An encoder includes a rotor including: a shaft and a code disk attached to the shaft; a stator including a scanning unit configured to generate an electrical signal corresponding to an angular position of the code disk; a cable configured to transfer the electrical signal; and a cover overmolded onto the stator, where the scanning unit is sealed from an outer environment by the cover. By utilizing such charging mode control circuit and method, a secondary battery fixed in a portable device can be quickly charged when the portable device communicate with an external computer. It is possible to prevent the separation of the liquid, which is disposed between a lower surface of a projection optical system and a substrate surface, from the lower surface of the projection optical system in accordance with the relative movement of the projection optical system and the substrate. The above described first layer is a semiconductor layer and the above described second layer is a metal layer. In one aspect of the invention, the sensor includes a light source such as an LED that imparts light through an aperture at the underside of the mirror surface. The disclosure describes decomposing a high-dimensional feature space into one or more low-dimensional feature spaces according to minimum dependence.