A5044047319- Cold Atom Physics and Bose-Einstein Condensates
- Orbital Angular Momentum in Optics
- Optical Coherence Tomography Applications
- Mechanical and Optical Resonators
- Random lasers and scattering media
- Spectroscopy Techniques in Biomedical and Chemical Research
- Advanced Fluorescence Microscopy Techniques
- Spectroscopy and Chemometric Analyses
- Advanced Optical Sensing Technologies
- Optical measurement and interference techniques
- Quantum Information and Cryptography
- Advanced Fiber Optic Sensors
- Spectroscopy and Laser Applications
- Quantum optics and atomic interactions
- Surface Roughness and Optical Measurements
- Near-Field Optical Microscopy
- Optical Polarization and Ellipsometry
- Atomic and Subatomic Physics Research
- Optical Imaging and Spectroscopy Techniques
- Photoacoustic and Ultrasonic Imaging
- Microfluidic and Bio-sensing Technologies
- Force Microscopy Techniques and Applications
- Visual perception and processing mechanisms
- Cell Image Analysis Techniques
- Plasmonic and Surface Plasmon Research
University of St Andrews
2015-2024
Teledyne e2v (United Kingdom)
2021
University of Strathclyde
2015-2017
Scottish Universities Physics Alliance
2015
University of Leeds
2013
Addenbrooke's Hospital
1988
CEA Paris-Saclay
1974
Abstract Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation objects, ranging from atoms to space sails. Since the pioneering work by Arthur Ashkin in 1970s, optical have evolved into sophisticated instruments been employed a broad range applications life sciences, physics, engineering. These include accurate force torque measurement at femtonewton level, microrheology complex fluids, single micro- nano-particle spectroscopy, single-cell...
The accurate determination and control of the wavelength light is fundamental to many fields science. Speckle patterns resulting from interference multiple reflections in disordered media are well-known scramble information content by complex but linear processes. However, these are, fact, exceptionally rich about illuminating source. We use a fibre-coupled integrating sphere generate wavelength-dependent speckle patterns, combination with algorithms based on transmission matrix method...
The measurement of the wavelength light using speckle is a promising tool for realization compact and precise wavemeters spectrometers. However, resolution these devices limited by strong correlations between patterns produced closely-spaced wavelengths. Here, we show how principal component analysis images provides route to overcome this limit. Using this, demonstrate wavemeter which measures changes stabilized diode laser 5.3 am, eight orders magnitude below correlation
The Na<sup>+</sup>/K<sup>+</sup> ATPase (NKA) is an essential membrane protein underlying the potential in excitable cells. Transmembrane ion transport performed by catalytic α subunits (α1–4). predominant neurons are α1 and α3, which have different affinities for Na<sup>+</sup> K<sup>+</sup>, impacting on kinetics. exchange rate of markedly influences activity expressing them. We investigated distribution function main isoforms subunit expressed mouse spinal cord. NKAα1 immunoreactivity...
We demonstrate all-optical sympathetic cooling of a laser-trapped microsphere to sub-Kelvin temperatures, mediated by optical binding feedback-cooled adjacent particle. Our study opens prospects for multi-particle quantum entanglement and sensing in levitated optomechanics.
Abstract Birefringent microspheres, trapped in vacuum and set into rotation by circularly polarised light, demonstrate remarkably stable translational motion. This is marked contrast to isotropic particles similar conditions. Here we that this stability obtained because the fast of these birefringent spheres reduces effect azimuthal spin forces created inhomogeneous optical light. At reduced pressures, unique profile rotationally averaged, effective results formation nano-scale limit cycles....
Abstract Optical tweezers have emerged as a powerful, versatile approach for range of studies in cellular and molecular biology. A particular highlight has been its use microrheology measurements miniscule sample volumes. In this study, we demonstrate the application optical to investigate viscosity extracellular matrix surrounding mammalian oocytes determine whether is associated with oocyte developmental potential. By analysing motion trapped particle, can quantify mechanical properties...
We demonstrate simultaneous control of both the phase and amplitude light using a conjugate gradient minimisation-based hologram calculation technique single phase-only spatial modulator (SLM). A cost function, which incorporates inner product field with chosen target within defined measure region, is efficiently minimised to create high fidelity patterns in Fourier plane SLM. F = 0.999997 achieved for pattern resembling an LG10 mode calculated light-usage efficiency 41.5%. Possible...
The fastest-spinning man-made object is a tiny dumbbell rotating at 5 GHz. smallest wind-up motor constructed from DNA molecule. Picoliter volumes of fluids are remotely controlled and their viscosity precisely measured using microrheometers based on miniscule particles. Theoretical predictions for extraordinarily weak forces related to the presence dark matter, energy vacuum-induced friction might be revealed, surprising properties light have already been experimentally evidenced. All these...
Cellular metabolism is a key regulator of energetics, cell growth, regeneration, and homeostasis. Spatially mapping the heterogeneity cellular metabolic activity great importance for unraveling overall tissue health. In this regard, imaging endogenous cofactors, nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) flavin (FAD), with subcellular resolution in noninvasive manner would be useful to determine viability clinical environment, but practical use limited by current techniques....
Direct minimisation of a cost function can in principle provide versatile and highly controllable route to computational hologram generation. However, date iterative Fourier transform algorithms have been predominantly used. Here we show that the careful design functions, combined with numerically efficient conjugate gradient minimisation, establishes practical method for generation holograms wide range target light distributions. This results guided optimisation process, crucial advantage...
We discuss the suitability of holographically generated optical potentials for investigation superfluidity in ultracold atoms. By using a spatial light modulator and feedback enabled algorithm, we generate smooth ring with variable bright regions that can be dynamically rotated to stir atoms induce superflow. also comment on its future integration into cold atom experiment.
The speckle pattern produced when a laser is scattered by disordered medium has recently been shown to give surprisingly accurate or broadband measurement of wavelength. Here it that deep learning an ideal approach analyse wavelength variations using wavemeter due its ability identify trends and overcome low signal noise ratio in complex datasets. This combination enables at high precision over broad operating range single step, with remarkable capability reject instrumental environmental...
We show that a phase-only spatial light modulator can be used to generate non-trivial distributions suitable for trapping ultracold atoms, when the hologram calculation is included within simple and robust feedback loop corrects imperfect device response optical aberrations. This correction reduces discrepancy between target experimental distribution level of few percent (RMS error). prove generality this algorithm by applying it variety relevance cold atomic physics.
We demonstrate a method to independently and arbitrarily tailor the spatial profile of light multiple wavelengths we show possible applications ultracold atoms experiments. A single modulator is programmed create pattern containing spatially separated structures in Fourier plane when illuminated with wavelength. When overlapped laser beams different wavelengths, position wavelength-dependent. Hence, by designing their separations appropriately, desired overlap at obtained. employ regional...
In recent years, light-induced atomic desorption (LIAD) of alkali atoms from the inner surface a vacuum chamber has been employed in cold atom experiments for purpose modulating background vapour. This is beneficial because larger trapped samples can be loaded vapour at higher pressure, after which pressure reduced to increase lifetime sample. We present an analysis, based on case rubidium adsorbed pyrex, various aspects LIAD that are useful this application. Firstly, we study intensity...
Speckle metrology is a powerful tool in the measurement of wavelength and spectra. Recently, speckle produced by multiple reflections inside an integrating sphere has been proposed showed high performance. However, to our knowledge, complete characterisation sensitivity that geometry not performed date. In this work, we derive general model predicting variation pattern as result generic transformation. Applying shift incident wavelength, show mainly governed radius surface reflectivity...
We use a phase-only spatial light modulator to generate distributions in which the intensity decays as power law from central maximum with order ranging 2 (parabolic) 0.5. suggest that sequence of these can be used time-dependent optical dipole trap for all-optical production Bose-Einstein condensates (BECs) two stages: efficient evaporative cooling adjustable strength and depth, followed by an adiabatic transformation cross BEC transition reversible way. Realistic experimental parameters...
Highly resolved determination of refractive index is vital in fields ranging from biosensing through to laser range finding. Laser speckle known be a sensitive probe the properties light and environment, but date speckle-based measurements have been restricted 10-6 resolution. In this work we identify strategy optimize sensitivity changes, namely, by maximizing width distribution optical path lengths medium. We show that can realized experimentally encapsulating medium interest within an...
As the fields of optical microscopy, semiconductor technology and fundamental science increasingly aim for precision at or below nanoscale, there is a burgeoning demand sub-nanometric displacement position sensing. We show that speckle patterns produced by multiple reflections light inside an integrating sphere provide exceptionally sensitive probe displacement. use split into two independent hemispheres, one which free to move in any given direction. The relative motion hemispheres produces...
The lifetime of an atom trap is often limited by the presence residual background gases in vacuum chamber. This leads to being inversely proportional pressure. Here we use this dependence estimate pressure and obtain rate-of-rise curves, which are commonly used science evaluate performance a system. We observe different rates increase response levels outgassing our Therefore suggest that sensitive method will be useful applications cold systems, particular where inclusion standard gauge impractical.
Many areas of optical science require an accurate measurement spectra. Devices based on laser speckle promise compact wavelength measurement, with attometer-level sensitivity demonstrated for single fields. The multimode spectra using this approach would be attractive, yet is currently limited to picometer resolution. Here, we present a method improve the resolution and precision speckle-based multi-wavelength measurements. We measure multiple wavelengths simultaneously, in device comprising...