| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that an imaging optical system with a simple configuration having no complicated internal mechanism cannot increase in coma aberration and field curvature due to variation of an object position.SOLUTION: The imaging optical system has an image surface having a spherical surface shape with an emission pupil as a center. In the imaging optical system, an angle formed by an incident main light beam and an optical axis, a focal distance of the optical system, a distance between the emission pupil and an image, and a height of the image surface substantially satisfy a predetermined relational expression for suppressing variation of a field curvature due to movement of an object distance, and the emission pupil and the main plane in the rear side substantially match with each other. |
