Patent ID: 7859761

Claim:
An illumination system, comprising: a coherent light source for providing a light beam; and a speckle-reducing module, disposed in an optical path of the light beam, the speckle-reducing module comprising: a rotator for rotating on a reference plane about a spindle axis passing through the rotator, wherein the spindle axis is substantially perpendicular to the reference plane; a carrier, disposed on the rotator and capable of being rotated by the rotator; a reflecting member, disposed on the carrier and in the optical path of the light beam and capable of being rotated by the carrier, wherein the reflecting member is rotated about the spindle axis passing through the rotator, and the reflecting member has a reflecting surface inclined at an angle with respect to the reference plane; a first optical plate disposed on the reflecting member and in the optical path of the light beam, wherein the first optical plate is used for reflecting a portion of the light beam and making another portion of the light beam pass therethrough; and a second optical plate disposed at a distance from the first optical plate and in the optical path of the light beam, and the second optical plate is used for reflecting a portion of the light beam and making another portion of the light beam pass through.