Catadioptric optical element and optical system including same
AssigneeCanon Kabushiki Kaisha
InventorMasatsugu Nakano
Life of this patent
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Abstract
A catadioptric lens comprises, a first surface configured to introduce a ray within the catadioptric lens; and a second surface, with a reflective film, configured to reflect the introduced ray to the first surface; the second surface having a first reflection area and a second reflection area surrounded by the first reflection area, wherein the ray, which has been introduced from the first surface and has traveled to the first reflection area, is reflected on the first reflection area by total internal reflection, and the ray, which has been introduced from the first surface and has traveled to the second reflection area, is reflected by the reflective film.
Claims10
A catadioptric element comprising:
- a first surface on which a ray is incident;
- and
- a second surface opposite to the first surface,
- wherein the second surface has a first area in which a reflective film having a ring shape centered on an optical axis is formed, and a second area surrounding the first area,
- wherein the first area is an area on which a ray emitted from an object point on the optical axis and incident on the first surface is incident at an incident angle smaller than a critical angle, and the ray incident on the first area is reflected by the reflective film towards the first surface, and
- wherein the second area is an area on which a ray emitted from an object point on the optical axis and incident on the first surface is incident at an incidence angle greater than a critical angle, and the ray incident on the second area is totally reflected by the second surface towards the first surface by total internal reflection.
Dependencies are inferred from the claim text.