Optical tomographic imaging apparatus

• US 8,274,660 B2
• Filed: 01/07/2010
• Issued: 09/25/2012
• Est. Priority Date: 01/22/2009
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sugita, Mitsuro
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Cook, Jonathon
• Application Number:
  US12/683,461
• Publication Number:
  US 20100181462A1
• Time in Patent Office: 992 Days
• Field of Search: 356/479, 356/497
• US Class Current: 356/479
• CPC Class Codes: G01B 9/02044 Imaging in the frequency domain, e.g. by using a spectrometer
• CPC Class Codes: G01B 9/02048 Rough and fine measurement
• CPC Class Codes: G01B 9/02063 by particular alignment of focus position, e.g. dynamic focussing in optical coherence tomography
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence

Abstract

Provided is an optical tomographic imaging apparatus that is capable of shortening a period of time of focusing at multiple focus positions when images split in a depth direction are obtained by zone focusing. The optical tomographic imaging apparatus includes: a focus position setting device for splitting a zone within a predetermined imaging depth range into multiple focus zones so as to set multiple focus positions; a reference position setting device for setting at least two reference positions in an imaging depth direction within the predetermined imaging depth range; and a focus controlling device for performing focusing at the multiple focus positions sequentially based on focus position information generated by the focus position setting device and a focus condition of an in-focus state for the at least two reference positions set in advance by the reference position setting device.

Claims

1. An optical tomographic imaging apparatus that takes a tomographic image of an object by splitting light from a light source into a measuring light and a reference light, guiding the measuring light to the object through scanning with a scanning optical system, and using a return light, which corresponds to the measuring light that is reflected or scattered by the object, and the reference light, the optical tomographic imaging apparatus comprising:

a pre-scan imaging unit configured to take a tomographic pre-scan image;

a focus position setting unit configured to set multiple focus positions within a predetermined imaging depth range of the pre-scan image;

a reference position setting unit configured to set at least two reference positions in an imaging depth direction within the predetermined imaging depth range;

a focus detecting unit configured to detect a focus condition of in-focus at the at least two reference positions; and

a focus controlling unit configured to control the performance of focusing at the multiple focus positions sequentially based on the focus condition of in-focus.

2. The optical tomographic imaging apparatus according to claim 1, further comprising:

a focus controlling data converting unit configured to create one of a conversion equation and a conversion table, in which a focus position in the imaging depth direction within the tomographic image is an input and position information of a focusing mechanism is an output, based on the focus condition of the in-focus detected by the focus detecting unit, and storing the one of the conversion equation and the conversion table so as to convert the input into the output; and

a focus driving information calculating unit configured to calculate driving information of the focusing mechanism based on the one of the conversion equation and the conversion table created by said focus controlling data converting unit and on the focus position information from said focus position setting unit,

wherein the focusing mechanism is driven and controlled by the focus controlling unit according to the driving information.

3. The optical tomographic imaging apparatus according to claim 1, wherein the focus detecting unit detects the focus condition of in-focus by determining an in-focus state for the at least two reference positions based on luminance of a the pre-scan image of the predetermined imaging depth range.

4. The optical tomographic imaging apparatus according to claim 1, wherein the focus detecting unit detects the focus condition of in-focus by determining an in-focus state for the at least two reference positions based on a definition of the pre-scan image of the predetermined imaging depth range.

5. The optical tomographic imaging apparatus according to claim 1, further comprising:

a mode selecting unit configured to select at least one mode from among multiple modes including a horizontal resolution mode and a luminance mode,

wherein the luminance mode uses a pixel larger than that of the horizontal resolution mode, and

wherein said focus position setting unit sets the multiple focus positions based on the at least one mode that has been selected.

6. An imaging method of taking a tomographic image of an object by splitting a light from a light source into a measuring light and a reference light, guiding the measuring light to the object through scanning with a scanning optical system, and using a return light corresponding to the measuring light that is reflected or scattered by the object and the reference light, the imaging method comprising:

a pre-scan imaging step of taking a tomographic pre-scan image;

a first setting step of setting multiple focus positions within a predetermined imaging depth range of the pre-scan image;

a second setting step of setting at least two reference positions in an imaging depth direction within the predetermined imaging depth range;

a focus detecting step of detecting a focus condition of in-focus at the at least two reference positions; and

a focusing step of focusing at the multiple focus positions sequentially based on the focus condition of in-focus.

7. A non-transitory computer-readable storage medium storing a program that causes a computer to execute the imaging method according to claim 6.