In a line type inkjet printer, a method for cleaning a nozzle effectively reducing the occurrence of clogging of nozzle. The image forming apparatus includes: the image forming target unit; a first projector; a second projector; a first planoconvex lens; and a second planoconvex lens. Second, a tip of a scanning probe microscope is disposed in proximity to the surface of the substrate. A spacer connects between a printer circuit board and mirror element to permit sufficient movement of the mirror surface.