An apparatus and method for correcting for the polarization mode distortion of an optical signal is described. It is thus made possible to increase the stacking space, thereby increasing the number of stackable sheets and to achieve the alignment of the rear end of the sheet bundle with a simple configuration, thereby improving the stacking-aligning property of the sheet bundle on the stacking tray. The processing circuitry may select one of the return energy-ranked vectors for generation of a clutter-orthogonal transmit waveform. The protein which is delivered and expressed in vivo is more effective than protein which is injected into the animal. Another wafer scanning operation to find the true defects is subsequently conducted by scanning the region outside the dont care region.