Showing papers in "Optics and Laser Technology in 1979"
TL;DR: In this article, the principal physical processes of holographic amplification of coherent light are analysed and a one-exposure technique of image subtraction or addition is proposed and realized in Fe-doped crystals of LiNbO 3.
Abstract: Possible applications of dynamic holograms for image amplification and image processing are discussed. The principal physical processes of holographic amplification of coherent light are analysed. Amplification of grey scale images during recording of dynamic holograms in pure reduced and Fe-doped crystals of LiNbO 3 is demonstrated. One-exposure technique of image subtraction or addition is proposed and realised in Fe-doped crystals of LiNbO 3 .
55 citations
TL;DR: Using birefringent crystals such as LiNbO3: Fe, reading and writing of holograms at different wavelengths and so nondestructive readout of information may be accomplished as mentioned in this paper.
Abstract: Using birefringent crystals such as LiNbO3: Fe, reading and writing of holograms at different wavelengths and so nondestructive readout of information may be accomplished.
31 citations
TL;DR: In this article, a theoretical model has been developed that relates the growth of an oxide layer to changes in coupling coefficients and has been used to measure the coupling coefficients for 10.6μm laser radiation on stainless steel.
Abstract: Coupling coefficients for 10.6μm laser radiation on stainless steel have been measured experimentally under oxidizing and vacuum conditions. A theoretical model has been developed that relates the growth of an oxide layer to changes in coupling coefficients.
25 citations
PARC1
TL;DR: In this article, an underfilled multifaceted rotating polygon beam scanning system is proposed to bring the input light beam to a tangentially extending line-like focus on successive facets of a rotating polygons.
Abstract: To provide a relatively compact and linear underfilled multifaceted rotating polygon beam scanning system, there are imaging optics for bringing a input light beam to a tangentially extending line-like focus on successive facets of a rotating polygonal scanning element and for restoring the light beam reflected from the facets to a generally circular focus on an image plane. Each of the facets subtends a sufficient angle about the axis of rotation of the scanner to ensure that the input beam remains fully seated on a single facet while the reflected beam is being scanned through a desired scan angle. Furthermore, improved linearity is achieved because the scanning system is symmetrical in the tangential and sagittal planes at all points between the imaging optics and the polygonal scanning element.
25 citations
TL;DR: In this paper, a transversely excited CO 2 laser has been used to investigate the interaction between laser pulses of duration ≈ 40 μs, and metallic targets, and the dependence of machining efficiency on power density has been studied.
Abstract: A transversely excited CO 2 laser has been used to investigate the interaction between laser pulses of duration ≈ 40 μs, and metallic targets. The dependence of machining efficiency on power density has been studied, and high speed photography has been used to compare interactions with different pulse durations. Metallurgical analysis has revealed important structural effects in both mild steel and aluminum samples.
17 citations
TL;DR: The Ronchi test of optical systems and components is very widely used but is usually regarded as a qualitative test as discussed by the authors, and it has been used to evaluate the quality of optical system and components.
Abstract: The Ronchi test of the quality of optical systems and components is very widely used but is usually regarded as a qualitative test In an attempt to make this very simple technique at least semi-quantitative, we have derived easy to use analytical formulae for some basic but important types of aberration A companion paper will describe their implementation and their experimental verification
17 citations
TL;DR: In this article, a new class of potential high power lasers, the halogens and the interhalogens, were investigated. But the authors focused on species which emit in the visible to the far ultra-violet spectral range.
Abstract: During the past few years the development of new lasers has concentrated on species which emit in the visible to the far ultra-violet spectral range. This paper deals with a new class of potential high power lasers, the halogens and the interhalogens. These molecules have attracted considerable interest because of the high fluorescence yield exhibited by some of them. More recently the F2 laser was successfully excited by the TEA discharge configuration as applied in rare gas halides lasers. During experiments to identify the exact pumping reaction, the first interhalogen laser CIF was found. The emission is centred around 284 mm.
16 citations
TL;DR: In this article, a method of improving the quality of interferograms obtained by means of polarization or grating interferometers used with a multi-mode pulsed laser as a light source was proposed.
Abstract: Methods of improving the quality of interferograms, obtained by means of polarization or grating interferometers used with a multi-mode pulsed laser as a light source, have been proposed. The adjustment procedure developed essentially allows the illuminating aperture size to be increased and, thus, a reduction of the speckle-effect. Tests have been carried out using a ballistic facility. The interferograms obtained are presented together with the processed results.
15 citations
TL;DR: In this paper, an investigation into the feasibility of laser welding types 316, 310 and DUCOL W30 steels in 6 mm thick plate has been made, the materials being typical of those used in CEGB power plant.
Abstract: Many welding applications in CEGB power plant involve components with wall thicknesses in the range 2–10 mm. Therefore, an investigation into the feasibility of laser welding types 316, 310 and DUCOL W30 steels in 6 mm thick plate has been made, the materials being typical of those used in CEGB power plant.
The welds were made using the high power, transverse flow, CO2 laser based at UKAEA Culham Laboratory. The laser welding process used has been compared with TIG (tungsten inert gas), plasma and electron beam using capital cost, power requirement, ease of handling and distortion in workpieces as the criteria for comparison. Possible applications of laser welding to power plant manufacture are discussed.
9 citations
TL;DR: In this article, a survey circumvents the Scylla of propagation theory and Charybdis of meteorological input by introducing simple physical concepts to explain the underlying interaction of random fluctuations of the refractive index typical of turbulence with basic electromagnetic waves.
Abstract: Turbulent air causes optical rays to deviate from otherwise straight paths by irregular slight undulations, and it also changes the phase velocities irregularly. These fluctuations cause a host of unpleasant degradations to communications signals. This survey circumvents the Scylla of propagation theory and Charybdis of meteorological input by introducing simple physical concepts to explain the underlying interaction of random fluctuations of the refractive index typical of turbulence with basic electromagnetic waves.
8 citations
TL;DR: In this article, the application of the common path shearing interferometric techniques to holography to study the phase variations in transparent specimens is described, and real-time reconstructed interferograms are shown.
Abstract: Application of the common path shearing interferometric techniques to holography to study the phase variations in transparent specimens is described. These shearing interferometers are less susceptible to vibration and other external disturbances. Real-time reconstructed interferograms are shown.
TL;DR: In this article, it was shown both analytically and experimentally that the smallest measurable displacement is smaller than the speckle size as it is usually defined, and it has been shown that this is the case even for one-beam interferometry.
Abstract: It has been customarily assumed that the smallest measurable displacement by one beam speckle interferometry is equal to the smallest speckle size (σ = 1.22 λ F ) as resolved by the recording camera. In this paper it is shown both analytically and experimentally that the smallest measurable displacement is smaller than the speckle size as it is usually defined.
TL;DR: In this paper, a review of recent developments in the techniques of generation and measurement of picosecond and sub-picosecond pulses from mode-locked lasers is presented. But the main emphasis is on the rapid advances of the last few years in ultra-fast streak-cameras.
Abstract: Recent developments in the techniques of generation and measurement of picosecond and sub-picosecond pulses from mode-locked lasers are reviewed. Particular attention is paid to frequency tunable, bandwidth-limited pulses from dye lasers, especially the cw dye laser. In measurement the main emphasis is put on the rapid advances of the last few years in ultra-fast streak-cameras, ans the recent developments in streak-camera synchronization to a cw mode-locked laser is described. Future prospects for shorter wavelenght pulses in the uv and vuv are briefly considered.
TL;DR: In this paper, the Ronchi test is treated as a form of wavefront shearing interferometer and the derivation of basic formulae for the test is given together with instructions for their use.
Abstract: Part 1 of this paper gave the derivation of basic formulae for the Ronchi test, treated as a form of wavefront shearing interferometer. In Part 2, practical, easy-to-apply versions of these formulae are given together with instructions for their use, and some experimental verifications of the formulae are described.
TL;DR: In this paper, a non-destructive and rapid stress determination is possible by observing the effective index distributions of propagating modes in TM and TE waves via the stress birefringence effect.
Abstract: Float glasses have tin-diffused layers on one side. These layers show an optical waveguide effect caused by refractive index gradients in the layer. Surface stress, caused by tempering, gives different refractive index distribution for TM and TE waves via the stress birefringence effect. Non-destructive and rapid stress determination is possible by observing the effective index distributions of propagating modes in TM and TE waves.
TL;DR: In this paper, the authors discuss the prospects of realizing the ultimate spectral resolving power and sensitivity of laser spectroscopy and some fields of application such as nuclear physics, chemical kinetics and molecular physics, quantum metrology.
Abstract: This concluding article in the series discusses the prospects of realizing the ultimate parameters — spectral resolving power and sensitivity — and some fields of application — nuclear physics, chemical kinetics and molecular physics, quantum metrology — of laser spectroscopy.
TL;DR: In this paper, an optical study of the silicone elastomers used to make teeth impressions in odontology bears on the sensitivity of the molding process and the diversity of the results obtained evinces the influence of experimental parameters such as temperature, hygrometry and conditions of impression and removal.
Abstract: The retraction of the silicone elastomers used to make teeth impressions in odontology bears on the sensitivity of the moulding process. An optical study of this retraction has been carried out using interferometry in monochromatic light - holographic interferometry - and in white light - channelled spectrum method. The diversity of the results obtained evinces the influence of experimental parameters such as temperature, hygrometry and conditions of impression and removal.
TL;DR: Some aspects of contemporary optical design are discussed in this paper, where the role of the computer has become an essential in today's optical design, and examples of recently designed optical systems are given to illustrate the results obtained using modern design methods.
Abstract: Some aspects of contemporary optical design are discussed. The more commonly encountered modern design methods and also some of the more unusual techniques are briefly described. Particular emphasis is placed on the role of the computer as this has become an essential in today's optical design. Examples of recently designed optical systems are given to illustrate the results obtained using modern design methods.
TL;DR: In this paper, the authors used two linearly polarized light beams which vibrate in directions vertical to and in parallel with the surfaces of a sheet and a plate glass to determine surface stress.
Abstract: Sheet and plate glasses have refractive index inhomogeneity parallel with their surfaces. Refractive index maxima near the surfaces behave as optical waveguides. Light waves can be excited in the guides from outside and can be extracted non-destructively, using the technique popular in optical integrated circuits. Stress birefringence, caused by surface stress in thermally tempered glasses, gives different effective indices for two linearly polarized light beams which vibrate in directions vertical to and in parallel with the surfaces. Effective index observation by two polarized light beams allows non-destructive surface stress determination.
TL;DR: In this paper, multiphoton transitions in laser spectroscopy were investigated with particular emphasis on their application to the study of highly absorbing domains in solid state physics, and their application was discussed.
Abstract: Multiphoton transitions in laser spectroscopy are investigated with particular emphasis on their application to the study of highly absorbing domains in solid state physics.
TL;DR: In this paper, the authors describe measurements made on a vibrating surface, using a laser velocity meter, incorporating a rotating radial diffraction grating to provide frequency shifting of the incident laser beams.
Abstract: The paper describes measurements made on a vibrating surface, using a laser velocity meter. The meter incorporates a rotating radial diffraction grating to provide frequency shifting of the incident laser beams. A description of the system used is included, and preliminary results are described.
TL;DR: Triple exposure holographic interferometry as mentioned in this paper provides knowledge of the displacement vector between the first two exposures by a calibrated amount, and before the last exposure it is translated by an unknown amount.
Abstract: Triple exposure holographic interferometry provides knowledge of the displacement vector. Between the first two exposures the object is displaced by a calibrated amount, and before the last exposure it is translated by an unknown amount.
TL;DR: In this article, the position of focus and the structure of the intensity distribution near the focus in the image space are clarified for an off-axis gaussian beam as a function of its incident position over the pupil, its beam size, and the amount of primary spherical aberration in the optical system.
Abstract: Focusing properties of an off-axis gaussian beam passing through the optical system with primary spherical aberration are investigated. The position of focus and the structure of the intensity distribution near the focus in the image space are clarified for an off-axis gaussian beam as a function of its incident position over the pupil, its beam size, and the amount of primary spherical aberration in the optical system.
TL;DR: In this paper, the possibility of producing front illuminated holographs of volumes large enough to allow holographic portraiture represents an important development in the field of holography.
Abstract: The possibility of producing front illuminated holographs of volumes large enough to allow holographic portraiture represents an important development in the field of holography. Here, a description of an experimental method used is given.
TL;DR: In this paper, the reconstructed interference patterns of a sphere's supersonic flow are presented. And a scheme for obtaining colour schlieren patterns is described. Butler et al.
Abstract: Interferograms with narrow fringes obtained with grating and polarization interferometers using a wide source allow the use of some processes of holographic interferometry and schlieren techniques for investigating a reconstructed wavefront. The reconstructed interference patterns of a sphere's supersonic flow are presented. A scheme for obtaining colour schlieren patterns is described.
TL;DR: In this article, the optimum configuration of a total-internal-reflection type laser light modulator with surface interdigital electrodes has been obtained, and the final specifications of the modulator were an effective half wavelenght voltage of 11.5 V, a capacitance between electrodes of 9.1 pF, and a modulation bandwidth of 400 MHz at 50 Ω load impedance.
Abstract: The optimum configuration of a total-internal-reflection type laser light modulator with surface interdigital electrodes has been obtained. The final specifications of the modulator were an effective half wavelenght voltage of 11.5 V, a capacitance between electrodes of 9.1 pF, and a modulation bandwidth of 400 MHz at 50 Ω load impedance. This corresponds to a remarkable safety factor of 1.7. Some effective means of eliminating harmful resonances due to acoustic waves excited in the electro-optic crystals by the interdigital electrodes were found. A practical optical communication system for transmitting catv signals in the open-air has been built and tested in the field using the modulator. In the system cross modulation and intermodulation between channels were found to be sufficiently small.
TL;DR: In this paper, the authors deal with the measurement of helium loss and the increase of tube life in He-Cd laser systems and show that a 30% helium loss results in the end of the tube life.
Abstract: The output power of He-Cd lasers decreases rapidly with the decrease of helium pressure. A 30% helium loss results in the end of tube life. The paper deals with the measurement of helium loss and the increase of tube life.