a correction effective region 21 indicated by the dotted line coincides with the optical axis 10 aberration correction is performed for the aberration of the return light 92 with a spatial shift resulting in improper aberration correction consequently the return light 92 is not properly focused at the pinhole 41 and hence the brightness or resolution of a retinal image is not improved this phenomenon applies to the positional relationship between the pupil 122 and the illumination light 90 to which a reverse component of aberration is given by the deformable mirror 2 that is the illumination light 90 is not focused into a desired spot diameter on the retina 121 in addition if the effective diameter of the overall optical system is equal to the diameter of the illumination light 90 and the correction effective region 21 of the deformable mirror 2 is equal to the effective diameter of the optical system the return light 91 passes outside the effective diameter of the optical system the light then strikes outside the correction effective region on the deformable mirror 2 resulting in improper wavefront correction in addition since the optical conjugate relationship pupil imaging relationship between the pupil 122 the deformable mirror.