Showing papers in "Optics and Laser Technology in 1972"
TL;DR: This paper discusses image rotation devices in general terms, and attempts to collect together the more commonly used devices and to present comparative information on them in order to provide a convenient reference source for optical designers.
Abstract: Optical systems which, when rotated, produce a rotation of an image about the optical axis have been known and used for a long time. Information on such systems is sparse, however, and widely scattered. This paper discusses image rotation devices in general terms, and then attempts to collect together the more commonly used devices and to present comparative information on them, in order to provide a convenient reference source for optical designers. In addition a number of lesser known and novel arrangements are described.
51 citations
TL;DR: This review describes how the interference properties of light have been applied to optical testing and indicates the main fields of application of the various techniques.
Abstract: The tolerances on optical systems and components are usually very tight and the testing of such products is a vital part of their manufacture. This review describes how the interference properties of light have been applied to optical testing and indicates the main fields of application of the various techniques.
34 citations
TL;DR: In this paper, the results of tests concerning the resolving power and photosensitivity of a combination of the monomers acryl amide and methylene-bis-acryls amide were presented.
Abstract: Photopolymers for application in holography have the advantage over silver halide emulsions that a phase hologram is formed in situ during exposure The article describes the results of tests concerning the resolving power and photosensitivity of a combination of the monomers acryl amide and methylene-bis-acryl amide This combination forms a copolymer under the influence of red light, when methylene blue is used as a sensibiliser In spite of their low sensitivity, photopolymers in some instances appear to be promising substitutes for the conventional silver halide materials
29 citations
TL;DR: In this paper, it is shown that by a filtering procedure carried out in the plane of the real image, fringe patterns can be formed that also give information about the displacement undergone by the surface of the object.
Abstract: Another method for the interpretation of double-exposure holograms is presented It is shown that by a filtering procedure carried out in the plane of the real image, fringe patterns can be formed that also give information about the displacement undergone by the surface of the object An interpretation for those patternis presented fo rsmall out-or plane displacements presented for small out-of-plane displacements A method for determining the three orthogonal displacement components for those patterns and the virtual image is outlined
16 citations
TL;DR: The CO 2 laser is a suitable cutting tool for numerous materials such as metals such as titanium or steel, combustible material such as paper, textiles and wood; and plastics as mentioned in this paper.
Abstract: Of all the types of lasers now available, the CO 2 laser is particularly suitable for materials working. It has a very high efficiency (15–20%) and a high out-put power (up to several kW). When the laser light is focused by means of a lens or a mirror, a c.w. power density of more than 10 9 W cm -2 can be attained. The laser need not be used in vacuum. The CO 2 laser is a suitable cutting tool for numerous materials. These include metals such as titanium or steel; combustible materials such as paper, textiles and wood; and plastics. The CO 2 laser can also cut hard and brittle materials such as aluminum oxide and silicon carbide. If metals are cut in an oxidizing atmosphere, the cutting speed may be increased. The cutting width, however, is determined by the size of the laser spot. Another important field of application is the growth of single crystals. Experiments are reported in which the CO 2 laser was used for welding steel, titanium, plastics, quartz, and glass. The advantages of the laser for this application are discussed. A comparative study of laser and electron beam techniques is included.
14 citations
TL;DR: In this paper, the reliability of tracer particles following turbulent fluid motion when using laser anemometers was examined and it was shown that tracer particle studies with liquids are more accurate and to be preferred to those in which gases are used.
Abstract: An examination is made of the reliability with which tracer particles can follow turbulent fluid motion when using laser anemometry. Studies with liquids are more accurate and to be preferred to those in which gases are used. In addition to fluid measurements, laser anemometers have many hitherto unexploited applications in the study of particle motion in fluidised systems.
12 citations
TL;DR: In this paper, the desirability of having an objective method for production testing of optical systems is discussed and a test philosophy based on the use of an m.t.f. criterion in conjunction with veiling glare and paraxial transmission measurements, is outlined.
Abstract: The desirability of having an objective method for production testing of optical systems is discussed and a test philosophy based on the use of an m.t.f. criterion in conjunction with veiling glare and paraxial transmission measurements, is outlined. Finally an instrument is described embodying this test philosophy and designed for testing afocal systems.
12 citations
9 citations
TL;DR: A multi-channel correlator for holographic matched filtering is described and preliminary experimental results show that this method can be succesfully used in some cases where the results of simple matched filtering remain unsatisfactory.
Abstract: A multi-channel correlator for holographic matched filtering is described. The two-dimensional channels are separated spatially in the Fourier plane. This arrangement allows individual filters to be realized for each channel for different spatial frequency ranges etc. The multi-channel correlator is addressed by a generator of multiple object waves, i.e. by different directions of object illumination. Parallel and sequential evaluation of the correlation signals is possible. The efficiency and signal-to-noise ratio for both modes of operation are discussed. In each channel, linear superimposed multiple Vander-Lugt filters may be introduced to increase the over-all capacity of learning steps. The risk of over-exposure is small because the centres of the frequency spectra are separated on the hologram filter plate. With a multi-channel correlator, combined matched and feature filtering may be performed. Preliminary experimental results show that this method can be succesfully used in some cases where the results of simple matched filtering remain unsatisfactory. The results and discussions are presented from a more general point of view with some remarks concerning comparable methods and possible future aspects.
8 citations
TL;DR: In this paper, a new family of semiconductor injection lasers with high efficiencies and low threshold currents has recently shown promise for use in a wide range of applications and the reasons for their improved performance are discussed.
Abstract: A new family of semiconductor injection lasers with high efficiencies and low threshold currents has recently shown promise for use in a wide range of applications. The heterostructure lasers are described here and the reasons for their improved performance are discussed.
8 citations
TL;DR: In this paper, a practical example of an application of interferometry and holography to a particular wind tunnel and a particular aerodynamic project is given, where the authors show that the practical problems have been overcome and that good accuracy is attainable.
Abstract: In previous papers the author has discussed the uses of interferometry and holography in aerodynamics and the design of interferometers using laser sources. The present paper gives a practical example of an application of these technique to a particular wind tunnel and a particular aerodynamic project. The nature of the wind tunnel and the type of flow leads naturally to the use of holography with non-diffuse light and to a particular interferometer design—an aperture-expanding interferometer in which the light is reflected back through the tunnel. It leads also to the use of a sensitivity doubling technique in the analyser. The optical and engineering design of the interferometer, analyser, and of automatic systems for model rotation and camera operation are described. Some results are presented which show that the practical problems have been overcome and that good accuracy is attainable.
TL;DR: A simple hologram plate holder has been developed, which with normal processing techniques using selected photographic plates, enables the zero fringe condition to be readily obtained and maintained.
Abstract: The authors have applied real-time and real-time/time-averaged hologram interferometry and time-averaged holography to the visualization of the complete vibrational patterns on a variety of large objects. A simple hologram plate holder has been developed, which with normal processing techniques using selected photographic plates, enables the zero fringe condition to be readily obtained and maintained. The use of retro-reflective painted models with point source illumination enables small, inexpensive lasers to illuminate large objects and still retain short exposures by using fast photographic plates at the focused point of reflected object light. The retro-reflective paint does not depolarize the reflected light and thus high contrast fringes can be seen through the viewing hologram.
TL;DR: In this paper, the results of experimental studies of differential wavefront and amplitude-divided schemes are given, and the operation of laser velocity meters of the Doppler and interference types are examined.
Abstract: The operation of laser velocity meters of the Doppler and interference types are examined. The results of experimental studies of differential wave-front and amplitude-divided schemes are given.
TL;DR: In this article, an advanced system for monitoring and controlling the automatic deposition of metal oxide coatings has been investigated by English, Putner and Holland, with the ultimate object of removing operator error from the deposition cycle.
Abstract: Over the last few years there has been rapid growth in the application of vacuum-deposited metal oxides in production optical and micro-electronic film systems. As a result, development of process control apparatus has also advanced and many of the difficulties experienced in producing reliable films from chemically active materials have been overcome. An advanced system for monitoring and controlling the automatic deposition of metal oxide coatings has been investigated by English, Putner and Holland 1 , with the ultimate object of removing operator error from the deposition cycle. The work included studies and practical experimentation into the reactive evaporation of metal oxides under controlled automatic evaporation rate conditions. This work and some of the results obtained is given in more detail in the following. The historical background to the vacuum deposition of metal oxides using evaporation methods and some of the work in the last decade on its control is also discussed.
TL;DR: The Institut d'Optique de Paris has been interested for many years in fabricating flat optical surfaces for Fabry-Perot interferometers as discussed by the authors, and a few conclusions obtained about pitch surfacing from a study which took place in these laboratories.
Abstract: The Institut d'Optique de Paris has been interested for many years in fabricating flat optical surfaces for Fabry-Perot interferometers. This paper details a few conclusions obtained about pitch surfacing from a study which took place in these laboratories.
TL;DR: In this article, an electronic fringe counter for use with optical interferometers is described, which allows automatic fringe counting and indication of change in the direction of motion of the interferometer flats.
Abstract: An electronic fringe counter for use with optical interferometers is described. Provision is made for automatic fringe counting and indication of change in the direction-of-motion of the interferometer flats. Two cadmium sulphide cells, with peak spectral response closely matched to the wavelength of the interferometer light source, serve as photosensors. Changes in cell resistance are measured with dc bridge circuits, the output of which is amplified and plotted on strip recorders. In this manner, a continuous display of fringe to fringe displacements is obtained. The system described here permits integral fringe counting accurate to ∼0.01 fringe.
TL;DR: In this paper, two Q-switched laser pulses each of energy 30 mJ and separated by 25 μs are used to record holographically the transient impulse response of diffusely reflecting objects occupying volumes of about (30 cm)3.
Abstract: Some examples of dynamic holographic interferometry are presented. Two Q-switched laser pulses each of energy 30 mJ and separated by 25 μs are used to record holographically the transient impulse response of diffusely reflecting objects occupying volumes of about (30 cm)3. The laser was of simple form and was not confined to single axial or transverse mode.
TL;DR: In this article, an interferometer has been designed for analysis of the longitudinal mode outputs of Q-switched visible and near infra-red LIDAR, which is described in detail including full specifications for the mirrors and their coatings as well as a complete assembly drawing.
Abstract: An interferometer has been specially designed for analysis of the longitudinal mode outputs of Q-switched visible and near infra-red lasers. The device is described in some detail including full specifications for the mirrors and their coatings as well as a complete assembly drawing. Tests have been conducted on the prototype using 633 nm radiation from a c.w. He-Ne laser and the 532 nm harmonic of a Q-switched Nd: CaWO4 laser.
TL;DR: In this article, the physical principles of operation of several types of optical sensor for spacecraft attitude determination are described, including sensors which detect solar radiation, reflected sunlight (albedo) from the earth or moon, the infra-red radiation contrast between earth and space, or the radiation from stars.
Abstract: This article sets out the physical principles of operation of several types of optical sensor for spacecraft attitude determination. These include sensors which detect solar radiation, reflected sunlight (albedo) from the earth or moon, the infra-red radiation contrast between earth and space, or the radiation from stars. Practical details of selected sensors which have been successfully flown in space are given.