A filtration apparatus includes a tank having an upper chamber and a lower baffle, layers of stone and carbon between the upper chamber and the lower baffle, a water inlet to the upper chamber, and a water outlet below the lower baffle. The system includes a first integrated circuit including input pins, output pins, normal operating logic, and control logic. The air brush is constructed by detachably and threadedly connecting a cap member to a rear section of an air brush body in such a manner that the cap member covers an adjusting screw and a rear portion of the needle. An engagement protruding piece that engages with each engagement notch is provided at both side end portions of the back foil on one side in the circumferential direction of the bearing housing. Accordingly, it is possible to form an aperture approximately in a circular shape, so that the light emitting angle and shape of the VCSEL are easily controlled. Register error is determined by computing the lateral and circumferential distance between marks printed by a print cylinder and a master print cylinder.