Patent ID: 6178028
Filing Date: 2001-01-23
Classification: G02B,G03F

Abstract:
A multibeam scanning exposure device that forms a plurality of scanning beam spots on a photosensitive medium, comprising:a light source that emits a light beam;a multiple beam splitting element provided with a diffractive grating that divides said light beam from said light source into a plurality of beams, said diffractive grating having a corrugated surface with a plurality of periodical phase patterns arranged in parallel at a predetermined fixed pitch, said multiple beam splitting element dividing a single beam into an odd number of beams, each periodical phase pattern having a shape that causes a non-linear phase difference to said light beam passing therethrough within one pitch, adjacent phase patterns being connected without phase gaps at boundaries therebetween;a deflector that deflects exist beams from said multiple beam splitting element; anda scanning lens that converges said deflected beams onto said photosensitive medium to form a plurality of scanning beam spot, wherein each periodical phase pattern of said plurality of periodical phase patterns is formed such that a phase difference .delta. at a coordinate Coord. falls within an allowable range around a center value indicated in a table below when a width of said periodical phase pattern is divided into 64 coordinates, andwherein said diffractive grating divides said incident beam into nine beams:Coord. .delta. Coord. .delta. Coord. .delta. 0 0.00000 22 6.29969 43 5.74883 1 0.08727 23 6.42061 44 5.37594 2 0.28157 24 6.45338 45 5.03895 3 0.58121 25 6.40383 46 4.77212 4 0.94548 26 6.26897 47 4.54875 5 1.28199 27 6.04448 48 4.33621 6 1.55363 28 5.77626 49 4.09535 7 1.77708 29 5.53539 50 3.78851 8 1.98986 30 5.37669 51 3.38602 9 2.22728 31 5.29971 52 2.93113 10 2.53102 32 5.29971 53 2.53102 11 2.93113 33 5.37669 54 2.22728 12 3.38602 34 5.53539 55 1.98986 13 3.78851 35 5.77626 56 1.77708 14 4.09535 36 6.04448 57 1.55363 15 4.33621 37 6.26897 58 1.28199 16 4.54875 38 6.40383 59 0.94548 17 4.77212 39 6.45338 60 0.58121 18 5.03895 40 6.42061 61 0.28157 19 5.37594 41 6.29969 62 0.08727 20 5.74883 42 6.07744 63 0.00000 21 6.07744 .