The plant growth based on the scanning laser beam is newly developed. Three semiconductor lasers with three primary
colors, i.e., blue, green and red are used. Here, the laser scanned position is restricted only to the plant leaves, where the
light illumination is needed. The feedback system based on the perspective projection is developed. The system consists
of the automatic position correction from the camera image. The automatic image extraction of the leaf parts is also
introduced. The electric power needed for this system is as small as 6.25% compared with the traditional white
fluorescent lamp. Furthermore, experimental results show that the red-color laser light is particularly efficient for the
growth of the radish sprouts.