Source: https://patents.google.com/patent/US20110205490A1/en
Timestamp: 2018-12-18 18:05:47
Document Index: 229079653

Matched Legal Cases: ['Application No. 2010', 'art 23', 'art 23', 'art 23', 'art 23', 'art 23', 'art 70', 'art 70', 'art 23', 'art 70', 'art 70', 'art 70', 'art 70', 'art 23', 'art 61', 'art 70', 'art 70', 'art 70', 'art 70', 'art 70']

US20110205490A1 - Optical tomographic image photographing apparatus - Google Patents
US20110205490A1
US20110205490A1 US13034147 US201113034147A US2011205490A1 US 20110205490 A1 US20110205490 A1 US 20110205490A1 US 13034147 US13034147 US 13034147 US 201113034147 A US201113034147 A US 201113034147A US 2011205490 A1 US2011205490 A1 US 2011205490A1
US13034147
US8534835B2 (en )
An aspect of the invention allows for enhancement of the visibility of a tomographic image movie-displayed on a monitor. An optical tomographic image photographing apparatus includes: an interference optical system for combining reflected light with reference light on an object to guide the combined light to a detector; a driving part for moving an optical member in an optical-axis direction in order to adjust an optical path difference between measurement light and the reference light; an image obtaining part for obtaining a tomographic image of the object based on a light receiving signal output from the detector; and a control unit configured to detect positional deviation with respect to a depth direction in the tomographic image and to correct a display position of the tomographic image such that the tomographic image is displayed in a predetermined position within a display region on a monitor.
This application is based on Japanese Patent Application No. 2010-040586 filed with the Japan Patent Office on Feb. 25, 2010, the entire content of which is hereby incorporated by reference.
An aspect of the invention is related to an optical tomographic image photographing apparatus for photographing a tomographic image of an object.
This kind of apparatus also includes an apparatus which displays a tomographic image at a predetermined position on a display monitor by changing an optical path difference between a measurement light and a reference light at any time, even if the object moves while being photographed (refer to JP-A-2008-154939). In such an apparatus, an optical-path-length varying member (for example, a reference mirror) is moved by driving a motor in order to change the optical path difference.
A technical object of an aspect of the invention is to provide an optical tomographic image photographing apparatus which enhances the visibility of a tomographic image movie-displayed on a monitor.
An optical tomographic image photographing apparatus for photographing a tomographic image of an object, includes: an interference optical system including: a measurement light source; and a splitter that splits light emitted from the measurement light source, such that the light is split in a measurement optical path for guiding part of the light to the object as measurement light and in a reference optical path for generating reference light, the interference optical system combining reflected light from the measurement optical path, the reflected light being obtained by reflection of the measurement light on the object, with the reference light from the reference optical path, to guide combined light to a detector; an optical scanner that is arranged in the measurement optical path for scanning the measurement light on the object; a driving part for moving an optical member arranged in the measurement optical path or the reference optical path in an optical-axis direction in order to adjust an optical path difference between the measurement optical path and the reference optical path; an image obtaining part that is connected to the detector for obtaining a tomographic image of the object based on a light receiving signal output from the detector; a monitor; and a control unit configured to detect positional deviation of the tomographic image in a depth direction thereof based on the signal output from the detector, and to correct a display position of the tomographic image such that the tomographic image obtained by the image obtaining part is displayed in a predetermined position on the monitor by controlling a display of the monitor based on the detected positional deviation.
In an optical path for emitting the measurement light toward the eye E, an end 39 b of the optical fiber 38 b, a collimator lens 22, a focusing lens 24 and a scanning part 23 are arranged. The focusing lens 24 is movable in the optical-axis direction in line with a refraction error of the eye E for adjustment of a focus on the fundus. The scanning part 23 is capable of scanning the fundus in XY directions with the measurement light. This scanning part 23 includes two galvanometer mirrors, and is operated by driving of a scanning driving mechanism 51. The dichroic mirror 40 and an objective lens 10 serve as a light guiding optical system for guiding OCT measurement light from the OCT optical system 200 to the fundus. It is to be noted that the scanning part 23 of the embodiment arbitrarily adjusts a reflection angle of the measurement light by means of the two galvanometer mirrors. Hence a direction of scanning by means of the measurement light on the fundus is arbitrarily set. A tomographic image in an arbitrary area of the fundus is thus obtained. It is to be noted that the end 39 b of the optical fiber 38 b is arranged in a position conjugate with the fundus of the eye E. Further, the two galvanometer mirrors of the scanning part 23 are position arranged in a position substantially conjugate with a pupil of the eye E.
Meanwhile, in an optical path for emitting reference light toward the reference mirror 31 (reference optical path), an end 39 c of the optical fiber 38 c, a collimator lens 29 and the reference mirror 31 are arranged. The reference mirror 31 is configured to be movable in the optical-axis direction by a reference mirror driving mechanism 50. This allows the reference mirror 31 to change an optical path length of the reference light. That is, in this case, the reference mirror 31 is used as an optical-path-length varying member.
The reference light generated as described above and the fundus reflected light obtained by reflection of the measurement light on the fundus are combined in the coupler 26, to become interference light. The interference light is emitted from the end 84 a through the optical fiber 38 d.
The light emitted from the end 84 a is made to be parallel light in the collimator lens 80, and thereafter split in the grating 81 into each frequency component (each wavelength component). The split light is then collected on the light receiving surface of the light receiving device 83 via the condenser lens 82. Thereby, spectrum information with interference fringes is recorded in the light receiving device 83. The spectrum information (light receiving signal) is then input into a control part 70. The control part 70 analyzes the spectrum information by use of Fourier transformation, to measure information (A-scan signal) in the depth direction of the eye. Using the scanning part 23, the control part 70 scans the fundus in a predetermined transverse direction with the measurement light, to obtain a tomographic image. For example, the control part 70 scans the fundus in the X-direction or the Y-direction with the measurement light, to obtain a tomographic image of the fundus in an X-Z plane or a Y-Z plane (it is to be noted that in the embodiment, such a method for one-dimensionally scanning the fundus with the measurement light to obtain a tomographic image is referred to as B-scan). In addition, the obtained tomographic image is stored in a memory 72 connected to the control part 70. Further, the control part 70 scans two-dimensionally the fundus in the XY directions with the measurement light, to obtain a three-dimensional image of the fundus. Meanwhile, in the embodiment, an OCT image is obtained by the two galvanometer mirrors provided on the scanning part 23
The light emitting part 61 has a first light source (SLO light source) 61 a, a second light source (fixation optical system) 61 b, a mirror 69, and a dichroic mirror 101. The first light source 61 a emits light with a wavelength in the infrared region (e.g., λ=780 nm), and the second light source 61 b emits light with a wavelength in a visible region (e.g., λ=630 nm). It is to be noted that as the first light source 61 a and the second light source 61 b, a light source is used which emits light with high luminance and high directivity (such as a laser diode light source or an SLD light source). Infrared light emitted from the first light source 61 a passes through the dichroic mirror 101, and travels to a beam splitter 62 through a collimator lens 65. Visible light emitted from the second light source 61 b is bent by the mirror 69, and thereafter reflected on the dichroic mirror 101. This visible light then travels along the same axis as that of the infrared light emitted from the first light source 61 a. The first light source 61 a is used for obtaining a fundus front image for observation. Meanwhile, the second light source 61 b is used for guiding the sight direction of the eye.
The control part 70 detects the amount of positional deviation (positional deviation information) in the depth direction of the tomographic image based on an output signal from the light receiving element 68 (refer to FIGS. 3, 4A, and 4B). The amount of the detected positional deviation may also be detected, for example, based on the obtained tomographic image, and it may also be detected based on an A scan signal at an arbitrary scanning position before image formation.
FIG. 3 is a flow chart for explaining the example of display position correction of the fundus tomographic image. First, as shown in FIGS. 4A and 4B, the control part 70 sets scanning lines extending in the depth direction (an A scanning direction) on the fundus tomographic image. The control part 70 then obtains the luminance distribution L on these scanning lines. Next, the position in the depth direction at which the luminance value is maximum (hereinafter, abbreviated to “maximum luminance value”) is detected from the luminance distribution L, and this position is set as a peak position P. A reference position B is the center position in the depth direction of the tomographic image, and corresponds to the center position C in the display region 102 on the monitor 75.
In the embodiment, for example, 50 pixels are set as the allowable range D1. This corresponds to 1/10 of an image data set to 512×512 pixels. Further, a maximum movement distance of the reference mirror 31 while obtaining a fundus tomographic image of one frame may be set to D2 (for example, approximately 10 pixels). Thus, if the deviation amount from the limit position of the allowable range D1 is D2 or greater, the control part 70 gradually moves the position of the tomographic image over several frames while moving it by D2 in each single frame. If the deviation amount from the limit position of the allowable range D1 is smaller than D2, then the control part 70 moves the position of the tomographic image by the detected deviation amount ΔD in each single frame.
In the above explanation, in order to adjust the optical path difference between the measurement light and the reference light, an optical-path-length varying member is provided in the optical path of the reference light. However, the embodiment is not limited to this configuration, and the optical-path-length varying member may also be provided in the optical path of the measurement light. In this case, for example, the collimator lens 22 and the end of the optical fiber 39 b are moved in the optical axis direction.
1. An optical tomographic image photographing apparatus for photographing a tomographic image of an object, comprising:
a splitter that splits light emitted from the measurement light source, such that the light is split in a measurement optical path for guiding part of the light to the object as measurement light and in a reference optical path for generating reference light,
the interference optical system combining reflected light from the measurement optical path, the reflected light being obtained by reflection of the measurement light on the object, with the reference light from the reference optical path, to guide combined light to a detector;
an optical scanner that is arranged in the measurement optical path for scanning the measurement light on the object;
a driving part for moving an optical member arranged in the measurement optical path or the reference optical path in an optical-axis direction in order to adjust an optical path difference between the measurement optical path and the reference optical path;
an image obtaining part that is connected to the detector for obtaining a tomographic image of the object based on a light receiving signal output from the detector;
a control unit configured to detect positional deviation of the tomographic image in a depth direction thereof based on the signal output from the detector, and to correct a display position of the tomographic image such that the tomographic image obtained by the image obtaining part is displayed in a predetermined position on the monitor by controlling a display of the monitor based on the detected positional deviation.
2. The optical tomographic image photographing apparatus according to claim 1, wherein the control unit adjusts a position of the optical member in the optical axis direction by controlling the driving part, in a case that the detected positional deviation is larger than a predetermined allowable range.
3. The optical tomographic image photographing apparatus according to claim 2, wherein the control unit adjusts the position of the optical member such that the detected positional deviation falls within the predetermined allowable range.
4. The optical tomographic image photographing apparatus according to claim 2, wherein the control unit simultaneously performs correction of the display position of the tomographic image by controlling the display of the monitor and adjustment of the position of the optical member by controlling the driving part, in the case that the detected positional deviation is larger than the predetermined allowable range.
5. The optical tomographic image photographing apparatus according to claim 1, wherein the object is an eye.
6. The optical tomographic image photographing apparatus according to claim further comprising:
an optical system that obtains a front image of the object; and
a scanning position correction unit configured to detect deviation of a scanning position of the measurement light on the object in a horizontal direction and a vertical direction based on the obtained front image, and corrects, by controlling the optical scanner, the scanning position of the measurement light such that the deviation of the scanning position is corrected.
7. The optical tomographic image photographing apparatus according to claim 1, wherein the control unit continuously corrects the display position of the tomographic image.
8. The optical tomographic image photographing apparatus according to claim 2, wherein the control unit adjusts the position of the optical member when the detected positional deviation exceeds positional deviation corresponding to micromotion of the tomographic image.
9. The optical tomographic image photographing apparatus according to claim 2, wherein the control unit adjusts the position of the optical member when the detected positional deviation exceeds positional deviation at which an entire tomographic image can be sufficiently observed.
10. The optical tomographic image photographing apparatus according to claim 1, further comprising:
a moving unit configured to move the entire interference optical system relative to the object,
wherein the control unit adjusts a position of the entire interference optical system by controlling the moving unit, in the case that the detected positional deviation is larger than a predetermined allowable range.
11. The optical tomographic image photographing apparatus according to claim 1, further comprising:
a driving part for mechanically correcting the display position of the tomographic image.
US13034147 2010-02-25 2011-02-24 Optical tomographic image photographing apparatus Active 2031-09-09 US8534835B2 (en)
JP2010040586A JP5511437B2 (en) 2010-02-25 2010-02-25 Optical tomographic imaging apparatus
JP2010-040586 2010-02-25
US20110205490A1 true true US20110205490A1 (en) 2011-08-25
US8534835B2 US8534835B2 (en) 2013-09-17
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EP2371273A1 (en) 2011-10-05 application
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