An ambidextrous vernier caliper includes a main ruler and a vernier having a slide channel in which the main ruler is inserted. The fan further includes a casing-inlet-port-side air passage and triangular prism shaped first inlet-port-sound-absorber air passage. The images include at least one first image containing the first line reflected off the first side of the sheet and the second line transmitted through the sheet and at least one second image containing the second line reflected off the second side of the sheet and the first line transmitted through the sheet. A determination is made whether the first confidence level meets or exceeds a first threshold. The housing is unitarily formed with a pump chamber of the oil pump and a body of the pressure adjusting mechanism. The rotor is mounted by way of at least one outer bearing that is arranged at a radial distance from the rotor shaft.