Focus scanning with feedback-control for fiber-optic nonlinear endomicroscopy

Li, Ang; Liang, Wenxuan; Guan, Honghua; Gau, Yung Tian A.; Bergles, Dwight E.; Li, Xingde

doi:10.1364/boe.8.002519

Cited by 17 publications

(14 citation statements)

References 20 publications

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“…ETLs are attractive because they are transmissive and can be placed directly in the optical path, so they don’t require the extra complexity of reflective surfaces in the optical path. ETLs can be enabled by shape-memory alloys 17 or pneumatic actuation 18 , however, these solutions are too slow for fast 3D scanning and not easily miniaturized. Other types of ETLs include shape-changing polymer lenses 19 , 20 , pressure-driven lenses 21 , and responsive hydrogel lenses 22 .…”

Section: Introductionmentioning

confidence: 99%

Three dimensional two-photon brain imaging in freely moving mice using a miniature fiber coupled microscope with active axial-scanning

Ozbay

Futia

et al. 2018

Sci Rep

116

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We present a miniature head mounted two-photon fiber-coupled microscope (2P-FCM) for neuronal imaging with active axial focusing enabled using a miniature electrowetting lens. We show three-dimensional two-photon imaging of neuronal structure and record neuronal activity from GCaMP6s fluorescence from multiple focal planes in a freely-moving mouse. Two-color simultaneous imaging of GFP and tdTomato fluorescence is also demonstrated. Additionally, dynamic control of the axial scanning of the electrowetting lens allows tilting of the focal plane enabling neurons in multiple depths to be imaged in a single plane. Two-photon imaging allows increased penetration depth in tissue yielding a working distance of 450 μm with an additional 180 μm of active axial focusing. The objective NA is 0.45 with a lateral resolution of 1.8 μm, an axial resolution of 10 μm, and a field-of-view of 240 μm diameter. The 2P-FCM has a weight of only ~2.5 g and is capable of repeatable and stable head-attachment. The 2P-FCM with dynamic axial scanning provides a new capability to record from functionally distinct neuronal layers, opening new opportunities in neuroscience research.

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Section: Introductionmentioning

confidence: 99%

Three dimensional two-photon brain imaging in freely moving mice using a miniature fiber coupled microscope with active axial-scanning

Ozbay

Futia

et al. 2018

Sci Rep

116

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“…42,43 The 500-μm working distance of the current design is optimized for mucosa penetration, and the penetration depth in teeth can reach as deep as ∼2 mm. Dynamic focus tuning through a solid tunable lens [44][45][46] or shape memory alloy 47 can also be implemented in future designs to better accommodate different imaging setups.…”

Section: Discussionmentioning

confidence: 99%

Low-cost, ultracompact handheld optical coherence tomography probe for in vivo oral maxillofacial tissue imaging

Li¹,

Yang

Liang

et al. 2020

J. Biomed. Opt.

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Significance: Optical coherence tomography (OCT) has proven useful for detecting various oral maxillofacial abnormalities. To apply it to clinical applications including biopsy guidance and routine screening, a handheld imaging probe is indispensable. OCT probes reported for oral maxillofacial imaging were either based on a bulky galvanometric mirror pair (not compact or long enough) or a distal-end microelectromechanical systems (MEMS) scanner (raised safety concerns), or adapted from fiber-optic catheters (ill-suited for oral cavity geometry). Aim: To develop a handheld probe featuring great compactness and excellent maneuverability for oral maxillofacial tissue imaging. Approach: A dual-axis MEMS scanner was deployed at the proximal end of the probe and the scanned beam was relayed to the distal end through a 4f configuration. Such design provides both a perfect dual-axis telecentric scan and excellent compactness. Results: A handheld probe with a rigid part 70 mm in length and 7 mm in diameter and weighing 25 g in total was demonstrated through both ex vivo and in vivo experiments, including structural visualization of various oral maxillofacial tissues and monitoring the recovery process of an oral mucosa canker sore. Conclusions: The proposed probe exhibits excellent maneuverability and imaging performance showing great potential in clinical applications.

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“…A marked benefit of the lensless microendoscope system presented is the ability to computationally refocus on objects that are positioned at different depths without any actuated components and using only a single camera frame. Conventionally, optical endoscopes with depth-scanning capabilities require components capable of physically varying the focal plane, such as electrically tunable lens, which makes brain mounting of freely moving animals difficult due to increased distal footprint and weight (23)(24)(25)(26). In stark contrast to these bulky approaches, we can simply calibrate the system responses at different depths and reconstruct the scene volumetrically without actuation from a single camera snapshot.…”

Section: Computational Refocusingmentioning

confidence: 99%

A minimally invasive lens-free computational microendoscope

et al. 2019

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Ultra-miniaturized microendoscopes are vital for numerous biomedical applications. Such minimally invasive imagers allow for navigation into hard-to-reach regions and observation of deep brain activity in freely moving animals. Conventional solutions use distal microlenses. However, as lenses become smaller and less invasive, they develop greater aberrations and restricted fields of view. In addition, most of the imagers capable of variable focusing require mechanical actuation of the lens, increasing the distal complexity and weight. Here, we demonstrate a distal lens-free approach to microendoscopy enabled by computational image recovery. Our approach is entirely actuation free and uses a single pseudorandom spatial mask at the distal end of a multicore fiber. Experimentally, this lensless approach increases the space-bandwidth product, i.e., field of view divided by resolution, by threefold over a best-case lens-based system. In addition, the microendoscope demonstrates color resolved imaging and refocusing to 11 distinct depth planes from a single camera frame without any actuated parts.

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Focus scanning with feedback-control for fiber-optic nonlinear endomicroscopy

Cited by 17 publications

References 20 publications

Three dimensional two-photon brain imaging in freely moving mice using a miniature fiber coupled microscope with active axial-scanning

Three dimensional two-photon brain imaging in freely moving mice using a miniature fiber coupled microscope with active axial-scanning

Low-cost, ultracompact handheld optical coherence tomography probe for in vivo oral maxillofacial tissue imaging

A minimally invasive lens-free computational microendoscope

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