title: High-spectral-resolution terahertz imaging with a quantum-cascade laser.
abstract: We report on a high-spectral-resolution terahertz imaging system operating with a multi-mode quantum-cascade laser (QCL), a fast scanning mirror, and a sensitive Ge:Ga detector. By tuning the frequency of the QCL, several spectra can be recorded in 1.5 s during the scan through a gas cell filled with methanol (CH3OH). These experiments yield information about the local absorption and the linewidth. Measurements with a faster frame rate of up to 3 Hz allow for the dynamic observation of CH3OH gas leaking from a terahertz-transparent tube into the evacuated cell. In addition to the relative absorption, the local pressure is mapped by exploiting the effect of pressure broadening.
authors.forename: Till
authors.initials: T
authors.lastname: Hagelschuer
authors.forename: Nick
authors.initials: N
authors.lastname: Rothbart
authors.forename: Heiko
authors.initials: H
authors.lastname: Richter
authors.forename: Martin
authors.initials: M
authors.lastname: Wienold
authors.forename: Lutz
authors.initials: L
authors.lastname: Schrottke
authors.forename: Holger T
authors.initials: HT
authors.lastname: Grahn
authors.forename: Heinz-Wilhelm
authors.initials: HW
authors.lastname: Hübers