Illumination device

An illumination device comprising:

• a coherent light source which emits a coherent light;
• an optical scan unit which is capable of changing an optical path of the coherent light from the coherent light source;
• an optical path adjustment element on which the coherent light from the optical scan unit is incident, an incidence position of the coherent light on the optical path adjustment element varying depending on the optical path determined by the optical scan unit, an emission angle of the coherent light of the optical path adjustment element varying depending on the incidence position;
• and
• a light diffusion element on which the coherent light from the optical path adjustment element is incident, the light diffusion element diffusing the coherent light and emitting diffused light, an emission angle of the diffused light varying depending on an incidence angle of the coherent light, wherein:
• the coherent light whose optical path is changed by the optical scan unit contains light components having wavelengths different from each other,
• a spectroscopic unit is provided between the optical path adjustment element and the light diffusion element,
• the coherent light from the optical path adjustment element is incident on the light diffusion element via the spectroscopic unit, and
• the spectroscopic unit spectrally disperses the coherent light from the optical path adjustment element into a plurality of light components having wavelengths different from each other and emits the plurality of light components towards the light diffusion element.