| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of detecting a beam row, by which the result of detection can be determined instantaneously and the intervals of beam spots can be specified accurately. SOLUTION: A multi-beam drawing device has a light source 1, a beam expander 2, a diffraction branch element 3, a convergent lens 4, a relay optical system 5, a multi-channel modulator 6, a collimator lens 7, a polygon mirror 8, an fθlens 9 and a drawing surface 10. When the beam row is detected, a phase filter 20 dividing the cross section of luminous flux L into four fan-shaped areas and imparting the optical path difference of a half wave between the adjacent areas is arranged between the beam expander 2 and the diffraction branch element 3. When the phase filter 20 is arranged in an optical path, luminous fluxes mutually cancel and the intensity reaches zero in sections corresponding to the boundary sections of the areas, and cross-shaped dark lines are formed because optical path difference having a similar figure to the areas of the phase filter 20 is generated even in the beam spot on the drawing surface 10. |
