RESEARCH TODAY, AND SOON TO BE EVERYDAY LIFE? LASER COMPONENTS BUILDS MIRRORS FOR THE WORLD’S MOST POWERFUL LASERS. WITH QUADRILLIONS OF WATTS, THEY GENERATE X-RAYS THAT MAKE CANCER VISIBLE – SOONER THAN EVER BEFORE.
New Diagnostic Precedure will Save Lives
To detect cancer cells even earlier, scientists on the CALA team are exploring new avenues in medical imaging. For this purpose, they are using ATLAS-3000, one of the most powerful lasers in the world: Its ultrashort pulses generate extremely high-energy X-ray light, which is comparable to the intensity of synchrotron radiation. Until it is bundled into a small dot, the laser beam passes through a maze of hundreds of laser optics, including mirrors from LASER COMPONENTS.
Cancer remains one of the leading causes of death. According to the World Health Organization (WHO), around 9.6 million people died from this disease worldwide in 2018 alone. Everybody knows somebody who has faced cancer. The fight against cancer has, therefore, long been an important area of medical research. Early detection plays a crucial role here because the sooner a potential tumor is discovered, the greater the chance of successfully combating it.
Lasers declare war on tumors
Lasers are providing important therapeutic services, especially when it comes to removing diseased tissue. Laser scalpels can make much more precise cuts than their mechanical counterparts; however, the focused light beams are particularly useful for microinvasive work inside the body. For example, they are used to literally vaporize individual cell layers.
Laser-based methods are not yet well established for the detection of tumors. It is possible to use Raman spectroscopy to distinguish healthy from degenerated tissue. However, a diagnosis on a patient would take several hours, and that is not something anyone can be expected to do. Researchers are currently working to speed up this process and have already made great progress. However, it will be some time before the technology is ready for everyday use in hospitals.
Quadrillions of watts for research
Scientists at the Centre of Advanced Laser Applications (CALA) in Garching near Munich are working on a completely different process: They aim to generate X-rays at an energy level that would normally require a particle accelerator. These beams can be used to make the smallest details visible, including cancer cells at a particularly early stage. They are using a high-energy laser as the energy source.
The 3000-terawatt advanced Ti:sapphire laser (ATLAS-3000) generates a laser beam at an energy of around 60 J for a few quadrillionths of a second. This may not seem like much at first glance, but because this energy is released in such an extremely short time, ATLAS achieves a power of several quadrillion watts. In a vacuum environment, this beam is focused on a small spot using more than a hundred mirrors and lenses. LASER COMPONENTS is one of the few manufacturers of laser optics that can meet the high demands of such projects.
The sun on a pin
»Imagine focusing all of the solar energy that reaches the Earth’s surface at any given time on the tip of a pin. That should give you a rough idea of what our laser optics have to withstand,« explains Barbara Herdt, head of laser optics.
The head of process development, Dr. Sina Malobabic, and her team faced several challenges when designing the mirrors for the ATLAS project: First, there was the large diameter of the laser beam. This requires optics of 200 mm to 300 mm. This is very large for laser optics, and absolutely flat substrates with such dimensions are rare.
Experts for long durability
A second challenge was the laser damage threshold. »Substrates are coated with a dielectric layer to optimally direct the laser beam, but even the best layer designs don’t last forever,« says Dr. Malobabic. »In ultrashort pulsed lasers like ATLAS-3000, they are destroyed primarily by nonlinear electronic effects such as so-called multiphoton ionization. This happens when molecules absorb multiple photons simultaneously, converting some of the absorbed energy into kinetic energy. Our task is to develop coatings that can withstand this particular stress for as long as possible.«
New machine for more homogeneity
»As the size of the substrate increases, so do the challenges in the coating process. For the first petawatt laser job, we actually purchased a new machine with an ion-assisted technology that was set up exactly according to our requirements,« reports Christian Grunert, production manager. »It is particularly important that the coating material be applied evenly across the entire surface because the vapor deposition beam is usually stronger in the center than at the edges. To compensate for this, people often use hemispherical substrate holders when bulk coating smaller optics. The optics at the edges are then closer to the material source than those in the center, so that in the end they all get the same amount of vapor. Of course, this is not possible for large flat surfaces. That’s when you need a special system.«
Six months for one mirror
»To meet all the requirements for ultrashort pulsed lasers, we have had to invest quite a bit,« Barbara Herdt recounts. »But our customer has ultimately always trusted us to deliver the perfect optics. Even now – a few years later – these mirrors are still a challenge for everyone involved. You can estimate six months for development and coordination alone. It can also take a year before being able to deliver the finished product.«
Miniature particle accelerator
CALA uses our optics to direct the beam of the ATLAS-3000 to the point of use. The beam is bundled only at the very end because otherwise this would stress the expensive deflection mirrors too much. Finally, the researchers unleash several quadrillions of watts on various particles. The laser then acts like a miniature version of a particle accelerator. Depending on which particles it hits, the scientists can produce different effects: High-energy electrons generate X-rays with unprecedented brilliance, which is used for imaging. In this way, a high image resolution is achieved that enables a detailed diagnosis of the soft tissue. Accelerated ions could be used to create new, affordable forms of therapy. Laser-induced ion beams, for example, could be used specifically to kill tumors. Until now, such projects have failed because of the amount of energy involved, but with the high-power laser, a new, considerably more powerful source is available.
Previously not even possible in dreams
When the first optics were coated at LASER COMPONENTS in 1986, petawatt lasers and high-power mirrors were still unthinkable. The triumphant advance of laser technology has since changed the world – and the company along with it. »There is hardly an area of life in which a laser is not used somewhere,« summarizes the general manager, Patrick Paul. »Accordingly, there are many different types of lasers today, and each of them places different demands on the components. That’s why we now have numerous different technologies in house. With this equipment, we work out the optimum solution for the customer’s application in close consultation with the customer. After forty years, this still makes our work as exciting and varied as it was in the early days of LASER COMPONENTS.«
Cancer detection with terawatt lasers is still a thing of the future, but today you encounter our products in hospitals every day.
»TO STAY ON TOP OF THINGS, WE ARE INVOLVED IN THE STANDARDS COMMITTEE AND REGULARLY PARTICIPATE IN THE WORLDWIDE DAMAGE THRESHOLDS COMPETITION.«
DR. LARS MECHOLD / Technical Director LASER COMPONENTS Germany
This is where the threads come together: As technical director, Dr. Mechold coordinates all development projects and production processes at LASER COMPONENTS Germany
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