91 results found
Berk J, Paterson C, Foreman MR, 2020, Tracking single particles using surface plasmon leakage radiation speckle, Journal of Lightwave Technology, ISSN: 0733-8724
Label free tracking of small bio-particles such as proteins or viruses is of great utility in the study of biological processes, however such experiments are frequently hindered by weak signal strengths and a susceptibility to scattering impurities. To overcome these problems we here propose a novel technique leveraging the enhanced sensitivity of both interferometric detection and the strong field confinement of surface plasmons. Specifically, we show that interference between the field scattered by an analyte particle and a speckle reference field, derived from random scattering of surface plasmons propagating on a rough metal film, enables particle tracking with sub-wavelength accuracy. We present the analytic framework of our technique and verify its robustness to noise through Monte Carlo simulations.
Sparks H, Dvinskikh L, Firth J, et al., 2020, Development a flexible light-sheet fluorescence microscope for high-speed 3D imaging of calcium dynamics and 3D imaging of cellular microstructure, Journal of Biophotonics, Vol: 13, ISSN: 1864-063X
We report a flexible light‐sheet fluorescence microscope (LSFM) designed for studying dynamic events in cardiac tissue at high speed in 3D and the correlation of these events to cell microstructure. The system employs two illumination‐detection modes: the first uses angle‐dithering of a Gaussian light sheet combined with remote refocusing of the detection plane for video‐rate volumetric imaging; the second combines digitally‐scanned light‐sheet illumination with an axially‐swept light‐sheet waist and stage‐scanned acquisition for improved axial resolution compared to the first mode. We present a characterisation of the spatial resolution of the system in both modes. The first illumination‐detection mode achieves dual spectral‐channel imaging at 25 volumes per second with 1024 × 200 × 50 voxel volumes and is demonstrated by time‐lapse imaging of calcium dynamics in a live cardiomyocyte. The second illumination‐detection mode is demonstrated through the acquisition of a higher spatial resolution structural map of the t‐tubule network in a fixed cardiomyocyte cell.
Wu P-J, Masouleh MI, Paterson C, et al., 2019, Detection of proteoglycan loss from articular cartilage using Brillouin microscopy, with applications to osteoarthritis, Biomedical Optics Express, Vol: 10, Pages: 2457-2466, ISSN: 2156-7085
The degeneration of articular cartilage (AC) occurs in osteoarthritis (OA), which is a leading cause of pain and disability in middle-aged and older people. The early disease-related changes in cartilage extra-cellular matrix (ECM) start with depletion of proteoglycan (PG), leading to an increase in tissue hydration and permeability. These early compositional changes are small (<10%) and hence difficult to register with conventional non-invasive imaging technologies (magnetic resonance and ultrasound imaging). Here we apply Brillouin microscopy for detecting changes in the mechanical properties and composition of porcine AC. OA-like degradation is mimicked by enzymatic tissue digestion, and we compare Brillouin microscopy measurements against histological staining of PG depletion over varying digestion times and enzyme concentrations. The non-destructive nature of Brillouin imaging technology opens new avenues for creating minimally invasive arthroscopic devices for OA diagnostics and therapeutic monitoring.
Gouveia RM, Lepert G, Gupta S, et al., 2019, Assessment of corneal substrate biomechanics and its effect on epithelial stem cell maintenance and differentiation, NATURE COMMUNICATIONS, Vol: 10, ISSN: 2041-1723
Wu P-J, Kabovka I, Ruberti J, et al., 2018, Water content, not stiffness, dominates Brillouin spectroscopy measurements in hydrated materials, Nature Methods, Vol: 15, Pages: 561-562, ISSN: 1548-7091
Kabakova IV, Azuri I, Chen Z, et al., 2018, The effect of ionic composition on acoustic phonon speeds in hybrid perovskites from Brillouin spectroscopy and density functional theory, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 6, Pages: 3861-3868, ISSN: 2050-7526
Kim Y, Warren S, Favero F, et al., 2018, Semi-random multicore fibre design for adaptive multiphoton endoscopy, Optics Express, Vol: 26, Pages: 3661-3673, ISSN: 1094-4087
This paper reports the development, modelling and application of a semi-random multicore fibre (MCF) design for adaptive multiphoton endoscopy. The MCF was constructed from 55 sub-units, each comprising 7 single mode cores, in a hexagonally close-packed lattice where each sub-unit had a random angular orientation. The resulting fibre had 385 single mode cores and was double-clad for proximal detection of multiphoton excited fluorescence. The random orientation of each sub-unit in the fibre reduces the symmetry of the positions of the cores in the MCF, reducing the intensity of higher diffracted orders away from the central focal spot formed at the distal tip of the fibre and increasing the maximum size of object that can be imaged. The performance of the MCF was demonstrated by imaging fluorescently labelled beads with both distal and proximal fluorescence detection and pollen grains with distal fluorescence detection. We estimate that the number of independent resolution elements in the final image – measured as the half-maximum area of the two-photon point spread function divided by the area imaged – to be ~3200.
Kabakova IV, Xiang Y, Paterson C, et al., 2017, Fiber-integrated Brillouin microspectroscopy: towards Brillouin endoscopy, Journal of Innovative Optical Health Sciences, Vol: 10, ISSN: 1793-5458
Brillouin imaging (BI) for micromechanical characterization of tissues and biomaterials is a fast-developing field of research with a strong potential for medical diagnosis of disease-modified tissues and cells. Although the principles of BI imply its compatibility with in vivo and in situ measurements, the integration of BI with a flexible catheter, capable of reaching the region of interest within the body, is yet to be reported. Here, for the first time, we experimentally investigate integration of the Brillouin spectroscope with standard optical fiber components to achieve a Brillouin endoscope. The performance of single-fiber and dual-fiber endoscopes are demonstrated and analyzed. We show that a major challenge in construction of Brillouin endoscopes is the strong backward Brillouin scattering in the optical fiber and we present a dual-fiber geometry as a possible solution. Measurements of Brillouin spectra in test liquids (water, ethanol and glycerol) are demonstrated using the dual-fiber endoscope and its performance is analyzed numerically with the help of a beam propagation model.
Figueiredo GS, Bojic S, Rooney P, et al., 2017, Gamma-irradiated human amniotic membrane decellularised with sodium dodecyl sulfate is a more efficient substrate for the ex vivo expansion of limbal stem cells, ACTA BIOMATERIALIA, Vol: 61, Pages: 124-133, ISSN: 1742-7061
Sherlock B, Warren SC, Alexandrov Y, et al., 2017, In vivo multiphoton microscopy using a handheld scanner with lateral and axial motion compensation, Journal of Biophotonics, Vol: 11, ISSN: 1864-063X
This paper reports a handheld multiphoton fluorescence microscope designed for clinical imaging that incorporates axial motion compensation and lateral image stabilization. Spectral domain optical coherence tomography is employed to track the axial position of the skin surface, and lateral motion compensation is realised by imaging the speckle pattern arising from the optical coherence tomography beam illuminating the sample. Our system is able to correct lateral sample velocities of up to ~65 μm s-1. Combined with the use of negative curvature microstructured optical fibre to deliver tunable ultrafast radiation to the handheld multiphoton scanner without the need of a dispersion compensation unit, this instrument has potential for a range of clinical applications. The system is used to compensate for both lateral and axial motion of the sample when imaging human skin in vivo.
Connon CJ, Gouveia RM, Paterson C, et al., 2017, The mechanical properties of the human corneal limbus and its influence on epithelial stem cell phenotype, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404
Warren SC, Kim Y, Stone JM, et al., 2016, Adaptive multiphoton endomicroscopy through a dynamically deformed multicore optical fiber using proximal detection, Optics Express, Vol: 24, Pages: 21474-21484, ISSN: 1094-4087
This paper demonstrates multiphoton excited fluorescenceimaging through a polarisation maintaining multicore fiber (PM-MCF)while the fiber is dynamically deformed using all-proximal detection.Single-shot proximal measurement of the relative optical path lengths of allthe cores of the PM-MCF in double pass is achieved using a Mach-Zehnderinterferometer read out by a scientific CMOS camera operating at 416 Hz.A non-linear least squares fitting procedure is then employed to determinethe deformation-induced lateral shift of the excitation spot at the distal tip ofthe PM-MCF. An experimental validation of this approach is presented thatcompares the proximally measured deformation-induced lateral shift infocal spot position to an independent distally measured ground truth. Theproximal measurement of deformation-induced shift in focal spot position isapplied to correct for deformation-induced shifts in focal spot positionduring raster-scanning multiphoton excited fluorescence imaging.
Lepert G, Gouveia RM, Connon CJ, et al., 2016, High-resolution imaging of limbal structural properties using Brillouin spectro-microscopy, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404
Kim Y, Warren SC, Stone JM, et al., 2016, Adaptive Multiphoton Endomicroscope Incorporating a Polarization-Maintaining Multicore Optical Fibre, IEEE Journal of Selected Topics in Quantum Electronics, Vol: 22, ISSN: 1558-4542
We present a laser scanning multiphoton endomicroscopewith no distal optics or mechanical components that incorporatesa polarization-maintaining (PM) multicore optical fibre todeliver, focus, and scan ultrashort pulsed radiation for two-photonexcited fluorescence imaging. We show theoretically that the use ofa PM multicore fibre in our experimental configuration enhancesthe fluorescence excitation intensity achieved in the focal spot comparedto a non-PM optical fibre with the same geometry and con-firm this by computer simulations based on numerical wavefrontpropagation. In our experimental system, a spatial light modulator(SLM) is utilised to program the phase of the light input to each ofthe cores of the endoscope fibre such that the radiation emergingfrom the distal end of the fibre interferes to provide the focusedscanning excitation beam. We demonstrate that the SLM can enabledynamic phase correction of path-length variations across themulticore optical fibre whilst the fibre is perturbed with an updaterate of 100 Hz.
Lepert G, Gouveia RM, Connon CJ, et al., 2016, Assessing corneal biomechanics with Brillouin spectro-microscopy., Faraday Discussions, Vol: 187, Pages: 415-428, ISSN: 1364-5498
A new Brillouin spectro-microscope was designed and built to investigate the mechanical properties of bovine and human corneas. This instrument integrates a single-stage virtually imaged phased array spectrometer with a novel adaptive-optics interferometric filter to achieve unprecedented rejection of the elastic background signal. As a result, highly-resolved, reproducible data from both thin and thick collagen-based materials were obtained. In particular, this technique is capable of rigorously measuring the relative stiffness of different areas of human corneas, thus providing a true non-contact method to characterise the fundamental mechanical features of both live and fixed biological tissue samples.
sherlock B, Yu F, Stone J, et al., 2016, Tunable fibre-coupled multiphoton microscopy with a negative curvature fibre, Journal of Biophotonics, Vol: 9, Pages: 715-720, ISSN: 1864-0648
Negative curvature fibre (NCF) guides light in its core by inhibiting the coupling of core andcladding modes. In this work, an NCF was designed and fabricated to transmit ultrashort opticalpulses for multiphoton microscopy with low group velocity dispersion (GVD) at 800 nm. Itsattenuation was measured to be <0.3 dB.m-1over the range 600-850 nm and the GVD was-180±70 fs2.m-1at 800 nm. Using an average fibre output power of ~20 mW and pulserepetition rate of 80 MHz, the NCF enabled pulses with a duration of <200 fs to be transmittedthrough a length of 1.5 m of fibre over a tuning range of 180 nm without the need for dispersioncompensation. In a 4 m fibre, temporal and spectral pulse widths were maintained to within10% of low power values up to the maximum fibre output power achievable with the lasersystem used of 278 mW at 700 nm, 808 mW at 800 nm and 420 mW at 860 nm. When coupledto a multiphoton microscope, it enabled imaging of ex vivo tissue using excitation wavelengthsfrom 740 nm to 860 nm without any need for adjustments to the set-up.
Antonacci G, Pedrigi RM, Kondiboyina A, et al., 2015, Quantification of plaque stiffness by Brillouin microscopy in experimental thin cap fibroatheroma, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 12, ISSN: 1742-5689
Antonacci G, Lepert G, Paterson C, et al., 2015, Elastic suppression in Brillouin imaging by destructive interference, APPLIED PHYSICS LETTERS, Vol: 107, ISSN: 0003-6951
Sherlock B, Warren S, Stone J, et al., 2015, Fibre-coupled multiphoton microscope with adaptive motion compensation, BIOMEDICAL OPTICS EXPRESS, Vol: 6, Pages: 1876-1884, ISSN: 2156-7085
Shaw M, O'Holleran K, Paterson C, 2013, Investigation of the confocal wavefront sensor and its application to biological microscopy, OPTICS EXPRESS, Vol: 21, Pages: 19353-19362, ISSN: 1094-4087
Thompson AJ, Paterson C, Neil MAA, et al., 2011, Adaptive phase compensation for ultracompact laser scanning endomicroscopy, OPTICS LETTERS, Vol: 36, Pages: 1707-1709, ISSN: 0146-9592
Faisan S, Lara D, Paterson C, 2011, Scanning ophthalmoscope retinal image registration using one-dimensional deformation fields, Optics Express, Vol: 19
Lara D, Paterson C, 2011, High resolution confocal polarimeter for the living human retina, 22nd Congress of the International Commission for Optics - Light for the Development of the World, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Shaw M, Hall S, Knox S, et al., 2010, Characterization of deformable mirrors for spherical aberration correction in optical sectioning microscopy, OPTICS EXPRESS, Vol: 18, Pages: 6900-6913, ISSN: 1094-4087
Lara D, Paterson C, 2010, Confocal polarimeter for the living human retina, 1st NanoCharM Workshop on Advanced Polarimetric Instrumentation (API), Publisher: E D P SCIENCES, ISSN: 2100-014X
Ng J, Clay ST, Barman SA, et al., 2010, Maximum likelihood estimation of vessel parameters from scale space analysis, IMAGE AND VISION COMPUTING, Vol: 28, Pages: 55-63, ISSN: 0262-8856
Lara D, Paterson C, 2009, Stokes polarimeter optimization in the presence of shot and Gaussian noise, Optics Express, Vol: 17, Pages: 21240-21249, ISSN: 1094-4087
An error minimization method is presented for Stokes polarimeters applicable when the detected signals are affected by a combination of shot and Gaussian noise. The expectation of the Stokes vector variance is used as a performance measure. This measure is compared with the condition number of a polarization state analyzer matrix that is commonly used as a figure of merit. We show that a polarimeter with the minimum condition number is not necessarily optimal. The approach is used to optimize existing prism based polarimeters giving improvements in the performance when shot-noise cannot be neglected. (C) 2009 Optical Society of America
Owen CG, Rudnicka AR, Mullen R, et al., 2009, Measuring Retinal Vessel Tortuosity in 10-Year-Old Children: Validation of the Computer-Assisted Image Analysis of the Retina (CAIAR) Program, INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE, Vol: 50, Pages: 2004-2010, ISSN: 0146-0404
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