A photosynthesis illumination system, including: a curved ray directing element, such as a lens, for directing an illumination beam towards at least one plant； a motor for rotating the ray directing element, for selecting different locations of the at least one plant to be illuminated by the illumination beam； motorized optical focusing means, for adjusting for each of the locations an area size, thereby determining a portion of the at least one plant to be illuminated； and a controller, for controlling the motor and the motorized optical focusing means, to provide an equal illumination energy to each area unit of the at least one plant.
