BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of an optical device according to a first aspect of the present invention;
FIGS. 2A and 2B show aberration graphs of the astigmatism and distortion;
FIG. 3 is a sectional view of an optical device according to a second aspect of the present invention;
FIGS. 4A and 4B show aberration graphs of the astigmatism and distortion according to the second embodiment;
FIGS. 5A and 5B show aberration graphs of the astigmatism and distortion according to the third embodiment;
FIGS. 6A and 6B show aberration graphs of the astigmatism and distortion according to the fourth embodiment;
FIGS. 7A and 7B show aberration graphs of the astigmatism and distortion according to the fifth embodiment;
FIGS. 8A and 8B show aberration graphs of the astigmatism and distortion according to the sixth embodiment;
FIGS. 9A and 9B show aberration graphs of the astigmatism and distortion according to the seventh embodiment;
FIGS. 10A and 10B show aberration graphs of the astigmatism and distortion according to the eighth embodiment;
FIGS. 11A and 11B show aberration graphs of the astigmatism and distortion according to the ninth embodiment;
FIG. 12 is a sectional view of the related art;
FIG. 13 is a sectional view of the related art; and
FIG. 14 is a sectional view of the related art.