FUNDUS IMAGING APPARATUS AND CONTROL METHOD

• US 20140118689A1
• Filed: 10/18/2013
• Published: 05/01/2014
• Est. Priority Date: 10/26/2012
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Saito, Yohei, Aikawa, Satoshi, Ohban, Hideyuki, Nakano, Yoshitaka
• Granted Patent: US 8,960,908 B2
• Time in Patent Office: Days
• US Class Current: 351/206
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence

Abstract

A fundus imaging apparatus selects a focal position detection method in accordance with whether a diopter correction lens is inserted in an optical path of an imaging optical system that includes an imaging unit; and detects a focal position based on a signal from the imaging unit according to the selected focal position detection method.

Claims

1. A fundus imaging apparatus comprising:

an illumination optical system operable to project illumination light on a fundus of an eye to be examined;

an imaging optical system operable to guide reflected light from the fundus to an imaging unit;

a driveable focus lens which is provided in an optical path of said imaging optical system and which is operable to focus the reflected light onto the imaging unit;

a focusing unit operable to detect a focal position of the reflected light based on a signal from said imaging unit and to drive the focus lens according to the detected focal position; and

a selection unit operable to select a focal position detection method used by said focusing unit in accordance with whether a diopter correction lens is inserted in the optical path or not.

2. The apparatus according to claim 1, wherein said selection unit is operable, when a diopter correction lens is not inserted in the optical path, to select a split focal position detection method of calculating a focal position of the reflected light by evaluating a shift between split images, and

said selection unit is operable, when said diopter correction lens is inserted in the optical path, to use a focal position detection method of detecting a focal position without using split images.

3. The apparatus according to claim 1, wherein said focusing unit is configured to use at least one of:

i) a split focal position detection method of evaluating a shift between split images; and

ii) a contrast focal position detection method of evaluating a contrast of an image, and

said selection unit is operable to select between the split focal position detection method and the contrast focal position detection method in accordance with whether a diopter correction lens is inserted in the optical path.

4. The apparatus according to claim 2, wherein said selection unit is operable to select the focal position detection method to be used by said focusing unit so as to use the split focal position detection method and the contrast focal position detection method when the diopter correction lens is not inserted in the optical path and to use the contrast focal position detection method when the diopter correction lens is inserted in the optical path.

5. The apparatus according to claim 2, wherein said selection unit is configured to select the focal position detection method to be used by said focusing unit so as to select the split focusing scheme when the diopter correction lens is not inserted in the optical path and to select the contrast focusing scheme when the diopter correction lens is inserted in the optical path.

6. A method of controlling a fundus imaging apparatus comprising:

selecting a focal position detection method in accordance with whether a diopter correction lens is inserted in an optical path of an imaging optical system that includes an imaging unit; and

detecting a focal position based on a signal from the imaging unit according to the selected focal position detection method.

7. A method according to claim 6, wherein the selecting step comprises selecting at least one of a split focal position detection method using split images for determining focal position and a contrast focal position detection method that does not use split images.

8. A non-transitory computer readable medium storing a program for causing a computer to execute a control method comprising:

selecting a focal position detection method in accordance with whether a diopter correction lens is inserted in an optical path of an imaging optical system that includes an imaging unit; and

detecting a focal position based on a signal from the imaging unit according to the selected focal position detection method.