# US 2010/0166293 A1 · Image forming method and optical coherence tomograph apparatus using optical coherence tomography > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0166293 A1 - Document ID: US20100166293A1 - Status: Published application - Kind: A1 - Application number: 12/296,400 - Filed: 2008-04-03 - Published: 2010-07-01 - Earliest claimed: 2007-05-02 - Assignees: Canon Kabushiki Kaisha - Inventors: Mitsuro Sugita; Koji Nozato - Web page: https://patentgrep.com/patent/US20100166293A1 ## CPC - G01N 21/4795: {spatially resolved investigating of object in scattering medium (in vivo A61B)} - A61B 3/102: {for optical coherence tomography [OCT]} - A61B 5/004: {adapted for image acquisition of a particular organ or body part (A61B5/0082 takes precedence; arrangements for optical scanning A61B5/0062)} - G01B 9/02004: using frequency scans - G01B 9/02011: {using temporal polarization variation} - G01B 9/02027: {Two or more interferometric channels or interferometers} - G01B 9/02044: {Imaging in the frequency domain, e.g. by using a spectrometer} - G01B 9/02048: {Rough and fine measurement} - G01B 9/02063: {by particular alignment of focus position, e.g. dynamic focussing in optical coherence tomography} - G01B 9/02077: {of the object} - G01B 9/02085: {Combining two or more images of different regions} - G01B 9/02091: Tomographic interferometers, e.g. based on optical coherence - G01B 2290/70: Using polarization in the interferometer - G01N 2021/1787: {Tomographic, i.e. computerised reconstruction from projective measurements} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS ## Abstract An image forming method uses an optical coherence tomography as to an optical axis direction of plural pieces of image information of an object. First image information of an object is obtained at a first focus with respect to an optical axis direction to then object. A focusing position is changed by dynamic focusing from the first focus to a second focus along the optical axis. The second image information of the object is obtained at the second focus. A third image information, tomography image information of the object and including a tomography image of the first focus or the second focus, is obtained by Fourier domain optical coherence tomography. A tomography image or a three-dimensional image of the object is formed in positional relation, in the optical axis direction, between the first image information and the second image information using the third image information. ## Claims ### Claim 1 An image forming method using an optical coherence tomography comprising: a first image information deriving step for deriving a first image information of an object at a first focus position along an optical axis in a direction of a light incidence in the object; a step of shifting the focus position along the optical axis by dynamic focusing from the first image information into a second focus position different from the first image information; a second image information deriving step for deriving the second image information of the object at the second focus position along an optical axis in a direction of a light incidence in the object; and a third image information deriving step for deriving by Fourier Domain Optical coherence tomography a third image information of a tomography image information of the object including a tomography image of the object at least one of the first and second focus positions, wherein based on the third image information, correlating position relations in the optical axis direction of the first and second image information, a tomography image or a three dimensional image of the object is formed. ### Claim 2 (depends on 1) The image forming method according to claim 1, wherein the third image information is a tomography image information along the optical axis at the first focus position, and includes the tomography image information of the object at the second focus position, and the position relation in the optical axis direction between the first and second image information is corrected based on the third image information. ### Claim 3 (depends on 1) The image forming method according to claim 1, wherein the third image information includes a first tomography image of the object at the first focus position along the optical axis derived by Fourier Domain Optical coherence tomography, and a second tomography image of the object at the second focus position along the optical axis derived by the Fourier Domain Optical coherence tomography, and based on the an information in a region in which the first and second tomography images are overlapped, a position relation in the optical axis direction between the first and second image information related respectively to the first and second tomography images is corrected. ### Claim 4 (depends on 1) The image forming method according to claim 1, wherein as the third image information, tomography images of the object at both of the first and second focus positions are derived by the Fourier Domain Optical coherence tomography, and using an information of a position at which the tomography images are overlapped, the position relation in the optical axis direction between the first and second image information is corrected based on the third image information. ### Claim 5 (depends on 1) The image forming method according to claim 1, wherein the first and second image information deriving steps are steps for deriving one or two dimensional image of the object by a Time Domain Optical coherence tomography. ### Claim 6 (depends on 1) The image forming method according to claim 1, wherein the third image information is derived by a Spectral Domain Optical coherence tomography. ### Claim 7 An image forming method using an optical coherence tomography comprising: a first image information deriving step for deriving by a Time Domain Optical coherence tomography a first image information of C-scan image of an object at a first focus position along an optical axis in a direction of a light incidence in the object; a step of shifting the focus position along the optical axis by dynamic focusing from the first image information into a second focus position different from the first image information; a second image information deriving step for deriving by the Time Domain Optical coherence tomography the second image information of C-scan image of the object at the second focus position along an optical axis in a direction of a light incidence in the object; and a third image information deriving step for deriving by Spectral Domain Optical coherence tomography a third image information of a tomography image information of the object including a tomography image of the object at least one of the first and second focus positions, wherein based on the third image information, correlating position relations in the optical axis direction of the first and second image information, a tomography image or a three dimensional image of the object is formed. ### Claim 8 (depends on 1) An optical coherence tomography apparatus for executing the image forming method according to claim 1, comprising: a light source of a light incident in an object; a first light dividing unit for dividing the light from the light source into a signal light and a reference light; and a detecting unit for detecting a coherent light between the reference light and the signal light. ### Claim 9 (depends on 8) The optical coherence tomography apparatus according to claim 8, further comprising: a frequency shifter for forming a difference between frequencies of the signal light and the reference light; and a control unit, wherein the control unit controls the frequency shifter so as to shift the frequencies of the signal light and the reference light for deriving the first or second image information, and so as not to shift the frequencies of the signal light and the reference light for deriving the third image information. ### Claim 10 (depends on 8) The optical coherence tomography apparatus according to claim 8, further comprising: a light path conversion unit for converting a light path though which a coherent light passes; and a control unit, wherein the control unit controls the light path modulation unit so that the coherent light passes through a light path for deriving the image by the Time Domain Optical coherence tomography, at deriving the first or second image information, and so that the coherent light passes through another light path for deriving the image by the Spectral Domain Optical coherence tomography, at deriving the third image information. ### Claim 11 (depends on 8) The optical coherence tomography apparatus according to claim 8, further comprising: a second light dividing unit for dividing the coherent light into a light for deriving the image by the Time Domain Optical coherence tomography, and a light for deriving the image by the Spectral Domain Optical coherence tomography; a spatial polarization converter for converting polarization of light passing though the second light dividing unit; and a control unit, wherein the control unit controls the spatial polarization converter so that the light for deriving the image by the Time Domain Optical coherence tomography is stronger than the light for deriving the image by the Spectral Domain Optical coherence tomography, at deriving the first or second image information, and so that the light for deriving the image by the Spectral Domain Optical coherence tomography is stronger than the light for deriving the image by the Time Domain Optical coherence tomography, at deriving the third image information. ### Claim 12 (depends on 8) The optical coherence tomography apparatus according to claim 8, further comprising: a frequency shifter for forming a difference between a frequency of a reference light and a frequency of the signal light; a second light dividing unit for dividing the coherent light into a light for deriving the image by the Time Domain Optical coherence tomography, and a light for deriving the image by the Spectral Domain Optical coherence tomography; a spatial polarization converter for converting polarization of light passing though the second light dividing unit; and a control unit, wherein the control unit controls the frequency shifter so as to shift the frequency of the reference light or the signal light at deriving the first or second image information, and so as not to shift the frequency of the reference light or the signal light at deriving the third image information, and the control unit controls the spatial polarization converter so that the light for deriving the image by the Time Domain Optical coherence tomography is stronger than the light for deriving the image by the Spectral Domain Optical coherence tomography, at deriving the first or second image information, and so that the light for deriving the image by the Spectral Domain Optical coherence tomography is stronger than the light for deriving the image by the Time Domain Optical coherence tomography, at deriving the third image information. ### Claim 13 (depends on 8) The optical coherence tomography apparatus according to claim 8, further comprising: a light beam dividing unit for pupil dividing. ### Claim 14 (depends on 8) The optical coherence tomography apparatus according to claim 8, further comprising: a frequency shifter for forming a difference between frequencies of the signal light and the reference light, wherein the light source comprising a first light source of a light having a plurality of center wavelengths and second light source of a light having a single center wavelength, the frequency shifter is disposed on a light path of the second light source, and a light path of the first light source is different from the light path of the second light source. ### Claim 15 An image forming method using an optical coherence tomography comprising: a first image information deriving step for deriving by Fourier Domain Optical coherence tomography a first image information of an object at a first focus position along an optical axis in a direction of a light incidence in the object; a step of shifting the focus position along the optical axis by dynamic focusing from the first image information into a second focus position different from the first image information; and a second image information deriving step for deriving by Fourier Domain Optical coherence tomography the second image information of the object at the second focus position along an optical axis in a direction of a light incidence in the object, wherein based on a tomography information of the object derived by at least one of the first and second image information deriving steps, correlating position relations in the optical axis direction of the first and second image information, a tomography image or a three dimensional image of the object is formed. ### Claim 16 (depends on 15) The image forming method according to claim 15, wherein the first and second image information is derived by a Spectral Domain Optical coherence tomography. ### Claim 17 (depends on 15) An optical coherence tomography apparatus for executing the image forming method according to claim 15, comprising: a light source of a light incident in an object; a light dividing unit for dividing the light from the light source into a signal light and a reference light; and a detecting unit for detecting a coherent light between the reference light and the signal light. ### Claim 18 An image forming method using an optical coherence tomography comprising: a first image information deriving step for deriving a first image information of an object at a first focus position along an optical axis in a direction of a light incidence in the object; a step of shifting the focus position along the optical axis by dynamic focusing from the first image information into a second focus position different from the first image information; a second image information deriving step for deriving the second image information of the object at the second focus position along an optical axis in a direction of a light incidence in the object; and a step for deriving by Fourier Domain Optical coherence tomography a tomography image information of the object in the optical axis direction, wherein based on the tomography image information, correlating position relations in the optical axis direction of the first and second image information, a tomography image or a three dimensional image of the object is formed. ### Claim 19 (depends on 18) The image forming method according to claim 18, wherein the image information is derived at a third focus position different from the first and second focus positions in the optical axis direction, and is derived to include an image information of the object at the first and second focus positions.