See a list of publications below or visit the Photonics academic staff page and click on a particular member of staff to access their personal web page, which includes a list of their own publications.
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Journal articleTageldeen MK, de Pooter GJ, Sardini A, et al., 2025,
Compact modular open platform for low-cost ultrasound imaging: Realisation and measurements in biological settings
, Measurement: Journal of the International Measurement Confederation, Vol: 244, ISSN: 0263-2241Ultrasound Open-Platforms (OPs) offer the flexibility required for developing novel ultrasound techniques but are generally bulky and expensive, impeding deployment in primary care and low-resource settings. This paper introduces a modular OP to address these challenges by enabling trade-offs in size and cost to meet performance targets. Comprising five modules, the proposed OP integrates a digital back-end controller tailored for ultrasound imaging. Key features of the OP include generating arbitrary waveforms with a 20-MHz maximum frequency and ±100 V amplitude, precise delays with a 200-ps maximum error, programmable gain (12-dB to 51-dB), and a 12-bit ADC with a conversion rate of 100-MSPS. The OP modular structure enables performance scalability through extension modules. In-vivo experiments, including imaging E12 mouse embryos and rabbit aorta, demonstrate that the OP yields high-quality images and enables the detection of anatomical structures in small animals at a fraction of the cost and size of commercially available OPs.
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Journal articleLiu H, Kumar S, Garcia Castano EA, et al., 2024,
Open-source implementation of polarisation-resolved single-shot differential phase contrast microscopy (pDPC) on a modular openFrame-based microscope
, HardwareX, ISSN: 2468-0672 -
Journal articleLiu H, Kumar S, Garcia Castano E, et al., 2024,
Open-source implementation of polarisation-resolved single-shot differential phase contrast microscopy (pDPC) on a modular openFrame-based microscope
, HardwareX, ISSN: 2468-0672 -
Journal articleTan Q, Riemer K, Hansen-Shearer J, et al., 2024,
Transcutaneous imaging of rabbit kidney using 3-D acoustic wave sparsely activated localization microscopy with a row-column-addressed array
, IEEE Transactions on Biomedical Engineering, Vol: 71, Pages: 3446-3456, ISSN: 0018-9294Objective: Super-resolution ultrasound (SRUS) imaging through localizing and tracking microbubbles, also known as ultrasound localization microscopy (ULM), can produce sub-diffraction resolution images of micro-vessels. We have recently demonstrated 3-D selective SRUS with a matrix array and phase change contrast agents (PCCAs). However, this method is limited to a small field of view (FOV) and by the complex hardware required. Method: This study proposed 3-D acoustic wave sparsely activated localization microscopy (AWSALM) using PCCAs and a 128+128 row-column-addressed (RCA) array, which offers ultrafast acquisition with over 6 times larger FOV and 4 times reduction in hardware complexity than a 1024-element matrix array. We first validated this method on an in-vitro microflow phantom and subsequently demonstrated non-invasively on a rabbit kidney in-vivo. Results: Our results show that 3-D AWSALM images of the phantom covering a 25×25×40 mm 3 volume can be generated under 5 seconds with an 8 times resolution improvement over the system point spread function. The full volume of the rabbit kidney can be covered to generate 3-D microvascular structure, flow speed and direction super-resolution maps under 15 seconds, combining the large FOV of RCA with the high resolution of SRUS. Additionally, 3-D AWSALM is selective and can visualize the microvasculature within the activation volume and downstream vessels in isolation. Sub-sets of the kidney microvasculature can be imaged through selective activation of PCCAs. Conclusion: Our study demonstrates large FOV 3-D AWSALM using an RCA probe. Significance: 3-D AWSALM offers an unique in-vivo imaging tool for fast, selective and large FOV vascular flow mapping.
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Journal articleKoufidis SF, Lakhtakia A, Mccall MW, 2024,
Comment on 'No circular birefringence exists in a chiral medium: an analysis of single-mode refraction'
, NEW JOURNAL OF PHYSICS, Vol: 26, ISSN: 1367-2630 -
Journal articleKoufidis SF, Koutserimpas TT, Monticone F, et al., 2024,
Electromagnetic wave propagation in time-periodic chiral media
, OPTICAL MATERIALS EXPRESS, Vol: 14, Pages: 3006-3029, ISSN: 2159-3930 -
Journal articleBharadwaj A, Kumar A, Kalita R, et al., 2024,
Super-resolved fluorescence imaging utilising accessible stochastic optical reconstruction microscopy (easySTORM) implemented on a low-cost, modular open-source (openFrame) microscope
, Measurement Science and Technology, Vol: 35, ISSN: 0957-0233Optical super-resolution microscope is a powerful tool for the life sciences, including cell biology and pathology yielding information on, e.g. biological structure and protein distribution in the nano-scale range. In recent years, there has been an exponential rise in the interest to apply super-resolution microscopes in diverse areas, but its wider utility is hindered by the cost of purchasing and maintaining super-resolved microscopes. In this paper we present the implementation of easySTORM, an accessible implementation of stochastic optical reconstruction microscopy (STORM) at Indian Institute of Technology Guwahati (IITG), India, in a flexible, user friendly and cost-effective manner using a state-of-the-art, modular, open-source, optical microscope platform called: 'openFrame'. Providing comparable imaging performance to commercial optical super-resolution microscopes, the openFrame-based implementation of easySTORM uses in-expensive multimode diode lasers and industry grade CMOS cameras, and the open-source and modular nature of the instrument makes it easy to maintain and to upgrade. To demonstrate its successful implementation at IITG, we image quantum dots and actin-tubulin structure in both normal and cancer cells, resolved features separated by a few tens of nanometers. This work demonstrates that openFrame-enabled easySTORM instrumentation can be widely accessible to provide affordable, research grade super-resolution microscopy capability for academic and medical research.
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Journal articleXiao H, Damzen MJ, 2024,
High-efficiency 5-watt wavelength-tunable UV output from an Alexandrite laser
, APPLIED PHYSICS B-LASERS AND OPTICS, Vol: 130, ISSN: 0946-2171 -
Journal articleDe Corte A, Koufidis SF, Mccall MW, et al., 2024,
Exceptional points in negatively refracting chirowaveguides due to giant chirality
, PHYSICAL REVIEW A, Vol: 110, ISSN: 2469-9926 -
Conference paperXiao H, Damzen MJ, 2024,
5-Watt level widely wavelength-tunable UV output from a frequency-doubled Alexandrite laser
, ISSN: 2101-6275We demonstrate a record 5-Watt level, wavelength tunable, continuous-wave UV output based on a diode-pumped Alexandrite laser employing intra-cavity second harmonic generation. A wide wavelength tuning range from 364nm to 402nm was achieved.
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Conference paperDamzen MJ, 2024,
Alexandrite Lasers: Review of recent laser progress and developments for vegetation lidar
, ISSN: 2101-6275A review is made of recent progress in diode-pumped Alexandrite lasers as a high-power, tunable-wavelength source, and our advances in developing Alexandrite as a short-pulse, high-pulse-rate vegetation lidar source for satellite-based Earth Observation.
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Conference paperJiang X, Xiao H, Damzen MJ, 2024,
Transient Analysis of Pump-induced Lensing Effects in Alexandrite Lasers Using Pump-Probe Technique
, ISSN: 2101-6275A novel transient pump-probe method is used to differentiate thermal and population pump-induced lensing mechanisms. In diode-pumped Alexandrite lasers, excellent agreement is found between theory and experiment and the population lens is found to be dominant in non-lasing amplifier.
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Journal articleKoufidis SF, Koutserimpas TT, Monticone F, et al., 2024,
Enhanced scattering from an almost-periodic optical temporal slab
, PHYSICAL REVIEW A, Vol: 110, ISSN: 2469-9926 -
Conference paperKoufidis SF, Koutserimpas TT, Monticone F, et al., 2024,
Time-Periodic Optical Activity
, 2024 Eighteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials), Publisher: IEEE, Pages: 1-3 -
Conference paperDe Corte A, Koufidis SF, McCall MW, et al., 2024,
Exceptional Points of Degeneracy in Coupled Chirowaveguides
, 2024 Eighteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials), Publisher: IEEE, Pages: 1-3 -
Journal articleLerendegui M, Riemer K, Papageorgiou G, et al., 2024,
ULTRA-SR challenge: assessment of UltrasoundLocalization and TRacking algorithms for super-resolution imaging
, IEEE Transactions on Medical Imaging, Vol: 43, Pages: 2970-2987, ISSN: 0278-0062With the widespread interest and uptake of super-resolution ultrasound (SRUS) through localization and tracking of microbubbles, also known as ultrasound localization microscopy (ULM), many localization and tracking algorithms have been developed. ULM can image many centimeters into tissue in-vivo and track microvascular flow non-invasively with sub-diffraction resolution. In a significant community effort, we organized a challenge, Ultrasound Localization and TRacking Algorithms for Super-Resolution (ULTRA-SR). The aims of this paper are threefold: to describe the challenge organization, data generation, and winning algorithms; to present the metrics and methods for evaluating challenge entrants; and to report results and findings of the evaluation. Realistic ultrasound datasets containing microvascular flow for different clinical ultrasound frequencies were simulated, using vascular flow physics, acoustic field simulation and nonlinear bubble dynamics simulation. Based on these datasets, 38 submissions from 24 research groups were evaluated against ground truth using an evaluation framework with six metrics, three for localization and three for tracking. In-vivo mouse brain and human lymph node data were also provided, and performance assessed by an expert panel. Winning algorithms are described and discussed. The publicly available data with ground truth and the defined metrics for both localization and tracking present a valuable resource for researchers to benchmark algorithms and software, identify optimized methods/software for their data, and provide insight into the current limits of the field. In conclusion, Ultra-SR challenge has provided benchmarking data and tools as well as direct comparison and insights for a number of the state-of-the art localization and tracking algorithms.
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Journal articleDarling C, Kumar S, Alexandrov Y, et al., 2024,
Optical projection tomography implemented for accessibility and low cost (OPTImAL)
, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol: 382, ISSN: 1364-503XOptical projection tomography (OPT) is a three-dimensional mesoscopic imaging modality that can use absorption or fluorescence contrast, and is widely applied to fixed and live samples in the mm-cm scale. For fluorescence OPT, we present OPT implemented for accessibility and low cost, an open-source research-grade implementation of modular OPT hardware and software that has been designed to be widely accessible by using low-cost components, including light-emitting diode (LED) excitation and cooled complementary metal-oxide-semiconductor (CMOS) cameras. Both the hardware and software are modular and flexible in their implementation, enabling rapid switching between sample size scales and supporting compressive sensing to reconstruct images from undersampled sparse OPT data, e.g. to facilitate rapid imaging with low photobleaching/phototoxicity. We also explore a simple implementation of focal scanning OPT to achieve higher resolution, which entails the use of a fan-beam geometry reconstruction method to account for variation in magnification. This article is part of the Theo Murphy meeting issue 'Open, reproducible hardware for microscopy'.
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Journal articleHansen-Shearer J, Yan J, Lerendegui M, et al., 2024,
Ultrafast 3-D Transcutaneous Super Resolution Ultrasound Using Row-Column Array Specific Coherence-Based Beamforming and Rolling Acoustic Sub-aperture Processing: In Vitro, in Rabbit and in Human Study
, ULTRASOUND IN MEDICINE AND BIOLOGY, Vol: 50, Pages: 1045-1057, ISSN: 0301-5629 -
Journal articleLerendegui M, Yan J, Stride E, et al., 2024,
Understanding the effects of microbubble concentration on localization accuracy in super-resolution ultrasound imaging
, PHYSICS IN MEDICINE AND BIOLOGY, Vol: 69, ISSN: 0031-9155 -
Journal articleDent LG, Curry N, Sparks H, et al., 2024,
Environmentally dependent and independent control of 3D cell shape
, CELL REPORTS, Vol: 43, ISSN: 2211-1247 -
Journal articleRiemer K, Tan Q, Morse S, et al., 2024,
3D Acoustic Wave Sparsely Activated Localization Microscopy With Phase Change Contrast Agents
, INVESTIGATIVE RADIOLOGY, Vol: 59, Pages: 379-390, ISSN: 0020-9996 -
Journal articleZeng H-J, Xue W-Z, Murray RT, et al., 2024,
In-band pumped Kerr-lens mode-locked Tm,Ho-codoped calcium aluminate laser
, OPTICS EXPRESS, Vol: 32, Pages: 16083-16089, ISSN: 1094-4087 -
Journal articleTemel T, Murray RT, Wang L, et al., 2024,
Narrowband-seeded PPLN non-resonant optical parametric oscillator
, OPTICAL MATERIALS EXPRESS, Vol: 14, ISSN: 2159-3930 -
Journal articleXiao H, Jiang X, Damzen MJ, 2024,
Transient pump-probe analysis of pump-induced lensing in laser amplifiers
, Optics Express, Vol: 32, Pages: 12783-12799, ISSN: 1094-4087Understanding of pump-induced lensing in laser amplifiers is essential for the optimized design of high-power lasers with high spatial quality, but there is usually incomplete knowledge of the interplay between thermal and population induced lensing mechanisms, lensing under lasing and non-lasing conditions, and transient lensing effects under pulsed operation. This paper provides quantitative insight of pump-induced lensing effects by using experimental transient pump-probe measurements in an alexandrite laser amplifier end-pumped by a short pulse pump beam with Gaussian spatial intensity distribution. Lensing results are presented showing a large difference in lensing under both non-lasing and lasing conditions and distinction of the population lens and thermal lens contributions from their different response time. Different pump beam sizes are used to show the variation of the relative strength of the lensing mechanisms. Comparison of experimental results with the analytical transient theory developed in this paper for the Gaussian pump beam gives excellent agreement and quantitative information on the thermal and population contributions to the amplifier lens. This paper provides a methodology for quantitative investigation of pump-induced lensing in general laser amplifier systems, and potentially other classes of optical materials with residual optical absorption.
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Conference paperCodescu M-A, Murray JM, Zawilski KT, et al., 2024,
Optical Parametric Generation in Non-Critically Cut CdSiP2 with a Nanosecond 1.064 μm Nd:YAG Laser
, Optica High-Brightness Sources and Light-Driven Interactions Congress -
Conference paperMurray RT, Battle RA, Simon D, et al., 2024,
Visualizing metabolites at the cellular level: advancements in 3-micron laser desorption mass spectrometry imaging
, SPIE BiOS, Publisher: SPIE, Pages: 4-4By combining high beam quality picosecond pulsed optical parametric amplifiers at 2.94 μm with Rapid Evap-ortive Ionisation Mass Spectrometry (REIMS), we have demonstrated record spatial pixel resolutions for ambientmass spectrometry (MS) imaging of < 10 μm. In this contribution, we introduce our work in this area, demon-strating the platform workflow and highlighting recent results of metabolic imaging at the single cell resolutionlevel.
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Journal articleTemel T, Murray RT, Wang L, et al., 2024,
Energy scaling of a narrowband, periodically poled LiNbO3, nanosecond, nonresonant optical parametric oscillator
, APPLIED OPTICS, Vol: 63, Pages: 1811-1814, ISSN: 1559-128X -
Journal articleBharadwaj A, Kalita R, Kumar A, et al., 2024,
A cost-effective, modular, research-grade optical microscope
, CURRENT SCIENCE, Vol: 126, Pages: 244-254, ISSN: 0011-3891 -
Conference paperMurray JM, Codescu M-A, Zawilski KT, et al., 2024,
Optical Parametric Generation in Non-Critically Cut CdSiP2 with a Nanosecond 1.064 μm Nd:YAG Laser
, Optica High-Brightness Sources and Light-Driven Interactions Congress -
Conference paperWang Y, Battle RA, Simon D, et al., 2024,
Laser Ablation of Biological Tissue with a 2.94 μm Picosecond Optical Parametric Amplifier for Ambient Mass Spectrometry Imaging
We report a 2.94 μm OPA with ∼100 ps pulse duration, 400 nJ pulse energy and a 500 kHz repetition rate, which enables high resolution (≤10 μm) laser desorption-based mass spectrometry imaging of biological tissue.
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