In order to evaluate the quality of a given quantum cascade laser, the DiaMonTech laboratory conducts detailed measurements on all of them to answer the following questions:
- What does the laser beam profile look like?
- What is the output power of the laser?
- How divergent is the beam?
- What is the pulse repetition rate?
- What is the pulse-to-pulse stability and shape of the pulse?
- How large is the focal spot on the skin?
In the company's early days, the team relied on the knifeedge technique for laser measurement to obtain the beam profiles. But because the number of measuring points required is large, it takes several hours to measure a laser beam this way. Had the company applied this method in the development of its new, compact blood glucose meter, it would have lost a lot of time – and still, the results would not have been precise enough. After in-depth research and conducting an array of tests in their own laboratories, the experts decided on the Ophir Pyrocam-III-HR-C-A-PRO. Using this high-resolution pyroelectric matrix camera, the beam profile of an infrared laser can be measured both quickly and reliably. For the application at DiaMonTech, the camera was individually calibrated to the appropriate signal level. The camera data is then evaluated with the BeamGage software. Output power, beam profile and beam divergence can be determined by the camera in just a few seconds. Sergius Janik explains: "The Ophir Pyrocam is our key measuring device for characterizing the laser beam, and we use it every day. We use it not only for developing new prototypes, but also for quality assessment and troubleshooting. As necessary, we also make the Pyrocam available to our development partners, so they can make precise and reliable adjustments."
Sergius Janik describes a concrete application as an example of the enormous time savings achieved by the Pyrocam. During a series of tests conducted by the DiaMonTech lab on a new laser, the engineers were unable to focus the beam. The power distribution of the beam was very irregular, but the cause was not obvious at first glance.