JP6836212B2 - Ophthalmologic imaging equipment - Google Patents

Description

The present disclosure relates to an ophthalmologic imaging apparatus that images an eye to be examined.

Conventionally, an ophthalmologic imaging apparatus has been known that adjusts various conditions such as imaging conditions using an image of an eye to be inspected.

For example, Patent Document 1 discloses the following device as a scanning laser ophthalmoscope which is a kind of ophthalmologic imaging device. That is, a plurality of fundus images are acquired while changing the diopter correction amount, and as a result of comparing the imaging states of the fundus images, the diopter correction amount when obtaining the captured image is a suitable imaging state. A device that adjusts to a value that becomes

Further, for example, Patent Document 2 discloses the following device as an optical interference tomography device which is a kind of ophthalmologic imaging device. That is, a plurality of tomographic images were acquired while changing the optical path length difference between the measurement light and the reference light, and as a result of comparing the signal distributions in the depth direction in each tomographic image, the imaging range in the depth direction was obtained. A device for adjusting the optical path length difference is disclosed so as to include the desired tissue.

JP-A-2009-291253 Japanese Unexamined Patent Publication No. 2012-21348

In the above adjustment method, when adjusting a certain condition, it is necessary to acquire a plurality of images of an eye to be inspected having different conditions. Further, the process of detecting the information regarding the condition is performed on each of the plurality of images of the eye to be inspected. Therefore, the time required for adjusting the conditions tends to be prolonged.

The present disclosure has been made in view of the problems of the prior art, and it is a technical subject to provide an ophthalmologic imaging apparatus in which the time required for adjusting the conditions is easily suppressed.

In order to solve the above technical problem, the ophthalmologic imaging apparatus according to the first aspect of the present disclosure includes an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a return from the eye to be inspected. An imaging optical system having a light receiving optical system having at least a light receiving element that receives at least light, an image forming means for acquiring a front image of the eye to be inspected as a captured image based on a signal from the light receiving element, and the captured image. A second image based on the front image, which takes less time to form an image per frame than the other, is formed by the image forming means based on a signal from the light receiving element, and at least one of the conditions related to the captured image is satisfied. A condition setting means for setting based on the second image and a shooting execution means for capturing the shot image under the set conditions are provided .
Further, the ophthalmologic imaging apparatus according to the second aspect of the present disclosure includes an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a light receiving element that at least receives return light from the eye to be inspected. An image forming means for acquiring an OCT image of an eye to be examined as a photographed image based on a signal from the light receiving element, and an image per frame as compared with the photographed image. A second image based on the OCT image, which takes a short time to form, is formed by the image forming means based on a signal from the light receiving element, and as a condition for the captured image, the optical path length between the focus, the measurement light, and the reference light. It includes a condition setting means for setting at least one of a difference and polarization by a polarizer based on the second image, and a shooting execution means for capturing the shot image under the set conditions.
Further, the ophthalmologic imaging apparatus according to the third aspect of the present disclosure includes an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a light receiving element that at least receives return light from the eye to be inspected. An image forming optical system having a light receiving optical system, an image forming means for acquiring a photographed image of an eye to be inspected based on a signal from the light receiving element, and an image forming per frame as compared with the photographed image. A condition setting means for forming a second image having a short time required by the image forming means based on a signal from the light receiving element and setting at least one of the conditions related to the captured image based on the second image. The imaging execution means for capturing the captured image under the above-mentioned conditions is provided, and the above-mentioned condition is the focus adjustment amount of the optometry imaging apparatus.
Further, the ophthalmologic imaging apparatus according to the fourth aspect of the present disclosure includes an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a light receiving element that at least receives return light from the eye to be inspected. A light receiving optical system having a light receiving optical system, an image forming means for acquiring a photographed image of an eye to be inspected based on a signal from the light receiving element, and an image forming per frame as compared with the photographed image. A condition setting means for forming a second image having a short time required by the image forming means based on a signal from the light receiving element and setting at least one of the conditions related to the captured image based on the second image. A photographing execution means for capturing the photographed image under the said condition is provided, and the condition is at least one of an output from the light source and an amplification factor of a signal from the light receiving element.

According to the present disclosure, the time required for adjusting the conditions is likely to be suppressed.

It is a figure which showed the appearance of the SLO which concerns on Example. It is a figure which showed the optical system of SLO which concerns on Example. It is a figure which showed the control system of SLO which concerns on Example. It is a flowchart which showed the operation of SLO which concerns on Example. It is a graph which showed the histogram of the differential value of the image luminance used in the autofocus in SLO of an Example.

First, the first embodiment of the present disclosure will be described. The ophthalmologic imaging apparatus according to the first embodiment irradiates the eye to be inspected with light from a light source, and takes an image of the eye to be inspected as a result of receiving the return light. Such a device may be, for example, an anterior segment imaging device, a fundus imaging apparatus, or a device capable of photographing both the anterior segment and the fundus.

Further, the ophthalmologic imaging device may be, for example, a scanning type device that scans light on the tissue of the eye to be inspected, or a camera that receives the return light from the eye to be inspected by a light receiving element in which a plurality of pixels are arranged. It may be a type device or a device having both characteristics. Examples of the scanning type device include SLO (scanning laser ophthalmoscope: Scanning Laser Optics), OCT (optical coherence tomography), and the like. Examples of the camera-type device include a fundus camera, an anterior ocular segment camera, and an ophthalmic shine pluque camera.

Hereinafter, the ophthalmologic imaging apparatus will be referred to as this apparatus. The apparatus may include, for example, a photographing optical system (irradiation optical system and a light receiving optical system), an image forming unit, a condition adjusting unit, a condition setting unit, and a photographing execution unit. At least a part of the image forming unit, the condition adjusting unit, the condition setting unit, and the photographing execution unit may be shared by one unit such as a computer built in the present apparatus.

<Shooting optical system>
The photographing optical system is the main optical system of this device used for acquiring the image of the eye to be inspected. The photographing optical system includes at least an irradiation optical system and a light receiving optical system.

The irradiation optical system irradiates the eye to be inspected with light from a light source. The irradiation optical system includes, for example, at least a part of a light source and an optical member (for example, a lens and a mirror) for guiding the light from the light source to the eye to be inspected. Further, in the case of a scanning type device (SLO, OCT, etc.), the irradiation optical system may be provided with a scanning unit (optical scanner). The scanning unit is a unit for scanning the light emitted from the light source on the eye to be inspected (more specifically, on the observation surface of the eye to be inspected).

The SLO is a two-dimensional scanning method in which spot-shaped light is two-dimensionally scanned (for example, raster scan) on the observation surface, and a line scanning method in which line-shaped light is scanned in one direction on the observation surface. Is known. In either method, at least the scanning unit includes an optical scanner for scanning light in the sub-scanning direction. The present embodiment may be applied to either a two-dimensional scan type device or a line scan type device.

The light receiving optical system has at least a light receiving element. The light receiving optical system receives at least the return light from the eye to be inspected by the light receiving element. For example, in the case of OCT, the light receiving element does not receive the light reflected from the fundus of the fundus (a type of return light) of the measurement light itself, but the light in a state where the reflected light of the fundus and the reference light interfere with each other. It may be received by a light receiving element.

The present device may be provided with another optical system separately from the photographing optical system or by sharing at least a part of the photographing optical system. For example, an optometry optical system may be provided. Further, in the case of OCT, a reference optical system for obtaining reference light may be provided.

<Image formation part, shooting execution part>
The image forming unit forms an image of the eye to be inspected based on the signal from the light receiving element. The image of the eye to be inspected formed by the image forming portion may be a frontal image or a cross-sectional image (or tomographic image). The image forming unit includes at least an image processing processor. This image processing processor may be a processor that controls the operation of the entire apparatus. This also applies to other configurations that handle images.

The captured image is an image of the eye to be inspected that is captured based on the captured trigger signal. As a result of the capture, the captured image is stored in memory. The captured image may be a raw image of the image of the eye to be inspected formed by the image forming unit, or may be an image obtained by processing, correcting, or both of the raw image. The capture is performed by the shooting execution unit.

<Condition adjustment unit>
The condition adjusting unit adjusts at least one of the conditions set for obtaining the shooting condition. The conditions adjusted by the condition adjusting unit may be hard conditions (collectively referred to as shooting conditions) related to the arrangement and operation of each part in the photographing optical system, or when forming a captured image from a received signal. It may be a condition in soft processing (referred to as an image forming condition in this embodiment).

The shooting conditions may be adjustable conditions for each part of the shooting optical system and may affect the shooting result (that is, an image). For example, the output from the light source, the amplification factor (gain) of the signal from the light receiving element, the correction amount (focus) of the diopter, the arrangement of other optical members on the optical path, or the parameters related to the operation of the optical member, etc. Can be mentioned. The condition adjusting unit can adjust at least a part of such shooting conditions.

Further, the image forming condition may be, for example, a condition in the process in which the image forming unit forms an image (mainly an image of the eye to be inspected) based on a signal from the light receiving element. For example, the brightness correction amount (brightness and at least one of the contrast correction amounts), the position correction amount of each part of the image, and the like can be mentioned as conditions. That is, the condition adjusting unit adjusts each condition by controlling a part of the photographing optical system or by adjusting the content of the image forming process in the image forming unit.

When applied to OCT, focus, optical path length difference between measurement light and reference light, polarization by a polarizer, and the like are exemplified as the above conditions.

<Condition setting unit>
The condition setting unit causes the image forming unit to form a second image in which the number of pixels is smaller than that of the captured image or the time required to form an image per frame is shorter than that of the captured image. The second image may be an image in which the eye to be inspected is the subject, such as a photographed image, or an image in which the eye to be inspected is not the subject.

The conditions (conditions such as shooting conditions) set when the second image is taken are reflected in the information (for example, luminance information, position information, etc.) included in the second image. Therefore, for example, the suitability of the condition can be determined by analyzing and evaluating the second image. The analysis / evaluation method may be an evaluation of the image quality of the second image or an evaluation of a histogram. In addition, an element that correlates with at least one of various conditions may be evaluated.

The difference in the number of pixels between the captured image and the second image may reflect, for example, a difference in the shooting range (shooting angle of view), a difference in the pixel density with respect to the angle of view, or both. When the present device is a scanning type device, the condition setting unit may make the operation of the scanning unit different from each other depending on whether the captured image is acquired or the second image is acquired.

For example, the condition setting unit may make one of the scanning range and the scanning speed in the scanning unit different from each other in each case. That is, the scanning range when acquiring the second image may be narrower than when acquiring the captured image, and the scanning speed when acquiring the second image is compared with when acquiring the captured image. , May be faster. As the scanning speed increases, the distance between the pixel extraction points on the eye to be inspected increases, so that the number of pixels of the image per frame is reduced.

Further, the difference in the time required to form the image per frame between the captured image and the second image reflects the difference in the scanning range and the scanning speed as well as the difference in the exposure time. May be good.

The condition setting unit sets at least one of the conditions to be set when capturing the captured image based on the second image. For example, a plurality of second images may be generated under different conditions by forming the second images one after another by the image forming unit while changing at least one condition by the condition adjusting unit. Then, by analyzing and evaluating a plurality of second images, conditions for obtaining a good captured image may be searched for. In addition, each second image may be associated with information indicating a condition for generating the image.

The condition setting unit may set the searched condition as "a condition to be set when capturing a captured image". As a result, when capturing the captured image, the shooting execution unit captures the captured image under the conditions set by the condition setting unit.

Since the number of pixels of the second image is smaller than that of the captured image, for example, the time required for the detection operation of "conditions to be set for capturing the captured image" can be easily suppressed. More specifically, as compared with the case of detecting "conditions to be set for capturing the captured image" from a plurality of images formed with the same number of pixels as the captured image, as in the present embodiment. In addition, using the second image enables processing in a shorter time because the number of pixels is smaller.

Further, as a result of controlling the scanning unit so that the time required to acquire the image per frame when generating the second image is shorter in the second image than in the captured image, the second image When the number of pixels is smaller than that of the captured image, the time required to generate the second image out of the time required for the detection operation is preferably suppressed.

At this time, the scanning unit may be controlled so that the scanning range when acquiring the second image is narrower than that when acquiring the captured image. In this case, the narrowed scanning range is preferably set near the center of the photographing optical axis. Since the influence of eclipse by the pupil is unlikely to occur near the center of the shooting optical axis, it becomes easier to satisfactorily detect "conditions to be set for capturing the shot image" using the second image.

Further, the scanning unit may be controlled so that the scanning speed at the time of acquiring the second image is faster than that at the time of acquiring the captured image. For example, in the case where the image of the eye to be inspected is continuously imaged during the condition detection operation by the condition setting unit and before and after that, and the image of the eye to be inspected is displayed on the monitor in real time. The display range of the captured image can be kept constant at all times.

The condition setting unit is temporarily used for at least a part of the period from the trigger for starting the adjustment of the shooting condition or the image forming condition to the detection of the "condition to be set when capturing the shot image". To form a second image.

Further, in the case of a device in which the image of the eye to be inspected is continuously captured before and after the operation of the condition setting unit and the image of the eye to be inspected is displayed on the monitor in real time, the second image is The number of pixels may be smaller than the image of the eye to be inspected that is displayed in real time before and after the operation of the condition setting unit.

<Example>
Next, an embodiment to which the technique of the above embodiment is applied will be shown. Here, an example applied to SLO is shown. For convenience, SLO1 according to the embodiment will be described as a configuration in which spot-shaped light is two-dimensionally scanned on the fundus. The SLO1 may be a device integrated with other ophthalmic devices such as an optical coherence tomography (OCT) and a perimeter.

<Appearance configuration>
First, a schematic configuration of SLO1 will be described with reference to FIGS. 3 to 8. As shown in FIG. 3, the SLO 1 mainly includes a photographing unit 4. The photographing unit 4 includes at least the main optical system (see FIG. 4) in SLO1.

The SLO1 may include an alignment mechanism. The alignment mechanism in SLO1 is used, for example, to arrange the position where the turning point of the laser beam is formed at an appropriate position with respect to the eye E to be inspected. The alignment mechanism is a drive mechanism that adjusts the relative position between the eye to be inspected and the photographing unit 4 (photographing optical system). The alignment mechanism may adjust the positional relationship between the eye to be inspected and the imaging unit 4 (imaging optical system) in each of the X (left and right), Y (up and down), and Z (front and back) directions. In the specific example shown in FIG. 3, the base 5, the moving base 6, and the Z drive mechanism 7 are used as alignment mechanisms in the horizontal direction (XZ direction) and the vertical direction (Y direction). That is, the moving table 6 can move in the XZ direction on the base 5 with the photographing unit 4 mounted on it. Further, the Y drive mechanism 7 is mounted on the moving table 6 and displaces the photographing unit 4 in the Z direction. As a result, the positional relationship between the eye to be inspected and the photographing unit 4 (photographing optical system) in the XYZ direction is adjusted. The alignment mechanism may have an actuator that performs a predetermined operation based on a control signal in each of the X, Y, and Z directions, and may realize the above operation by driving control of the actuator.

<Optical configuration>
Next, the optical system provided in SLO1 will be described with reference to FIG. As shown in FIG. 4, the SLO 1 includes an irradiation optical system 10 and a light receiving optical system 20 (collectively referred to as a “photographing optical system”). SLO1 captures a fundus image using these optical systems 10 and 20.

The irradiation optical system 10 includes at least a scanning unit 16 and an objective optical system 17. Further, as shown in FIG. 4, the irradiation optical system 10 further includes a laser light emitting unit 11, a collimating lens 12, a perforated mirror 13, and a lens 14 (in this embodiment, a part of the diopter adjusting unit 40). ), And the lens 15.

The laser light emitting unit 11 is a light source of the irradiation optical system 10. In this embodiment, the laser light from the laser light emitting unit 11 is used as the illumination light emitted from the irradiation optical system 10 to the fundus Er. The laser light emitting unit 11 may include, for example, a laser diode (LD), a super luminescent diode (SLD), and the like. Although the description of the specific structure is omitted, the laser light emitting unit 11 emits light in at least one or more wavelength ranges. In this embodiment, it is assumed that light of a plurality of colors is emitted from the laser light emitting unit 11 simultaneously or selectively. For example, in this embodiment, a total of four colors of light, three colors in the visible region of blue, green, and red, and one color in the infrared region, are emitted from the laser light emitting unit 11. The light of each color can be emitted simultaneously or alternately. The three colors in the visible range of blue, green, and red are used, for example, for color photography.

The laser beam is guided to the fundus Er in the path of the light beam shown in FIG. That is, the laser light from the laser light emitting unit 11 passes through the opening formed in the perforated mirror 13 via the collimating lens 12, passes through the lens 14 and the lens 15, and then heads toward the scanning unit 16. The laser light reflected by the scanning unit 16 passes through the objective optical system 17 and then irradiates the fundus Er of the eye E to be inspected. As a result, the laser beam is reflected and scattered by the fundus Er, or excites a fluorescent substance existing in the fundus to generate fluorescence from the fundus. These lights (that is, reflected / scattered light, fluorescence, etc.) are emitted from the pupil as return light.

In this embodiment, the lens 14 shown in FIG. 4 is a part of the diopter adjusting unit 40 (focus adjusting unit in this embodiment). The diopter adjusting unit 40 is used to correct (reduce) the diopter error of the eye E to be inspected. For example, the lens 14 can be moved in the optical axis direction of the irradiation optical system 10 by the drive mechanism 14a. The diopter of the irradiation optical system 10 and the light receiving optical system 20 changes according to the position of the lens 14. Therefore, by adjusting the position of the lens 14, the error in the diopter of the eye E to be inspected is reduced, and as a result, the focused position of the laser light is moved to the observation site (for example, the surface of the retina) of the fundus Er. It can be set. An optical system different from that shown in FIG. 4, such as a Badal optical system, may be applied to the diopter adjusting unit 40.

The scanning unit 16 (also referred to as an “optical scanner”) is a unit for scanning the laser beam emitted from the light source (laser light emitting unit 11) on the fundus. In this embodiment, the scanning unit 16 includes two optical scanners in which the scanning directions of the laser light are different from each other. That is, it includes an optical scanner 16a for main scanning (for example, scanning in the X direction) and an optical scanner 16b for sub-scanning (for example, scanning in the Y direction). The scanning cycle, scanning speed, and the like by the optical scanners 16a and 16b may be changeable.

In the following, the optical scanner 16a for the main scan will be described as a resonant scanner, and the optical scanner 16b for the sub scan will be described as a galvanometer mirror. In this embodiment, the resonant scanner, which is the optical scanner 16a for the main scanning, is designed to vibrate the mirror portion in a predetermined constant period and a constant scanning range (swing angle). On the other hand, in the optical scanner 16b for sub-scanning, the scanning speed and the scanning range are variable. However, other optical scanners may be applied to the optical scanners 16a and 16b. For example, for each of the optical scanners 16a and 16b, in addition to other reflection mirrors (galvano mirror, polygon mirror, resonant scanner, MEMS, etc.), an acoustic optical element (AOM) that changes the traveling (deflection) direction of light, etc. May be applied.

When a line scan type device is applied to the SLO 1, the scanning unit 16 may be replaced with an optical scanner that scans a line-shaped laser beam in a direction intersecting the line. This optical scanner is an optical scanner for sub-scanning, and may be, for example, a galvano mirror, an acoustic optical element, or the like.

The objective optical system 17 is an objective optical system of SLO1. The objective optical system 17 is used to guide the laser beam scanned by the scanning unit 16 to the fundus Er. Therefore, the objective optical system 17 forms a turning point P in which the laser beam passing through the scanning unit 16 is swirled. The turning point P is formed on the optical axis L1 of the irradiation optical system 10 at a position optically cooperating with the scanning unit 16 with respect to the objective optical system 17. In the present disclosure, the term "conjugate" is not necessarily limited to a perfect conjugate relationship, but includes "substantially conjugate". That is, the case where the fundus image is arranged with a deviation from the perfect conjugate position within a range permitted in relation to the purpose of use (for example, observation, analysis, etc.) is also included in the "conjugate" in the present disclosure. However, the objective optical system of SLO1 is not limited to the lens system, and may be a mirror system, a combination of the lens system and the mirror system, or other optical systems. There may be.

The laser light that has passed through the scanning unit 16 passes through the objective optical system 17 and is irradiated to the fundus Er in the swirl point P. Therefore, the laser beam that has passed through the objective optical system 17 is swirled around the swirl point P as the scanning unit 16 operates. As a result, in this embodiment, the laser beam is two-dimensionally scanned on the fundus Er. The laser beam applied to the fundus Er is reflected at the condensing position (for example, the surface of the retina). In addition, the laser light is scattered in the tissues before and after the condensing position. The reflected light and the scattered light are emitted from the pupil as parallel light, respectively.

Next, the light receiving optical system 20 will be described. The light receiving optical system 20 has one or more light receiving elements. For example, as shown in FIG. 4, a plurality of light receiving elements 25, 27, 29 may be provided. In this case, the light from the fundus Er by the laser beam emitted by the irradiation optical system 10 is received by the light receiving elements 25, 27, 29.

As shown in FIG. 4, in the light receiving optical system 20 in this embodiment, each member arranged from the objective optical system 17 to the perforated mirror 13 may be shared with the irradiation optical system 10. In this case, the light from the fundus is guided back to the perforated mirror 13 in the optical path of the irradiation optical system 10. The perforated mirror 13 receives light from the fundus Er while removing at least a part of noise light due to reflection by the cornea of the eye to be inspected and the optical system inside the device (for example, the lens surface of the objective optical system). It leads to the independent optical path of the optical system 20.

The optical path branching member for branching the irradiation optical system 10 and the light receiving optical system 20 is not limited to the perforated mirror 13, and other beam splitters may be used.

The light receiving optical system 20 of this embodiment has a lens 21, a pinhole plate 23, and an optical separation unit (optical separation unit) 30 in the reflected optical path of the perforated mirror 13. Further, lenses 24, 26, 28 are provided between the light separation unit 30 and the light receiving elements 25, 27, 29.

The pinhole plate 23 is arranged on the fundus conjugate surface and functions as a confocal diaphragm in SLO1. That is, when the diopter is properly corrected by the diopter adjusting unit 40, the light from the fundus Er that has passed through the lens 21 is focused at the opening of the pinhole plate 23. The pinhole plate 23 removes light from a position other than the focusing point (or focal plane) of the fundus Er, and the rest (light from the focusing point) is mainly guided to the light receiving elements 25, 27, 29. ..

The light separation unit 30 separates the light from the fundus Er. In this embodiment, the light from the fundus Er is wavelength-selectively separated by the light separation unit 30. Further, the optical separation unit 30 may also serve as an optical branching unit that branches the optical path of the light receiving optical system 20. For example, as shown in FIG. 4, the optical separation unit 30 may include two dichroic mirrors (dichroic filters) 31 and 32 having different optical separation characteristics (wavelength separation characteristics). The optical path of the light receiving optical system 20 is branched into three by two dichroic mirrors 31 and 32. Further, one of the light receiving elements 25, 27, and 29 is arranged at the end of each branch optical path.

For example, the light separation unit 30 separates the wavelengths of light from the fundus Er, and causes the three light receiving elements 25, 27, and 29 to receive light in different wavelength ranges. For example, the light receiving elements 25, 27, and 29 may receive light of three colors of blue, green, and red one by one. In this case, a color image can be obtained from the light receiving results of the light receiving elements 25, 27, and 29.

Further, the light separation unit 30 causes at least one of the light receiving elements 25, 27, and 29 to receive light in the infrared region used in infrared photography. In this case, for example, the fluorescence used in the fluorescence imaging and the light in the infrared region used in the infrared imaging may be received by different light receiving elements. In this embodiment, the light receiving element 25 receives the fundus reflected light by infrared light.

<Control system configuration>
Next, the control system of SLO1 will be described with reference to FIG. Each unit of SLO1 is controlled by the control unit 70. The control unit 70 is a processing device (processor) having an electronic circuit that performs control processing of each unit of SLO1 and arithmetic processing. The control unit 70 is realized by a CPU (Central Processing Unit), a memory, or the like. The control unit 70 is electrically connected to the storage unit 71 via a bus or the like. Further, the control unit 70 is electrically connected to each unit such as the laser light emitting unit 11, the light receiving elements 25, 27, 29, the driving unit 14a, the scanning unit 16, the input interface 75, and the monitor 80.

Various control programs, fixed data, and the like are stored in the storage unit 71. Further, temporary data or the like may be stored in the storage unit 71. The image obtained by SLO1 may be stored in the storage unit 71. However, the present invention is not necessarily limited to this, and the image obtained by SLO1 may be stored in an external storage device (for example, a storage device connected to the control unit 70 by LAN and WAN).

In this embodiment, the control unit 70 also serves as an image processing unit (image forming unit). As an image processing unit, the control unit 70 forms a fundus image based on, for example, the light receiving signals output from the light receiving elements 25, 27, and 29. More specifically, the control unit 70 forms a fundus image in synchronization with the optical scanning by the scanning unit 16. For example, the control unit 70 takes at least one frame (in other words, one) of the fundus image (light receiving element) each time the optical scanner 16b for sub-scanning reciprocates n times (n is an integer of 1 or more). Form (every time). In the following, unless otherwise specified, for convenience, one frame of fundus image based on one round trip of the optical scanner 16b for sub-scanning is formed. In this embodiment, since the three light receiving elements 25, 27, 29 are provided, the control unit 70 scans up to three types of images based on the signals from the respective light receiving elements 25, 27, 29 for sub-scanning. It is generated every time the optical scanner 16b of the above reciprocates once.

The control unit 70 may display the fundus images of a plurality of frames sequentially formed based on the operation of the device as described above on the monitor 80 as observation images in chronological order. The observation image is a moving image consisting of a fundus image acquired in real time. Further, the control unit 70 captures (captures) a part of the plurality of fundus images sequentially formed as a captured image (captured image). At that time, the captured image is stored in the storage medium. The storage medium in which the captured image is stored may be a non-volatile storage medium (for example, a hard disk, a flash memory, etc.). In this embodiment, for example, a fundus image formed at a predetermined timing (or period) after the output of a trigger signal (for example, a release operation signal) is captured.

The control unit 70 can form the fundus image with different numbers of pixels. For example, the fundus image is displayed with four types of pixels: 4096 × 4096, 2048 × 2048, 1024 × 1024, 512 × 512 (all of which are “the number of pixels in the main scanning direction” × “the number of pixels in the sub scanning direction”). It may be formable. For example, the number of pixels of the fundus image may be switched by changing the swing angle of the optical scanners 16a and 16b according to the number of pixels, but in this embodiment, when the fundus image is obtained with any number of pixels. Also, it is assumed that the swing angles of the optical scanners 16a and 16b are constant.

In this embodiment, the scanning speed of the optical scanner 16b for sub-scanning is adjusted according to the number of pixels. That is, the smaller the number of pixels of the fundus image to be acquired, the faster the optical scanner 16b for sub-scanning is operated.

In this embodiment, with respect to the optical scanner 16a (resonant scanner) for main scanning, the cycle of reciprocating operation and the scanning range (swing angle) are substantially constant, and it is difficult to control the scanning speed and scanning range. Therefore, the number of pixels in the main scanning direction may be switched by adjusting the pixel sampling period. The sampling of the signal from the light receiving element is performed, for example, in synchronization with the clock. When the clock cycle is variable, the number of pixels in the main scanning direction may be switched by switching the sampling cycle itself of the signal from the light receiving element. On the other hand, when the clock cycle is constant and the sampling cycle of the signal from the light receiving element is constant, the extraction interval (resampling interval) of the signal used for pixel formation is switched from the once sampled signal. The number of pixels in the main scanning direction may be switched.

Further, in this embodiment, the driver of the optical scanner 16a (resonant scanner) for the main scanning outputs a signal (for example, a square wave) synchronized with the cycle of each outward scanning. The generation timing of this signal, or the timing when a predetermined time elapses from the generation timing, is used as the acquisition timing of the first pixel in the pixel sequence (one of the first pixel sequence and the second pixel string) (in other words, For example, horizontal synchronization can be obtained). Further, for example, the timing at which half a cycle of the reciprocating scan elapses from the timing is further used as the acquisition timing of the first pixel in the remaining one of the first pixel row and the second pixel row. As a result, the first pixel row and the second pixel row are distinguished, and a fundus image is constructed (details will be described later).

The input interface 75 is an operation unit that accepts the operation of the examiner. For example, a touch panel, a mouse, a keyboard, and the like may be used as the input interface 75. Such an input interface 75 may be a device separate from the SLO1. The control unit 70 controls each of the above members based on the operation signal output from the input interface 75 (operation unit).

<Operation explanation>
Next, the operation of SLO1 according to the embodiment will be described with reference to FIG. After making various adjustments, the SLO1 acquires (captures) a captured image of the fundus image. For convenience, in the following description, unless otherwise specified, a still image having a pixel count of 2048 × 2048 is acquired as a captured image. Further, it is assumed that an image having 1024 × 1024 pixels is acquired as an observation image. However, the present invention is not limited to this, and the number of pixels of the captured image may be appropriately selected depending on the photographing mode, the intended use of the captured image, and the like.

First, in this embodiment, the positional relationship between the device and the eye to be inspected is adjusted (aligned). In this embodiment, the alignment is performed with the subject facing SLO1 so that the subject is placed in front of the examination window. Various methods can be considered for alignment, but here, a method using an observation image (moving image) of the eye to be inspected will be introduced. For example, in this embodiment, an image (observation image) acquired via the photographing optical system 10 is used in alignment. In this case, the control unit 70 starts acquiring and displaying the observation image (S2), and executes various processes for alignment (S3). In this case, for example, an alignment projection optical system that projects an index luminous flux for alignment on the corneal surface may be provided in SLO1. The emission position of the index luminous flux may be a position conjugate with the center of the radius of curvature of the cornea and the midpoint of the corneal surface when the working distance is appropriate. In such a configuration, the index image due to the index luminous flux is reflected in the image obtained through the photographing optical system at the proper working distance and before and after it. By adjusting the positional relationship between the device and the eye to be inspected with respect to the direction intersecting the working distance direction according to the position where the index image is formed on the observation image, the alignment can be performed in the vertical and horizontal directions. Further, by adjusting the positional relationship between the device and the eye to be inspected with respect to the working distance direction according to the degree of blurring of the index image, the alignment in the working distance direction can be performed. For more details, refer to "Japanese Patent Laid-Open No. 2016-022261" by the applicant. The control unit 70 may detect the alignment state based on the index image included in the observation image in at least one of the working distance direction and the direction intersecting the working distance direction.

The alignment is not necessarily limited to this, and an observation image of the anterior segment acquired by an anterior segment observation system (anterior segment camera) (not shown) may be used for alignment. By moving the housing with the built-in imaging optical system relative to the eye E to be inspected while checking the observation image of the anterior eye, the device and the eye to be inspected are adjusted to a positional relationship suitable for fundus photography. You may.

The alignment as described above may be a manual alignment in which the examiner manually adjusts the alignment, or an auto alignment method in which the control unit 70 automatically adjusts the alignment. In the auto-alignment method, the actuator for adjusting the positional relationship between the photographing optical system 10 and the eye to be inspected E corresponds to the observed image so that the photographing optical system 10 and the eye to be inspected E have a positional relationship suitable for photographing. It is driven and controlled by the control unit 70.

Next, autofocus (correction of diopter of the photographing optical system) is performed. First, the control unit 70 switches the number of pixels of the fundus image formed as the observation image. More specifically, the number of pixels is set to be smaller than that of the captured image (S4). Here, the fundus image having the number of pixels: 512 × 512 is set so as to be obtained as an observation image. As a result, the fundus image per frame can be acquired in a shorter time than the captured image. In this state, the diopter correction process is executed (S5).

In the diopter correction process (S5), the control unit 70 drives and controls the lens 14 to change the diopter correction amount, and the observation image acquired at any time based on the signals from the light receiving elements 25, 27, 29. The imaging state in each of the above is evaluated.

For example, the control unit 70 may perform differential processing on the image data of the observation image and evaluate the imaging state by using the differential histogram information based on the result of the differential processing. The differential histogram information may be obtained as a histogram of the contour image after converting the image data of the observed image into a contour image by applying a filter for edge extraction (for example, Laplacian conversion, SOBEL, etc.).

FIG. 8 is a diagram showing an example of a differential histogram. In FIG. 8, the horizontal axis represents the absolute value of the differential (hereinafter abbreviated as the differential value) d (d = 1, 2, ... 254), and the vertical axis represents the number of pixels H (d) corresponding to each differential value. , Each of which is normalized by the number of pixels H (dp) in the differential value showing the peak number of pixels ((H (d) / H (dp)) is expressed as a percentage (%). In the histogram of 8, the data of two points (d = 0, d = 255) are excluded. Here, the differential value d represents the brightness value in the contour image in 255 gradations. ..

Here, the control unit 70 uses the maximum value of the luminance value (differential value) having the number of pixels of a predetermined ratio or more in the entire image in the histogram information acquired as described above to form an image of the SLO fundus image. Focus state) Calculate the evaluation value. For example, as the imaging state evaluation value C1 for evaluating the imaging state of the SLO fundus image, the difference between the maximum value Dmax and the minimum value Dmin of the differential values above the threshold value S1 (for example, 20%) in the differential histogram is obtained. (C1 = Dmax-Dmin). The threshold value S1 is set to a value such that the evaluation value C1 changes sensitively to a change in the imaging state of the SLO fundus image while avoiding the influence of noise. Further, in the above, only the maximum value Dmax of the differential value at the threshold value S1 or higher may be set as the imaging state evaluation value C1.

The image formation state evaluation value C1 shows a high value when the lens 14 is in the in-focus position (when the photographing optical system is in focus), and becomes lower as the lens 14 deviates from the in-focus position. It can be used to determine the focus state (imaging state) in SLO1.

The control unit 70 samples the imaging state evaluation value C1 while moving the position of the lens 14, determines the focusing state based on the sampling result, and drives the lens 14 to the focusing position.

For example, the control unit 70 drives and controls the drive mechanism 40a in order to search for an appropriate focus position, and moves the lens 14 to a plurality of movement positions discretely set in the movable range of the lens 14, respectively. Acquire a fundus image at the moving position. For example, -12D to + 12D
The lens 14 is moved within the range of. Then, the control unit 70 creates a differential histogram of each of the fundus images acquired for each moving position, and calculates the imaging state evaluation value C1 respectively. In this case, the control unit 70 may continuously move the lens 14 to continuously calculate the image formation state evaluation value C1.

The image formation state evaluation value C1 is a discrete value for each position of the sampled lens 14. The control unit 70 may select the position having the largest image formation state evaluation value C1 from the positions of the lens 14 on which sampling has been executed as the focusing position. However, it is not necessarily limited to this. For example, the imaging state evaluation value C1 corresponding to the intermediate position of the position of each of the sampled lenses 14 may be derived by performing interpolation processing such as curve approximation on the sampling result. Then, a more accurate focusing position may be estimated from the result of the interpolation processing. As a method for detecting the in-focus position by the above interpolation processing, a function approximation, a center of gravity, a calculation of an average value, or the like may be used.

As described above, autofocus is roughly performed using a fundus image having a relatively small number of pixels. Further, in this embodiment, more precise autofocus may be subsequently performed using a fundus image having a larger number of pixels. That is, the control unit 70 increases the number of pixels of the fundus image formed as the observation image when the rough autofocus is executed. In the case of this embodiment, since the fundus image having 512 × 512 pixels was used in the rough autofocus, for example, the control unit 70 has any one of 1024 × 1024, 2048 × 2048, and 4096 × 4096. To form a fundus image. Then, while moving the lens 14 in the vicinity of the in-focus position obtained by rough autofocus, the imaging state of each fundus image obtained with the movement of the lens 14 is evaluated (in this embodiment, the conclusion). Image state evaluation value C1 is obtained). Then, for example, the in-focus position may be detected again by comparing the imaging states of the fundus images at each position of the lens 14 with each other. By moving the lens 14 to this in-focus position, the focus adjustment in the present embodiment is completed. In this embodiment, after the focus adjustment is completed, the control unit 70 sets the number of pixels of the observation image to 1024 × 1024 (S7).

When the imaging state evaluation value C1 is sampled as described above, the movement of the lens 14 may be stopped when the imaging state evaluation value C1 starts to rise and then falls.

The diopter correction start trigger may be, for example, that the control unit 70 automatically detects the completion of alignment, or that a predetermined operation is input by the examiner.

After that, other shooting conditions are set (S8). For example, the examiner's operation is input to specify the shooting conditions. For example, one of infrared imaging, color imaging, IA (indocyanine green fluorescence contrast), FA (fluorescein fluorescence contrast), and FAF (fundus spontaneous fluorescence imaging) is selected by the examiner, and the selected imaging method is selected. The control unit 70 may set the shooting conditions corresponding to the above. Specific examples of the shooting conditions include the wavelength of the laser light, the amount of the illumination light, the gain of the received signal, and the like.

The control unit 70 captures a fundus image based on a trigger signal (for example, a release operation signal or the like). The shooting conditions and image formation conditions at the time of capture reflect the results of various adjustments so far. For example, in this embodiment, the in-focus position at the time of capture is the position set by the adjustment by the process of S5. As described above, in this embodiment, a still image having the number of pixels: 2048 × 2048 is acquired as a result of capture.

In addition, in the fundus image, when the deviation between the pixel array by the outward scan and the pixel array by the return scan becomes a problem, the image in which the deviation is corrected may be acquired as a result of the capture.

Although the description has been given above based on the embodiment, the content of the embodiment can be appropriately changed in carrying out the present disclosure.

For example, in the embodiment, the focus (diopter of the device) has been described as being adjusted based on the second image, but the present invention is not necessarily limited to this, and the second image is used when adjusting other conditions. May be used. For example, the positional deviation between the pixel sequence due to the outward scan and the pixel array due to the return scan may be detected based on the second image. Further, the positional relationship between the eye to be inspected and the photographing optical system (alignment state of SLO1) may be detected based on the second image. The control unit 70 may switch the image acquisition control so that the second image is temporarily acquired as an observation image when performing each detection. This makes it easier to adjust each condition in a short time.

Further, for example, in the above embodiment, the diopter adjustment unit 40 is driven when correcting the pixel reading timings of the outward scanning and the inbound scanning using the reflected image of the lens, so that the eye to be inspected is observed during that time. And shooting becomes difficult. Therefore, for example, the SLO1 may further have a second correction control process for detecting and correcting the deviation between the first pixel row and the second pixel row based on the image of the eye to be inspected. For example, the second correction control process may be repeatedly executed at regular intervals during the acquisition of the observation image. On the other hand, the correction process using the reflected image of the lens is a shooting method in which shooting is continuously performed by different shooting methods when the device is started, the subject is changed, the device returns from the sleep state, and so on. It may be executed at the time of switching.

When the deviation between the first pixel row and the second pixel row is detected and corrected based on the image of the eye to be inspected, the deviation is not necessarily detected and corrected each time the image of the eye to be inspected is acquired. There is no. For example, when displaying or analyzing the acquired image, the image of the eye to be inspected acquired in advance may be processed to detect and correct the deviation. In this case, the amount of correction for the deviation in each image to be inspected may be set based on the images of the eyes to be inspected in a plurality of frames obtained in time series.

For example, as described above, the SLO1 according to the embodiment may be integrated with an optical coherence tomography (OCT). In this case, the control unit 70 may reflect the focus adjustment result of the SLO1 described above in the OCT optical system. Specifically, at least the diopter adjusting unit 40 may be shared between the photographing optical system of SLO1 and the OCT optical system. Further, not limited to this, the diopter adjusting unit in the OCT optical system may be separate from the diopter adjusting unit 40 of SLO1. In this case, for example, the diopter adjusting unit in the OCT optical system has a structure that is mechanically interlocked with the diopter adjusting unit 40 of SLO1 and the diopter adjusting unit 40 of SLO1 so that the diopter correction amount is the same value as each other. It may be.

10 Irradiation optical system 11 Light source 16 Scanning unit 20 Light receiving optical system 25, 27, 29 Light receiving element 70 Control unit

Claims (4)

An imaging optical system having an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a light receiving optical system having a light receiving element that at least receives the return light from the eye to be inspected.
An image forming means for acquiring a front image of the eye to be inspected as a captured image based on a signal from the light receiving element, and an image forming means.
The time required to form an image per frame is shorter than that of the captured image. A second image based on the front image is formed by the image forming means based on a signal from the light receiving element, and at least the conditions relating to the captured image are met. A condition setting means for setting one based on the second image, and
A fundus photography apparatus including a photographing execution means for capturing the captured image under the set conditions. An imaging optical system having an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a light receiving optical system having a light receiving element that at least receives the return light from the eye to be inspected.
An image forming means for acquiring an OCT image of an eye to be inspected as a captured image based on a signal from the light receiving element, and an image forming means.
The time required to form an image per frame is shorter than that of the captured image. A second image based on the OCT image is formed by the image forming means based on a signal from the light receiving element, and as a condition for the captured image, A condition setting means for setting at least one of the focus, the optical path length difference between the measurement light and the reference light, and the polarization by the polarizer based on the second image.
A fundus photography apparatus including a photographing execution means for capturing the captured image under the set conditions. An imaging optical system having an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a light receiving optical system having a light receiving element that at least receives the return light from the eye to be inspected.
An image forming means for acquiring a photographed image of an eye to be inspected based on a signal from the light receiving element, and an image forming means.
A second image, which takes less time to form an image per frame than the captured image, is formed by the image forming means based on a signal from the light receiving element, and at least one of the conditions relating to the captured image is satisfied. Condition setting means to be set based on the second image,
A shooting execution means for capturing the shot image under the set conditions is provided.
The condition is a focus adjustment amount der Ru ophthalmology imaging apparatus of the ophthalmologic photographing apparatus. An imaging optical system having an irradiation optical system that irradiates an eye to be inspected while scanning light from a light source by a scanning unit, and a light receiving optical system having a light receiving element that at least receives the return light from the eye to be inspected.
An image forming means for acquiring a photographed image of an eye to be inspected based on a signal from the light receiving element, and an image forming means.
A second image, which takes less time to form an image per frame than the captured image, is formed by the image forming means based on a signal from the light receiving element, and at least one of the conditions relating to the captured image is satisfied. Condition setting means to be set based on the second image,
A shooting execution means for capturing the shot image under the set conditions is provided.
The condition is output from the light source, and, at least one Der Ru ophthalmology imaging apparatus of the amplification factor of the signal from the light receiving element.

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