Image capturing apparatus and focusing method thereof

An apparatus for capturing an image of a sample, the apparatus comprising:

• a stage configured to support a sample;
• an objective lens configured to face to the sample;
• a stage control unit configured to move the stage at a moving speed;
• a light dividing unit optically coupled and configured to divide an optical image of at least a portion of the sample into a first optical image and a second optical image;
• a first imaging unit configured to capture the at least a portion of the first optical image;
• a second imaging unit configured to capture the at least a portion of the second optical image and provide image data;
• a focus control unit configured to analyze the image data so as to control a focus position of the objective lens based on the analysis result;
• a region control unit configured to set at an imaging area of the second imaging unit a first imaging region and a second imaging region so as to capture the at least the portion of the second optical image;
• and
• an optical path difference producing member configured to give an optical path difference to the second optical image along an in-plane direction of the imaging area, wherein the optical path difference producing member is disposed in such a manner that the optical path difference of the second optical image is symmetrical to the axis of the imaging area orthogonal to a direction at which the second optical image moves in association with scanning of the sample, and
• the region control unit reverses a position of the first imaging region and a position of the second imaging region on the imaging area with respect to the axis in association with reversal of the scanning direction of the sample.

A method of capturing an image of a sample, the method comprising:

• by an objective lens, acquiring an optical image of at least a portion of a sample supported on a stage;
• dividing the optical image into a first optical image and a second optical image;
• capturing at least a portion of the first optical image;
• setting a first imaging region and a second imaging region at an image area of an imaging unit;
• by the first imaging region and the second imaging region, capturing the at least the portion of the second optical image and providing image data;
• and
• analyzing the image data so as to control a focus position of the objective lens based on the analysis result in an analysis period;
• giving an optical path difference to the second optical image in such a manner that the optical path difference of the second optical image is symmetrical with respect to the axis of the imaging area orthogonal to a scanning direction, and
• reversing a position of the first imaging region and a position of the second imaging region on the imaging area with respect to the axis in association with reversal of the scanning direction.

A method of capturing an image of a sample, the method comprising:

• by an objective lens, acquiring an optical image of at least a portion of a sample supported on a stage;
• dividing the optical image into a first optical image and a second optical image;
• capturing at least a portion of the first optical image;
• capturing at least a portion of the second optical image and providing image data;
• and
• analyzing the image data so as to control a focus position of the objective lens based on the analysis result in an analysis period;
• giving an optical path difference to the second optical image in such a manner that the optical path difference of the second optical image is symmetrical.