Nonlinear optical endoscopy based on a double-clad photonic crystal fiber and a MEMS mirror

Fu, Ling; Jain, Ankur; Xie, Huikai; Cranfield, Charles G.; Gu, Miṅ

doi:10.1364/oe.14.001027

Cited by 147 publications

(99 citation statements)

References 19 publications

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“…Phase-and amplitude-deviations in spiral scanners can be compensated by empirical radius-dependent angular lag functions [24] or -as shown hereby experimentally determined scan-trajectories. Alternative scanning approaches such as MEMS-based scan engines [27,28] and "piezolever" fiber scanners [26], enable galvanometric-like beam-steering and random-access scanning albeit at the cost of slower scan speeds and expensive, time-consuming manufacturing processes. Finally, imaging through coherent fiber bundles suffers from reduced spatial resolution [19,30].…”

Section: Discussionmentioning

confidence: 99%

“…Key technological achievements have been the application of micro-optical components such as GRIN lenses [17][18][19], the use of special optical fibers for efficient laser pulse delivery [20][21][22][23] and fluorescence collection [24,25], respectively, and the development of compact laser scanning devices. Two scanning methods have prevailed: (1) mechanical deflection or vibration of fiber cantilevers [11,23,26], and (2) microelectromechanical systems (MEMS) with small mirrors [27,28]. Alternatively, a coherent fiber bundle can circumvent the need for scanning at the microscope headpiece albeit at the cost of reduced spatial resolution and sensitivity [19].…”

Section: Introductionmentioning

confidence: 99%

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Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo

et al. 2008

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(2008). Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo. Optics Express, 16(8) Abstract: We present a small, lightweight two-photon fiberscope and demonstrate its suitability for functional imaging in the intact brain. Our device consists of a hollow-core photonic crystal fiber for efficient delivery of near-IR femtosecond laser pulses, a spiral fiber-scanner for resonant beam steering, and a gradient-index lens system for fluorescence excitation, dichroic beam splitting, and signal collection. Fluorescence light is remotely detected using a standard photomultiplier tube. All optical components have 1 mm dimensions and the microscope's headpiece weighs only 0.6 grams. The instrument achieves micrometer resolution at frame rates of typically 25 Hz with a field-of-view of up to 200 microns. We demonstrate functional imaging of calcium signals in Purkinje cell dendrites in the cerebellum of anesthetized rats. The microscope will be easily portable by a rat or mouse and thus should enable functional imaging in freely behaving animals. References and links 1.E. Seibel, T. Soper, R. Johnston, and R. Glenny, "Ultrathin laser scanning bronchoscope and guidance system for the peripheral lung," Lung Cancer 49, S162-S162 (2005 L. Fu and M. Gu, "Fibre-optic nonlinear optical microscopy and endoscopy," J. Microsc. 226, 195-206 (2007). 9.J. C. Jung, A. D. Mehta, E. Aksay, R. Stepnoski, and M. J. Schnitzer, "In vivo mammalian brain Imaging using one-and two-photon fluorescence microendoscopy,"

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo

et al. 2008

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“…A similar micromirror was later applied to two-photon fluorescence and second-harmonic generation endoscopy by combining with a double-clad photonic crystal fiber, and the system was used for rat esophagus imaging [29]. In order to achieve two-dimensional scanning necessary for obtaining 3D volumetric images in OCT, a similar structure was designed and demonstrated instead with thermoelectric-bimorph beams that enabled an added rotation axis, as shown in Figure 1 [20].…”

Section: Thermoelectric Actuationmentioning

confidence: 99%

Progress of MEMS Scanning Micromirrors for Optical Bio-Imaging

Lin

Keeler

2015

Micromachines

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Microelectromechanical systems (MEMS) have an unmatched ability to incorporate numerous functionalities into ultra-compact devices, and due to their versatility and miniaturization, MEMS have become an important cornerstone in biomedical and endoscopic imaging research. To incorporate MEMS into such applications, it is critical to understand underlying architectures involving choices in actuation mechanism, including the more common electrothermal, electrostatic, electromagnetic, and piezoelectric approaches, reviewed in this paper. Each has benefits and tradeoffs and is better suited for particular applications or imaging schemes due to achievable scan ranges, power requirements, speed, and size. Many of these characteristics are fabrication-process dependent, and this paper discusses various fabrication flows developed to integrate additional optical functionality beyond simple lateral scanning, enabling dynamic control of the focus or mirror surface. Out of this provided MEMS flexibility arises some challenges when obtaining high resolution images: due to scanning non-linearities, calibration of MEMS scanners may become critical, and inherent image artifacts or distortions during scanning can degrade image quality. Several reviewed methods and algorithms have been proposed to address these complications from MEMS scanning. Given their impact and promise, great effort and progress have been made toward integrating MEMS and biomedical imaging.

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“…8 Compared to a NLOM device using a single-mode fiber coupler and a GRIN lens, the signal level was increased by a factor of approximately 160 as a result of the large collection area and the high numerical aperture of the doubleclad PCF. 8 In our most recent design, 9 the laser beam is steered from the fiber by a 2D MEMS mirror and focused on a sample through a GRIN lens to form an image. The MEMS mirror is based on electrothermal actuation and can perform large bidirectional 2D optical scans.…”

Section: Continued On Next Pagementioning

confidence: 99%

“…7,8 We first used a custom-designed double-clad PCF with an inner cladding of 165µm and a numerical aperture of 0.6. 7 Unlike other fibers, it offers the single-mode delivery of near infrared light in the central core combined with the efficient propagation of visible light through the inner cladding in a single fiber (see Figure 1).…”

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confidence: 99%

Nonlinear optical endoscopy allows 3D deep tissue imaging

Gu¹

2007

SPIE Newsroom

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Double-clad photonic crystal fibers and microelectromechanical mirrors significantly improve the sensitivity and miniaturization of nonlinear optical endoscopes.During the last two decades, nonlinear optical microscopy (NLOM) has emerged as a rapidly-growing new optical engineering field. The technique is primarily based on multiphotonexcited fluorescence combined with second-or third-harmonic generation and can provide images inside a thick specimen with sub-micrometer resolution. The main advantage of NLOM is the ability to maintain resolution and contrast within scattering tissues. 1 A drawback, however, for in vivo applications has been the bulky optical microscopy instrumentation that prevents the imaging of internal organs in intact and moving animals. Hence, the development of miniature nonlinear optical microscopes and endoscopes that allow imaging under conditions unfeasible for a conventional microscope has attracted a high level of interest. The design of such devices also has the potential of expanding optical imaging modalities to cancer monitoring and minimally invasive surgery.Key challenges, however, must be met before these devices can be fully exploited. One of the most important is the high sensitivity required for biological and clinical applications. Laser scanning mechanisms must also be efficiently miniaturized, and flexible and compact imaging probes must be designed. Efforts addressing these technical issues have recently been reported. [2][3][4][5][6] For example, miniaturized scanning mechanisms such as piezoelectric actuators 6 and fiber-optic devices such as single-mode fibers 3 and hollow-core photonic-crystal fibers (PCFs) 5 have been proposed. However, currently available miniature NLOM devices are not yet suitable for endoscopic operation. This is due to a lack of flexibility in the overall system design or to fiberoptic devices that are inefficient for both excitation beam delivery and signal collection.We have recently used double-clad PCFs and microelectromechanical systems (MEMS) mirrors to fabricate a prototype non- linear optical endoscope that represents a significant breakthrough in high sensitivity in vivo imaging. 7,8 We first used a custom-designed double-clad PCF with an inner cladding of 165µm and a numerical aperture of 0.6. 7 Unlike other fibers, it offers the single-mode delivery of near infrared light in the central core combined with the efficient propagation of visible light through the inner cladding in a single fiber (see Figure 1). This allowed us to overcome the characteristic low signal levels of conventional fiber-optic microscopy systems. A coupling efficiency of up to 90% in the 410 to 800nm-wavelength range is achievable. When compared to conventional fibers, use of the double-clad PCF enhanced the signal level of the endoscopy system by two orders of magnitude. 7 This result will undoubtedly pave the way for the development of a flexible nonlinear optical endoscopy for internal organs.To steer the beam out of the PCF, we used a MEMS mirror fabricated ...

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Nonlinear optical endoscopy based on a double-clad photonic crystal fiber and a MEMS mirror

Cited by 147 publications

References 19 publications

Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo

Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo

Progress of MEMS Scanning Micromirrors for Optical Bio-Imaging

Nonlinear optical endoscopy allows 3D deep tissue imaging

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