A5078704053- Orbital Angular Momentum in Optics
- Microfluidic and Bio-sensing Technologies
- Digital Holography and Microscopy
- Advanced Fluorescence Microscopy Techniques
- Photoreceptor and optogenetics research
- Spaceflight effects on biology
- Microtubule and mitosis dynamics
- Near-Field Optical Microscopy
- Erythrocyte Function and Pathophysiology
- Cellular Mechanics and Interactions
- Spectroscopy Techniques in Biomedical and Chemical Research
- Micro and Nano Robotics
- Optical Polarization and Ellipsometry
- Optical Coherence Tomography Applications
- Mechanical and Optical Resonators
- DNA Repair Mechanisms
- Sperm and Testicular Function
- Laser Applications in Dentistry and Medicine
- Laser-Ablation Synthesis of Nanoparticles
- Advanced Optical Imaging Technologies
- Optical Imaging and Spectroscopy Techniques
- Random lasers and scattering media
- Cold Atom Physics and Bose-Einstein Condensates
- Topological Materials and Phenomena
- Chemical and Physical Studies
The University of Queensland
2011-2025
University of California, Irvine
2019-2024
Beckman Laser Institute and Medical Clinic
2020-2024
University of California, San Diego
2015-2022
University of California, Berkeley
2019
La Jolla Bioengineering Institute
2017
University of Glasgow
2008-2013
Quantum (Australia)
2013
University of Bristol
2010
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...
Light emerging from a spiral phase plate with non-integer step has complicated vortex structure and is unstable on propagation.We generate light carrying fractional orbital angular momentum (OAM) not but by synthesis of Laguerre-Gaussian modes.By limiting the number different Gouy phases in superposition we produce beam which well characterised terms its believe that their structural stability makes these beams ideal for quantum information processes utilising OAM states.
Microrheology is a branch of rheology having the same principles as conventional bulk rheology, but working on micron length scales and µl volumes.Optical tweezers have been successfully used with Newtonian fluids for rheological purposes such determining fluid viscosity.Conversely, when optical are to measure viscoelastic properties complex results either limited material's high-frequency response, discarding important information related low-frequency behaviour, or they supplemented by...
Osmotic conditions play an important role in the cell properties of human red blood cells (RBCs), which are crucial for pathological analysis some diseases such as malaria. Over past decades, numerous efforts have mainly focused on study RBC biomechanical that arise from unique deformability erythrocytes. Here, we demonstrate nonlinear optical effects RBCs suspended different osmotic solutions. Specifically, observe self-trapping and scattering-resistant propagation a laser beam through...
Mechanobiology helps us to decipher cell and tissue functions by looking at changes in their mechanical properties that contribute development, differentiation, physiology, disease. sits the interface of biology, physics engineering. One key technologies enables characterization cells is microscopy. Combining microscopy with other quantitative measurement techniques such as optical tweezers scissors, gives a very powerful tool for unraveling intricacies mechanobiology enabling forces,...
We present a holographic optical tweezers system capable of position clamping multiple particles. Moving an trap in response to the trapped object's motion is powerful technique for control and force measurement. have now realised this experimentally using Boulder Nonlinear Systems Spatial Light Modulator (SLM) with refresh rate 203Hz. obtain reduction 44% variance bead's position, corresponding increase effective stiffness 77%. This relies on generation holograms at high speed. software...
Abstract The ability to successfully fertilize ova relies upon the swimming of spermatozoa. Both in humans and animals, sperm motility has been used as a metric for viability semen samples. Recently, several studies have examined efficacy low dosage red light exposure cellular repair increasing motility. Of prime importance practical application this technique is absence DNA damage caused by radiation exposure. In study, we examine effect 633 nm coherent, laser on using novel wavelet-based...
We have developed a microrheometer, based on optical tweezers, in which hydrodynamic coupling between the probe and fluid boundaries is dramatically reduced relative to existing microrheometers. Rotational Brownian motion of birefringent microsphere within an angular trap observed by measuring polarisation shifts transmitted light. Data gathered this manner, strongly viscoelastic Celluvisc, quantitatively agree with results conventional (bulk) rheometry. Our technique will significantly...
Force measurement in an interactive 3D micromanipulation system can allow the user to make delicate adjustments, and explore surfaces with touch as well vision. We present a achieve this on micron scale using stereoscopic particle tracking combined holographic optical tweezers, which track particles nanometre accuracy. 2D of each stereo images gives positions for particle. This takes less than 200 µs per image pair, 1D 'symmetry transform' applied row column image, maintain throughout 10 µm...
We demonstrate the control and rotation of an optically trapped object, optical paddle-wheel, with direction normal to beam axis. This is in contrast usual situation where about The paddle-wheel can be driven moved any position field view microscope, which interest for various biological applications controlled application a fluid flow needed particular location specific direction. signal transduction studies cells, especially when cell flat spread out on surface.
Bacterial biofilms underlie many persistent infections, posing major hurdles in antibiotic treatment. Here, we design and demonstrate tug-of-war optical tweezers that can facilitate assessment of cell-cell adhesion - a key contributing factor to biofilm development, thanks the combined actions scattering gradient forces. With customized landscape distinct from conventional tweezers, not only such stably trap stretch rod-shaped bacterium observing plane, but, more importantly, they also...
Abstract Optogenetics uses light to control and observe the activity of neurons, often using a focused laser beam. As brain tissue is scattering medium, beams are distorted spread with propagation through neural beam’s degradation has important implications in optogenetic experiments. To address this, we present an analysis loss intensity at different depths within brains zebrafish larvae. Our experimental set-up 488 nm spatial modulator focus diffraction-limited spot brain. We use...
We present a system which uses single spatial light modulator to control the spin angular momentum of multiple optical traps. These traps may be independently controlled both in terms location and their content. The relies on used "split-screen" configuration generate beams orthogonal polarisation states are subsequently combined at polarising beam splitter. Defining phase difference between with enables state light. demonstrate functionality by controlling rotation orientation birefringent...
We implement a paraxial azimuthally-radially polarized beam (ARPB), novel class of structured light beams that can be optimal chiral (OC), leading to maximum chirality density at given energy density. By using vectorial shaping techniques, we successfully generated ARPB with precise control over its features, validating theoretical predictions. Our findings demonstrate the ability finely adjust across entire range by manipulating single parameter. Although our experimental investigations are...
Understanding the mitotic DNA damage response (DDR) is critical to our comprehension of cancer, premature aging and developmental disorders which are marked by repair deficiencies. In this study we use a micro-focused laser induce in selected chromosomes subsequent response. Our findings demonstrate that (1) cells capable as evidenced synthesis at sites, (2) Repair attenuated when DNA-PKcs ATM simultaneously compromised, (3) Laser may permit observation previously undetected DDR proteins...
Exquisite manipulations of light can be performed with devices such as spatial modulators (SLMs) and digital micromirror (DMDs). These used to simulate transverse paraxial beam wavefunction eigenstates the Hermite–Laguerre–Gaussian mode families. We investigate several shaping methods in terms wavefunctions scattered light. Our analysis efficiency, behaviour limitations is applied both theory experiment. The deviation from ideal output a valid method shown due experimental factors which are...
Holographically generated optical traps confine micron- and sub-micron sized particles close to the center of focused light beams. They also provide a way trapping multiple moving them in three dimensions. However, many systems user interface is not always advantageous or intuitive especially for collaborative work when depth information required. We discuss evaluate set multi-beam tweezers that utilize off shelf gaming technology facilitate interaction. use Microsoft Kinect sensor bar as...
We propose a method for generation of tunable three-dimensional (3D) helical lattices with varying helix pitch. In order to change only the lattice pitch, periodically phase along propagation direction is added central beam - one interference beams construction. The periodicity determines which can be reconfigured at ease. Furthermore, structure an interface (domain wall) also achieved by changing lateral beams, leading opposite rotating (helicity) on different sides interface. When Gaussian...
Astrocytes respond to brain injury at a cellular level by the process of reactive astrogliosis, and are able adjust their response according severity insult. Included in is phagocytosis, where astrocytes clean up surrounding debris from damaged cells. In this study, we observe phagocytosis primary cortical presence media flow across apical surface Both static cells under conditions consistently via laser-induced debris. We found that exposed shear initiate faster rate than observed...
We study linear and nonlinear topological edge states on the domain wall (DW) of two helical waveguide arrays with opposite helicities. This composite structure is constructed by using multibeam interference (MBI) method, in which helix pitch helicity readily modulated varying charge an interfering vortex beam. The are characterized gap Chern number, their propagation dynamics controlled tunable lattice DW structure. In region, we find exist only within a threshold value radius for certain...
We design and demonstrate new types of optical tweezers with lateral pulling forces that allow full control biological samples complex geometric shapes. With appropriate beam shaping, the dual tug-of-war effectively hold stretch elongated objects different sizes, triangular threefold rotational symmetry steadily asymmetric in plane observation exert stretching along three directions. successfully apply these to manipulate microparticles bacterial cells aqueous media.