Patent ID: 7474685

Claim:
A differential absorption light detection and ranging (DIAL) system comprising: a plurality of laser sources, each tunable to emit a beam of light; at least one tuning controller for real time tuning and locking of each beam of light to a predetermined wavelength having a spectral line-width, wherein each beam of light is tunable during real time operation of the DIAL system; a beam combiner for combining each beam of light to form a combined beam of light having multiple wavelengths; a transmitter for transmitting the combined beam of light toward the at least one target; a receiver for receiving light returning from the at least one target and converting returned light having multiple wavelengths to digital signals; and a processor for analyzing the digitized signals to identify the at least one target based on its multi-dimensional spectral characteristics; wherein the plurality of laser sources includes N lasers, N being an integer equal to or greater than 4, M of the lasers are each tuned to a wavelength that is partially absorbed by the target, M being an integer equal to or greater than 2, L of the lasers are tuned to a wavelength that is absorption-free of the target, L being an integer equal to or greater than 2, N is equal to M+L, and the N lasers are tuned to N different wavelengths for detecting the at least one target characterized by M different partially absorbed spectral lines, and L different spectral absorption-free lines; and the beam combiner comprising a mask, a focusing lens, a spatial filter and a collimator lens, arranged in spatial sequence, wherein the mask includes multiple apertures symmetrically arranged about a central point on the mask, each aperture configured to pass a respective beam of light at a predetermined wavelength, the focusing lens is configured to focus the beams of light transmitted from the multiple apertures, the spatial filter includes a central aperture, which is disposed symmetrically about the central point and is configured to transmit the beams of light toward the collimator lens, and the collimator lens is configured to receive diverging beams of light from the central aperture and combine the diverging beams of light into parallel beams of light.