Abstract: In representative embodiments, a system includes an acoustic emitter, a controller, an optical sensor, and an indicator for indicating a detection of a predetermined trace chemical vapor by the optical sensor. The acoustic emitter is positioned at a predetermined distance above the ground surface and configured to project a beam of acoustic energy toward the ground surface with a variable angle of incidence ?. The controller is configured to control the acoustic emitter to vary the angle of incidence of the acoustic beam within the variable angle of incidence ?, while the optical sensor is configured for standoff sensing of a trace chemical vapor proximate the ground surface. Excitation of the ground surface, particularly at a critical angle of incidence ?, causes the release of trace chemical vapors from a buried source and the soil into the air above the buried source.

Abstract: An apparatus comprising a vibration generation system, a vibration measurement system, and an optical system associated with the vibration measurement system, and a controller. The vibration generation system is configured to generate acoustic energy that causes vibrations to occur in the ground. The vibration measurement system is configured to transmit laser beams to the surface of the ground in which the vibrations occur, receive responses to the laser beams, and generate vibration data from the responses. The optical system is configured to direct the laser beams to the surface of the ground such that the laser beams have a selected spatial arrangement relative to the surface. The controller is configured to determine whether an object is present under the surface of the ground using the vibration data.

Abstract: In representative embodiments, a system includes an acoustic emitter, a controller, an optical sensor, and an indicator for indicating a detection of a predetermined trace chemical vapor by the optical sensor. The acoustic emitter is positioned at a predetermined distance above the ground surface and configured to project a beam of acoustic energy toward the ground surface with a variable angle of incidence ?. The controller is configured to control the acoustic emitter to vary the angle of incidence of the acoustic beam within the variable angle of incidence ?, while the optical sensor is configured for standoff sensing of a trace chemical vapor proximate the ground surface. Excitation of the ground surface, particularly at a critical angle of incidence ?, causes the release of trace chemical vapors from a buried source and the soil into the air above the buried source.