Showing papers in "Optics and Laser Technology in 1980"
83 citations
TL;DR: The polarization properties of optical fibres are of interest in several different communications and measurement applications as mentioned in this paper, and the properties ideally required of a fibre for use in current measurement systems and described an extremely low birefringence fibre which meets many of these requirements.
Abstract: The polarization properties of optical fibres are of interest in several different communications and measurement applications. This paper indicates the properties ideally required of a fibre for use in current measurement systems and describes an extremely low birefringence fibre which meets many of these requirements. Measurements of the polarization properties of this fibre are given and a laboratory prototype current measurement system using the fibre is described.
63 citations
TL;DR: In this article, a CARS spectrometer designed for temperature and concentration measurements in flames is described, and experimental results in various mixtures and in a simulated jet engine combustor are also reported.
Abstract: A CARS spectrometer designed for temperature and concentration measurements in flames is described. Experimental results in various mixtures and in a simulated jet engine combustor are also reported.
43 citations
TL;DR: In this paper, a one-dimensional analysis of a double exposed speckle photograph is used to calculate the errors in displacements that arise if the diffraction halo is not divided from the fringe pattern prior to calculation of the fringe spacing.
Abstract: A one-dimensional analysis of a double exposed speckle photograph is used to calculate the errors in displacements that arise if the diffraction halo is not divided from the fringe pattern prior to calculation of the fringe spacing. Relative errors in displacements calculated from fringe maxima are higher than those calculated from fringe minima. They are also a function of fringe visibility, increasing as visibility becomes lower.
38 citations
27 citations
TL;DR: In this article, the authors described the techniques used for producing a single longitudinal mode TEA-Co 2 laser using a double unstable resonator and showed that the simplest technique seems to be a double-stable resonator.
Abstract: Techniques used for producing a single longitudinal mode TEA-Co 2 laser are described. The simplest technique seems to be a double unstable resonator.
22 citations
TL;DR: In this paper, case hardening of a carbon steel, Armco Iron, an alloyed steel and a high-speed steel was carried out with a CO 2 laser beam, and the indispensibility of an absorptive coating in the laser heat treatment was established.
Abstract: Case hardening of a carbon steel, Armco Iron, an alloyed steel and a high-speed steel was carried out with a CO 2 laser beam. The indispensibility of an absorptive coating in the laser heat treatment was established. Four coatings capable of absorbing CO 2 laser radiation of a 10.6 μm wave length were examined. The influence of spot size, power and scanning speed on the depth of hardening were studied. Processing at optimal conditions yielded a hardening depth of up to 0.7 mm and a surface hardness of up to 220 H v .
18 citations
TL;DR: Optoacoustic imaging is a new technique with unusual features as discussed by the authors, it allows not only optical imaging, but also imaging of thermal structures on and in the sample, and images are produced from sample depths exceeding the optical penetration depth by several orders of magnitude.
Abstract: Optoacoustic imaging is a new technique with unusual features. It allows not only optical imaging, but also imaging of thermal structures on and in the sample. With optical radiation, images are produced from sample depths exceeding the optical penetration depth by several orders of magnitude. The resolution of, at present, about 7μm reveals microscopic structures. With simple image processing techniques information can be obtained from certain sample layers, and background structure can be suppressed.
15 citations
TL;DR: In this paper, a simple double exposure technique was proposed for making binary amplitude gratings with preset opening ratio, where the Ronchi type master ruling was imaged onto the photographic plate by a laser projection system.
Abstract: A simple double exposure technique is proposed for making binary amplitude gratings with preset opening ratio. Commercially available Ronchi type master ruling is imaged onto the photographic plate by a laser projection system. The controlled lateral displacement of the ruling or the photographic plate between two exposures results in the composite grating with the required opening ratio. A zoom-effect spherical beam projection system is suggested for producing binary gratings with continuously variable period.
13 citations
TL;DR: In this paper, an automatic dual reference beam method for the evaluation of holographic interferograms is presented based on the principle of image intensity subtraction, the method employs video electronic recording of the interograms and high speed digital image processing.
Abstract: An automatic dual reference beam method for the evaluation of holographic interferograms is presented. Based on the principle of image intensity subtraction, the method employs video electronic recording of the interograms and high speed digital image processing. Quantitative results are given for the bending of a cantilever.
12 citations
TL;DR: In this paper, a critical ray was excited along the glass surface by laser beam incidence, and part of the critical ray were refracted during propagation, and the angle of refraction depended on the refractive index of the glass face.
Abstract: A critical ray was excited along the glass surface by laser beam incidence. Part of the critical ray was refracted during propagation. The angle of refraction depended on the refractive index of the glass sirface. When the glass surface was birefringent due to the photoelastic effect, the angles of refraction differed from each other between two linearly polarized beams. This difference allows surface stress determination.
TL;DR: In this article, the use of laser microspectral analysis for the quantitative measurement of silicon and chromium, present in concentrations as low as 0.08% in mild steels, is investigated.
Abstract: The use of laser microspectral analysis for the quantitative measurement of silicon and chromium, present in concentrations as low as 0.08% in mild steels, is investigated. A comparison is made between the use of Q-switched and normal ruby laser operation, both spark assisted. Time integrated electron temperature measurements of iron plasmas and time resolved spectra of A1 plasmas are presented and used to determine if the ‘local thermodynamic equilibrium’ model applies to these laser initiated plasmas.
TL;DR: In this article, a method for obtaining a holographic image of desired magnification consistent with the stipulated criteria for its resolution and aberrations is described, and a new method is described.
Abstract: The article describes a new method for obtaining a holographic image of desired magnification, consistent with the stipulated criteria for its resolution and aberrations.
TL;DR: In this article, a high launched power, hermetic cw laser package with integral photodetector for feedback control, designed to meet the needs of the fibre optic market, is described.
Abstract: In recent years a large number of papers have been presented describing both the physics of semiconductor lasers and the design of fibre optic systems. The interface between these two areas of technology however has largely been ignored. This paper aims to describe a high launched power, hermetic cw laser package with integral photodetector for feedback control, designed to meet the needs of the fibre optic market. It is believed that this cw packaged device bridges the gap by providing the system designer with a component which can be incorporated with ease and confidence in his fibre optic system. The laser source is described with the design concepts of the package, its construction and performance.
TL;DR: Theoretical analysis of a pulsed CO2 laser beam aluminum target interaction demonstrates increased efficiency if the main laser pulse is preceded by a pulse of enough power to induce breakdown in air and create plasma in front of the metal target surface as mentioned in this paper.
Abstract: Theoretical analysis of a pulsed CO2 laser beam aluminum target interaction demonstrates increased efficiency if the main laser pulse is preceded by a pulse of enough power to induce breakdown in air and create plasma in front of the metal target surface.
TL;DR: In this paper, a laser Doppler velocimeter was designed to measure a small oscillatory velocity component superposed to the steady water flow of a resonant hydraulic circuit in fully developed turbulent conditions.
Abstract: Described is a laser Doppler velocimeter designed to measure a small oscillatory velocity component superposed to the steady water flow of a resonant hydraulic circuit in fully developed turbulent conditions. A frequency tracker with lock-in analysis of the velocity output is used. The rms amplitude of the oscillatory velocity component is measured with an accuracy of 1.5 mm s-1, and the mean velocity is about 3 ms-1. The resonance behaviour of the velocity amplitude measured at a fixed point of the circuit is reported for the exciting frequency range 2–5 Hz.
TL;DR: In this paper, a new primary laboratory measurement is described for testing field standards and measurement techniques used to detect trace amounts of toxic organic substances in water, and a new measurement technique is described.
Abstract: A new primary laboratory measurement is described for testing field standards and measurement techniques used to detect trace amounts of toxic organic substances in water.
TL;DR: In this paper, industrial and research uses of high power lasers are discussed, stressing the use of solid state and gas lasers for material processing, measuring magnetically confined plasma and creating localized plasmas.
Abstract: Industrial and research uses of high power lasers are discussed, stressing the use of solid state and gas lasers for material processing, measuring magnetically confined plasma and creating localized plasmas
TL;DR: In this article, the question of optimum ways to use such readings from P different spatial filters to assign the input image to one of N categories is asked, and all input distortions, rotations, etc.
Abstract: In space-variant optical pattern recognition there is a single reading which measures the correlation of the input image with the image to which a given spatial filter is matched. Here the question of optimum ways to use such readings from P different spatial filters to assign the input image to one of N categories is asked. No special relationship between P and N is necessary, and all input distortions, rotations, etc. can be taken into account.