Tessella Support Services plc

High energy challenges

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Courtesy of Tessella Support Services plc

The UK’s Central Laser Facility (CLF), part of the Science and Technology Facilities Council (STFC), has recently developed an advanced high-powered laser, created to help research and development in the scientific community. CLF was tasked with developing a laser system for the HiLASE research facility, and Tessella (an international analytics and data science consulting services company) joined the project to create and build bespoke software to enable control of the laser. Through innovative design techniques the resulting product has all the capabilities of a high-powered laser, while also possessing a high repetition rate which is not typically found in such high energy systems.

The new laser technology for HiLASE, a project in the Czech Republic tagged ‘New lasers for industry and research’, will benefit industry and science in areas ranging from welding to testing the resistance of optical materials. The set-up will provide a laser capability significantly more powerful, efficient and stable than current systems across Europe.

Pan European Networks asked David Michel, a software engineer at Tessella, about the inherent challenges of creating a novel high energy laser which also has a significantly higher repetition rate than its predecessors.

Could you explain how the laser developed in the project differs from the other lasers and techniques typically used?

Typically, high energy lasers are pulsed lasers – they produce a pulse of light at given intervals, usually half an hour or an hour apart. These pulses, whilst low in repetition, are high in energy. Conversely, lasers which shoot a pulse at very short intervals – multiple times a second – are very low energy. This new laser technology CLF has bridges that gap to create one which combines both high energy and high repetition rate.

How was this made possible?

Quite simply, it was a result of the necessary technology evolving to the desired level. The technology CLF used here is based on pumped laser diodes; it is a solid state laser as opposed to the old technology which tends to be based on flash lamps.

You were specifically involved in the software side of the project. Were there unique challenges involved in this novel laser?

One of the main challenges was a result of increasing the repetition rate up to approximately 10Htz, (ten times a second), which meant that a lot of data is generated in every shot. The challenge thus concerned ensuring that the software system was able to cope with this huge amount of data that is being generated ten times a second.

There are also a lot of devices involved here too. Indeed, the system is, for instance, some 20-25 metres long with hundreds of pieces of equipment involved, such as about 50 high resolution cameras, dozens of motors to move the mirrors used to steer the beam into alignment, the oscilloscopes, the vacuum and cryo-cooling systems, shutters and filters, and so on, and all of these elements need to be controlled. Cameras of course generate quite a lot of data if they are high resolution, and at ten times a second these various elements have to be co-ordinated. From a software point of view, this presented a significant challenge.

What, then, were the hurdles involved in enabling the different parts of the system to communicate with each other, and why is this important?

One of the aims of the laser was to incorporate some kind of machine safety, which means being able to stop the laser as soon as there is a problem. When this concerns a laser that fires a shot every hour then this can be relatively easy to achieve because there is time between shots to check everything is fine, to (re)align it, and make the necessary diagnostics. At ten times a second, however, there is not enough time for a human to be able to make sure everything is OK. As such, things need to be automated, and that, of course, requires software.

For example, some of the cameras look at the laser beam and provide diagnostics on how it is performing (e.g. whether it has the right shape or edges, etc.), and so there are numerous automation rules required. That is, if the camera detects a problem, whatever that may be, the laser will have to be stopped, or the amplification will have to be stopped, or the shutter will have to be closed depending on the issue, in order to bring it back into safe operation mode.

The need for this high level of automation stems, again, from the fact that the repetition rate is so much higher than in any of the high-powered lasers that have come before it. For lasers that are low energy but have a high repetition rate, there is much less need for this – if the need is there at all – because the low energy levels mean that not much damage will be done if things go wrong. With high energy levels, this capability therefore becomes much more important.

Alongside the issue of machine safety, were you involved in any of the human safety elements?

This issue was the responsibility of a separate interlock group in the project that was designed specifically for that purpose. This included things such as microswitches on the doors which detected when they were opened and, if triggered, made the room safe.

How would you say initiatives such as this help to raise the profile of British expertise?

The project has clearly raised the profile of British science and has certainly promoted UK capabilities by demonstrating how academic research taking place in the public sector is able to successfully develop a new technology and, furthermore, is able to go on to build it for researchers working in other countries – such as here in the Czech Republic – whilst also working closely with industry partners both within and without the UK in order to make this a reality. The project was a huge success, and another of these lasers is now being developed for the European XFEL in Hamburg.

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