Direct imaging of a digital-micromirror device for configurable microscopic optical potentials

Programable spatial light modulators (SLMs) have significantly advanced the configurable optical trapping of particles. Typically, these devices are utilized in the Fourier plane of an optical system, but direct imaging of an amplitude pattern can potentially result in increased simplicity and computational speed. Here we demonstrate high-resolution direct imaging of a digital micromirror device (DMD) at high numerical apertures (NA), which we apply to the optical trapping of a Bose-Einstein condensate (BEC). We utilise a (1200 x 1920) pixel DMD and commercially available 0.45 NA microscope objectives, finding that atoms confined in a hybrid optical/magnetic or all-optical potential can be patterned using repulsive blue-detuned (532 nm) light with 630(10) nm full-width at half-maximum (FWHM) resolution, within 5% of the diffraction limit. The result is near arbitrary control of the density the BEC without the need for expensive custom optics. We also introduce the technique of time-averaged DMD potentials, demonstrating the ability to produce multiple grayscale levels with minimal heating of the atomic cloud, by utilising the high switching speed (20 kHz maximum) of the DMD. These techniques will enable the realization and control of diverse optical potentials for superfluid dynamics and atomtronics applications with quantum gases. The performance of this system in a direct imaging configuration has wider application for optical trapping at non-trivial NAs.Comment: 9 page

Microstructure encryption and decryption techniques in optical variable and invariable devices in printed documents for security and forensic applications.

Today, document counterfeiting is a global menace because of the advanced technologies available at ever decreasing prices. Instead of eschew the paper documents; applying efficient cost effective security methodologies are the feasible solutions. This paper reports a novel cost effective and simple optical technique using micro text encrypted optical variable device (OVD) threads, ultra-violet (UV) based optical invariable device (OID) patterns and artistic fonts for secure preparation of the documents and its forensic application. Applying any one of the above technique or together can effectively enhance the level of security of the most valuable document. The genuineness of the documents can be verified using simple decryption techniques

Spontaneity and Materiality: What Photography Is in the Photography of James Welling

Images are double agents. They receive information from the world, while also projecting visual imagination onto the world. As a result, mind and world tug our thinking about images, or particular kinds of images, in contrary directions. On one common division, world traces itself mechanically in photographs, whereas mind expresses itself through painting.1 Scholars of photography disavow such crude distinctions: much recent writing attends in detail to the materials and processes of photography, the agency of photographic artists, and the social determinants of the production and reception of photographs. As such writing makes plain, photographs cannot be reduced to mechanical traces.2 Yet background conceptions of photography as trace or index persist almost by default, as no framework of comparable explanatory power has yet emerged to replace them. A conception of photography adequate to developments in recent scholarship is long overdue. Rather than constructing such a conception top-down, as philosophers are wont to do, this paper articulates it by examining selected works by James Welling.3 There are several reasons for this: Welling’s practice persistently explores the resources and possibilities of photography, the effect of these explorations is to express a particular metaphysics of the mind’s relation to its world, and appreciating why this metaphysics is aptly expressed by exploring photography requires a revised conception of what photography is. In as much as it provides a framework for a richer interpretation of Welling, the new conception is also capable of underwriting a wide range of critical and historical approaches to photography

Compositional structures in mural design : towards a site-specific deconstructive mural methodology

A thesis submitted to the University of Bedfordshire in partial fulfilment of the requirements of the degree of Doctor of Philosophy (PhD)Murals have been the formal visual interpretation of the cultural, social and political life of all ages. Throughout they have been consistently combined with their architectural setting, for example, in ancient Egyptian tombs, in Renaissance churches and on the external walls of buildings in Mexico in the twentieth century. This is a central feature of mural painting. However many contemporary murals do not integrate with their architectural settings, in other words, do not fulfil the site-specificity of the architectural spaces for which they were made. This means that the most important aspect that distinguishes murals from other types of painting is absent. I studied and analysed a number of murals produced in the Italian Renaissance, Baroque and Rococo as this particular period is considered to be not only one of the most significant in the history of art but also a period in which painting and architecture were very closely allied as practices. In particular the radical developments in painting of pictorial space took place along side the developments in architecture. I argue that Renaissance murals could be described, using the terminology of contemporary art, as site-specific art. By identifying the relationship between pictorial space, architectural space and compositional structure I was able to test, through my own practice, the importance of these relationships in understanding the site-specificity of the compositional structure of murals. To address the issue of sitespecificity in murals, I investigated and developed a set of compositional structures through my mural practice that could be applied in the design, execution, and teaching of contemporary mural design. I have developed the notion of a deconstructive method of mural design in which the illusory space of the mural derives its compositional structure from the architectural space in which it sited. I have applied it, tested it and refined it through the execution of a number of hypothetical and live mural commissions. I believe that the approach to the study and practice of mural design I have developed from the perspective of a practice lead researcher contributes to the furtherance of mural design as both a profession and field of study. In particular the identification of compositional structures in mural design and the proposal of a deconstructive method contributes to our understanding of what a mural is as well as current notions of site-specificity in contemporary art

Structural biology: a century-long journey into an unseen world

© Institute of Materials, Minerals and Mining 2015.When the first atomic structures of salt crystals were determined by the Braggs in 1912–1913, the analytical power of X-ray crystallography was immediately evident. Within a few decades the technique was being applied to the more complex molecules of chemistry and biology and is rightly regarded as the foundation stone of structural biology, a field that emerged in the 1950s when X-ray diffraction analysis revealed the atomic architecture of DNA and protein molecules. Since then the toolbox of structural biology has been augmented by other physical techniques, including nuclear magnetic resonance spectroscopy, electron microscopy, and solution scattering of X-rays and neutrons. Together these have transformed our understanding of the molecular basis of life. Here I review the major and most recent developments in structural biology that have brought us to the threshold of a landscape of astonishing molecular complexity