Laser used in stomach ulcer test. A carbon dioxide laser emits pink fluorescence during the analysis of a patient's breath sample, testing for stomach ulcers caused by bacteria. It is a Laser Assisted Ratio Analyzer (LARA). It determines the ratio of carbon-12 to carbon-13 in a carbon dioxide sample. The patient with suspected stomach ulcer is given urea enriched with non-radioactive carbon-13. The bacteria Helicobacter pylori, a cause of ulcers, breaks down urea to produce carbon dioxide (CO2). Half an hour after ingesting urea, the patient breathes into a sample tube, and this CO2 laser analyses the gas for raised CO2 (carbon-13) levels which confirms the diagnosis of stomach ulcer.