Abstract: A triacetone triperoxide cloud associated with a triacetone triperoxide explosive attached to a hard target is remotely detected by operating differential-absorption lidar lasers to transmit a laser beam toward the hard target at differing wavelengths. A backscattered laser beam reflected from the lidar target (hard target, person, aerosols, clouds, buildings) is detected because a cloud of triacetone triperoxide in front of the lidar target and between the lidar target and the differential-absorption lidar system produces a differential-absorption signal having characteristics that identify the triacetone triperoxide. In a second embodiment, a triacetone triperoxide cloud that is absorbing optical radiation from its ambient environment and which is attached to a hard target is detected from a location remote from the triacetone triperoxide explosive by detecting an optical radiation absorption signature characterized by triacetone triperoxide absorption lines.

Abstract: The system and method in accordance with the present invention provides a non-contact detection and location of acoustic sources, which will be useful for locating signaling humans and will assist in the structural analysis of damaged building based upon structural movement. In accordance an embodiment of the present invention is provided a multi-beam, non-contact, laser vibrometer adapted to locate, via triangulation, an acoustic source buried underground.

Abstract: An open-path optical communication system has either optical or laser sources and communicates between the source and a detector. In a first embodiment, the laser source includes a gas cell in the laser cavity to regulate laser wavelengths based on the minimum absorption between spectral lines of the gas in the cell. The laser is tuned close to a minimum absorption wavelength and the minimum absorption line locks the laser wavelength to the minimum position. In a second embodiment, the strong absorption lines of a gas in a gas cell positioned at a receiver site are used to provide channel isolation of the receiver. In a third embodiment, an atmospheric gas provides the channel isolation. In the fourth embodiment, individual wavelength channels are positioned between the absorption lines of atmospheric or non-atmospheric gases to prevent cross-talk between adjacent channels.