Homogeneous Optical Illumination Profiles
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Illumination spots with a square spatial intensity distribution and a relatively large area are generated in the focal plane F of a facette lens 2 from a collimated optical beam 1 with a variable spatial intensity profile (Fig. 1). The plane facettes of lens 2 are arranged on circles with radii R1 (Fig. 2) and have an angle of inclination a which is such that the partial beams, generated by the facettes, are superimposed on each other in the focal plane to yield the desired intensity distribution. For a thin facette lens, having a thickness x that is small with respect to its focal length fn, the inclination a is ai = R1 / (n-1) where n is the index of refraction. If three circles of facettes are used, nineteen partial beams are superimposed upon one another.