Autofocusing method

Abstract

Abstract PURPOSE:To obtain a focused image with a desired wavelength, by correcting the focusing position on the basis of infrared rays and visible rays which are detected independently of each other. CONSTITUTION:A light receiving device 23 where the image of an object 21 is formed by a lens 22 is provided with an optical path dividing prism 26 having a semitransparent face 24 and a total reflective face 25 and photodetecting element arrays 28 and 29 provided on a substrate 27. Optical paths from the lens to arrays 28 and 29 are different in length, and the middle position between arrays 28 and 29 is a focal plane conjugate to a film surface, and the light of all wavelengths is incident to arrays. An infrared cut filter 32 which permits visible rays to transmit through and cuts infrared rays and an infrared transmissive filter 33 which permits near infrared rays to transmit through and cuts visible rays are arranged on auxiliary photodetecting element 30 and 31, respectively. The lens 22 is driven to the focus position for the light having a desired wavelength on the basis of the deviation of the focus position between visible rays and infrared rays and a correction value obtained from output signals of photodetectors 30 and 31.

Inventors

• 👤 Kenichi Oikami
• 👤 大井上　建一
• 👤 Masatoshi Ida
• 👤 井田　正利
• 👤 Masahiro Aoki
• 👤 雅弘 青木
• 👤 Asao Hayashi
• 👤 林　朝男
• 👤 Junichi Nakamura
• 👤 淳一 中村
• 👤 Kenji Fukuoka
• 👤 謙二 福岡

Bibliographic Details