JP2016028786A - Fundus imaging apparatus, method of controlling fundus imaging apparatus, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform wavefront correction, even when a position of a subject eye shifts, corresponding thereto.SOLUTION: A fundus imaging apparatus which images a fundus oculi of a subject eye which is irradiated with illumination light through an optical system comprises: a position detection section for detecting a position of a pupil of the subject eye; a wavefront detection section for detecting a wavefront of return light from the subject eye; a correction section for correcting the wavefront of the return light on the basis of the detected wavefront; and a control section for performing control so as to set a correction effective region of the correction section on the basis of the detected position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fundus imaging apparatus, a fundus imaging apparatus control method, and a program, and more particularly, to a fundus imaging apparatus having an adaptive optical function, a fundus imaging apparatus control method, and a program.

  As a fundus imaging device for observing and capturing a front two-dimensional image of a retina of a subject eye and a tomographic image, a fundus camera, a laser scanning ophthalmoscope (SLO), an optical coherence tomography (OCT) Is well known and has been in practical use for a long time.

  These illuminate the retina to be imaged with illumination light and focus the return light from the retina on the light receiving element to obtain a retinal image, or interfere with reference light to obtain a tomographic image. is there. As the illumination light, light having a wavelength of near-infrared light with little absorption and scattering in a transmissive living tissue (for example, cornea, crystalline lens, glass body) in the eye to be examined is often used.

  The spatial resolution (hereinafter referred to as “lateral resolution”) of the acquired image in the plane direction (lateral direction) of the retina is basically determined by the beam spot diameter (or the numerical aperture of the optical system) scanned on the retina. . In order to reduce the diameter of the beam spot collected on the retina, it is only necessary to increase the diameter of the illumination light incident on the eye to be examined (or increase the numerical aperture of the optical system).

  However, the cornea and the crystalline lens, which are mainly affected by refraction in the eye to be examined, have incomplete uniformity in the curved surface shape and refractive index, and generate higher-order aberrations in the wavefront of light passing through them. For this reason, even when illumination light having a large light beam diameter is incident, the spot on the retina may not be condensed to a desired diameter, but rather may spread.

  As a result, the lateral resolution of the obtained image is lowered, and the S / N of the image signal acquired in the confocal optical system is also deteriorated. Therefore, conventionally, a thin beam of about 1 mm which is not easily affected by the aberration of the optical system such as the cornea of the eye to be inspected is generally incident, and a spot of about 20 μm is formed on the retina.

  In order to solve such problems, adaptive optics technology is being introduced also in fundus imaging devices. This is because the wavefront aberration of the return light from the measurement object, which occurs due to the characteristics of the measurement object itself such as the eye and fluctuations in the measurement environment, is sequentially measured by the wavefront sensor, and active objects such as deformable mirrors and spatial light modulators are used. This is corrected by a simple wavefront corrector. So far, even if a thick beam of about 7 mm is incident on the subject's eye using this technique, the spot diameter on the retina can be condensed to about 3 μm, which is close to the diffraction limit, by wavefront compensation. The example which acquired the image of OCT has been reported (refer nonpatent literature 1).

Japanese Patent No. 0451534

R. Zawadzki et. al. "Ultrahigh-resolution optical coherence with monochromic with chromatographic and chromatographic correction", OPTICS EXPRESS / Vol.16, No. 11/2008. Seiichi Mishima et al. “Eye development and aging [Ophthalmology MOOK No.38]”, Kanehara Publishing, 1989

  In a fundus imaging apparatus using adaptive optics, one of the major factors that make it difficult to acquire a stable image is that the pupil (iris) position of the eye to be examined fluctuates. This occurs because the subject's head moves back and forth and right and left during measurement, and various eyeball rotations are unavoidable even when trying to fix the line of sight by observing the fixation lamp. .

  Although it is possible to suppress the fluctuation of the head by using a bite bar, there is a case where it is not preferable because it places a burden on the subject. In addition, there are individual differences in the strengths and weaknesses of continuing to watch the fixation lamp stably.

  When head position variation, that is, pupil position variation of the eye to be examined occurs in a direction perpendicular to the optical axis of the eyepiece optical system, first, wavefront correction is first placed at a position optically conjugate with the pupil. On the vessel, there also arises a problem that the return light (reflected / backscattered light) from the retina is also shifted. At this time, when the wavefront feedback correction is performed in an open loop, the return light is shifted and incident on the wavefront correction value formed on the wavefront corrector. This leads to image degradation, such as a reduction in resolution.

  The generation of wavefront correction values is generally expressed by the addition of orthogonal functional systems such as Zernike polynomials, but even when using a closed-loop real-time wavefront correction method, it is difficult to express this shift. If the next function is not used, the reproducibility of the curved surface deteriorates. If the order is limited to shorten the calculation time, the wavefront correction is not ideally performed, which causes the image deterioration as described above.

  Secondly, there arises a problem that illumination light for image acquisition is kicked (restricted) by the pupil of the eye to be examined. For example, when it is desired to form a 3 μm spot on the retina, illumination light having a diameter of about 7 mm needs to be incident on the pupil, but the iris is usually about 8 mm even when it is wide open.

  In such a case, if the head moves 1 to 2 mm over time, the spot diameter on the retina is enlarged to 4 to 5 μm and the resolution deteriorates even if aberration correction is appropriately performed. become. Moreover, since the amount of illumination light reaching the retina is also lost by 10 to 20% due to “kicking”, the brightness of the image also decreases.

  Third, the pupil, wavefront corrector, and wavefront detector of the eye to be examined are placed at optically conjugate positions by the afocal optical system. However, if the pupil moves, the return light is reduced from the effective diameter of the optical system. If it deviates even in the part, the coincidence of the wave fronts at the respective positions deteriorates. Therefore, the feedback accuracy of the wavefront correction is deteriorated, and there is a problem that it takes time for convergence or diverges without convergence.

  The following solution is proposed in Patent Document 1 for the first problem. This includes means for observing the anterior segment including the pupil, thereby measuring the amount of pupil position fluctuation in real time and tracking the position of the wavefront corrector placed on the mechanical stage according to the calculated value. The correction effective range and the position of the return light from the retina are always matched.

  However, with this configuration, the first problem can be solved, but the second problem cannot be solved. There is no mention of the third problem. Furthermore, since the wavefront corrector generally has a volume of about several centimeters to 10 centimeters, the size of the mechanical stage to be employed is increased, the system is enlarged, and the cost is increased. There is also concern about the effect on image quality due to vibration.

  In view of the above problems, an object of the present invention is to provide a technique capable of performing wavefront correction corresponding to a shift in the position of the eye to be examined.

A fundus imaging apparatus according to the present invention that achieves the above-described object,
A fundus imaging apparatus that images the fundus of an eye to be examined that has been irradiated with illumination light through an optical system,
Position detecting means for detecting the position of the pupil of the eye to be examined;
Wavefront detection means for detecting the wavefront of the return light from the eye;
Correction means for correcting the wavefront of the return light based on the detected wavefront;
Control means for controlling to set a correction effective area of the correction means based on the detected position;
It is characterized by providing.

  According to the present invention, even if the position of the eye to be examined is shifted, wavefront correction is performed correspondingly, and a bright and high-resolution image can be stably obtained.

The block diagram of SLO which concerns on 1st Embodiment of this invention. The figure showing the positional relationship of the pupil of a to-be-tested eye and illumination light. The figure showing the positional relationship of illumination light and the return light from the eye to be examined. The figure showing the positional relationship of the illumination light and return light on a wavefront correction device. The figure showing the position of the return light on a wavefront detector. The conceptual diagram which concerns on 1st Embodiment of this invention. The block diagram of SLO which concerns on 2nd Embodiment of this invention. The block diagram of the adaptive optics part which concerns on 3rd Embodiment of this invention. The conceptual diagram of the wavefront corrector in 3rd Embodiment of this invention. The figure showing the statistical data of a pupil diameter.

(First embodiment)
First, the configuration of a laser scanning ophthalmoscope (SLO) according to the first embodiment of the present invention will be described with reference to FIG. In the SLO 100 shown here, first, light from the image acquisition laser light source 6 propagates through the single mode fiber 60 and is emitted as illumination light 90 from the fiber end. The emitted illumination light 90 is converted into parallel light by the collimator lens 71 (the broken line represents the marginal ray of the illumination light 90 and the effective diameter range of the optical system).

  The illumination light 90 converted into parallel light passes through the half mirror 76, is reflected by the first dichroic mirror 77, is reflected by the wavefront corrector 2 through the first afocal optical system 73, and then the second light. The light enters the scanner mirror 5 through the afocal optical system 74. The illumination light 90 reflected by the scanner mirror 5 is incident on the eye 11 to be examined (illustrated by a broken line) by the eyepiece optical system 75 and condensed on the retina 111.

At this time, the diameter of the exit pupil 9 of the eyepiece optical system 75 and the luminous flux of the illumination light 90 (the diameter of the region where the intensity is 1 / e ^{2 of the} central intensity (e is the base of the natural logarithm)) is the diameter of the pupil of the eye 11 to be examined. It is set larger than (pupil diameter). Accordingly, the effective diameters of the first and second afocal optical systems 73 and 74, the collimator lens 71, and the imaging lens 72 are also set larger than the pupil diameter (pupil diameter) of the eye 11 to be examined. Although the pupil diameter varies depending on the individual, according to the investigation example shown in FIG. 10 (see Non-Patent Document 2), the maximum diameter is about φ8 mm even when no mydriatic is used. Increase the value of pupil 9. Here, it is assumed that a mydriatic agent is used, and φ12 mm is set in consideration of a possible pupil shift amount of the eye 11 to be examined.

  Here, the eye to be examined 11 represents the eye to be examined when the optical axis 10 (one-dot chain line) of the optical system is coincident with the center of the pupil. The return light 91 from the retina 111 of the eye to be examined 11 propagates backward in the optical path of the illumination light 90, is reflected by the half mirror 76, is collected by the imaging lens 72, passes through the pinhole 41, and is light. It is detected by the detector 4. Here, the marginal ray of the return light 91 is indicated by a dotted line. The scanner mirror 5 is driven by the driver 50, scans the illumination light 90 in a two-dimensional direction, and captures an electrical signal from the photodetector 4 in the personal computer 8 to acquire a retina image (fundus image).

  On the other hand, the wavefront detection light 63 (two-dot chain line) generated from the light source 62 is reflected by the second dichroic mirror 78 and enters the eye 11 to be examined. Here, the second dichroic mirror 78 has a transmittance close to 100% for the wavelength of the light source 6 and a transmittance of 50% for the wavelength of the light source 62. Since the wavefront detection light 63 has a light beam diameter of about φ1 mm, it is hardly affected by the aberration of the eye and forms a spot diameter of about φ20 μm stably on the retina 111.

  Since the return light from the retina 111 by the wavefront detection light 63 includes a large amount of scattered (diffused) light and has a spread, the same diameter as the pupil diameter from the pupil of the eye 11 to be examined, like the return light 91 by the illumination light 90. Is emitted as a luminous flux having Thereafter, the light passes through the second dichroic mirror 78, passes through the first dichroic mirror 77 via the optical system 75 to the optical system 73, and the wavefront is detected in the detection region of the wavefront detector 3. The wavefront corrector 2 corrects the wavefront of the return light 91 by using the data detected and calculated here.

  With the above configuration, the illumination light 90 for image acquisition is appropriately imaged on the retina 111, and the return light 91 is also appropriately imaged on the pinhole 41, thereby reducing the influence of the aberration of the eye 11 to be examined. Thus, a bright and high-resolution image can be obtained stably.

  Here, a variable shape mirror is used as the wavefront corrector 2, and a Hartmann-Shack detector (HS sensor) is used as the wavefront detector 3. The effective diameters (drive regions) are φ12 mm and φ6 mm, respectively, and the magnifications of these positions with respect to the exit pupil 9 of the optical system are β2 = 12/12 = 1.0 and β3 = 6/12 = 0.5, respectively. Is set. If the pupil diameter of the eye 111 to be examined is φ6 mm, the return light diameter at the position of the exit pupil 9 is also φ6 mm. Therefore, the return light from the wavefront corrector 2 (shape variable mirror 2) and the wavefront detector 3 (HS sensor 3). The diameters of 91 are φ6 mm and φ3 mm, respectively.

  The HS sensor 3 calculates the wavefront of the measurement light from the displacement of each point image formed on the two-dimensional image sensor by each microlens arranged in a two-dimensional matrix. A collection of these point images (HS image) is observed in a range of φ3 mm corresponding to the pupil on a two-dimensional element.

  On the other hand, consider a case where the eye 11 to be examined moves on the xy plane perpendicular to the optical axis (z direction) and moves to the position of the eye 12 to be shown by a solid line. At this time, if the light beam diameter of the illumination light 90 is equal to or smaller than the diameter of the pupil 122 of the eye 12 to be examined, the pupil 122 is relative to the optical axis 10 of the optical system, that is, the illumination light 90 as shown in FIG. The illumination light 90 is partly “kicked” by the pupil 122, the amount of illumination light reaching the retina 121 decreases, and at the same time the light beam is kicked, The spot diameter formed on the top also increases. As shown in FIG. 3, the light beam of the illumination light 90 is “kicked”, but the return light 92 from the retina 121 contains a large amount of scattered (diffused) light and has a spread, so that from the pupil 122 of the eye 12 to be examined, It is emitted as a light beam having the same diameter as the pupil diameter. However, since the position of the pupil 122 is shifted with respect to the optical axis 10, the same shift is maintained at a position optically conjugate with the pupil position. FIG. 4 shows the positional relationship between the illumination light 90 and the return light 92 on the variable shape mirror 2. The chief ray of the illumination light 90 represented by the broken line coincides with the optical axis 10, but the return light 92 represented by the solid line is shifted and enters the variable shape mirror 2.

  Here, if the center of the effective correction area 21 indicated by the dotted line is aligned with the optical axis 10, the wavefront correction is performed spatially shifted with respect to the aberration of the return light 92. Aberration is not corrected. Therefore, the return light 92 is not properly condensed on the pinhole 41, and the brightness and resolution of the retinal image are not improved. This phenomenon is the same in the positional relationship between the illumination light 90 to which the inverse component of aberration is given by the deformable mirror 2 and the pupil 122, and the illumination light 90 is not condensed on the retina 121 to a desired spot diameter. become.

  The effective diameter of the entire optical system is also equal to the diameter of the illumination light 90. If the effective correction area 21 of the deformable mirror 2 is equal to the effective diameter of the optical system, the return light 91 is outside the effective diameter of the optical system. Will pass. Also on the deformable mirror 2, it is outside the effective correction range, and the wavefront is not corrected correctly. In addition, since the optical conjugate relationship (pupil imaging relationship) among the pupil 122, the shape variable mirror 2, and the HS sensor 3 is partially broken, the wavefront shapes at the respective positions are not matched, and thus Correct correction becomes difficult.

  On the other hand, in the present embodiment, the HS sensor 3 is used to detect the shift amount with respect to the optical axis 10 of the optical system of the eye 12 to be examined, and the correction effective region 21 on the deformable mirror 2 is shifted to the return light 92. It is configured to follow the position of. Assuming now that the eye 11 to be examined is shifted from the optical axis 10 and is at the position of the eye 12 to be examined, the HS image 30 on the HS sensor 3 is also observed to be shifted with respect to the optical axis 10 as shown in FIG. The Accordingly, if the center coordinates (x3, y3) of the HS image 30 are calculated, the coordinates of the center position of the pupil 122 of the eye to be examined are obtained as (xp, yp) = (x3 / β3, y3 / β3). At the same time, the center coordinates of the return light 92 on the deformable mirror 2 are also obtained as (x2, y2) = (x3 · β2 / β3, y3 · β2 / β3). Should be set to this value. As a configuration for detecting the shift amount of the pupil 122, the position information of the HS image obtained by the HS sensor 3 is used in the position detection process according to the present embodiment. However, the present invention is not limited thereto, and an anterior ocular segment observation system that images the anterior ocular segment with a camera may be provided, and the eye position to be examined may be detected from the positional information of the pupil image as the obtained observation result.

  A conceptual diagram at this time is shown in FIG. Only the xz cross section is considered here. Now, the principal ray 921 of the return light 92 is incident on the optical axis (center of the deformable mirror 2) 10 with a shift of x2. At this time, the correction function shape 22 measured and calculated by the HS sensor 3 is formed in the correction effective area 21, but the center of the correction effective area 21 remains the optical axis 10 as shown in FIG. , The return light 92 does not match. Here, as shown in FIG. 6 (b), the centers of the correction effective area 21 and the correction function shape 22 are shifted by the value of x2 simultaneously measured and calculated by the HS sensor 3, and the main part of the return light 92 is shifted. It matches with the position of the light ray 921. In FIG. 1, the solid line portion on the wavefront 2 corresponds to the correction effective area 21. Thereby, the return light 92 is appropriately corrected for aberrations without being inconsistent with the correction effective area 21.

  For example, consider a case where a Zernike polynomial is used to represent a measured wavefront. When used when expressing the aberration of the eye, each term is represented by the relationship of the following item number, order, and mathematical expression.

Term number Order Formula 0 0 1
1 1 2y
2 1 2x
3 2 2√6 · xy
4 2 √3 (2x ² + 2y ² -1)
5 2 √6 (x ² −y ² )
6 3 √8 (3x ² y−y ³ )
7 3 √8 (3x ² y + 3y ² -2y)
8 3 √8 (3x ³ + 3xy ² -2x)
9 3 √8 (x ³ -3xy ² )
10 4 ・
11 4 ・
12 4 ・
・ ・ ・
・ ・ ・
Each term corresponds to each aberration item of optics, and wavefront aberration is expressed as a corrected shape function W (x, y) obtained by multiplying these by a coefficient. In the aberration correction, coefficients applied to these terms are used as parameters for the feedback operation.

  The correction function shape W ′ (x, y) can be expressed by these coefficients including the pupil shift as well as the aberration component corresponding to each originally included item. However, in order to ensure the accuracy of the correction function shape, a larger number of terms are required, and a longer calculation time is required. Conversely, if the number of terms is limited, the accuracy of the correction function shape is reduced.

  Here, using the value of (x2, y2) detected and calculated by the HS sensor 3, W (x-x2, y-y2) is used as a corrected shape function formed on the deformable mirror 2. As a result, it is possible to form the correction function with high accuracy with as few terms as possible. Accordingly, it is possible to make the return light 92 and the correction function in the correction effective region coincide with each other without requiring a mechanism for moving the variable shape mirror itself.

  On the other hand, illumination light is also considered. Even in the subject eye 12 shifted from the optical axis 10, in order to prevent the light beam from being kicked, the light beam diameter of the illumination light 90 should be set to a value obtained by adding the assumed shift amount of the pupil 122 to the pupil diameter. That's fine. In this embodiment, since the exit pupil of the optical system is φ12 mm, the luminous flux diameter of the illumination light is also made equal. At this time, since the diameter of the pupil 122 is 6 mm, the illumination light is not always kicked into the pupil 122 even if the pupil is shifted by ± 3 mm, and both the incident light quantity and the light beam diameter are stably incident. Accordingly, the illumination light 90 and the return light 92 incident on the eye 12 to be inspected always coincide with each other as a light beam having a marginal ray represented by a solid line in FIG.

  Further, if the luminous flux of the illumination light 90 and the return light 92 are controlled within the effective diameter range of the optical system, the pupil imaging relationship among the pupil 122, the deformable mirror 2, and the HS sensor 3 is not broken. Wavefront correction is performed appropriately.

  In this embodiment, the diameter of the illumination light beam incident on the eye 12 to be examined is determined by the diameter of the pupil 122. In this case, the larger the diameter of the pupil 122 is, the more the wavefront correction is performed. The spot diameter on the retina becomes smaller. At this time, as the spot diameter becomes smaller, the irradiation energy per area increases, so the burden on the subject increases. Therefore, in the present embodiment, not only the position of the return light 92 but also the beam diameter is calculated from the HS image by the HS sensor 3, and the light emission amount of the illumination light source 6 is adjusted as needed according to the value (light amount control process). .

  Further, in this embodiment, the wavefront detection light 63 is fixed so as to be incident on the subject's eye after being shifted by about 2 mm from the optical axis 10 of the optical system. However, depending on the detected shift amount of the subject's eye 12, The position may be followed. In FIG. 1, the light is incident immediately before the eye to be examined, but may be incident from the light source side of the scanner mirror 5.

  As described above, according to the present embodiment, there is no spatial mismatch between the illumination light 90 and the return light 92, and the wavefront correction is appropriately performed in the deformable mirror, and the return light is stably supplied to the pinhole 41. Is imaged. In addition, it is possible to obtain a stable retinal image with appropriate utilization efficiency without causing light loss or spot diameter enlargement due to illumination light kicking.

(Second Embodiment)
Next, the SLO 101 according to the second embodiment of the present invention will be described with reference to FIG. The basic configuration and the reference numerals of the respective parts are the same as those of the first embodiment described with reference to FIG. 1, and FIG. 7 shows an xz cross section. The difference from the case of FIG. 1 is that the light beam diameter of the illumination light 90 is φ6 mm, which is the same as the diameter of the pupil of the eye to be examined. That is. The illumination light 90 collimated by the collimator lens 71 is reflected at a substantially right angle by the mirror 79 and propagates through the optical system after the first half mirror. Further, the mirror 79 is installed on a mechanical mechanism that shifts in the optical axis direction of the reflected light. In this embodiment, the illumination light 90 for image acquisition also serves as wavefront detection light, and 77 is not a dichroic mirror, but a half mirror having a transmittance of 10% and a reflectance of 90%. The second dichroic mirror 78 is not installed.

  When the eye 11 to be examined is at a position where there is no shift from the optical axis 10, the mirror 79 is at the reference position (the position indicated by the broken line), and the illumination light 90 propagates as a light beam having a marginal ray represented by a dotted line, It enters the eye 11 to be examined. When the eye 12 is in the position shifted in the x direction, the mirror 79 is set to the position indicated by the solid line shifted by the shift amount x3 of the return light 92 detected by the HS sensor 3.

  By this method, the illumination light 90 can be matched with the pupil 122 at any time, and the return beam 92 and the illumination light 90 can be matched with each other by preventing the light beam from being kicked. Here, only the shift in the x direction was considered. However, if you want to follow the y direction as well, another mirror is installed near the mirror 79 to reflect the illumination light in the yz cross-sectional direction, and a mechanism to shift in the reflected optical axis direction is added. Then, it is possible to correspond to a two-dimensional shift of the pupil 122 in the xy direction. Further, the same function can be obtained by using the exit end of the fiber 60 and the collimator lens 71 as one unit without using the mirror 79 and providing a mechanism for shifting the unit in the xy direction. The correction effective area 21 of the deformable mirror 2 is controlled so as to always match the illumination light 90 and the return light 92 as in the first embodiment.

  According to the configuration of the present embodiment, it is possible to acquire a stable image while keeping the spot diameter of the illumination light on the retina constant regardless of the pupil diameter of the eye to be examined.

(Third embodiment)
The adaptive optics unit 102 of the fundus imaging apparatus according to the third embodiment will be described with reference to FIG. Here, only the portion showing the relationship between the eye to be examined and the wavefront corrector 2 is shown. The reference numerals of the respective parts are the same as those of the first embodiment described with reference to FIG. 1, and FIG. 8 shows an xz cross section. In this embodiment, a phase spatial modulator (SLM) using liquid crystal is used as the wavefront corrector 2. The variable shape mirror changes the shape of the mirror to change the spatial distance to change the optical path length, whereas the SLM changes the refractive index of the liquid crystal to change the optical path length as refractive index x spatial distance. By doing so, the wavefront is corrected. Although a transmissive SLM is shown in FIG. 8, a reflective type may be used.

  In FIG. 8, the pupil 122 of the eye 12 to be examined and the SLM 2 are arranged in an optically conjugate relationship by the optical system 70. It is assumed that the optical system 70 includes the optical systems 74 and 75 and the scanner mirror 5 in the configuration shown in FIGS. Light beams 900 and 901 indicated by diagonal lines indicate illumination light, and light beams having marginal rays indicated by broken lines indicate return light. The broken line also indicates the effective diameter of the optical system. The SLM 2 has an effective diameter equivalent to that of the optical system.

  When the illumination light 900 is incident on the SLM 2, the phase is modulated in accordance with the corrected shape function W (x, y) detected and calculated by a wavefront detector (not shown), and incident on the optical system 70 and the pupil 122 of the eye 12 to be examined. Then, the light is condensed on the retina 12 by the anterior eye optical system of the eye 12 to be examined. The return light 920 from the retina 12 is emitted after being given aberration at the anterior eye part, re-entered into the SLM 2 via the optical system 70, modulated and emitted from the SLM 2, via an optical system not shown. It is detected by a detector.

  Now, in the SLM2, the correction shape function W (x, y) is displayed only within the correction effective area 21, and only the light transmitted through this range is corrected for the wavefront in both the illumination light 900 and the return light 920. ing. Further, the center of the effective correction area 21 is set from time to time based on the shift amount of the eye 12 detected and calculated by the wavefront detector 3 as in the first and second embodiments.

  FIG. 9 shows how the SLM2 surface is modulated. A rectangular frame 20 is a modulation driving area of the SLM 2. The center 10 is the optical axis of the optical system. A broken line 900 (920) indicates incident illumination light or return light, and 21 indicates a correction effective area. A large number of curves shown in the modulation drive region 20 indicate a collection of points where the phase modulation amount is a multiple of 2π (correction amount expressed in wavelength units).

  Here, the correction shape function W (x, y) is displayed in the correction effective region 21 as described above, and the outer region 22 has a concentric circle whose phase modulation amount is 2π units with the center 10 as a reference. Is modulated so that many are displayed at small intervals. This corresponds to the fact that a diffraction grating having an optical power is set so that the diffraction direction becomes large. If appropriate modulation is performed so that the diffraction direction is away from the optical axis 10 (so that the diffraction power is negative), the light 902 transmitted through the region 22 deviates from the effective diameter of the optical system 70 and is applied to the eye 12 to be examined. Does not reach. The same applies to the return light, and the light 922 transmitted through the region 22 does not pass through the subsequent optical system and is not detected by the detector.

  With this configuration, even if there are individual differences and fluctuations in the pupil diameter, the beam diameter of the illumination light 901 incident on the eye 12 to be examined is made constant without using a mechanical mechanism, and the spot diameter (resolution) on the retina 121 is made constant. It is possible to obtain a picture with stable brightness and resolution. If necessary, the correction effective diameter 21 and the amount of illumination light can be set to capture an image with a desired resolution.

  In the above embodiment, the SLO has been described as an example. However, as an application example, the same effect can be obtained in an OCT or a fundus camera.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  2: wavefront corrector, 3: wavefront detector, 4: light detector, 5: scanner mirror, 9: exit pupil, 11: eye to be examined, 21: correction effective area, 41: pinhole, 50: driver, 71: Collimator lens, 72: imaging lens, 73: first afocal optical system, 74: second afocal optical system, 75: eyepiece optical system, 76: half mirror, 77: first dichroic mirror, 78: Second dichroic mirror, 100: SLO, 111: Retina

A fundus imaging apparatus according to the present invention that achieves the above-described object,
A fundus imaging apparatus that images the fundus of an eye to be examined that has been irradiated with illumination light through an optical system,
Wavefront detection means for detecting the wavefront of the return light from the eye;
Based on the detected wavefront, correction means for correcting the wavefront of the return light by the correction effective area set in the drive region ;
A correction effective area set in the drive area of the correction means and a position detection means for detecting a positional deviation of the return light on the drive area of the correction means;
Control means for controlling the shift of the correction effective area of the correction means so as to follow the position of the return light on the drive area of the correction means based on the detected displacement ;
It is characterized by providing.

Claims (10)

A fundus imaging apparatus that images the fundus of an eye to be examined that has been irradiated with illumination light through an optical system,
Position detecting means for detecting the position of the pupil of the eye to be examined;
Wavefront detection means for detecting the wavefront of the return light from the eye;
Correction means for correcting the wavefront of the return light based on the detected wavefront;
Control means for controlling to set a correction effective area of the correction means based on the detected position;
A fundus imaging apparatus comprising: An observation means for observing the anterior segment of the eye to be examined;
The fundus imaging apparatus according to claim 1, wherein the position detection unit detects the position based on an observation result by the observation unit.   The fundus imaging apparatus according to claim 1, wherein the position detection unit detects the position based on a position of the return light irradiated on a detection region of the wavefront detection unit.   The fundus imaging apparatus according to any one of claims 1 to 3, wherein the position detection unit further detects a pupil diameter of the eye to be examined.   The fundus imaging apparatus according to claim 4, further comprising a light amount control unit that controls a light amount of the illumination light based on the position detected by the position detection unit and the pupil diameter. The size of the effective correction area to be set is fixed,
The fundus imaging apparatus according to claim 1, further comprising propagation means for propagating light outside the effective correction range outside the effective diameter of the optical system. Further comprising generating means for generating wavefront detection light for detecting the wavefront;
The wavefront detection unit detects the wavefront based on return light obtained by irradiating the eye to be examined with the wavefront detection light generated by the generation unit via the optical system. The fundus imaging apparatus according to any one of claims 1 to 6.   The diameter of the luminous flux of the illumination light is larger than the pupil diameter of the eye to be examined, and the effective diameter of the wavefront detection means and the effective diameter of the correction means are larger than the luminous flux diameter of the illumination light. The fundus imaging apparatus according to any one of 1 to 7. A method for controlling a fundus imaging apparatus that includes a position detection unit, a wavefront detection unit, and a control unit, and that images the fundus of a subject's eye irradiated with illumination light through an optical system,
A position detecting step in which the position detecting means detects the position of the pupil of the eye;
The wavefront detecting means detects a wavefront of return light from the eye to be examined; and
A control step for controlling the correcting means for correcting the wavefront of the return light based on the detected wavefront;
In the control step, based on the detected position, control is performed so as to set a correction effective range of the correction unit.   The program for making a computer perform each process of the control method of the fundus imaging apparatus of Claim 9.