Abstract: An airborne the multi-spectral lidar instrument emits and/or detects radiation from target vegetation to assess the condition of the foliage. Time of flight analysis at multiple wavelengths permits three dimensional measurements to discriminate material at different heights, from ground to top of canopy. Radiation at 531 nm (emission and detection, vertically resolved) is used to measure de-epoxidation of the xanthophyll pigments (used for PRI), and also for stimulation of fluorescence. Radiation at 550 and/or 570 or 571 nm (emission and detection, vertically resolved) serves as a reference waveband unaffected by the de-epoxidation (used for PRI). Radiation at 690 and 740 nm (Detection only, no height resolution) or other lines for chlorophyll fluorescence, optionally using Fraunhofer/Oxygen wavelength windows and/or time gating to improve SNR. Wavelengths of 860 and 1200 nm, or similar (emission and detection, vertically resolved) are applied to measurement of water absorption and estimation of NDWI.