Photon-counting dual-comb spectrometer (IMAGE) Max-Planck-Gesellschaft Caption Two mode-locked femtosecond laser beams of slightly different pulse repetition frequencies are superimposed with a beam splitter. One output is highly attenuated before passing through a sample and reaching a photon-counting detector. At power levels one billion times weaker than usually employed, the statistics of the detected photons carries the information about the sample with its possibly highly complex optical spectrum. Credit Nathalie Picqué Usage Restrictions Use of images is limited to editorial coverage of scientific topics relating to the activities of the Max Planck Society. Any kind of commercial use (including, in particular, the exploitation of images by means of sale or incorporation in image databases or image catalogues) as well as any promotional use/use for merchandise purposes, disclosure to third parties or granting of related rights to third parties is expressly not permitted. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.