# US 2017/0285306 A9 · Image capturing apparatus and focusing method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0285306 A9 - Document ID: US20170285306A9 - Status: Published application - Kind: A9 - Application number: 14/398,011 - Filed: 2013-01-17 - Published: 2017-10-05 - Earliest claimed: 2011-12-19 - Assignees: Hamamatsu Photonics K.K. - Applicants: Hamamatsu Photonics K.K. - Inventors: Hideshi Oishi - Web page: https://patentgrep.com/patent/US20170285306A9 ## CPC - G02B 13/0055: {employing a special optical element} - G02B 21/244: {using image analysis techniques} - H04N 23/673: {based on contrast or high frequency components of image signals, e.g. hill climbing method} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract In the image capturing apparatus, the optical path difference producing member is disposed on the second optical path. Thereby, it is possible to suppress the amount of light when an optical image which is focused at the front of an optical image made incident into the first imaging device (front focus) and an optical image which is focused at the rear thereof (rear focus) are respectively imaged at the second imaging device and also to secure the amount of light on image pickup by the first imaging device. Further, in the image capturing apparatus, a position of the first imaging region and a position of the second imaging region on the imaging area are reversed with respect to the axis P in association with reversal of a scanning direction of the sample. Therefore, despite the scanning direction of the sample, it is possible to obtain a deviation direction of the focus position under the same conditions. ## Claims ### Claim at position 1 1-14. (canceled) ### Claim 15 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. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein on the imaging area, a region into which an optical image conjugate to the first optical image made incident into the first imaging unit is substantially in alignment with the axis of the imaging area. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the axis of the imaging area is substantially in alignment with the central axis of the imaging area orthogonal to a direction at which the second optical image moves in association with scanning of the sample. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the optical path difference producing member is a flat plate member which is disposed so as to overlap at least on a part of the imaging area, the region control unit sets the first imaging region and the second imaging region to give respectively a region which will overlap on the flat plate member and a region which will not overlap on the flat plate member in order to avoid a shadow of the second optical image by an edge part of the flat plate member. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein the optical path difference producing member is a member which has a part undergoing a continuous change in thickness along an in-plane direction of the imaging area, and the region control unit sets the first imaging region and the second imaging region so as to overlap on the part of the optical path difference producing member which is different in thickness. ### Claim 20 (depends on 15) The apparatus of claim 15, further comprising: an objective lens control unit configured to control a position of the objective lens relatively with respect to the sample based on control by the focus control unit, wherein the objective lens control unit will not actuate the objective lens during analysis of the focus position which is being performed by the focus control unit and will allow the objective lens to move with respect to the sample in one direction during analysis of the focus position which is not being performed by the focus control unit. ### Claim 21 (depends on 15) The apparatus of claim 15, wherein the region control unit sets waiting time from image pickup at the first imaging region to image pickup at the second imaging region based on a scanning speed of the stage and an interval between the first imaging region and the second imaging region. ### Claim 22 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. ### Claim 23 (depends on 22) The method of claim 22, wherein on the imaging area, a region into which an optical image is made incident which is conjugate to the first optical image made incident into the first imaging unit is allowed to be substantially in alignment with the axis of the imaging area. ### Claim 24 (depends on 22) The method of claim 22, wherein the axis of the imaging area is allowed to be substantially in alignment with the central axis of the imaging area orthogonal to a direction at which the second optical image moves in association with scanning of the sample. ### Claim 25 (depends on 22) The method of claim 22, wherein as an optical path difference producing member, there is used a flat plate member which is disposed so as to overlap at least on a part of the imaging area, and the region control unit sets the first imaging region and the second imaging region to give respectively a region which will overlap on the flat plate member and a region which will not overlap on the flat plate member in order to avoid a shadow of the second optical image by an edge part of the flat plate member. ### Claim 26 (depends on 22) The method of claim 22, wherein as an optical path difference producing member, there is used a member having a part which undergoes a continuous change in thickness along an in-plane direction of the imaging area, and the region control unit sets the first imaging region and the second imaging region so as to overlap on the part of the optical path difference producing member which is different in thickness. ### Claim 27 (depends on 22) The method of claim 22, further comprising: controlling a position of the objective lens relatively with respect to the sample based on control by the analysis result, wherein the control is not actuated the objective lens in analysis period. ### Claim 28 (depends on 22) The method of claim 22, further comprising: waiting time from image pickup at the first imaging region to image pickup at the second imaging region. ### Claim 29 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.