Zürich: Multi-pass cell for high- and low-temperature spectroscopy

Licensing opportunity

Researchers at the ETH-Zürich, Switzerland, have developed a sensor that can measure gases and vapours at very high temparatures or very low temperatures. The device is now available for licensing.

Infrared spectroscopy is used to identify a substance present in a sample and to monitor its concentration. To measure hot gases or condensable vapours, a beam of infrared light is typically directed through a heated single-pass gas cell. Multi-pass cells, where the light is reflected back and forth a high number of times by mirrors before exiting the cell again, are two orders of magnitude more sensitive – but so far they have not been suitable for measurements involving cryogenic or high temperatures because of problems with condensation on the mirrors and with thermal expansion (which leads to optical misalignments).

The ETH multi-pass cell gets round these problems by heating the mirrors separately, and using continuous compensation for any thermal expansion. It can operate at temperatures up to 723 K, and at cryogenic temperatures as well. A patent on the device is currently pending.