New lidar family member at MIM – POLIS1064

"POLIS9" - the combination of the new POLIS1064 (left) and POLIS6 (right). Their data recorder, power supply and control laptop in the background. The laser of POLIS1064 can be seen mounted below the 300 mm telescope.

We are happy to announce that our lidar family got a new member! Our POLIS6, a 6-channel portable lidar system for 355nm and 532nm, got a sibling. The new POLIS1064 (see Figure, left side) completes the three common aerosol remote sensing wavelengths with 1064nm depolarisation and rotational Raman channels. Together they are now "POLIS9" for the 9 measurement channels in total. All together they are an extended ACTRIS aerosol remote sensing reference lidar (ACTRIS project at MIM, ACTRIS aerosol remote sensing,).

The quality of aerosol optical products retrieved from lidar measurements mainly depend on the performance of the measuring lidar systems. In this sense POLIS9 as a high quality reference lidar system allows to transfer quality control of POLIS9 to other aerosol remote sensing lidars in ACTRIS via comparison measurements. The basic idea behind the new lidar, developed together with and built by the Greek company Raymetrics SA, is a simple setup with only one polarizing beam splitter cube and two subsequent partially reflective mirrors for the rotational Raman channel and the alignment camera. This way performance characterisation is easy and highly reliable. In the Figure below a schematic of the optical analyser is depicted.

Another inovative technological aspect of the new system are new prototype photon detectors, so called avalanche photodiodes (APDs), designed and manufactured by Licel GmbH in Berlin. The goal of these prototypes is to overcome problems of currently existing APDs for lidars. This new APD features lower electronic background noise, lower susceptibility to interspersions from surrounding electromagnetic noise sources and thus a highly stable system. After the first year of testing, including a first comparison campaign in Garmisch-Partenkirchen in October and November 2025, the measurements confirm a remarkable performance of the new system. We looking are forward to future campaigns with our growing lidar family.