Title:
FOCUS DETECTING OPTICAL SYSTEM
Document Type and Number:
WIPO Patent Application WO/2013/183320
Kind Code:
A1
Abstract:
The purpose of the present invention is to obtain a focus detecting optical system for which focus detection error generated by differences in light source color temperature is sufficiently small.
This focus detecting optical system is provided with: a condenser lens disposed behind an expected image plane for an imaging lens; a separator mask disposed behind the condenser lens and having at least one pair of openings; a separator lens disposed behind the separator mask and having at least one pair of lenses facing the at least one pair of openings of the separator mask; and a photoelectric conversion element disposed behind the separator lens. The focus detecting optical system has a phase difference detection method in which a subject image on the expected image plane for the imaging lens is re-imaged on a sensor region of the photoelectric conversion element and is characterized by being provided with a diffraction color aberration correcting element that is positioned before or behind the separator mask and has a diffraction plane that is formed in an asymmetrical shape with respect to the optical axis of the condenser lens and by the following conditional equation (1) being satisfied.
(1) 0.9 < L1/L2 < 1.1(L1/L2 ≠ 1.0)
Wherein,
L1: air-equivalent distance from the expected image plane for the imaging lens to diffraction plane for the diffraction color aberration correcting element,
L2: air-equivalent distance from the expected image plane for the imaging lens to diffraction color aberration correcting element side surface of the separator mask
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Inventors:
KANAI MORIYASU (JP)
TAKAKUBO YUTAKA (JP)
TAKAKUBO YUTAKA (JP)
Application Number:
PCT/JP2013/052970
Publication Date:
December 12, 2013
Filing Date:
February 08, 2013
Export Citation:
Assignee:
RICOH IMAGING CO LTD (JP)
International Classes:
G02B7/34; G02B13/00; G03B13/36; H04N5/225; H04N5/232
Foreign References:
| JP2005195786A | 2005-07-21 | |||
| JP2011158893A | 2011-08-18 | |||
| JP2003015030A | 2003-01-15 | |||
| JPH09329414A | 1997-12-22 | |||
| JP2009025454A | 2009-02-05 |
Attorney, Agent or Firm:
MIURA, Kunio et al. (JP)
Kunio Miura (JP)
Kunio Miura (JP)
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