HoloCam: A subsea holographic camera for recording marine organisms and particles

The HoloCam system is a major component of a multi-national multi-discipline project known as HoloMar (funded by the European Commission under the MAST III initiative). The project is concerned with the development of pulsed laser holography to analyse and monitor the populations of living organisms and inanimate particles within the world's oceans. We describe here the development, construction and evaluation of a prototype underwater camera, the purpose of which is to record marine organisms and particles, in-situ. Recording using holography provides several advantages over conventional sampling methods in that it allows non-intrusive, non-destructive, high-resolution imaging of large volumes (up to 10^5 cm^3) in three dimensions. The camera incorporates both in-line and off-axis holographic techniques, which allows particles from a few micrometres to tens of centimetres to be captured. In tandem with development of the HoloCam, a dedicated holographic replay system and an automated data extraction and image processing facility are being developed. These will allow, optimisation of the images recorded by the camera, identification of species and particle concentration plotting

The development and sea trials of a subsea holographic camera for large volume in-situ recording of marine organisms

We describe the development, construction and sea testing of an underwater holographic camera (HoloCam) for in situ recording of marine organisms and particles in large volumes of sea water. HoloCam comprises a laser, power supply, holographic recording optics and plate holders, a water-tight housing and a support frame. Added to this are control electronics such that the entire camera is remotely operable and controllable from ship or dock-side. Uniquely the camera can simultaneously record both in-line and off-axis holograms using a pulsed frequency doubled Nd-YAG laser. In-line holography is capable of producing images of organisms with a resolution of better than 10 Pm (at concentrations up to a few thousand per cubic centimetre at the smallest sizes). Off-axis holograms of aquatic systems of up to 50,000 cm3 volume, have been recorded. Following initial laboratory testing, the holo-camera was evaluated in an observation tank and ultimately was tested in Loch Etive, Scotland. In-line and off-axis holograms were recorded to a depth of 100 m. We will present results on the test dives and evaluation of the camera performance

A holographic system for subsea recording and analysis of plankton and other marine particles

We report here details of the design, development, initial testing and field-deployment of the HOLOMAR system for in-situ subsea holography and analysis of marine plankton and nonliving particles. HOLOMAR comprises a submersible holographic camera ("HoloCam") able to record in-line and off-axis holograms at depths down to 100 m, together with specialised reconstruction hardware ("HoloScan") linked to custom image processing and classification software. The HoloCam consists of a laser and power supply, holographic recording optics and holographic plate holders, a water-tight housing and a support frame. It utilises two basic holographic geometries, in-line and off-axis such that a wide range of species, sizes and concentrations can be recorded. After holograms have been recorded and processed they are reconstructed in full three-dimensional detail in air in a dedicated replay facility. A computer-controlled microscope, using video cameras to record the image at a given depth, is used to digitise the scene. Specially written software extracts a binarised image of an object in its true focal plane and is classified using a neural network. The HoloCam was deployed on two separate cruises in a Scottish sea loch (Loch Etive) to a depth of 100 m and over 300 holograms were recorded

In-situ velocity imaging of ultracold atoms using slow--light

The optical response of a moving medium suitably driven into a slow-light propagation regime strongly depends on its velocity. This effect can be used to devise a novel scheme for imaging ultraslow velocity fields. The scheme turns out to be particularly amenable to study in-situ the dynamics of collective and topological excitations of a trapped Bose-Einstein condensate. We illustrate the advantages of using slow-light imaging specifically for sloshing oscillations and bent vortices in a stirred condensate

Introduction: contains Cover, Table of Contents, Letter from the Editor, and Masthead

The Richmond Journal of Law and Technology is proud to present its second issue of the 2006–2007 academic school year. The Journal staff has worked diligently during the first half of the year to produce an exceptional issue

Introduction: contains Cover, Table of Contents, Letter from the Editor, and Masthead

The Richmond Journal of Law and Technology (“JOLT”) is proud to present the first issue of the 2006 -2007 academic year. Volume 13, Issue 1 is the product of the Journal’s Third Annual Student Writing Competition, held in the spring semester of 2006. As always, the student writing competition focuses on emerging issues in the field of technology and the law. This year’s issue holds special significance to JOLT’s staff, as it was made possible by the generous donation of Mr. Richard Klau. His contribution to our publication will allow us to recognize the brightest student minds in the legal community for many years to come

Transverse Fresnel-Fizeau drag effects in strongly dispersive media

A light beam normally incident upon an uniformly moving dielectric medium is in general subject to bendings due to a transverse Fresnel-Fizeau light drag effect. In conventional dielectrics, the magnitude of this bending effect is very small and hard to detect. Yet, it can be dramatically enhanced in strongly dispersive media where slow group velocities in the m/s range have been recently observed taking advantage of the electromagnetically induced transparency (EIT) effect. In addition to the usual downstream drag that takes place for positive group velocities, we predict a significant anomalous upstream drag to occur for small and negative group velocities. Furthermore, for sufficiently fast speeds of the medium, higher order dispersion terms are found to play an important role and to be responsible for peculiar effects such as light propagation along curved paths and the restoration of the spatial coherence of an incident noisy beam. The physics underlying this new class of slow-light effects is thoroughly discussed

Measurement of the electron electric dipole moment using YbF molecules

The most sensitive measurements of the electron electric dipole moment d_e have previously been made using heavy atoms. Heavy polar molecules offer a greater sensitivity to d_e because the interaction energy to be measured is typically 10^3 times larger than in a heavy atom. We report the first measurement of this kind, for which we have used the molecule YbF. Together, the large interaction energy and the strong tensor polarizability of the molecule make our experiment essentially free of the systematic errors that currently limit d_e measurements in atoms. Our first result d_e = (- 0.2 \pm 3.2) x 10^-26 e.cm is less sensitive than the best atom measurement, but is limited only by counting statistics and demonstrates the power of the method.Comment: 4 pages, 4 figures. v2. Minor corrections and clarifications made in response to referee comment