A machine for detecting sulfur hexafluoride (SF6) leaks using the mid-infrared differential absorption lidar (DIAL) technique with a commercically available, air-cooled, compact, pulsed transversely-excited-atmospheric (TEA) carbon dioxide (CO.sub.2) laser, a Cassegranian optical telescope for focusing both the laser emission and returning reflected signal, a user-operated focusing mechanism, a two-dimensional, thermoelectrically-cooled focal plane array (FPA) sensitive in the mid-infrared wavelength range (10.2-10.6 micrometers), a charge-coupled device (CCD) for 2-D imaging, a computer-based control system to rapidly switch the laser wavelength between 10.2470 micrometers, 10.7415 micrometers, and 10.5518 micrometers to utilize the Differential Absorption Lidar (DIAL) chemical detection technique, a rechargeable battery pack and power supply, and an image and data storage device using a solid-state memory stick.