With lasers at ever higher power levels, and being used increasingly by non-photonics specialists, test equipment has to adapt to be accessible and user-friendly. Gemma Church looks at how laser testing equipment manufacturers are addressing this need
Lasers are popping up everywhere, but with a widening range of applications, an increasing number of people need to make sure the kit works within a range of safety standards.
Many users working with such laser testing and calibration equipment are not always photonics experts. Sean Bergman, product line manager of laser measurement and control at Coherent, says: ‘We are seeing this more and more, especially as the adoption of lasers into new fields expands. Within these applications a system integrator that builds a laser into a manufacturing or medical device is typically going to have photonics experts involved in the development. However, the end users of that equipment are often not photonics experts.’
And this seems to be the crux of the issue. As the application net for lasers expands, so does the number of users, which might lead to a non-specialist being faced with having to test sometimes quite complicated pieces of kit. Paul Tozer, managing director of Lasermet, says: ‘Percentage-wise, we would say that there is an increase. In terms of absolute numbers there are more non-experts involved, simply because there are more people involved in laser technology.’
Greg McKee, director of Light Metrology at Labsphere, agrees: ‘In emerging industries like solid state lighting, we are finding a larger number of non-specialists who need more of an introduction to integrating such technology.
‘Laser test and measurement is a blend of two distinct skill sets: optical and electrical engineering. This is a problem for end users who are not well versed in developing their own systems, or simply do not have the time to do so. One problem that has long been treated as a necessary evil is the lack of repeatability and reproducibility in laser testing.’
But the non-specialists are currently in the minority. Bergman adds: ‘I would estimate that the majority of our customers are knowledgeable about photonics, but an important and significant segment of our customer base is not so knowledgeable. We have adopted changes into our product design to make laser measurement more accessible to these people.’
Gary Wagner, president of Ophir-Spiricon, says: ‘As the uses of lasers increase, the knowledge has tended to be less and less critical depending on how the laser is used. Most users of test equipment are using it due to a regulation or requirement by their company or ISO compliance. Some of the users are obviously extremely knowledgeable, for example within research, universities and laser manufacturers. But some are not, for example maintenance teams, job shop users, and so on.’
So what changes can designers make to help non-specialists feel their way through the laser testing minefield? There are a number of challenges faced by such companies when developing laser testing and/or calibration products. Bergman notes: ‘In terms of power and energy measurement products, the challenge is making a product versatile enough to meet the needs of a very diverse universe of lasers and laser applications, yet simple enough for the end users of those applications to use.’
Modern test equipment, such as this device from Coherent, needs to be simple to operate to cope with a user base with a broad range of abilities.
And, as the lasers are required to run at increasingly higher powers, this throws up further problems. McKee says: ‘In the past year, there has been a continued increase in application and manufacture of high-power industrial lasers. This growth emphasises the need for continuing improvements in optical power measurements of these systems and devices. Inaccurate measurements can cause an acceptable device to be graded incorrectly or rejected, effectively reducing production yield or forcing companies to increase the window of acceptance.’
Complexity, too, can pose problems for less laser-savvy users. Mike Mason, VP of technology at Powerlase, says: ‘The difficulty is that our lasers are very complex. In order to get the best performance from them they need to be used in the right way. Once they have been set up they are relatively straightforward to operate, but that setup phase is tricky and requires close cooperation between ourselves and the customer. A non-specialist would be able to operate the laser on a daily basis, but not be able to perform the initial set up or diagnose any applications problems.’
So what does a non-photonics specialist user do when faced with the flashing lights of a new laser and list of standards to which it must comply? Echoing the words of author Douglas Adams, Lasermet’s Tozer says: ‘Don’t panic. What we find is that a lot of people will initially think in terms of carrying out their own optical safety assessment of the product. Then they look at the standard, realise it is highly complex, and panic. That’s when they call us. Sometimes, of course, they don’t call us and try to do it themselves, and many people make a mess of it. Often, we’ll see the end result of this when a wrongly-classified product is sent to us for testing, because someone has picked up the problem or is simply questioning it.’
Lasermet is a different beast from the companies that produce laser testing and calibration equipment. It tests and certifies laser products to the relevant standards, and recently opened up a new calibration lab in the UK for the testing of laser and LED products to the relevant laser safety standards.
Essentially, such testing work consists of measuring the optical output of the equipment under specific conditions, calculating the desired classification limit and comparing the two answers. Tozer adds: ‘However, choosing the correct measurement conditions and carrying out the calculations correctly can be complex, particularly for non-point sources such as LEDs and stacked laser diodes. In addition, measurements need to be carried out under reasonably foreseeable single fault conditions, which often mean assessing the drive electronics and simulating failure modes. All of this makes the work suited to a specialist test house like Lasermet.’
But for those users without the option of farming out their testing equipment to a separate facility, there is still hope. The manufacturers are aware that testing equipment needs to be easy to use for all. Bergman says: ‘We also do not want to have too many overlapping products on the market, so many of our products need to serve many applications and many different types of users. We address this by optimising our meter front panels and graphical user interface in such a way as to make basic operation very intuitive, while also providing features and capabilities important to more advanced users that might be available in advanced setup screens, for example.’
Manufacturers also need to produce clear documentation as well as an easy-to-understand design. Bergman adds: ‘Making a product easier to use is a combination of understanding the needs of your customers and then modifying the design and documentation. In some cases, individuals in these situations might be looking for a very simple way of measuring the power output of their laser, so we have devices available that are simple to use without extra features like on-board data analysis. Alternatively, our new higher end LabMax meter has the most common measurement tasks (measure, tune, and trend) directly accessible via large buttons on the front panel of the meter. We have also incorporated quick start guides into our user manuals, and provide installable PC applications software on CD. These types of features and ergonomic designs have become much more important in the laser measurement business in recent years.’
Ophir-Spricon is also improving its kit to be more user-friendly and providing more means for users to train themselves up. Wagner says: ‘Typically you will design products with limited features to address the specific low-tech market you are trying to reach. This can be from a single readout on a power/energy meter to a basic picture of the laser beam or single spectrum readout of the wavelength – the simpler the better in many cases. One of the most critical aspects is a quick tutorial on basic uses. Secondly, one needs a top notch customer service department that is both patient and knowledgeable to be able to step new users through an application. Having application notes and web tutorials also helps in this training.’
But there is no substitute for sitting down with a user and taking them through the kit. Powerlase’s Mason says: ‘A number of customers have used our lasers to replace non-laser applications, but they are usually laser-savvy enough to know roughly what they want from the system. We usually work closely with the customer to make sure he gets the functionality he needs for his particular application. We try to make the laser as user-friendly as we can by giving the customer exactly the type of interface he requires. The user manuals are useful, but there is no substitute for the customer being trained in how to use the laser either at the time of install, or by visiting us.’
Ophir’s laser beam profiling equipment offers ease of use.
But will users ever have a piece of laser testing kit that is 100 per cent foolproof? Don’t hold your breath. Bergman says: ‘That would mean a laser measurement device would have to be so robust that it will measure the laser correctly, no matter how the user operates it. In the end, there are lots of laser wavelengths so a user has to be able to set that up in the device, because laser light reflects off surfaces differently depending upon the wavelength.’
Bergman adds: ‘Many beams are not visible to the eye, so the user has to make sure the beam is completely on the sensor, otherwise the measurement will be off. So, no, 100 per cent foolproof seems unrealistic. But we do our best to make our devices easier to use by addressing these types of setup requirements by making coatings that vary less and less across the laser spectrum, and by creating sensors that can show the position of the beam on the sensor, for example.’
Wagner notes: ‘Like any tool, lasers cannot predict how you will use them – nor can the manufacturer simulate every application. Nothing is 100 per cent foolproof.’
It all depends on the piece of kit being used. Mason adds: ‘Some pieces of equipment, for example a laser power meter, are hard to use incorrectly (although quite possible). Some pieces of equipment, such as for measuring beam quality, are very easy to set up incorrectly and make a bad measurement. We don’t usually perform these types of tests in the field, just as part of the setup and qualification process at Powerlase.’
Leave it to the experts
But is there ever a danger that, when making a piece of testing equipment easy to use, this could reduce the safety of the system? Wagner warns that education is the key to making sure accidents do not happen: ‘Special care is taken to educate users on the use of test equipment. It is critical that all laser and photonics users get the proper education.’
Bergman maintains that safety is paramount. He says: ‘Making a measurement device easier to use does not make it more dangerous. In our experience, the most common result of making a mistake during a laser measurement is that the accuracy might be off. Typically if someone is running into problems like this they will call us and we will walk them through the process of making a correct laser measurement. Often the problem has to do with a wavelength set-up problem or some other setting that was forgotten. Worst case, for example when measuring a high power kW laser, a customer could damage the sensor coating if the laser power is too high, which could damage the sensor itself. But these are not safety issues.’
Powerlase’s Mason believes education is the key to a safer laser user. ‘We would never sacrifice safety for ease of use,’ he says. ‘Customers usually have a more relaxed attitude to laser safety than we do. This is usually due to a lack of understanding of the hazards involved. We try to educate them during system install.’
And Bergman too cites safety training as being the most important aspect within any laser testing environment. He adds: ‘This, of course, assumes a person understands how to be around and operate their laser safely in the first place. A person always requires laser safety training if they are going to operate lasers. This is even more important if they are going to operate it outside of safety enclosures. We always remind people at the beginning of our user manuals that the use and measurement of lasers is potentially dangerous. Proper laser operating practice in accordance with manufacturer recommendations is vital.’
But the message from the manufacturers seems to be clear: within laser testing there cannot be any non-specialists. Even users inexperienced within the world of photonics need a basic level of training to make sure that they are using the testing equipment correctly. Even once such training is received, a mass of documentation and help should be available to make sure any user has the information required to test and calibrate lasers accurately and, most importantly, safely.