Hybrid photoacoustic-fluorescence microendoscopy through a multimode fiber using speckle illumination

Caravaca-Aguirre, Antonio M.; Singh, Sakshi; Labouesse, Simon; Baratta, Michael V.; Piestun, Rafael; Bossy, Emmanuel

doi:10.1063/1.5113476

Cited by 51 publications

(43 citation statements)

References 45 publications

(61 reference statements)

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“…In computational ghost imaging, the variation is provided by intentionally controlling the laser profile, e.g. with a DMD [17]. However, ghost imaging can also exploit natural variation in the drive laser profile to measure a QE map without interrupting normal accelerator operation.…”

Section: Classical Ghost Imaging For Cathodesmentioning

confidence: 99%

Mapping photocathode quantum efficiency with ghost imaging

Kabra

Cropp

et al. 2020

Phys. Rev. Accel. Beams

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Measuring the quantum efficiency (QE) map of a photocathode injector typically requires laser scanning, an invasive operation that involves modifying the injector laser focus and rastering the focused laser spot across the photocathode surface. Raster scanning interrupts normal operation and takes considerable time to setup. In this paper, we demonstrate a novel method of measuring the QE map using a ghost imaging framework that correlates the injector laser spatial variation over time with the total charge yield. Ghost imaging enables passive, real-time monitoring of the QE map without manually modifying the injector laser or interrupting injector operation. We first demonstrate the method at the UCLA Pegasus photoinjector with the help of a digital micromirror device (DMD) and a piezoelectric mirror to increase our control of the overall transverse variance of the illumination profile. The reconstruction algorithm parameters are fine-tuned using simulations and the results are validated against the ground truth map acquired using the traditional rastering method. Finally, we apply the technique to data acquired parasitically from the LCLS photoinjector, showing the feasibility of this method to retrieve a QE map without interrupting normal operation.

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Section: Classical Ghost Imaging For Cathodesmentioning

confidence: 99%

Mapping photocathode quantum efficiency with ghost imaging

Kabra

Cropp

et al. 2020

Phys. Rev. Accel. Beams

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“…The guided modes in MMF have different phase velocities, and consequently coherent light injected into a MMF most generally emerges as speckle patterns. Although speckle illumination may be exploited directly in some cases [ 16 , 31 ], most applications require to image the sample by scanning a focused excitation spot at the MMF output, which can be obtained by wavefront shaping. Initially developed to focus light through scattering media [ 32 ], wavefront shaping consists in manipulating the complex wavefront injected into a MMF in order to obtain a given output field pattern.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, ultrathin optical-resolution photoacoustic endoscopy has been demonstrated with both capillary waveguide [ 39 ] and a MMF [ 31 ]. In Ref.…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. [ 31 ], a hybrid photoacoustic-fluorescence endoscope based on a MMF for light excitation and a fiber ultrasound sensor for acoustic detection was presented. The proposed approach involved illuminating the sample with a set of ‘natural’ speckles obtained at the MMF output by projecting random intensity patterns at its input, using a digital mirror device (DMD).…”

Section: Introductionmentioning

confidence: 99%

“…Here we present an alternative MMF-based photoacoustic endoscopy approach, to improve measurement SNR and imaging speed. Using wavefront shaping, the excitation laser is focused at the distal tip of the MMF, which enhances the power density by several orders of magnitude, compared to speckle illumination [ 31 ]. Such focus can then be raster-scanned to image the sample.…”

Section: Introductionmentioning

confidence: 99%

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Single-shot hybrid photoacoustic-fluorescent microendoscopy through a multimode fiber with wavefront shaping

Mézil¹,

Caravaca-Aguirre²,

Zhang³

et al. 2020

Biomed. Opt. Express

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We present a minimally-invasive endoscope based on a multimode fiber that combines photoacoustic and fluorescence sensing. From the measurement of a transmission matrix during a prior calibration step, a focused spot is produced and raster-scanned over a sample at the distal tip of the fiber by use of a fast spatial light modulator. An ultra-sensitive fiber-optic ultrasound sensor for photoacoustic detection placed next to the fiber is combined with a photodetector to obtain both fluorescence and photoacoustic images with a distal imaging tip no larger than 250 µm. The high signal-to-noise ratio provided by wavefront shaping based focusing and the ultra-sensitive ultrasound sensor enables imaging with a single laser shot per pixel, demonstrating fast two-dimensional hybrid in vitro imaging of red blood cells and fluorescent beads.

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Deep Learning Enabled Scalable Calibration of a Dynamically Deformed Multimode Fiber

Fan

Wang

Ruddlesden

et al. 2022

Advanced Photonics Research

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Multimode fibers (MMF) are miniaturized, flexible, and high‐capacity information channels, promising to open up new applications in endoscopic imaging. However, precise light control through an MMF with continuous deformations is still a challenge. Here, a scalable calibration framework for a dynamically deformed MMF using deep learning is proposed. The proof‐of‐concept experiments demonstrate that the proposed continual generative adversarial model has the ability to characterize the MMF transmission states sequentially and detect the fiber deformation using proximal reflection in real‐time synchronously, allowing self‐adaptively cross‐state focusing through a semi‐flexible MMF without distal access after the scalable calibration. This framework is a continual learning scheme under extreme memory constraints where the model is able to synthesize training data and prevent forgetting the previously learned bending states. The proposed method paves the way for the experimental realization of scalable calibration of a dynamically deformed MMF.

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Hybrid photoacoustic-fluorescence microendoscopy through a multimode fiber using speckle illumination

Cited by 51 publications

References 45 publications

Mapping photocathode quantum efficiency with ghost imaging

Mapping photocathode quantum efficiency with ghost imaging

Single-shot hybrid photoacoustic-fluorescent microendoscopy through a multimode fiber with wavefront shaping

Deep Learning Enabled Scalable Calibration of a Dynamically Deformed Multimode Fiber

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