LightBox: A multiwell plate illumination system for photoactive molecule characterization.

Multiwell plates (MWPs) are the workhorses of the life sciences. However, biophotonics research with MWPs is limited, in part due to the lack of equipment suitable for photo-irradiation of photoactive molecules in a MWP-suitable, high-throughput manner, either commercially or through open-source MWP systems. Here we present "LightBox", a calibrated controllable MWP illumination system with broad applications including screening of photoactive molecules and characterization of photocatalytic chemicals. LightBox is a high intensity, accurately controllable, uniform illumination system designed for MWPs with electronics and a control unit that provides a simple and intuitive interface. LightBox can reach intensities of 0.23 mW/mm2 at wavelengths of 405 nm with variance between well sites of <5%. The usefulness of LightBox is demonstrated by assessing the IC50 of a photosensitizing compound using a live/dead assay following simultaneous irradiation of the sample at a range of concentrations, eliminating uncontrolled variables between concentrations and drastically increasing assessment speed.

Individually-addressable flip-chip AlInGaN micropixelated light emitting diode arrays with high continuous and nanosecond output power.

Micropixelated blue (470 nm) and ultraviolet (370 nm) AlInGaN light emitting diode ('micro-LED') arrays have been fabricated in flip-chip format with different pixel diameters (72 microm and 30 microm at, respectively, 100 and 278 pixels/mm(2)). Each micro-LED pixel can be individually-addressed and the devices possess a specially designed n-common contact incorporated to ensure uniform current injection and consequently uniform light emission across the array. The flip-chip micro-LEDs show, per pixel, high continuous output intensity of up to 0.55 microW/microm(2) (55 W/cm(2)) at an injection current density of 10 kA/cm(2) and can sustain continuous injection current densities of up to 12 kA/cm(2) before breakdown. We also demonstrate that nanosecond pulsed output operation of these devices with per pixel onaxis average peak intensity up to 2.9 microW/microm(2) (corresponding to energy of 45pJ per 22ns optical pulse) can be achieved. We investigate the pertinent performance characteristics of these arrays for micro-projection applications, including the prospect of integrated optical pumping of organic semiconductor lasers.

Effects of maternal anxiety and depression on fetal neuro-development.

BACKGROUND: Fetal development is affected by maternal mental health with research indicating that maternal anxiety and depression are co-morbid; nevertheless differential effects on the fetus have been found. This study examines, prenatally, effects of maternal stress, anxiety and depression on fetal eye-blink reactions to experimental sound and light stimulation. METHODS: Two groups of singleton fetuses (mean 32-weeks gestation) were examined using 4D ultrasound: a control group (N = 14, 7 female) with no stimulation and an experimental group (N = 21, 13 female) exposed to experimental sound, light and cross-modal stimulation. For both groups ultrasound scans were performed and fetal eye-blink was assessed. Mothers completed the Hospital-Anxiety-and-Depression Scale and the Perceived-Stress Scale. Analysis was carried out using Poisson mixed effects modelling. RESULTS: Fetal eye-blink rate during experimental stimulation was significantly and differentially associated with maternal mental health with a 20% increase of fetal eye-blink rate for each unit increase in anxiety score (p = 0.02) and a decrease of 21% of eye blink rate for each unit of increase in depression score (p = 0.02). Sound stimulation but not light stimulation significantly affected blink-rate with fetuses habituating to the stimuli (p < 0.001). LIMITATIONS: Limitations are the relatively small number of fetuses and that a follow up after birth is essential to establish potential long-term effects. CONCLUSIONS: Of clinical importance is the finding that although fetuses are affected by maternal mental health in general here we demonstrate, using eye-blink-rate during stimulation as measure of neuro-development, that fetuses are differentially affected by maternal anxiety and depression with anxiety increasing and depression decreasing fetal reactivity significantly.

Adaptive optics for enhanced signal in CARS microscopy.

We report the use of adaptive optics with coherent anti-Stokes Raman scattering (CARS) microscopy for label-free deep tissue imaging based on molecular vibrational spectroscopy. The setup employs a deformable membrane mirror and a random search optimization algorithm to improve signal intensity and image quality at large sample depths. We demonstrate the ability to correct for both system and sample-induced aberrations in test samples as well as in muscle tissue in order to enhance the CARS signal. The combined system and sample-induced aberration correction increased the signal by an average factor of approximately 3x for the test samples at a depth of 700 microm and approximately 6x for muscle tissue at a depth of 260 microm. The enhanced signal and higher penetration depth offered by adaptive optics will augment CARS microscopy as an in vivo and in situ biomedical imaging modality.

Optical ferris wheel for ultracold atoms.

We propose a versatile optical ring lattice suitable for trapping cold and quantum degenerate atomic samples. We demonstrate the realisation of intensity patterns from pairs of Laguerre-Gauss (exp(i??) modes with different ? indices. These patterns can be rotated by introducing a frequency shift between the modes. We can generate bright ring lattices for trapping atoms in red-detuned light, and dark ring lattices suitable for trapping atoms with minimal heating in the optical vortices of blue-detuned light. The lattice sites can be joined to form a uniform ring trap, making it ideal for studying persistent currents and the Mott insulator transition in a ring geometry.

Development of fibre-optic confocal microscopy for detection and diagnosis of dental caries.

We report on the development of a fibre-optics-based confocal imaging system for the detection and potential diagnosis of early dental caries. A novel optical instrument, capable of recording axial profiles through caries lesions using single-mode optical fibres, has been developed. The practical study illustrates that miniature confocal devices based around single-mode optical fibres may provide additional diagnostic information for the general dental practitioner.

Precise spatio-temporal control of rapid optogenetic cell ablation with mem-KillerRed in Zebrafish.

The ability to kill individual or groups of cells in vivo is important for studying cellular processes and their physiological function. Cell-specific genetically encoded photosensitizing proteins, such as KillerRed, permit spatiotemporal optogenetic ablation with low-power laser light. We report dramatically improved resolution and speed of cell targeting in the zebrafish kidney through the use of a selective plane illumination microscope (SPIM). Furthermore, through the novel incorporation of a Bessel beam into the SPIM imaging arm, we were able to improve on targeting speed and precision. The low diffraction of the Bessel beam coupled with the ability to tightly focus it through a high NA lens allowed precise, rapid targeting of subsets of cells at anatomical depth in live, developing zebrafish kidneys. We demonstrate that these specific targeting strategies significantly increase the speed of optoablation as well as fish survival.

Advances in laser sources for confocal and multiphoton microscopy.

The illumination source for all high-resolution, optical sectioning, scanning microscopes is crucially important to the overall performance of the system. We examine advances that have been made in laser sources for both confocal and multiphoton microscopy where the emphasis has been on the development of potentially low-cost, easy to use sources. Growing interest in temporally and spatially resolved techniques has directed laser research towards addressing these challenges. We present the most recent developments in sources for confocal and multiphoton microscopy along with the considerations that should be made when a new source is being considered.

Evaluation of enamel dental restoration interface by optical coherence tomography.

Evaluation of molar dental restorations on enamel is performed using optical coherence tomography (OCT) with 10 microm resolution. Images of approximately 50 microm failure gaps in the restorations are demonstrated and the OCT images are compared with x-ray and optical microscopy pictures. The results demonstrate the potential of the technique for clinical evaluation of dental restorations.