An object of the present invention is to provide a manufacturing method by which alumina-silica based fibers excellent in mechanical strength can be readily and securely obtained, and the present invention obtains precursor fibers as a material by using an alumina-silica based fiber spinning stock solution for use in an inorganic salt method. In its simplest form, the HPU comprises a Transformer, inverter means, rectifier means, a control unit, connection means to the HEV and external electrical loads or sources and switching means to change operation between charger and generator function. An electrical connection mechanism is provided to connect the semiconductor package to the support plate pass. Furthermore, an optical path can be refracted by 90 degrees with respect to the height direction just above the object to be measured, by means of the parallel prism.