical Technology Enterprise Consortium under Grant 9MTEC 16-02-BMI-09, and in part by the Hartwell Foundation. Funding Information: NA, and2)a micro objectiveof alower magnificationfiber(DCF)cantilevertopre-amplifythesingle-modecore WO-PHOTON microscopy (2PM), with its intrinsic (i.e., ∼2× in this design) to achieve final tight beam Tdepth-sectioning capability, deeper penetration and focusing. This new design enables either an ∼9-fold reduced photodamage, has become the three-dimensional increase in imaging area (throughput) or an ∼3-fold microscopy method of choice for in vivo deep imaging of improvement in imaging frame rate when compared to biological tissues [1], [2]. Among the numerous biomedical manceofanas-designedendomicroscopeofanenhancedtraditionalfiber-opticendomicroscopedesigns.Theperfor- applications of 2PM, two particularly appealing categories are: throughput-speedproductwasdemonstratedbytworep- 1) structural and functional imaging of unstained biological resentative applications: (1) high-resolution imaging of an tissue using native (auto)fluorescence (especially from NADH internal organ (i.e., mouse kidney) in vivo over a large and FAD) or second-harmonic generation signal from colla-fieldofviewwithoutusinganyfluorescentcontrastagents, gen fibers for translational clinical applications [3], [4], and and (2) real-time neural imaging by visualizing dendritic 2) optical recording of neural dynamics from multiple neurons and other excitable glial cells (such as astrocytes) of mouse ManuscriptreceivedApril27,2020;revisedJune15,2020;accepted models with genetically encoded calcium indicators (GECIs), November30,2020.ThisworkwassupportedinpartbytheNationalJune21,2020.DateofpublicationJune25,2020;dateofcurrentversion especially the family of GCaMP [5], [6]. The bulky footprint Institutes of Health (NIH) under Grant R01 CA153023 and Grant P50 of conventional bench-top 2PM embodiments, however, limits CA103175,inpartbytheNationalScienceFoundation:MajorResearch its clinical usage to superficial tissues (such as skin or oral TechnologyEnterpriseConsortiumunderGrant9MTEC16-02-BMI-09,Instrumentation(MRI)underGrantCBET-1430040,inpartbytheMedical cavity), and necessitates constraining the head of mouse mod-and in part by the Hartwell Foundation. (Corresponding author: Xingde els beneath the objective for neural dynamics acquisition [7]. Publisher Copyright: {\textcopyright} 1982-2012 IEEE.",
year = "2020",
month = dec,
doi = "10.1109/TMI.2020.3005067",
language = "English (US)",
volume = "39",
pages = "3779--3787",
journal = "IEEE transactions on medical imaging",
issn = "0278-0062",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "12",
}