Patent ID: 8755040

Claim:
An illuminating apparatus, comprising: a light source configured to generate coherent light; a rotating phase plate in which a plurality of step regions is arranged randomly and has a height equal to or less than a wavelength of the light, and configured to change a phase of a light beam from the light source by allowing the light beam to pass therethrough; and a fly's eye lens in which a plurality of lenses is arranged like an array and configured to allow the light beam having passed through the rotating phase plate to pass, wherein a portion in which a product of a maximum size of the plurality of step regions and an optical magnification from the rotating phase plate to a plane of incidence of the fly's eye lens is equal to or less than an arrangement pitch of the plurality of lenses, a portion in which the product is larger than the arrangement pitch of the plurality of lenses are mixed, the maximum size of the plurality of step regions is a maximum width size on a surface of each step region perpendicular to a direction of an optical axis and the surface of each step region is formed in a same shape.