IRsweep’s IRcell is a multipass cell for optical trace gas sensing. It consists of a single, circular mirror on the wall of the cell, which makes the cell less affected by mechanical stresses such as vibration or temperature changes. It also enables a compact setup: a 4 m pathlength can be achieved in a volume of 30 mL. The IRcell is targeted at applications requiring an optical pathlength between 1 m and 5 m.