A method for forming a patterns includes applying ink onto an etching object layer; forming ink patterns on the etching object layer as a printing roll having convex patterns thereon rotates on the ink and removes portions of the ink which contact the convex portions of the printing roll, thereby forming ink patterns; and hardening the ink patterns. The supporting surface of the profiled rails is provided with a track of punched holes, and the bottom plate can be attached by means of at least one joining element, which can be inserted in a hole in the track of punched holes and which damages the inside wall of the hole, thereby producing a positive locking. An angle adjustment mechanism is provided for adjusting a mounting angle of the light source unit relative to the base member, so that respective pitches of beam spots, formed on a scanned surface by the light beams, in the direction perpendicular to the main scanning direction are variable in accordance with the mounting angle adjustment. The lead wire projects from a surface of the board, and is bent close to the surface. A projecting wall is provided on the moving surface at a position before the unlocking position in a range where the ball moves from the locking position to the unlocking position. A slurry preparation apparatus for a CMP apparatus comprises a tank for preparing the slurry, a stock solution feeder for the slurry which feeds a stock solution for the slurry into the tank, and a concentration measurement instrument located outside the tank, which is capable of measuring an additive concentration in the slurry in the tank.