Patent ID: 8148689

Claim:
An apparatus for detecting substances at a distance, the apparatus comprising: a mount structure; an emitter mounted to the mount structure and configured to be substantially collimated to illuminate on a target located at an unknown distance from the emitter, the emitter comprising a source configured to emit radiation and a mirror configured to direct the radiation toward targets located more than 10 yards from the emitter; a collector mounted to the mount structure and configured to be trained on the target at the same time the emitter illuminates the target, the collector configured to collect radiation from the direction of the target and concentrate the collected radiation on a sensor, the collected radiation comprising radiation reflected by the target as modified by interactions with any vapor adjacent the target; a detection system located on the same side of the target as the emitter and collector, the detection system comprising the sensor and a Michelson interferometer configured to produce an interferogram based at least in part on a signal from the sensor in response to the collected radiation, the detection system further configured to perform a Fourier transform on the interferogram to produce a spectrogram and analyze the spectrogram to determine presence or absence of a substance or plurality of substances in or around the target; wherein the emitter, collector, and detection system are grouped together on the same side of the target and thereby form a reflection-based analysis system configured to direct radiation toward—and collect reflected radiation from—targets located more than 10 yards from the emitter, thereby allowing the apparatus to detect a substance at or within vapor adjacent to the distant target without placing any equipment on the far side of the target from the reflection-based analysis system.