Laser Ignition Device and Its Application to Forestry, Fire and Land Management

A laser ignition device for controlled burning of forest logging slash has been developed and successfully tested. The device, which uses a kilowatt class carbon dioxide laser, operates at distances of 50 to 1500 meters. Acquisition and focus control are achieved by the use of a laser rangefinder and acquisition telescope. Additional uses for the device include back burning, selected undergrowth removal, safe ignition of oil spills, and deicing. A truck mounted version will be operational by fall 1987 and an airborne version by summer 1988. A laser ignition device (LID), intended initially for the controlled burning of forest logging slash, has been developed and successfully tested, for this and a number of other applications. The device employs a kilowatt class carbon dioxide laser, the output of which is beam expanded and then focused to give a small, intense "spot" of heat at distances from approximately 50 to 1500 meters. Acquisition and precise focus control are achieved by the use of a laser rangefinder and acquisition telescope. The device is fully steerable, can be ground based, airborne, or mounted on seacraft. Initially, the device will be truck mounted and Presented at the Symposium on Wildland Fire 2000. April 27-30, 1987, South Lake Tahoe, California. University of Tasmania, Australia will be operational by fall 1987. An airborne version should be available by summer 1988. Many additional uses to that originally envisaged have been determined. These include back burning, spot lightings, fire break generation, selected undergrowth removal, tree stand spacing, pruning and trimming (e.g. near power lines), the safe ignition of oil spills and slicks, land management, and deicing applications, for example, of television towers, aircraft and airport runways, snow drifts. In summary, the device has an application wherever concentrated, localized, safe, at a distance, heat is required. "Spot" concentration diameters of a few centimeters are obtained, even at the greatest focal distance of 1500 meters. One major forestry application of the laser ignition device (LID) is the regeneration burning of "logging slash." Regeneration is the process by which the forest species harvested from a logging area (coupe) are replaced. To regenerate most forest types, or to establish new plantations, requires the use of hot fires set in fuels left on the ground after logging. The fires remove most of the fuel and prepare a suitable seed bed on which the new forest can be established. The controlled firing techniques aim to mimic nature's wildfire which originally produced much of the existing forests. Figure 1 shows a typical area ready for regeneration burning after logging, and Figure 2 shows an established regeneration burn. Many lighting techniques already exist. These include hand held drip-torches, aerial and electrical incendiary devices, and gun-operated incendiaries. All of these techniques have access or safety problems or both. In recent years there have been a significant number of