In an international cooperation with partners from industry and research, physicists from the University of Vienna, together with Thorlabs, the National Institute of Standards and Technology (NIST), and the University of Kansas, have now succeeded for the first time in demonstrating high-performance laser mirrors in the sensing-relevant mid-infrared wavelength range that absorb less than ten out of a million photons. Manufactured in a new process based on crystalline materials, these low-loss mirrors promise to open up completely new application areas, for example in optical respiratory gas analysis for early cancer detection or the detection of greenhouse gases. This work will be published in the current issue of the journal Optica.