ILLUMINATION DEVICE AND PLANT GROWTH CONTROL METHOD

摘要

The invention provides an illumination device capable of reducing the number of members for controlling polarization and of irradiating light of a natural tone without reducing the energy efficiency of the light irradiation, and a plant growth control method using said illumination device. This illumination device is equipped with a light-emitting light source and a polarization-controlling member that controls the polarization of said light-emitting light source. The polarization of a wavelength zone comprising a portion of the wavelengths of the emitted light is changed to circularly polarized light. Of the irradiated light, the degree of circular polarization of light in the controlled wavelength band is 0.3 or more. Embodiments and the like in which at least one controlled wavelength bandwidth of said polarization-controlling member is 60 nm to 250 nm are preferable.