A diagnosis apparatus is disclosed that is able to promote productivity of a diagnosis of the target program which may be for an image forming apparatus such as a printer, a copier, or a fax. Oxide is formed over a substrate, and first material is formed over the oxide. The lasers can be phase shifted DFBs for high single-mode yield. A combined output signal is provided at an output of the combiner. A gate insulating layer is formed on the first semiconductor layer and the substrate. Detent torque of the stepping motor is reduced either by reducing a cross-sectional area of a portion, which leads to a magnetic pole surface 51a of the stator yoke, to be less than an area of the magnetic pole surface 51a, or by disposing an intermediate magnetic substance 9 which is magnetically independent of the stator yokes 5a and 5b on both sides thereof.