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Photonics: The key to life in the 21st century


"The more you know about it, the more you can make it work for you"

Written by The Welsh Opto-electronics Forum

This article will give you a taste of the technology that now affects everyone’s life, and is becoming increasingly important in the 21st century. The 19th century is often seen as the golden age of steam, the 20th century an incredible advancement in electronics; whilst the 21st century is set to be age of photonics or light. This article will also give you an insight into careers that make use of this technology.

WHAT ARE PHOTONICS and OPTO-ELECTRONICS?

Photonics and Opto-electronics are often used interchangeably. However, photonics is concerned with thegeneration (e.g. lasers), control (e.g. optics) and the detection (e.g. photo-multipliers) of light. Opto-electronics is the innovative combination of optics and electronics hardware to produce an exciting new range of products. This technology is powerful because it enables many new technical systems to work effectively. It includes any combination of light or images that works with electronics and can be as simple as the red light emitting diode (LED) that shows you that the TV is on, or as complex as the Hubble telescope in space.

WORLD LEADERS

Wales has many companies working in this area and several of them are recognised as world leaders in the technology. The work can be exciting; to stay in this position the companies need to use state of the art technology in design, manufacturing and testing. Two examples where this can be found are in military systems and in space

Try this experiment: look out of the window, then look back at this text for long enough for your eyes to re-focus and the words to become clear, then look out of the window and refocus your eyes again. How long did this take? 1 second? 2 seconds? When a pilot is flying a fighter aircraft at the speed of sound he cannot spend this amount of time looking away from the target, so the information from the critical instruments is displayed on a special glass panel in front of him, imaged so that his eyes do not have to change focus to read it. To do this well needs very good optical design, high-precision manufacture and advanced technology in holography and optical coatings....and Wales leads the world in this technology, with two companies in North Wales supplying to UK, USA and other Air Forces

On TV you will have seen satellites in space with large solar panels attached. These convert the sunlight directly into electricity, and the material to make solar cells for some of these satellites is made in South Wales. Space is a harsh environment for these electronic materials, and if unprotected the electrical output would fade away in about 18 months - which would mean no satellite TV programmes. To prevent this, greater than 50% of the satellites put up by the western world have their solar cells protected by an extremely thin piece of special glass made in North Wales.

OPTO-ELECTRONICS IN THE HOME

Without realising it, you are using opto-electronics throughout the day; look around for these examples, and imagine how modern life would be without them

Displays. How many displays of numbers that glow red or green do you have in your house? They are to be found on the alarm clock, the TV and video recorder, the microwave cooker and some ovens. There are even more liquid crystal displays which look black on grey; you will find them on watches, calculators, telephones, portable radios, tape and CD players and office machines such as faxes and copiers. Most laptop computers have liquid crystal displays and those in colour include other optoelectronic technology as well. Large flat screen TVs that you can hang on the wall are now available, and the price will soon be down to prices a home can afford.

Communications. When you make a phone call outside your local area you are almost certain to be using an optical fibre link with a laser sending the message down the fibre, and a detector receiving it at the other end. About 70% of the UK trunk lines are now optical fibre, and the rate at which optical fibre is being installed world wide now exceeds Mach 1! Optical fibre can carry far more information than copper wire and is the best way to link computers, outside broadcast TV cameras, Banks, Stock Exchange dealing rooms, etc. Again, in North Wales we have world class companies who make the fibre, the cables, and the electronics and control systems to go with it.

Cameras. Camcorders and Digital still cameras depend on a high quality multi- component optical lens, often with zoom capability - which needs an advanced computer programme to design. The picture is imaged onto an electronic detector with a regular array of extremely small picture elements (pixels). There can be more than 1000 x 1000 of these on an area the size of your thumbnail.

Entertainment. To control your TV you use a controller that sends a coded infra-red beam to the set. This light is detected at the set and converted to the control information. Your CD player uses a laser diode which is imaged onto the surface of the disc by a tiny precision lens made of plastic. Did you see the images of the football players projected onto the Arc de Triomphe after the World Cup final?. This was done using optoelectronic devices - lasers where the beam is switched on and off to create the image as it scans back and forth.

Manufacturing. Lasers are being used more and more for cutting and welding as the beam covers a small area, and can be directed by computer exactly where it is required. Most clothes made in large quantity for High Street stores have been cut to shape using a laser. The gears in your family car have probably been welded to the shaft using a laser. Also, the symbols all over the dashboard that show you (in the dark) where the heater controls are located, have been produced using a different type of laser to remove the black overcoat from a coloured, light transmitting piece of plastic to reveal the symbols.

Energy. The effect of sunlight on various materials, generating a voltage and flow of electrons, give rise to enormous possibilities in generating electricity with no CO2 production. The material most commonly used is silicon. Sharp the world leader in the manufacture of solar cells has its factory in North Wales, supplying 200MW for the European market! At the Technium OpTIC in North Wales the south facing part of the building is covered with 1000m2 of photovoltaic cells (solar cells). This can achieve up to 95kW peak on good days of strong sunshine in summer. However, it will also work on dull days and during the winter months.

IS OPTO-ELECTRONICS HARD TO UNDERSTAND?

Yes and No! If you are a research worker developing a new blue laser for use in the next generation of computer discs, you will be using skills that require more than a University degree, but the great importance of opto-electronics is that it finds many applications in life where what it does is important, and it is not necessary for the user to appreciate completely how it does it. After all, you can make good use of a TV controller without knowing what optics or electronics are inside it, or being able to design one.

But it does help to have some knowledge of the basic concepts, as this will help you to get the best out of the equipment - if you know that light has to come out of the red window on the controller you won’t cover it with your finger.

There are several different types of lasers and they are critical to many optoelectronic applications. What is a laser and how does it differ from a light bulb? There are two main differences; the light from a bulb is produced continuously from a white hot wire; it contains light of all colours and is emitted in all directions. A laser emits light of one colour (or light frequency), in a controlled way in one direction only and because of this high intensities can be achieved. Light can be emitted continuously or in a short burst. The latter gives a high power output over that very short time.

One way of understanding this difference in the way light is emitted is to compare it to sound. Imagine the River Dance group was on a stage and walking around in any direction they liked. The sound would be approximately continuous (but not very loud) and all frequencies are present as there is no control of the time when their feet touch the floor - this is like the light bulb. When they dance in time together, the sound of each footstep is much louder, and the beats come at a regular frequency - this is like the laser. If they all jump in the air and come down at the same time the sound is loudest, and this is like the pulse of the laser. In the laser, special mirrors at each end ensure that all the light comes out in one direction only.

WHAT OPPORTUNITIES ARE THERE FOR CAREERS USING OPTO-ELECTRONICS?

Because it finds application in so many fields, careers that need an understanding of opto-electronics are numerous: doctors use lasers for surgery as do civil engineers for surveying; biochemists use the detection of light emission to monitor the effectiveness of anti-cancer drugs, and even supermarket managers rely on the everyday bar code scanner used for controlling their stock. In depth examples follow.

Knowledge and understanding of opto-electronics comes from studying subjects like Maths, Physics, Chemistry and of course, Technology; studying at GCSE level will introduce you to opto-electronics, and you could go into a lot of depth by choosing an opto-electronics theme for your major project in Technology. Beyond 16, choosing apprenticeships, traineeships, or ‘A’ Levels can all lead to careers with opto-electronics companies in North Wales and beyond. Many employees have studied at Degree level, and they are now influencing the technologies we use everyday, both now and in the future.

CAREERS INVOLVING OPTO-ELECTRONICS

Careers using opto-electronics are for people with a wide range of skills and knowledge at different levels, and include the manufacture of components, design, assembly and testing of systems, technical sales and fundamental research. Some examples of occupations and their use of opto-electronics are:-

Biological Researcher and Technician - uses microscopes with video camera attachment so that images of samples can be enhanced by computer to bring out information not normally visible. By chemically attaching firefly-like molecules to drugs, and by measuring the weak light emitted after treatment, it is possible to measure how effectively they target cancer cells using sensitive opto-electronics.

Civil Engineer - uses a laser beam with a theodelite to create a straight line over long distances to measure the angle of a proposed road bridge from a reference position.

Autofocus camera lens designer - is part of a team who use computer programmes to design the lens, the sensors and electronics to measure the sharpness of the image to control the focus, and CAD (Computer Aided Design) to design the components and housings. Such components may be made with machines which depend on optoelectronic equipment to achieve the required accuracy.

Heating Engineer - uses a Thermal Imaging camera to give a high quality picture showing the temperature distribution across a scene, which enables them to measure heat loss from a poorly insulated factory or the discharge of hot effluent into a river.

Communications System Installer - couples optical fibres to electronic systems to route the information between computers, monitors etc. or to control a production machine.

Conservation Specialist - uses laser beams to blast away the grime that has built up on buildings and statues with less damage than other abrasive techniques.

Environmental Inspector - uses a laser beam projected into the smoke plume from a factory to monitor the levels of the different gases emitted to see if they are within permitted limits.

Quality Control Inspector - uses apparatus which measures the precise colour spectrum of the food product so that e.g. bad beans can be automatically rejected . Sorting of produce of different sizes into bins can be done using the dimensions of the video image.

Surgeon - uses a slip-on device over the patients thumb which monitors an infra-red beam to continuously measure the pulse rate. Also, inserts a fibre optic endoscope into the patient with a camera attached, and when the defect has been located cuts it away with a laser beam which is transmitted down the fibre optic.

Skilled Machinist - uses various types of laser beam under computer control e.g. to cut holes finer than a human hair, treat or decorate the metal surface, or join components together in a vacuum where there is negligible contamination of the weld.