What is Spectral sensitivity in Lidar and Photogrammetry

The wavelength of visible light varies from 0.4 to 0.7 micrometers, wavelengths slightly shorter than 0.4 are ultraviolet and that slightly longer than 0.7 called Near –infrared which cannot be detected by human eyes. The visible length composes of primary colors Blue, Green, and Red. All the other hues are combinations of the above.