A method of fabricating a buried channel FET including providing a relaxed SiGe layer on a substrate, providing a channel layer on the relaxed SiGe layer, providing a SiGe cap layer on the channel layer, and ion implanting a dopant supply. A height measuring unit measures mirror heights when the distortion detecting mirror is tilted in directions of an X axis and a Y axis. The data of the job are processed using the processor according to the selected job mode to provide six separations corresponding to respective colorants.