Basic Optical Principles Research Articles

Spatial dispersion in Casimir forces: a brief review

We present the basic principles of non-local optics in connection with the calculation of the Casimir force between half-spaces and thin films. At currently accessible distances $L$, non-local corrections amount to about half a percent, but they increase roughly as 1/L at smaller separations. Self consistent models lead to corrections with the opposite sign as models with abrupt surfaces.

The Doppler effect from a uniformly moving mirror

The formula for the frequency shift of a plane-polarized light wave reflected from a uniformly moving mirror is derived directly from the constant light speed postulate and the basic principles of wave optics. Unlike the original derivation by Einstein, our derivation does not involve Lorentz transformations. As such, it lies within the scope of a first course in special relativity.

Improved Human Factors of Electroluminescent Displays using Optical Interference Effect

We discuss main techniques to improve legibility of electroluminescent displays. Emphasis is placed on use of destructive optical interference to cancel ambient light reflected from the back electrode of the device. Basic optical principles and material composition of the optical interference contrast-enhancing stack (CES) are presented. We also describe the improved human factors of electroluminescent devices assisted with a CES. Achromatic contrast is the most important contributor to display's legibility. In some conditions color contrast may also be important. Contributing to both luminance and color contrast enhancement, the contrast-enhancing stack may play an important role in various display applications.

Optical Insights into Renaissance Art

In this feature, world-renowned artist David Hockney and University of Arizona optical sciences professor Charles Falco explain how Hockney's observation that certain Renaissance paintings seemed almost “photographic” in nature led them to launch an inquiry into the possibility of finding scientific evidence that some of the Old Masters relied on optical aids. Hockney's visual observations received scientific validation when application of basic optics principles to a number of Renaissance paintings began generating remarkably consistent results.

Finding internal defects through coating flaws : Claridge, J. Glass International, Vol. 19, No. 4, pp. 51–52 (Dec. 1996)

A recent order from the Ford Motor Co's Glass Division for an automatic laser system capable of inspecting coated float glass was the culmination of 12 months' intensive development activity at Image Automation. The problem had been to develop a system capable of finding flaws in the reflective coating itself, while still detecting tiny defects within the body of the ribbon. To solve the problem, it was necessary to return to the basic principles of optics and the properties of polarised light. This article explains

A practical guide to surgical loupes

Loupes are widely used in both surgical and dental procedures to enhance visualization of tissues and to facilitate optimal instrument placement. Most doctors, however, have limited knowledge of fundamental optical principals or of the various types of loupes available. This article reviews basic optical terminology and principles and highlights features of various commercially available loupes.

Principles of Practical Advantages and Limitations of Light Microscopic 3d Deconvolution

There has been much provocative discussion over the past few years about the advantages and limitations of deconvolution methods. In this tutorial we will provide a reasonable understanding of the underlying theoretical principles of deconvolution, with an aim at understanding expected advantages and limitations. These principles will be presented for a mixed audience composed of biologists, neuroscientists, engineers, physicists and other scientists and graduate students. These principles will be presented in the context of both widefield and confocal microscopy deconvolution.The basic principles of Fourier optics will be presented. From these principles, we can explain why it is that the confocal microscope provides a superior in-plane and axial (z-axis) resolving power, compared to the widefield microscope. In particular, for example, the Fourier transform of a 3D widefield image contains a missing cone region (to be explained in the tutorial), and this missing cone region effectively spoils the axial resolution of unprocessed widefield data.

The simulation of side-scan sonar images

This paper describes a system which applies the established ray-tracing techniques from computer graphics to the simulation of side-scan sonar images. Side-scan sonar is a widely used device in underwater searches for sunken vessels and inundated land sites in archaeology. It is also used in other fields, such as the defence and oil industries. Sonar techniques effectively use sound to ‘see’ through water, which would rapidly attenuate light, but whereas we are used to interpreting what we see with our eyes, the meaning of sonar images is often less immediately apparent. An archaeologist searching for an underwater site would benefit from being able to model the expected target and examine the images produced under varying conditions. A series of computer experiments predicting the various manifestations of a given target could save a great deal of time, and therefore money, at sea. Initially, the simulated sonar images are produced by applying the computer graphics model directly to sound. The model uses the basic principles of geometric optics, and even in this simple form produces simulated images that compare favourably with their real counterparts. As the model becomes more sophisticated it incorporates some of the many factors that degrade real sonar images, such as the beam pattern of the sonar transducer, the sea bed itself, towfish instabilities and multiple reflections. It is believed that this is the first time that ray tracing has been used in this way, and the system has the unique ability to present visual images of how a target on the sea-bed might look if the water were removed, together with simulated sonar images of that object. This would be of great value as a teaching tool, and simulated images are necessary in the testing of algorithms for, for example, distortion correction. Previous attempts at modelling the sonar process were mathematically intensive. The method developed here has the benefit of simplicity. Each ray hits a point on the seabed and that point is considered in isolation. Although millions of calculations are performed, each individual calculation is very simple. The application of ray tracing to the simulation of side-scan sonar images has proved that techniques from computer graphics can be applied to underwater acoustics, and examples are given to illustrate some of the difficulties of interpretation of side-scan sonar imagery.

Digital communications for protection. Part 3: Fibre optics

For pt.II see ibid., p.97 (April 1994). This tutorial describes the basic principles of fibre optics together with an outline of some of the practical considerations necessary in setting up a fibre optical system for transmission of digital data. The tutorial is the third in a series of three which describe the role of digital communications and fibre optics in power system protection.

Improvements on Littmann's method of determining the size of retinal features by fundus photography

Littmann's formula relating the size of a retinal feature to its measured image size on a telecentric fundus camera film is widely used. It requires only the corneal radius, ametropia, and Littmann's factor q obtained from nomograms or tables. These procedures are here computerized for practitioners' convenience. Basic optical principles are discussed, showing q to be a constant fraction of the theoretical ocular dimension k', the distance from the eye's second principal point to the retina. If the eye's axial length is known, three new methods of determining q become available: (a) simply reducing the axial length by a constant 1.82 mm; (b) constructing a personalized schematic eye, given additional data; (c) ray tracing through this eye to extend calculations to peripheral retinal areas. Results of all these evaluations for 12 subjects of known ocular dimensions are presented for comparison. Method (a), the simplest, is arguably the most reliable. It shows good agreement with Littmann's supplementary procedure when the eye's axial length is known.

Conceptually blindfolded in the optics laboratory. Dilemmas of inductive learning

In modern schooling, student activity and group work are emphasized as important vehicles for learning. Following the perspectives formulated by Piaget and other constructivist thinkers, self-discovery by students of scientific principles is seen as a means for avoiding the pitfalls ascribed to teacher centered lecturing. Teacher explanation in this pedagogical philosophy is often seen as counterproductive to real learning. In the study reported, it is illustrated by means of an example from student group work in a physics laboratory how the understanding of basic principles of optics do not follow from mere observation and physical manipulation of a particular type of educational instrument; the optical bench. It is argued that the optical bench itself is a product of a specific theory of optics and that it embodies principles of understanding the word which are discursive in nature and which are not accessible to learners unless they are provided guidance. In the instance analyzed, students already in some sense had an understanding of the principles illustrated (e.g., that light can only go straight forward, that it cannot go through solid objects, etc.), but they failed to realize the significance of these observations, since they fere not familiar with a theoretical position in which these observations called for an explanation. ‘Seeing’, also in the case of the optics laboratory, relies on the use of cultural tools that provide the observer with relevant contextualizations.

Détermination des temps d'arrivée de fronts d'onde acoustiques divergents dans une lame anisotrope

The present work is an attempt to extend to the acoustics of anisotropic media the basic principles of optics. The acoustical case is much more intricate because of the possibility of existence of the cuspidal caustics. Firstly, one discusses the mathematical transformation between phase and group wavespeeds. Then, the problem of the reflection of a divergent acoustical ray onto an interface is studied with the help of Huyghens construction. A generalization of the classical refraction law is obtained. Such a result can also be derived from Fermat principle. It is possible to numerically verify the absence of precursor on the converted mode, due to the non-existence of caustics after reflection. A discussion on the so-called Cagniard-de-Hoop contours is introduced, as well as a numerical procedure to compute the direction of the reflected ray. Different cases, depending on the source dimension (point-like or line) and on the orientation cut of the anisotropic solid, are discussed. The extension of the study to several reflections is proposed. Special attention is also devoted to the analysis of the head wavefront reflection. Last, some experimental results dealing with the measurements of group wavespeeds in a transversely isotropic composite material are described. The present study will be followed by the computation of the Green functions and the comparison with experimental displacement fields for various anisotropic solids

Optical properties of semiconductor superlattices in the far infrared

In the far infrared, superlattice dielectric functions can be well represented by an effective-medium model. The overall symmetry of a superlattice is uniaxial, and each of the principal components of the resulting dielectric tensor typically contains a different series of resonances. Here we examine some consequences that are of importance to many of the spectroscopy experiments that are undertaken. We describe sharp Brewster modes near longitudinal frequencies in p-polarized oblique incidence reflectivity and give details of guided wave and surface modes, including interface polaritons at the superlattice–vacuum interface. After discussing the basic optical principles we examine their application to the measurement of phonon confinement parameters.

Ion extraction systems: optics and design

Abstract The ion beam formation process and extraction systems are treated in this paper from a rather practical standpoint, with emphasis on, but not strict limitation to, the case of high-current beams extracted from plasma ion sources. Some basic principles of ion extraction optics are discussed and beam quality parameter definitions outlined. Based on the characteristics of an actual extraction system, a general scaling model is then derived for a wide range of beam current and energy values. It allows a determination of the main parameters of systems to be built under specific constraints, or a judgment of the performance of an existing system in terms of one figure of merit. Finally, some examples of special-purpose systems are presented, including multi-aperture, slit, and compound systems. The detailed mechanical contours of these systems are shown to scale in all cases.

Automatic Inspection of Photographic Materials

An infra-red laser scanning instrument has been developed for the automatic inspection of unexposed photographic strip products (film and paper) for visible defects. The system has been developed jointly by Sira and Kodak and one unit has been in constant use in an on-line application for over 2 years. The laser scanning head is designed to inspect web with a width of up to 1500 mm at line speeds up to at least 100 m/min. Scratches of width down to 50 w m running along the strip, and certain other defects such as digs down to 300 w m in diameter, can be detected. The basic optical principle is to scan an infra-red laser beam with a mirror drum scanner sequentially across the inspected surface, from which the specularly reflected light is collected by a large cylindrical mirror and directed at a photomultiplier detector. When defects in the surface are scanned the photomultiplier signal is temporarily increased or decreased, and it is these features which are extracted by the electronic signal processing u...

Book ReviewThe Photography of Patients: Including discussions of basic photographic and optical principles and infrared techniques.

Book ReviewThe Photography of Patients: Including discussions of basic photographic and optical principles and infrared techniques.

The Photography of Patients Including Discussions of Basic Photographic and Optical Principles and Infrared Techniques

The first edition of this book proved to be a valuable reference work for the physician who desired photographic recording in his office, in the clinic, or during a research project. It served as a guide and a reference to the clinical photographer as well. It is an excellent introduction to the solution of photographic problems most likely to be encountered by the busy physician. During the eight years since the book was published, many new photographic techniques have come into being. New equipment and cameras have been introduced, thereby simplifying the photography of patients and lessening the chance of error. It was reasonable, therefore, to expect a new and completely rewritten second edition. With the increasing awareness by the physician of the importance of photographing the patient, this new edition should prove to be of even more help than the first. The book is divided into 10 basic chapters,

Techniques of Flow Visualization

This article deals with the joint use of two branches of Physics for the solution of flow problems. These two branches arc Optics and Fluid Mechanics. The basic principles of Optics arc employed in the Fluid Mechanics Laboratory to provide insight into the flow of liquids and gases. Only techniques used in incompressible flow arc discussed: emphasis being laid on those useful in ‘free surface’ and ‘boundary’ type problems. Basic principles of similarity and optics are described and a brief appraisal of some of the methods is attempted, illustrated by experiments carried out in the Fluid Mechanics Laboratory of the Melbourne Technical College. Two techniques which are frequently used in problems of incompressible flow receive fairly detailed treatment; these are the fluid photo‐elastic apparatus and the smoke generator.

The Photography of Patients. Including Discussions of Basic Photographic and Optical Principles

The Photography of Patients. Including Discussions of Basic Photographic and Optical Principles