The DF laser's capabilities for monitoring natural gas and petroleum products in pipeline areas are considered. The absorption coefficients of methane, ethane, and propane were determine experimentally for 11 spectral lines in the 3.55- 3.75 micrometers range of the DF laser output. The criteria were formulated for selecting analytic and reference lines suitable for measuring atmospheric hydrocarbons by means of the differential absorption technique. Combinations of analytic and reference lines were chosen according to these criteria. The laboratory mock-up of hydrocarbon analyzer implemented around a DF laser was tested.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.