Recent developments

Recent developments

Recent developments Biocular Systems Conference in USA lasers in order to study chemical A special meeting is to be held in the USA on May 24th and ...

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Recent

developments

Biocular Systems Conference in USA lasers in order to study chemical A special meeting is to be held in the USA on May 24th and 25th on the design and evaluation of biocular optical systems intended for visual use. The meeting is jointly organised by the Optical Society of America and the Vision Committee of the National Academy of Sciences. When the use of biocular viewing systems is becoming widespread in such applications as head-up displays for aircraft and virtual-image displays for visual simulators, there exists very little useful data that allows optimization of such systems during the design or engineering stages. Basic data, such as the allowable aberration levels in a biocular visual system is missing from the literature. Parameters which must be taken into account include eye relief, field angle and dioptric image shift across the aperture. The purpose of this meeting is to explore all sides of the subject of visual biocular systems.

satisfactory. The LD Gauge is being manufactured in two sizes, to cover material diameter ranges between 5-38 mm and 10-75mm respectively, and there are two basic types: Type A for indication only; Type B for control. Models are available to measure either American Optical Corporation, one diameter or two right-angle Sou thbridge, Massachusetts 01550, diameters simultaneously, and include USA such features as bar-temperature compensation, automatic rejection of Rocket-borne fibre optics loose particles of scale smaller than Hawker Siddeley Dynamics have taken the minimum diameter to be measured, simple checking of calibration and delivery of some special bifurcated fibre optic bundles to enable a rocket- repeatability using ground samples, and born 16mm cine-camera to look at automatic reset to zero at the end of different parts of the rocket's structure each bar. during flight. Sunbury Glass Works A first order for the new instrument constructed the fibre optics and has just been received from the British P.W. Allen & Co provided the engineerSteel Corporation, and several other ing expertise in visual inspection. orders, from both the UK and abroad, P. W. Allen & Company, 253 Liverpool are expected to be placed very shortly. processes in the near UV. The 20ns 50MW UV pulse is generated by converting the IR output of a Q-switched glass laser to its fourth harmonic using a KDP and an ADP crystal.

Road, London N1 1NA

In-line, non-contact gauge for bar and rod mills

All abstracts and summaries must be sent to the Optical Society of America, Biocular Optics Meeting, 2100 Pennsylvania Avenue, N.W. Washington, D.C. 20037, before February 28th, 1972.

Davy and United have introduced an in-line, non-contact, rod-diameter gauge which is claimed to maintain performance despite rod vibration. The instrument has a digital read-out.

Papers invited so far include contributions by Thomas Brennan of Baird Atomic who will talk about biocular viewing as applied to direct view night vision systems, and Michael Freeman of Pilkington Perkin-Elmer who will present a paper on Optical design and evaluation methods. Other items on the programme are stereoscopic vision (Alfred Lit, Illinois University: Donald E. Mitchell, Dalhousie University; J. Pettigrew, California University) and rear vision from cars (W. Lewis Hyde, New York University).

A prototype (Fig. 1) was tested under field condition in BSC laboratories and on production mills, and proved itself

4

Optics and Laser Technology

Pattern recognition technique NASA have announced a new pattern recognition technique for detecting out-of-register patterns. This relies on determining the probability density function of intersection lengths of random lines with a given pattern.

Technology Utilisation Officer, NASA Pasadena Office, 4800 Oak Grove Drive Pasadena, Calif 91103, USA

Photomultiplier sensitivity enhancement The problem of increasing the light absorbed by photomultipliers having semitransparent photocathodes has been solved in NASA laboratories by reducing the light lines caused by transmission and reflection. This has been achieved by optically coupling a small prism to the piano-piano end window and thereby causing the light to have a high incident angle so that total internal reflection occurs at both the photocathode-vacuum and window-interfaces.

Glass laser orders Sandia Laboratories, Albuquerque have just ordered a 100J glass laser from AOC which has a 30ns output pulse of very narrow beam divergence. It uses a Q-switched oscillator with two amplifiers and has a folded design. A 1J 0.265/am glass laser was recently delivered by AOC to the University of California for use in pumping dye

Davy and United Instruments Ltd, Darnall Works, SheffieM 9, UK

Fig.

1 Prototype laser non-contact gauge on trial at a high-speed rod-mill

February 1972

Technology Utilisation Officer, Ames Research Centre, Moffett Field, Calif 94035, USA

Double pulse holography Double pulse holograms can now be generated by a new improved version of the Apollo Lasers' model 22H ruby laser (Fig. 2). Pulse separations can be varied from 1ms to arbitarily long intervals, and coherence lengths of

over 1m assure high quality holograms of extended sources. It uses digital timing to attain precise synchronisation with experimental events and in TEMoo output is attained with a single oscillator.

Apollo Lasers Inc, 6365 Airzona Code, Los Angeles, California 90045, USA

the laser thus permitting the laser light to propagate away from the area where it is generated in the semiconductor. At room temperature, the tiny transistor-size device converts up to 20% of incoming electric current directly into 3 million pulses per second of infrared light which is an information rate comparable to that for TV.

RCA Semiconductor Devices Laboratory, PHnceton, New Jersey 08540, USA

Review of Soviet holography In the November 1971 issue of Soviet Science Review, Yuri Ostrovsky reviews the theory, practice and applications of holography with special reference to the approach initiated by Y. Denisyuk in 1962.

Fig. 2 System for double pulse holography

Southampton research projects halted by fire In the early hours of Wednesday, 24th November 1971, fire swept through one of the main laser laboratories of The Electronics Department at Southampton University, UK, totally destroying experimental rigs, workshops and offices. Estimates of the value of equipment lost approach £100,000. Most severely affected is a Science Research Council programme on the development of tunable infrared lasers. This laser would have found important applications in fields such as pollution monitoring. In the three months immediately preceding the fire, two new types of infrared device had been successfully operated for the first time: an 'optical parametric oscillator' and a 'down-converter'; both used proustite (Ag3 AsS3 ), a 'non-linear' crystal grown at the Royal Radar Establishment, as the vital component. Limited tuning had been attained for three regions in the range 2-13/am and work was continuing with a view to covering the complete wavelength range.

within two to three months, but that it may take a year before the group regains its world-ranking position. The other important area of laser research at Southampton concerns the application of glass fibres to optical communications; Professor W.A. Gambling directs this work. Apparatus built for another Science Research Council project, to study the propagation of ultrashort light pulses along fibres, was very severely damaged by the fire. The equipment for the rest of the optical fibre work was fortunately housed in a separate building, but research records were destroyed. Laboratory space has been found for all major projects and generous offers are being received from many quarters for the loan of equipment and the necessary items.

Department of Electronics, The University, HighfieM, Southampton S09 5NH, UK

Possible use for laser in CCTV

By doubling the output efficiency of semiconductor lasers at high peak Experiments involving other non-linear powers, RCA scientists consider they have come a step closer to using crystals must also be started again. The leader of the programme, Dr R.C. Smith, lasers in CCTV and communication systems generally. They have achieved Reader in Electronics, believes that at this by placing an optical cavity within least one device will be operational

6

Optics and Laser Technology

February1972

Yuri Ostrovsky is senior worker at the A.F. Joffe Physico-Technical Institute of the Academy of Sciences of the USSR, and university lecturer in the physics faculty of the Mining Institute. He is the author of more than 50 papers, of 12 inventions, and of the book 'Holography' (Nauka Publishing House, 1970) and co-author, with A. Zaydel and G. Ostrovskaya, of the book 'Techniques and practice in spectroscopy' (Nauka Publishing House, 1972).

Soviet Science Review, Vol 2, No 6 (November 19 71) pp 351-358. (Obtainable from IPC Science and Technology Press Ltd, IPC House, 32 High Street, Guildford, Surrey, UK}

Laser anemometer An advanced laser anemometry system has been developed jointly by DISA and AERE Harwell and will be' marketed by DISA of Harrow, Middlesex. The use of an optical Doppler shift technique enables the system to measure and analyse fluid velocities (particularly turbulent) without disturbing the flow. High accuracy in a linear output is obtained with velocities ranging from cms -~ to 100 ms'L The response time for continuous measurement of a rapidly varying velocity is very short and the spatial resolution is about 0.1mm.

DISA, 116 College Road, Harrow, Middlesex, UK

Laser interferometer for transducer calibration The Metrology Calibration Section of the AQD Laboratories have developed a laser interferometer to calibrate linear displacement transducers and extensometers to a high degree of accuracy. A helium-neon laser is used and the reference and moving fringes are projected side by side on to a screen adjacent to the displacement micrometer drum (Fig. 3). Transducers with movements up to 2.5ram can be accommodated with a calibration accuracy of better than 3 x 10-s mm.

Moving reflectinq

Optical f l a t (mounted I,

Reference reflecting

)

Collimo

Metrology Calibration Section, A QD Laboratories, Harefield, Uxbridge, Middlesex, UK

erence fringes

Polarimetric refractometer The refractive index of a liquid is now being measured to a high degree of accuracy by a method under development at NPL using polarised light techniques. It uses well-proven polarimetric instrumentation (Fig. 4) and is suitable for automatic recording of the results. Two quartz wedges Q~ and Q2 are of left-handed and right handed material respectively and cemented to glass wedges G of matching refractive index. The relative thickness of quartz traversed by the beam in the two wedges is determined by the angle at which it leaves the sample wedge C and hence the refractive index of the liquid. The azimuth of the emergent polarised vibration is then measured by a Faraday effect polarimeter, F, to determine the liquid's refractive index. The relationship is substantially linear and measurement sensitivity and full scale range can be easily varied by changes the wedge separation. Precision of measurement is typically 2 x 10-s for a range of 0.05.

Department of Trade and Industry, National Physical Laboratory, Teddington, Middlesex, UK

Holographic service Jodon Engineering Associates are now offering an holographic applications service in a well-equipped vibration and dust-free laboratory. Laser repairs are also undertaken.

Jodon EngineeringAssociates, A G, Untermoosenstrasse 10, CH-8820 Wadenswil-Zurieh, Switzerland 8

Optics and Laser Technology

Fig. 3 Transdu

Glass wedge G

G

Collimated

Sample liquid

q

i i

-ll monoc~omo bc beam

F

P Q-1 O.a Polorlser Ouartz wedge

LI

= I

'

I

/ F.

I . . . . . . . . . . .

/

Farodoy effect pol~Orimeter

Fig. 4 Optical layout of polarimetric refractometer

Optical system senses voltages A new kind of optical voltage sensor has been developed from a ferroelectric ceramic at Sandia Laboratories. As the sensing element of an optical voltmeter, the device can be designed with full scale voltage ranges from 50 V 5kV and has essentially infinite input resistance. The accuracy is 2% of fsd and the response time is 0.5ms. A visible light beam is guided to and from the sensor via flexible optical fibres and the sensor occupies only about lcm 3.

Public Information Division, Sandia Laboratories, Albuquerque, New Mexico 87115, USA

Ion beam shaping of optical surfaces A new accelerator from Edwards High Vacuum is being used at the National Physical Laboratory to sputtermachine optical materials. The aim is

February1972

to produce a more precise and controllable shaping technique than is used at present, especially where complex surface shapes are required.

Central Research Laboratory, Edwards High Vacuum International, Manor Royal Crawley, Sussex, UK.

Optical retroreflector An NPL-designed optical retroreflector is described as being relatively precise, bearing in mind the simplicity of manufacture and adjustment. Incoming light is collected by an objective lens which focusses it on to a mirror in front of which is placed a field lens which increases the collection of offaxis light. By etching a reticule pattern on the mirror, the system permits measurement of rotational speed of objects to which it is attached.

Department of Trade and Industry, National Physical Laboratory, Teddington, Middlesex, UK

Compact C02 laser A new 450 W CO2 laser recently developed by Ferranti Ltd is only one third the length of a comparable laser of conventional design because of its multi-fold construction (Fig. 5). The first medel (Fig. 6) has been installed in the Rotherham works of Plascut Ltd who will be using it for shapecutting fine gauge metals, plastics and other materials requiring a finer cutting efficiency. Because of the twelve folds in the laser's resonator tube, the complete head is contained in a housing 1½ metres in length by ½ metre square and weighs only 54.4kg.

Ferranti Ltd, Ferry Road, Edblburgh EH5 2XS, Scotland

Fig. 5 Multi-fold construction of CO2 laser

Novel ro:tary motion for vacuum chambers A new patented method of achieving rotary motion is high vacuum chambers which have been developed by Electrotech Associates using the linear induction motor principle. This obviates the need for a drive to be transmitted into the chamber and offers overall savings in initial cost and maintenance.

Electrotech Associates, A bervan, Sou th Wales, UK

Increased efficiency laser welder A more flexible and efficient laser welder/driller, the A0 LWD/103 is announced by AOC. The unit has continuous pulse length and energy adjustment, built-in energy monitoring, digital read out, adjustable spot size and automatic lens protection.

10

Optics and LaserTechnology

i ka~

Fig. 7

Liquid laser awarded recognition

processing and in photochemistry, and as a scanned laser display or a high intensity spectroscopy source.

Light modulators

Kodak Limited, PO Box 66, Kodak House, Station Road, Hemel Hempstead, lterts, UK

Hadron Inc has recently introduced the Series 1100 of single and multichannel light modulators intended for use with collimated, plane polarized, coherent light. Their frequency response is from d.c. to 100 MHz, and they may be used for pulse modulation and carrier modulation as well as at audio frequencies. Temperature compensation is featured and operating wavelengths may be specified from the UV to the near IR. Collimated light with beam diameters up to 0.1 in may be passed through the length of the modulator and multiband versions are available on request.

Hadron hTc, 800 Shames Drive, Westbury, New York 11590, USA

The development of a liquid laser by Eastman Kodak was judged as one of the 100 most significant new products of 1971 by the American magazine 'Industrial Research'.

at Plascut Ltd

w~

American Optical Corporation, Southbridge, Mass 01550, USA

Liquid laser award

Fig. 6 C02 laser in operation

,# • '

The development was the first continuous wave dye laser capable of wide range tunable operation in the visible spectrum. The continuous dye laser has useful applications in communications systems, in optical data

February 1972

g measured by laser interfero-

meter A laboratory model of an absolute gravimeter laser allowed NASA workers to correct the Potsdam values by about 138 ~tms-2. The device is basically a Michelson laser beam interferometer in which one arm is a mass fitted with a corner cube reflector which is allowed to fall freely under gravity in a vacuum.

National Technical Information Service, Springfield, Virginia 22151, USA

Elimination of noise diffraction patterns The Goddard Space Flight Centre has reported that noise diffraction patterns formed in the images of coherent optical systems, can be eliminated by rotating the lenses about their optical axes. The energy diffracted by dust or bubbles in or on the lenses, whilst normally spread over a very small area of the image is now spread over a much larger annular area.

Technology Utilisation Officer, Goddard Space Flight Centre, Greenbelt, Maryland 20771, USA

Measuring output of CO2 laser

Low ripple gas laser

Automatic optometer

A microwave biased photoconductive detector has been used to measure the output of a CO2 laser at 10.6/am with a factor of 103 improvement sensitivity.

The new A0-45 American Optical industrialgas laser is claimed to have extremely low voltage ripple and precision current regulation. This 400 W CO2 laser also features 300 W TEMoo power, 2.0 kW pulsed power and up to 5 kHz pulse rate. It has the advantage of needing no warm-up time, and its chief uses are in paper slitting/trimming, drilling plastics and cutting of non-metals.

An optometer has been developed by NASA scientists to automatically monitor the refractive strength of the human eye to help in accommodation and response studies. An infrared test pattern is imaged on to the retina and the focus of the eye at any instant is determined by the adjustment needed to maintain focus of the pattern on the retina.

Technology Utilisation Officer, Goddard Space Flight Center, Greenbelt, Maryland 20 771, USA

High resolution IR viewers The Electrophysics Corporation announces a range of infrared viewers which use image converters with resolutions as high as 72 line-pairs mm -t and above. An extended spectral response gives a sensitivity of 0.6 to 0.75 mA W-~ at 1.06/am compared with 0.4 mA W-~ for a typical SI spectral response.

American Optical Corporation, Southbridge, Mass 01550, USA

Technology Utilisation Office, Ames Research Centre, Moffett Field, Calif94035, USA

Electrophysics Corporation, 48 Spruce Street, Nutley, New Jersey 07110, USA

Nitrogen laser system A ½W average power output at 3371A was announced by Avco for its new model C500 pulsed nitrogen laser system. It has a pulse repetition rate of 5-500 pulses per second and a peak power of 1OO kW and includes a number of safety features including pressure and temperature sensors.

Everett Research Laboratory, 2385 Renere Beach Parkway, Everett, Mass" 02149, USA

Tubular filter glass An ultraviolet transmitting, heat absorbing glass has been produced in tubular form up to 1 in diameter by Corning Glass Works. Designated 4601, it will be particularly useful as a filter in xenon arc systems designed to simulate daylight.

Cornhzg Glass International, SA, 1 Cumberland House, Kensington Court, London W8

Laser vibration analyser NASA engineers are using a laserpowered, Doppler phase-shift system to measure the vibration of a structure without the need to attach any sensors. A Bragg cell and beam-splitting system is used, and vibration frequencies from 1 to 0.5 MHz have been required with displacements from 1.27 cm peak to peak down to about 10-4 microns.

National Technical hTformation Service, Springfield, Virginia 22151, USA 12

Optics and Laser Technology

Fig. 8

Dr Dennis Gabor, FRS, stands beside a hologram of himself, which was illuminated by a 50mW He-Ne laser available from Jodon Engineering Associates, AG.

Gabor wins 1971 Nobel prize for physics Dr Dennis Gabor has been awarded the 1971 Nobel Prize for Physics. The announcement was made by the Nobel Prize Committee meeting in Stockholm, Sweden. Dr Gabor, who is known internationally as the 'father of holography', was honoured for his invention, 24 years ago, of the lensless photographic technique of producing three-dimensional objects by lightwave interference patterns on to a glass plate. Holography has since become a too] for use in industry, science and government, and has found practical applications in such areas as co]our television and medicine.

Dr Gabor worked out the mathematical basis for holography when he discovered how to reconstruct objects from their lightwave interference patterns. He constructed the first hologram in 1948, which he named after the Greek word 'holos' meaning whole. Dr Gabor has also been responsible for numerous mathematical contributions to the advancement of communications and colour television. He holds many patents in these fields.

February 1972

A native of Budapest, Hungary, Dr Gabor studies in Budapest and Berlin, where he acquired his doctorate. He is the recipient of numerous scientific honours, including the 1968 Michelson Medal for scientific achievement from the Franklin Institute; the 1968 International Christopher Columbus Prize for communication theory; the Rumford Medal in 1969 from the Royal Society (London) for outstanding scientific contributions to optics and the discovery of holography; and the 1970 Medal of Honor from the Institute of Electrical and Electronics Engineers (IEEE) for exceptional contributions to science and technology. Dr Gabor also received the Semmelweis Medal in 1970 for his outstanding contributions to humanity. He is a Fellow of the Royal Society, the Institute of Physics and the IEEE, and a Commander of the British Empire, CBE. His book on human social problems has been translated into seven languages, and Dr Gabor has also completed a book entitled 'Innovations', published by Oxford University Press of London. It is an assessment of science and technology, and presents Dr Gabor's views on the future of scientific endeavour.