The mobile reference lidar POLIS measures at two elastic wavelengths – 355 nm and 532 nm  and their N₂-Raman shifted wavelengths – 387 nm and 607 nm, and linear depolarisation ratio at 532 nm and 355 nm. It can be easily moved to the user’s site to perform side-by-side intercomparison. It is the only reference lidar with depolarization at 355 nm.