JP4509591B2 - Image forming apparatus with aberration correction function - Google Patents

Description

  The present invention provides an image forming apparatus suitable for use in an optical characteristic measuring apparatus that measures eye refractive power and corneal wavefront aberration, a fundus camera that records a fundus image of a subject's eye, an astronomical telescope that observes night-time astronomical objects, and the like. In particular, the present invention relates to an image forming apparatus with an aberration correction function that compensates for the measured aberration of an object such as an eye to obtain a clear object image.

  As an application of the image forming apparatus, for example, there is a fundus oculi observation device such as a fundus camera. With a fundus camera, a fundus image is taken, and an ophthalmologist or an optometrist examines the condition of the retina and fundus bleeding. By the way, the human eye optical system is composed of an eyeball composed of a cornea, a crystalline lens, a glass body, etc., but compared with a perfect optical system assumed in geometrical optics, the human eye optical system has There is distortion. In particular, in the field of ophthalmology, since the degree to which the subject's eye deviates from the normal eye is used as diagnostic information, a clear fundus image with little aberration is required. However, since the eye optical system constituting the object to be imaged is incomplete, there are cases where sufficient resolution cannot be obtained. Therefore, in order to correct the collapse of the wavefront in the eye optical system, a deformable mirror using a piezoelectric effect as shown in Patent Documents 1 and 2, for example, is used. However, when correcting reflected light including aberrations from the fundus, there is a case where the correction amount obtained from the displacement amount by a single deformable mirror may not be sufficient to obtain a clear fundus image. was there.

  The corneal wavefront aberration is expressed by a Zernike coefficient (Zernike) as shown in Patent Document 3, for example, and the Zernike coefficient is also converted into a diopter value. In the conventional fundus camera, the cylinder component (Zernike (2. ± 2) component) corresponding to the astigmatism of the wavefront aberration is corrected by the correcting cylinder lens inserted in the optical path. However, the refraction power interval of the cylinder lens is limited to a certain interval (for example, 3D (diopter) interval), and a clear fundus image with sufficiently corrected aberration cannot be obtained with the refraction factor of the certain interval. There was a problem.

Japanese Patent Laid-Open No. 11-137522 [0031], FIG. US Pat. No. 6,042,223, column 3, lines 51-65, FIG. JP, 2002-209854, A [0039], [0090], FIG. 19, FIG.

  The present invention solves the above-described problems, and a first object is to sufficiently reflect light from an object including aberrations such as the fundus, even when a wavefront aberration correction element that limits the aberrations that can be corrected is used. An object of the present invention is to provide an image forming apparatus with an aberration correction function that can be corrected easily. A second object of the present invention is to provide an image forming apparatus with an aberration correction function that can easily select a correction amount adjustment mode of a wavefront aberration correction element for improving the image quality of an object such as a fundus image. is there.

  The image forming apparatus with an aberration correction function of the present invention that achieves the first object, for example, as shown in FIG. 1, receives a light beam from an object 60 and measures a wavefront aberration measurement unit (5, 81), the image forming optical system 3 that forms the image of the object 60 by receiving at least two times the single wavefront aberration correcting optical element 71 to act on the light flux from the object 60, and the wavefront aberration. And a control unit (83, 85, 9) for controlling the aberration correction amount of the wavefront aberration correcting optical element 71 based on the wavefront aberration measured by the measuring unit. The observation light flux is the light emitted from the object when the object itself emits light, such as a night sky celestial body, and from the object when the object does not emit light itself, such as the fundus. Reflected light.

  In the apparatus configured as described above, the wavefront aberration measuring unit receives the reflected light reflected from the object 60 and measures the wavefront aberration. The image forming optical system 3 receives and observes the light beam from the object 60 by causing the single wavefront aberration correcting optical element 71 to act at least twice. Here, the action means a case where the light beam from the object reflects the wavefront aberration correcting optical element 71. Then, the control unit controls the aberration correction amount of the wavefront aberration correcting optical element based on the wavefront aberration measured by the wavefront aberration measuring unit, so that the aberration generated in the wavefront can be corrected.

  In the image forming apparatus with an aberration correction function of the present invention, preferably, the object 60 is a fundus 61 of the eye 60 to be examined, and further includes the illumination optical system 2 that illuminates the fundus 61 of the eye 60 to be examined, and the wavefront aberration measurement is performed. The unit may receive reflected light reflected from the fundus 61 and measure the wavefront aberration, and the image forming optical system 3 may be configured to form an image of the fundus 61 of the eye 60 to be examined. When the object is the fundus, the illumination optical system 2 is provided because it is necessary to irradiate the observation light beam from the outside.

  In the image forming apparatus with an aberration correction function of the present invention, the wavefront aberration correction optical element 71 is preferably composed of a deformable mirror. Since the deformable mirror has a large number of subdivided elements, for example, fine aberrations occurring in the wavefront can be corrected by appropriately adjusting the control amount of the individual elements. Preferably, it is preferable to have a recursive optical system 72 that reflects the light beam subjected to the first action by the wavefront aberration correcting optical element 71 to the wavefront aberration correcting optical element 71 side again.

  In the image forming apparatus with an aberration correction function of the present invention, for example, as shown in FIGS. 23 to 25, preferably, the recursive optical system 72 again causes the light beam first reflected from the deformable mirror 71 to be transferred again to the deformable mirror 71. It is preferable that the deformable mirror 71 is configured so as to be substantially conjugate with the eye to be examined.

  In the image forming apparatus with an aberration correction function of the present invention, for example, as shown in FIG. 23, the recursive optical system 72 preferably returns the light beam first reflected from the deformable mirror 71 toward the deformable mirror 71 again. It is preferable that the recursed light beam is formed again on the deformable mirror 71 as an erect image at the first reflection position. For example, two lenses (L11, L12) may be provided between the recursive optical system 72 and the deformable mirror 71.

  In the image forming apparatus with an aberration correction function of the present invention, preferably, the wavefront aberration measuring unit (5, 81) arranges the Hartmann optical element 51 at a position substantially conjugate with the pupil of the eye to be examined. It is preferable that the light receiving unit 52 is disposed at the position. Here, the light receiving unit 52 is disposed at a position substantially conjugate with the fundus 61 of the eye 60 to be examined.

  The image forming method with an aberration correction function of the present invention that achieves the first object receives a light beam from an object 60, for example, as shown in FIGS. 5, 81) for measuring wavefront aberration (S106), wavefront correction step (S114) for causing the single wavefront aberration correcting optical element 71 to act on the light beam from the object 60 at least twice, and wavefront correction. The aberration correction amount of the wavefront aberration correction optical element 71 based on the wavefront aberration measured in the step (S166) in which the light beam from the object 60 corrected in the step is received by the image forming optical system 3 and the wavefront aberration measurement step. (S108 to S114).

  The image forming apparatus with an aberration correction function of the present invention that achieves the second object, as shown in FIG. 1, for example, receives a light beam from an object 60 and measures wavefront aberration (5). 81) and the image forming optical system 3 that receives light by applying the wavefront aberration correcting optical element 71 to the light flux from the object 60, and a plurality of types of voltage changes for adjusting the wavefront aberration correcting optical element 71. A voltage change template storage unit 6 that stores a template, and a voltage change template selection unit that selects a type of voltage change template for correcting the wavefront aberration correction optical element 71 from the voltage change templates stored in the voltage change template storage unit 6 85 and the voltage change template selected by the voltage change template selection unit 85 based on the wavefront aberration measured by the wavefront aberration measurement unit. And a correction amount determining unit 83 for controlling the aberration correction amount of the aberration correcting optical element 71.

  In the image forming apparatus with an aberration correction function of the present invention that achieves the second object, preferably, for example, as shown in FIG. 1 and FIG. 9, the voltage change template storage unit 6 has a concentric template, and the voltage change has wavefront aberration. At least one kind of a symmetric template set symmetrically with respect to the center of the correction optical element 71 or a desired axis, and an asymmetric template whose voltage change is set asymmetrically with respect to the center of the wavefront aberration correction optical element 71 or the desired axis The voltage change template selection unit 85 forms a voltage change template for correcting the wavefront aberration correcting optical element 71 based on the determination of the wavefront aberration measured by the wavefront aberration measuring unit.

  According to the image forming apparatus with an aberration correction function of the present invention that achieves the first object, the same wavefront aberration correcting optical element acts twice while the light beam from the object 60 reaches the image forming optical system 3. By adopting the optical system, it is possible to increase the correction amount by a single wavefront aberration correcting optical element up to twice as compared with an optical system that acts once, thereby obtaining a clearer object image. be able to. Further, the number of wavefront aberration correcting optical elements can be reduced as compared with the case where two wavefront aberration correcting optical elements having the same characteristics are arranged side by side and applied to the light flux from the object 60 to the image forming optical system 3. Cost is low.

  According to the image forming apparatus with an aberration correction function of the present invention that achieves the second object, the wavefront aberration is determined by the voltage change template selected by the voltage change template selection unit based on the wavefront aberration measured by the wavefront aberration measurement unit. Since the aberration correction amount of the correction optical element is controlled, an aspect of adjusting the correction amount of the wavefront aberration correction element for improving the image quality of the object image can be easily selected.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Here, a fundus observation apparatus will be described as an example of an image forming apparatus with an aberration correction function. FIG. 1 is a block diagram illustrating an example of the entire fundus oculi observation device according to the present invention. The fundus oculi observation device includes a wavefront aberration measurement unit that measures aberrations included in an eye optical system such as a crystalline lens, a vitreous body, and a cornea, and a wavefront aberration correction optical element that corrects the aberrations. In the figure, the fundus oculi observation device includes a fundus illumination system 2, a fundus oculi observation system 3 as an image forming optical system, a point image projection optical system 4, a point image light receiving optical system 5, a voltage change template DB 6, an adaptive optics system 7, and a computer 8. And an operation control unit 9.

  Here, the point image projection optical system 4 and the point image light receiving optical system 5 constitute a wavefront measurement system, and the wavefront measurement system and the computer 8 constitute a wavefront correction system. The computer 8 includes an aberration measurement unit 81, an image data storage unit 82, a compensation amount determination unit 83, a voltage change template selection unit 85, and a display unit 86. The wavefront aberration measuring unit receives reflected light reflected from the fundus 61 and measures the wavefront aberration, and includes a point image receiving optical system 5 and an aberration measuring unit 81. The control unit controls the amount of aberration correction by the compensation optical system 7 (wavefront aberration correction optical element) based on the wavefront aberration measured by the wavefront aberration measurement unit, and includes a compensation amount determination unit 83, a voltage change template selection unit 85, and an operation. A control unit 9 is provided. The fundus 61 is a component of the eye 60 to be examined as an object.

  The fundus illumination system 2 includes a second light source unit 21, a condensing lens L1, and a beam splitter BS1, and illuminates a predetermined region on the retina 61 of the eye 60 to be examined with the second light flux from the second light source unit 21. Is. The second light source unit 21 may use, for example, a laser element that emits a red light beam having a wavelength of 630 nm as the second wavelength, and acts as a point light source or a surface light source with respect to the fundus 61, thereby making the fundus 61 a red region. it can. As the beam splitter BS1, for example, a polarization beam splitter that reflects the light beam from the second light source unit 21 toward the eye 60 to be examined and transmits the light beam reflected and returned by the eye 60 to be examined may be used. For illumination of the fundus 61, for example, illumination light in the observation region of the fundus 61 may be formed using a perforated mirror. When using a perforated mirror, the perforated mirror and the pupil are in a conjugate relationship to prevent reflection at the apex of the cornea 62. Further, regarding the illumination of the fundus 61, the center of the ring-shaped stop may be 100% transmitted, and the transmittance of the peripheral region with respect to the center may be about 10%, for example, and the entire fundus 61 may be illuminated by the peripheral region.

  The fundus oculi observation system 3 includes a fundus image forming optical system 31, a fundus image light receiving unit 32 (CCD), and a fundus image display unit 33. The fundus image forming optical system 31 includes, for example, a collimator lens or afocal lens L2, a beam splitter BS2, a lens L3, the compensation optical system 7, and a mirror M1. The fundus image forming optical system 31 sends the light of the second wavelength reflected by the fundus 61 to the compensation optical system 7 using the beam splitter BS2, and the light beam sent from the compensation optical system 7 to the beam splitter BS2 and the lens. The light is guided to the fundus image light receiving unit 32 via L3 and the mirror M1. The beam splitter BS2 is composed of, for example, a beam splitter (for example, a half mirror). The fundus image light receiving unit 32 receives the fundus image formed by the fundus image forming optical system 31 and displays the fundus image on the fundus image display unit 33. For example, a CCD, a condensing lens L9, and a dichroic mirror are used. It is composed of DM. The dichroic mirror DM branches the second wavelength light (red light) toward the light receiving element (CCD) 32 having sensitivity to the second wavelength light.

  The point image projection optical system 4 includes a first light source unit 41 and a condenser lens L8. The first light source unit 41 preferably has a large spatial coherence and a small temporal coherence. Here, as an example, a super luminescence diode (SLD) is adopted as the first light source unit 41, and a point light source with high luminance can be obtained. The first light source unit 41 is not limited to the SLD. For example, even with a laser having a large spatial coherence or temporal coherence, by inserting a rotating diffusion plate or the like and appropriately reducing the temporal coherence, Can be used. Furthermore, even an LED with small spatial coherence and temporal coherence can be used by inserting a pinhole or the like at the position of the light source in the optical path as long as the amount of light is sufficient. The first wavelength of the illumination light beam emitted from the first light source unit 41 is, for example, an infrared wavelength (for example, 780 nm).

  The point image receiving optical system 5 includes, for example, relay lenses L6 and L7, a beam splitter BS3, a Hartmann plate 51 that is a conversion member that converts a part of the reflected light beam (first light beam) into at least 17 beams, and the Hartmann And a point image receiving optical unit 52 for receiving a plurality of beams converted by the plate 51. The point image light receiving optical system 5 is for receiving the first light beam reflected and returned from the retina 61 of the eye 60 to be guided to the point image light receiving optical unit 52. The beam splitter BS3 reflects the light beam from the first light source unit 41, reflects from the retina 61 of the eye 60 to be examined, and transmits the reflected light beam that has returned through the compensation optical system 7 and the relay lenses L6 and L7. (For example, a polarization beam splitter). The Hartmann plate 51 is a wavefront conversion member that converts a reflected light beam into a plurality of beams. For example, a plurality of micro Fresnel lenses arranged in a plane orthogonal to the optical axis can be used. In general, the measurement target portion (eye 60 to be measured) is also measured to measure the spherical component of the eye 60, third-order astigmatism, and third-order and fourth-order aberrations of Zernike. It is known that measurements need to be made with at least 17 beams through the eye 60.

  FIG. 21 is an explanatory diagram of a wavefront sensor used in the point image light receiving optical system 5. The micro Fresnel lens used for the Hartmann plate 51 is an optical element, and includes, for example, an annular zone having a height pitch for each wavelength and an optimized blaze. The micro Fresnel lens here is, for example, an optical path length difference of 8 levels applying a semiconductor microfabrication technique, and achieves a high light collection rate (for example, 98%). The reflected light from the fundus 61 is collected on the point image receiving optical unit 52 via the Hartmann plate 51. Here, the point image receiving optical unit 52 employs a CCD with low lead-out noise. However, as the CCD, for example, a general low noise type, a cooling CCD of 2000 × 2000 elements for measurement, or the like can be used. A type of thing can be applied. The wavefront aberration appears as a point image moving distance (Δx, Δy) in the point image receiving optical unit 52.

  The wavefront aberration appears because the reflected light from the fundus 61 (retina) includes an aberration peculiar to the eye optical system of the subject and does not become a complete plane wave. When a wavefront having aberration is condensed by the Hartmann plate 51 of the wavefront sensor, the condensing point is displaced from the condensing position when a complete plane wave is input. A displacement point by the Hartmann plate 51 is photographed on the point image light receiving optical unit 52, and the displacement amount (Δx, Δy) can be measured.

  Preferably, the point image projection optical system 4 and the point image light receiving optical system 5 are provided with a prism (not shown) inserted in the middle of the optical path, and by adjusting the prism position, It is good to comprise so that a light beam may be condensed with the eye 60 to be examined. In this case, assuming that the light beam from the first light source unit 41 is reflected at the point where the light is focused, the relationship in which the signal peak at the point image receiving optical unit 52 due to the reflected light is maximized is maintained, and the point image receiving optical system is maintained. The prism position is adjusted in the direction in which the signal peak at the unit 52 increases.

  The compensation optical system 7 is a cylinder lens 77, a condensing lens L10, a deformable mirror 71 as a wavefront aberration correction optical element that compensates for the aberration of measurement light, a reflection mirror 72, and moves in the optical axis direction to correct a spherical component. It has a moving prism (not shown) and a spherical lens (not shown). The compensating optical system 7 is arranged in a light beam directed to the fundus oculi observation system 3 and the point image light receiving optical system 5, and compensates for aberration of the reflected light beam that is reflected back from the eye 60 to be examined. The light beam compensated by 71 is reflected by the reflecting mirror 72 and is compensated again by the deformable mirror 71, and returned to the fundus oculi observation system 3 and the point image receiving optical system 5 through the beam splitter BS2. In addition, the compensation optical system 7 may compensate the aberration with respect to the light beam emitted from the first light source unit 41 and illuminate a minute region on the fundus 61 of the eye 60 to be examined with the light beam subjected to the aberration compensation. good.

  The deformable mirror 71 changes the reflection direction of the light beam by deforming the mirror by an actuator provided inside the mirror. For example, the deformable mirror 71 is deformed by electrostatic attraction or deformed by using a piezoelectric element. is there. The function of the deformable mirror 71 can be replaced by another element used as an adaptive optical system that compensates for the aberration of the measurement light. For example, a spatial light modulator such as a liquid crystal can be used. . The liquid crystal spatial light modulator modulates the phase by utilizing the light distribution of the liquid crystal, and is used after being reflected in the same manner as the deformable mirror. In addition, when using a spatial light modulator, a polarizer may be needed in the middle of an optical path. In the deformable mirror and the spatial light modulator, a transmissive optical system may be used in addition to the reflective optical system. The cylinder lens 77 compensates the cylinder component corresponding to the astigmatism of the wavefront aberration, and is inserted between the anterior eye part 61 and the beam splitter BS1. In the cylinder lens 77, the refractive power can be selected at a predetermined interval (for example, 3D).

  FIG. 2 is a configuration diagram of the deformable mirror 71 and shows a single deformable mirror. In the deformable mirror, for example, a plurality of elements divided in a honeycomb shape are arranged, and the deformable mirror is deformed by changing each of them by an actuator. For example, an element number for identifying each element is assigned in advance to each element. The control unit 9 drives each element by an actuator according to a voltage value corresponding to the element number output from the computer 8. The number of elements is not limited to 37 as shown in the figure, and an appropriate number can be used so as to satisfy the required compensation resolution requirement. The element numbers can be appropriately assigned in addition to those shown in the figure. In addition to the number, appropriate identification information that can identify each element such as characters and coordinates can be used as the element number.

  FIG. 22 is a main part configuration diagram for explaining the arrangement of the deformable mirror and the reflection mirror. In an ideal optical system, the light beam from the eye 60 to be examined is reflected by the deformable mirror 71, then regularly reflected by the reflecting mirror 72, and returned to the deformable mirror 71 again. You need to go back to the same place above. Then, by reflecting twice at the same place, it is possible to obtain a double phase change with respect to the luminous flux.

  However, actually, as shown in FIG. 22, when the operation control unit 9 is driven, the deformable mirror 71 has a property that the reflecting surface has a slight curvature so as to overlap with the deformation for correcting the aberration. Therefore, when the reflecting mirror 72 is folded back and returned to the deformable mirror, the position of the light beam slightly changes. Therefore, it is necessary to suppress the positional deviation of the light beam to a level that causes no problem by making the distance L between the reflecting mirror 72 and the deformable mirror 71 appropriate. In general, it is empirically known that the radius of curvature R of the reflecting surface when the deformable mirror is driven is 2000 mm or more. Therefore, when the distance L between the deformable mirror 71 and the reflecting mirror 72 is 40 mm, the positional deviation of the light flux is about 0.14 mm at the maximum. If the distance L between the deformable mirror 71 and the reflecting mirror 72 is, for example, 40 mm or less, the positional deviation of the light beam is about 0.14 mm at the maximum, and can be made as small as no problem compared with the resolution of the wavefront aberration measurement system.

  Next, each component of the computer 8 will be described. The aberration measuring unit 81 obtains optical characteristics including high-order aberrations of the eye 60 based on the output from the point image light receiving optical unit 52. The output from the point image light receiving optical unit 52 is reflected light from the fundus (retina) 61 and includes an aberration because the eye optical system is incomplete, and does not become a plane wave. When the light including aberration is condensed by the micro lens of the Hartmann plate 51, the condensing point is displaced. The displacement point is photographed by the point image receiving optical unit 52, and the displacement amount (Δx, Δy) is measured by the aberration measuring unit 81. In addition to the output signal from the point image receiving optical unit 52, the aberration measuring unit 81 may receive wavefront measurement data indicating at least the wavefront aberration of the eye 60 to obtain optical characteristics.

The image data storage unit 82 stores the fundus image after the wavefront aberration is corrected. The compensation amount determination unit 83 determines the correction amount of the deformable mirror 71 using the voltage change template selected by the voltage change template selection unit 85 and outputs the correction amount for the deformable mirror 71 to the operation control unit 9. To do. The compensation amount determining unit 83 converts the aberration Z into a Zernike polynomial from the displacement (Δx, Δy) measured by the aberration measuring unit 81, and assigns weights (a, b, c,...) To the Zernike polynomial. Put on.
Z = aZernike (1,1) + bZernike (1, -1) + cZernike (2,0) + ... (1)
In the compensation amount determination unit 83, the aberration measured by the aberration measurement unit 81 is multiplied by ½, the correction amount for the light beam incident on the deformable mirror 71 from the beam splitter BS 2, and the light beam reflected from the reflection mirror 72. Control is performed so that the aberration measured by the aberration measuring unit 81 is compensated by combining the correction amounts for.

  In order to correct the aberration expressed by each Zernike polynomial, a voltage applied to each electrode of each deformable mirror 71 is held as a database in, for example, the voltage change template DB 6. The compensation amount determination unit 83 determines a voltage to be applied to each electrode of each deformable mirror 71 with reference to the voltage change template DB 6 and sends a correction signal to the operation control unit 9. The compensation amount determining unit 83 may be configured to sequentially repeat the measurement of the aberration of the eye 60 and the correction of the aberration by the deformation of the deformable mirror 71 until the aberration becomes a threshold value (for example, RMS 0.1 μm or 1 μm) or less.

  Preferably, the compensation amount determining unit 83 calculates evaluation data for evaluating the quality of the fundus image based on the simulation image data or the eye characteristic data to be examined for a plurality of voltage change templates, and the evaluation data An appropriate correction amount for the deformable mirror 71 may be determined based on this. As the evaluation data, for example, a value indicating the degree of matching between a simulation image and a predetermined pattern template or MTF (Modulation Transfer Function) can be used. Here, the MTF is an index indicating the transfer characteristic of the spatial frequency, and is widely used to express the performance of the optical system. For example, the MTF can be predicted in appearance by obtaining transfer characteristics for 0 to 100 sinusoidal gray gratings per degree.

  The voltage change template selection unit 85 selects a voltage change template stored in the voltage change template DB 6. The selection may be configured such that the computer 8 designates based on a predetermined selection criterion based on, for example, an operator's designation and optical characteristics such as wavefront aberration of the eye 60 to be examined. The voltage change template DB 6 stores a concentric circle template 64, a symmetric template 66, and an asymmetric template 68. The concentric template 64 copes with the property that the element located near the center of the deformable mirror 71 is more susceptible to the image quality than the element located near the center, and the concentric template 64 greatly increases the inner voltage change. It is good to set. In the symmetric template 66, a voltage change value that is symmetric with respect to the center point of the deformable mirror 71 can be set. The asymmetric template 68 sets an appropriate voltage change value that is asymmetric with respect to the center or axis. The display unit 86 is a man-machine interface such as a CRT or a liquid crystal display device.

  The operation control unit 9 deforms the deformable mirror 71 based on the output from the compensation amount determination unit 83. Further, the operation control unit 9 moves a moving prism (not shown) in the optical axis direction based on the output from the computer 8. The fundus oculi observation device may be further provided with an alignment system (not shown) and a fixation system (not shown). The alignment system illuminates an appropriate pattern such as a placido ring and guides the light beam reflected and returned from the anterior eye portion of the eye 60 or the cornea 62 to the alignment light receiving portion. To match the pupil and the optical axis. The fixation system includes an optical path for projecting a target for causing fixation or clouding of the eye 60 to be measured.

(Conjugate relationship)
The fundus 61 of the eye 60 to be measured is arranged to have a substantially conjugate relationship with the first light source unit 41 and the point image light receiving optical unit 52. The surface of the deformable mirror 71 is arranged to have a substantially conjugate relationship with the pupil 62 of the eye 60 to be measured and the Hartmann plate 51.

  FIG. 3 shows a format of a reference voltage value table that stores reference voltage values of voltage changes. Corresponding to each element number of the deformable mirror 71, a reference voltage value for changing a voltage applied to the element is stored. The computer 8 determines a voltage value Vi to be applied to the deformable mirror 71 based on the stored reference voltage value and a voltage change indicated by a voltage value change template described later, and outputs the voltage value Vi to the operation control unit 9. In the reference voltage value table, for example, the voltage value Vi given to the deformable mirror 71 before adjustment of the correction amount by the voltage change template is stored. Further, the computer 8 updates the voltage value after the correction amount adjustment.

  FIG. 4 is a table format of the concentric circle template. The concentric circle template 64 shown in FIG. 4 is an example in which nine templates are stored for the deformable mirror 71 having 37 elements. Each template stores a voltage change value corresponding to the element number. In general, an element located near the center of the deformable mirror 71 is more susceptible to image quality than an element located near the periphery, so it is preferable to set a large voltage change inside the concentric circle template 64. . However, it is not necessary to increase the inner voltage change. In the present embodiment, a template in which voltage changes are all zero is prepared. However, for example, it is possible to compare evaluation data when there is no voltage change and when there is a voltage change.

  FIG. 5 is a table format of a symmetric template. Each symmetrical template 66 stores a voltage change value corresponding to the element number. In the symmetric template 66, a voltage change value that is symmetric with respect to the center point of the deformable mirror 71 can be set. The symmetrical template 66 may be set with a voltage change value that is symmetric with respect to an appropriate axis such as the x-axis or the y-axis.

  FIG. 6 is a table format of an asymmetric template. Each asymmetric template 68 stores a voltage change value corresponding to the element number. The asymmetric template 68 sets an appropriate voltage change value that is asymmetric with respect to the center or axis. Note that the number of templates and the number of elements are not limited to the numbers shown in FIGS. 4 to 6 and may include appropriate numbers. Moreover, an appropriate value can be set as the value of the voltage change.

  FIG. 7 shows a format of matching numerical data by template matching. A matching numerical value by template matching described later, a voltage value given to each element of the deformable mirror 71 used for the measurement, and a template number are stored correspondingly. Further, instead of the matching numerical value, data such as MTF may be stored in association with the template number. The voltage value given to each element can be omitted. In this case, the computer 8 can calculate the voltage value given to each element of the deformable mirror 71 by referring to the reference voltage value table and the voltage change template based on the template number.

(Zernike analysis)
Next, Zernike analysis will be described. A method for calculating the Zernike coefficients c _i ^2j-i from a generally known Zernike polynomial will be described. The Zernike coefficient c _i ^2j−i is important for grasping the optical characteristics of the eye 60 based on the tilt angle of the light beam obtained by the point image receiving optical unit 52 via a changing member such as a Hartmann plate, for example. It is a parameter.

ただし、（Ｘ，Ｙ）はハルトマン板の縦横の座標である。 The wavefront aberration W (X, Y) of the eye 60 to be examined is expressed by the following equation using the Zernike coefficient c _i ^2j−i and the Zernike polynomial Z _i ^2j−i .

However, (X, Y) are the vertical and horizontal coordinates of the Hartmann plate.

ここで、ゼルニケ多項式Ｚ_ｉ ^２ｊ−ｉは、以下の数式で表される（より具体的な式は、例えば特開２００２−２０９８５４を参照）。

The wavefront aberration W (X, Y) is expressed by the vertical and horizontal coordinates of the point image receiving optical unit 52 (x, y), the distance between the Hartmann plate and the point image receiving optical unit 52 f, and the point image receiving optical unit 52. When the movement distance of the received point image is (Δx, Δy), the following relationship is established.

Here, the Zernike polynomial Z _i ^2j−i is expressed by the following formula (for more specific formula, see, for example, JP-A-2002-209854).

ただし、Ｗ（Ｘ、Ｙ）：波面収差、（Ｘ、Ｙ）：ハルトマン板座標、（△ｘ、△ｙ）：点像受光光学部５２で受光される点像の移動距離、ｆ：ハルトマン板と点像受光光学部５２との距離。 The Zernike coefficient c _i ^2j−i can be obtained with a specific value by minimizing the square error represented by the following equation.

Where W (X, Y): wavefront aberration, (X, Y): Hartmann plate coordinates, (Δx, Δy): movement distance of the point image received by the point image receiving optical unit 52, f: Hartmann plate And the point image receiving optical unit 52.

The computer 8 calculates the Zernike coefficients c _i ^2j-i and uses them to obtain eye optical characteristics such as spherical aberration, coma aberration, and astigmatism. Further, the computer 8 calculates the aberration amount RMS _i ^2j-i by the following equation using the Zernike coefficient c _i ^2j-i .

(flowchart)
FIG. 8 is a flowchart of fundus observation in the first embodiment of the present invention. First, the fundus oculi observation device aligns the eye 60 to be examined so that the optical axis of the fundus oculi observation device coincides with the pupil 62 and the fundus oculi 61 (S102). Then, the aberration measurement unit 81 of the computer 8 sets the position where the optical axis from the first light source unit 41 hits the fundus 61 with the macula as the origin ( _Xre , _Yre ) (S104). For example, the computer 8 can acquire a fundus image from the fundus image light receiving unit 32 and detect the position of the macula and the position where the optical axis corresponds to the fundus 61 by image processing. The position of the macular can be detected using a normalized correlation method, for example, by creating a macular template in advance and storing it in a memory (not shown) of the computer 8. Further, the computer 8 displays the acquired image on the display unit 86, and the operator of the fundus oculi observation device inputs the position of the macula and the position where the optical axis corresponds to the fundus 61 from an appropriate input unit such as a pointing device. Also good.

  Next, the aberration measuring unit 81 measures the wavefront aberration of the eye 60 based on the signal from the point image receiving optical unit 52 (S106). The compensation amount determination unit 83 converts the measured aberration into a Zernike polynomial (S108). The compensation amount determination unit 83 determines a correction amount target to be compensated by the deformable mirror 71. Next, the compensation amount determination unit 83 converts the voltage change template selected by the voltage change template selection unit 85 into a correction signal for the deformable mirror 71. (S110). Then, the compensation amount determination unit 83 outputs a correction signal to the operation control unit 9, and the operation control unit 9 outputs an applied voltage signal to the deformable mirror 71 (S112). Then, each element of the deformable mirror 71 is displaced according to the applied voltage signal, and the deformable mirror 71 is deformed (S114).

  Then, the computer 8 uses the aberration measuring unit 81 to measure the wavefront aberration of the eye 60 based on the signal from the point image receiving optical unit 52 (S116), and converts the wavefront aberration that is the measurement result into a Zernike polynomial. (S117). The computer 8 determines whether the measured aberration is smaller than a predetermined threshold value (S118). In the case of Yes in S118, the compensation amount determination unit 83 returns to S110. If No in S118, the process ends.

  FIG. 9 is a flowchart for explaining an example of the optimum selection rule for the voltage change template. The selection of the voltage change template in S110 of FIG. 8 is performed as follows, for example, in order to select an optimum voltage change template. First, the voltage change template selection unit 85 selects an arbitrary voltage change template k (k = 1, 2,..., M) (S152). For example, the computer 8 includes a concentric template 64 that mainly compensates for spherical aberration components, a symmetric template 66 that mainly compensates for astigmatism components, and an asymmetric template 68 that mainly compensates for coma-like aberration components based on the aberration amount RMS. Either one is selected, and the process proceeds to S154. The detailed process of selecting the voltage change template will be described later with reference to FIG.

Then, the compensation amount determination section 83, based on the voltage-change template k obtained in S152, and calculates the compensation amount A ^k indicating whether to what extent deforming the deformable mirror (S154). Operation control unit 9, a compensation amount ^{A k} obtained in step S154 to the deformable mirror 71 by using the initial voltage value Vi, the voltage value Ti is calculated by the following equation (S156).
Ti = Vi + A ^k · vi ^k (2 of 7)
Next, the operation control unit 9 outputs the calculated voltage value Ti to the deformable mirror 71 (S158). Then, the aberration measurement unit 81 considers the time during which the deformable mirror 71 is deformed, and measures the wavefront aberration after a predetermined time elapses from the output of the voltage value, for example (S160). The compensation amount determination unit 83 converts the aberration measured in S160 into a Zernike polynomial (S161). Then, the computer 8 determines whether or not the aberration amount RMS _i ^2j-i calculated using the Zernike coefficient c _i ^2j-i is smaller than the threshold Th (S162).

If No in S162, it is determined whether the aberration amount RMS _i ^2j-i is smaller than the reference aberration amount RMS ⁻ (S163). Here, the reference aberration amount RMS ⁻ is a reference aberration amount in which distortion of the deformation amount of the deformable mirror 71 is allowed. If the aberration amount RMS _i ^2j-i is excessive with respect to the reference aberration amount RMS ^{− in} S163, the process returns to S152 to select another voltage change template. In S163, the aberration _RMS ^{i 2j-i} are reference aberration RMS ^- smaller relative, the aberration _RMS ^{i 2j-i} new reference aberration RMS ^- set, set the voltage value Ti to the voltage value Vi Then, the process returns to S152 and another voltage change template is selected. In this way, the computer 8 repeats selection of the voltage change template until the aberration amount RMS value becomes smaller than the threshold value Th.

  On the other hand, when the RMS value becomes smaller than the threshold value Th, the computer 8 becomes Yes in S162. Therefore, the fundus image light receiving unit 32 receives the fundus image formed by the fundus image forming optical system 31. (S166). Then, the computer 8 stores the fundus image acquired by the fundus image light receiving unit 32 in the memory and appropriately displays the fundus image on the fundus image display unit 33 (S168).

In step S154 of the flow described above, the computer 8 changes the voltage value applied to the deformable mirror 71 according to the voltage change template selected in step S152, and the retinal image simulation result and pattern having the maximum MTF or a predetermined pattern. matching value of the template determine the compensation amount a ^k such that the maximum, it is also possible to obtain the voltage value Ti. Here, the amount of change in RMS by one template is roughly standardized. For example, ΔRMS = about 0.01 μm. If aberration component corresponding to the estimated concentric template when measured actually aberrations was RMS = 0.75 .mu.m, setting 75 the compensation amount A ^k multiplied concentrically template a value corresponding to the ratio as a coefficient To do. Details of MTF optimization will be described later with reference to FIGS. Details of the pattern optimization will be described later with reference to FIG.

なお、コンピュータ８は、上式を用いる以外にも、式（７）に示す式を用いて算出した収差量ＲＭＳを収差量Ｒ_ｉ ^２ｊ−ｉとしてもよい。 FIG. 10 is a flowchart for explaining the procedure for selecting the voltage change template type. First, the computer 8 sets an RMS value threshold th as a branching condition (S201). The computer 8 sets 1/3 or less of the set threshold Th (a sufficiently small value of aberration, for example, 0.1 μm) as the threshold th value (for example, 0.03 μm).
(1/3) xTh> th (7-3)
The computer 8 calculates the Zernike coefficient c _i ^2j-i from the aberration and converts it into the aberration amount R _i ^2j-i (S203). The aberration amount R _i ^2j−i can be obtained by the following equation.

In addition to using the above equation, the computer 8 may use the aberration amount RMS calculated using the equation (7) as the aberration amount R _i ^2j-i .

Next, the computer 8 determines whether or not the total amount of the concentric aberration amounts R ₂ ⁻² , R ₄ ⁻⁴ , R ₆ ⁻⁶ ,... Is equal to or greater than the threshold th (S207). In the case of Yes in step S207, the computer 8 adds or increases the “concentric circle template” component as the voltage change template (S209). And the computer 8 complete | finishes the process of a voltage change template setting, and progresses to the process of step S154 of FIG. On the other hand, if No at step S207, the computer 8 proceeds to the process at step S215.

In step S215, the computer 8 determines whether or not the total amount of R _i ^2j−i (i: even number and j ≠ 0) corresponding to the symmetric aberration component is greater than or equal to the threshold th (S215). In the case of Yes in step S215, the computer 8 adds or increases the “symmetric template” component as the voltage change template (S217). Then, the computer 8 ends the voltage change template selection processing of the deformable mirror 71. On the other hand, the computer 8 proceeds to the process of step S223 if No in step S215.

In step S223, the computer 8 determines whether or not the total amount of R _i ^2j−i (i: odd number) corresponding to the asymmetric aberration component is equal to or greater than the threshold th (S223). In the case of Yes in step S223, the computer 8 adds or increases the “asymmetric template” component as the voltage change template (S225). Then, the computer 8 ends the voltage change template selection process.

  In the flowcharts of FIGS. 8 to 10, the control of the deformable mirror is performed by deforming the deformable mirror, measuring the actual wavefront aberration at that time, and adjusting the deformable mirror again for the shortage. An embodiment employing a so-called feedback method is described.

Subsequently, as a second embodiment of the present invention, a method for obtaining an appropriate control amount in advance by performing a simulation based on the measured wavefront aberration will be described. Hereinafter, the operation principle of the computer 8 will be described for the second embodiment.
(MTF optimization)
FIG. 11 is an explanatory diagram for determining the best image based on a change in MTF. By using the MTF, it is possible to examine how much resolving power there is at a certain fineness. In the figure, the vertical axis shows the value of MTF, which is a distinguishable measure, and the horizontal axis shows the spatial frequency, which is a measure of fineness, and shows a graph when the deformable mirror 71 is deformed in two cases A and B. . As a unit of spatial frequency, [lines / mm], [cycles / degree], etc. are mainly used.

  In the graph shown in the figure, it can be seen that Case B has a smaller RMS value than Case A, and that M is higher than A when the value of MTF is 400 [lines / mm] or less, however, as in the case of adaptive optics. When it is desired to view an image up to the vicinity of the image limit, a graph such as case A having a resolving power in a high frequency region of 400 [lines / mm] or more is preferable to a graph like case B.

  In the present embodiment, when several types of voltages are applied to the deformable mirror 71 according to the voltage change template and moved, for example, 500 [lines / mm] (this is a value that can resolve an object of about 2 μm). The value of MTF is calculated. If a voltage value at which the calculated MTF is the highest is selected, a fine object image can be observed.

FIG. 12 is a flowchart of MTF optimization. First, the computer 8 calculates the distance from the position (X _re , Y _re ) where the optical axis of the light that illuminates the fundus 61 of the eye 60 to be examined to the fundus 61 to the macula (coordinate origin), and the spatial frequency table of the cells Is used to find the spatial frequency cf for the calculated distance (S301).

  FIG. 13 is a relationship diagram between the distance from the macula and the spatial frequency of the cells. In the case of the human eye, as shown in FIG. 13, as the distance from the macula increases, the spatial frequency of the cells decreases. For example, the relationship shown in this graph is stored in advance in a memory as a table in which the distance from the macula and the spatial frequency correspond to each other, and the computer 8 can read the corresponding spatial frequency cf from the memory based on the calculated distance. Further, an approximate expression representing the relationship between the distance from the macula and the spatial frequency as shown in FIG. 13 may be stored in the memory, and the computer 8 may calculate the spatial frequency cf using the approximate expression based on the calculated distance. .

Next, the computer 8 sets the initial voltage to V (V _i : i = 1 to n) (S303). Here, n is the number of elements of the deformable mirror 71. The computer 8 can read the voltage value corresponding to each element number from the reference voltage value table stored in the memory, for example, and set it as the initial voltage V.

  The computer 8 sets the value of the template number k to, for example, k = 1 (S305). The template number serves as a counter for calculating the MTF for a plurality of templates.

The computer 8 reads the voltage change template group from the memory as v ^(k) (k = 1, 2,..., M) (S307). For example, the computer 8 reads each voltage change amount of the template number 1 as v ⁽¹⁾ and each voltage change amount of the template number 2 as v ⁽²⁾ , and reads the number of templates stored in the memory. Further, the computer 8 reads the number m of templates from the memory. Instead of reading the number of templates, the computer 8 may count the number of read templates to obtain the number of templates m.

The computer 8 sets the voltage value T _i by the following equation (S309).
T _i = V _i + v _i ^(k) (i = 1 to n) (9)
Computer 8, a voltage value applied to each element of the deformable mirror 71 was changed to T _i, and outputs the operation control unit 9. (S311). Operation control unit 9 drives the respective elements of the deformable mirror 71 in accordance with the voltage value T _i output from the computer 8, to deform the deformable mirror 71. The computer 8 measures the wavefront aberration W (x, y) after the deformable mirror 71 is deformed (for example, after a predetermined time has elapsed) (S313).

The computer 8 calculates MTF (cf) based on the measured wavefront aberration (S315). MTF (cf) is, for example, an average value of MTFs at all angles according to the spatial frequency cf of the cell. The calculation of MTF (cf) will be described later. The computer 8 sets the calculated MTF (cf) as M _k (S317). Further, the computer 8 stores M _k in the memory corresponding to the template number k. The computer 8 is at an appropriate timing, the data based on the wavefront aberration and aberration was measured, may be stored in correspondence to the voltage value T _i to template number k.

The computer 8 determines whether the template number k is smaller than the template number m (S319). That is, the computer 8 determines whether _Mk has been obtained for all templates. When the template number k is smaller than the template number m (S319), the computer 8 sets k = k + 1 (S321), and executes the processing of step S309 and subsequent steps.

On the other hand, when the template number k is larger than the template number m (S319), the computer 8 substitutes the value of k when M _k (k = _{1 to} m) has the maximum value into a (S323). For example, the computer 8 searches for M _k having the maximum value from M _k stored in the memory, reads the template number k corresponding to the corresponding M _k , and substitutes it for the value a.

The computer 8 sets the voltage value T _i by the following equation (S325).
T _i = V _i + v _i ^(a) (i = 1 to n) (10)
In addition, the computer 8 stores the set voltage value T _i in a reference voltage value table in the memory. If the voltage value corresponding to M _k is stored in the memory, the computer 8 searches for M _k having the maximum value from M _k stored in the memory in the process of step S323, and the corresponding value is _obtained . reading a voltage value corresponding to the M _k, which may be a T _i. In this case, the process of step S325 can be omitted. The computer 8 ends the MTF optimization process, and proceeds to the process of step S158 in FIG. Through the above processing, the voltage value T _i is set so that MTF (cf) is maximized.

FIG. 14 is a flowchart for calculating MTF (cf). First, the computer 8 obtains the pupil function f (x, y) from the wavefront aberration W (x, y) as follows (S401).
f (x, y) = e ^{ikW (x, y)} (11)
(I: imaginary number, k: wave vector (2π / λ), λ: wavelength)
Next, the computer 8 calculates the spatial frequency distribution OTF (u, v) of the eyeball based on the pupil function (S403). Hereinafter, calculation of the spatial frequency distribution OTF of the eyeball will be described.

（λ：波長
Ｒ：瞳から像点（網膜）までの距離
（ｕ，ｖ）：像点Ｏを原点とし，光軸に直行する面内での座標値
（ｘ，ｙ）：瞳面内の座標値 ） First, the computer 8 obtains the amplitude distribution U (u, v) of the point image by the Fourier transform of the pupil function f (x, y) as follows:

(Λ: wavelength R: distance from pupil to image point (retina) (u, v): coordinate value (x, y) in plane perpendicular to optical axis with image point O as origin Coordinate value)

Next, the computer 8 multiplies U (u, v) and its complex conjugate to obtain I (u, v) which is a point image intensity distribution (PSF) by the following equation.
I (u, v) = U (u, v) U ^* (u, v) (13)
The computer 8 obtains the OTF by normalizing the PSF by Fourier transform (or autocorrelation) as in the following equation.

Next, the computer 8 calculates MTF (u, v) from OTF (u, v) using the following equation (S405).
MTF (u, v) = | OTF (u, v) | (16)
The computer 8 performs initial setting of parameters (S407). For example, the computer 8 sets the angle θ = 0 ° and the total MTF ALLMTF = 0. Also, an arbitrary value (for example, d = 36) is substituted for the division number d. The division number d indicates how many angles of 0 to 180 degrees are divided in the MTF calculation. For example, if d = 36, an angle θ every 5 degrees can be set. As the value of d, an appropriate number can be used, but a multiple of 2 is desirable.

The computer 8 calculates u and v by the following equation (S409).
u = cf × cos (θ)
v = cf × sin (θ) (17)
Here, cf is the spatial frequency obtained in step S301.

The computer 8 obtains MTF (u, v) based on the calculated values of u and v, and calculates ALLMTTF by the following equation (S411).
ALLMTF = ALLMTTF + MTF (u, v) (18)
Next, the computer 8 changes the angle θ by, for example, the following equation (S413).
θ = θ + 180 / d (19)
The computer 8 determines whether θ is greater than 180 degrees (S415). If θ is smaller than 180 degrees (S415), the computer 8 returns to the process of step S409. On the other hand, when θ is greater than 180 degrees (S415), the computer 8 calculates MTF (cf) by the following equation (S417).
MTF (cf) = ALL MTF / d (20)
In addition, the computer 8 ends the MTF (cf) calculation process, and proceeds to the process of step S317 in FIG.

(Pattern optimization)
FIG. 15 is a flowchart of pattern optimization. First, the computer 8 executes the processes of steps S303 to S313. Since the processing of each step is the same as described above, detailed description thereof is omitted. Next, the computer 8 calculates a pattern matching value _Pk (S515). The computer 8 simulates a retinal image of a predetermined pattern, compares the pattern template corresponding to the pattern and the retinal image obtained by the simulation by pattern matching, and calculates a pattern matching value _Pk . A specific method for calculating the pattern matching value _Pk will be described later. Further, the computer 8 stores the calculated pattern matching value P _k in the memory corresponding to the template number k and / or the voltage value V _i (S517).

Next, similarly to the above, the computer 8 determines whether the template number k is smaller than the template number m (S319). If the template number k is smaller than the template number m, k = k + 1 is set (S321), and step S309 and the subsequent steps. Execute the process. On the other hand, when the template number k is larger than the template number m (S319), the computer 8 substitutes the value of k when P _k (k = _{1 to} m) has the maximum value into a (S523). For example, the computer 8 searches for _Pk having the maximum value from _Pk stored in the memory, reads the template number k corresponding to the corresponding _Pk , and substitutes it for the value of a.

Computer 8 performs the above processing as well as step S325, sets the voltage value T _i, and stores the voltage value T _i set to the reference voltage value table in the memory. If the voltage value corresponding to P _k is stored in the memory, the computer 8 searches for P _k having the maximum value from the P _k stored in the memory in the process of step S523, and applies. A voltage value corresponding to P _k may be read out and used as T _i . In this case, the process of step S325 can be omitted. Through the above processing, the voltage value T _i is set so that the pattern matching value P _k is maximized.

FIG. 16 is a flowchart for calculating the pattern matching value _Pk . First, the computer 8 calculates the distance from the position (X _re , Y _re ) where the optical axis of the light that illuminates the fundus 61 of the eye 60 to the fundus 61 to the macula, and the calculated distance corresponds to the pattern type. The type of pattern and pattern template is selected with reference to the stored table (S601).

FIG. 17 is a diagram for explaining the relationship between the distance from the macula and the cell size. As shown in the figure, the size of cells in the fundus of the human eye varies depending on the distance from the macula. In pattern matching in the present embodiment, a pattern having a size corresponding to the distance from the macula is selected.
First, the computer 8 calculates a distance from the macula of (X _re , Y _re ), and obtains a cell size cs based on the calculated distance. For example, a table in which the distance from the macula and the cell size are associated with each other is stored in advance in the memory, and the computer 8 can read the cell size cs corresponding to the distance calculated with reference to this table. . Moreover, the approximate expression of the graph shown in FIG. 17 may be stored in the memory, and the computer 8 may obtain the cell size using the approximate expression based on the calculated distance. The computer 8 selects the pattern original image Pat (x, y) based on the obtained cell size cs.

  18A and 18B are explanatory diagrams of a pattern original image. FIG. 18A shows a case where the cell is small, FIG. 18B shows a case where the cell is intermediate, and FIG. 18C shows a case where the cell is large. The line portion of the pattern is created with a pixel value of 1 and a size that is somewhat smaller than the cell size cs. Also, the pixel value is set to 0 except for the line portion of the pattern. As the pattern original image, an appropriate number of patterns corresponding to the cell size cs is created in advance, and stored in the memory in correspondence with the range of the cell size cs for selecting the pattern. The computer 8 can select a pattern corresponding to the obtained cell size cs with reference to the range of the cell size cs stored in the memory.

  FIG. 19 is an explanatory diagram of the pattern template image PT (x, y). (A) shows a case where the cell is small, (B) shows a case where the cell is intermediate, and (C) shows a case where the cell is large. As a pattern template image corresponding to the pattern original image described above, a lattice-like image corresponding to the cell size cs is created in the same manner as the pattern original image, and further, if the number of pixels in the line portion is N1, The dot-shaped portion is created so that the number of pixels is N2 and the pixel value is -N1 / N2. These pattern template images are stored in the memory corresponding to the above-described patterns.

  Note that the pattern original image and the pattern template image are not limited to this, and appropriate patterns and pixel values can be set according to the size of the cells. In the above example, a square lattice is used as the pattern, but it is also possible to use a spherical object or the like for the cell. In addition to selecting a pattern and a pattern template that are created in advance and stored in the memory, a pattern or the like can be created in a timely manner based on the obtained cell size.

（ｉ：虚数、ｋ：波数ベクトル（２π／λ）、λ：波長）
次に、コンピュータ８は、瞳関数ｆ（ｘ，ｙ）から眼球の空間周波数分布ＯＴＦ（ｕ，ｖ）を計算する（Ｓ６０５）。続いて、コンピュータ８は、選択されたパターンの輝度分布関数Ｐａｔ（ｘ，ｙ）をメモリを参照して計算する（Ｓ６０７）。また、コンピュータ８は、Ｐａｔ（ｘ，ｙ）を２次元フーリエ変換して空間周波数分布ＦＰａｔ（ｕ，ｖ）を求める（Ｓ６０９）。 Returning to the flowchart of FIG. 16, the computer 8 calculates the pupil function f (x, y) by the following equation based on the wavefront aberration W (X, Y) (S603).

(I: imaginary number, k: wave vector (2π / λ), λ: wavelength)
Next, the computer 8 calculates the spatial frequency distribution OTF (u, v) of the eyeball from the pupil function f (x, y) (S605). Subsequently, the computer 8 calculates the luminance distribution function Pat (x, y) of the selected pattern with reference to the memory (S607). Further, the computer 8 obtains a spatial frequency distribution FPat (u, v) by two-dimensional Fourier transform of Pat (x, y) (S609).

Next, the computer 8 multiplies the spatial frequency distribution FPat (u, v) of the pattern and the spatial frequency distribution OTF (u, v) of the eyeball as The frequency distribution OR (u, v) of the image is obtained (S611).
FPat (u, v) × OTF (u, v) → OR (u, v) (22)

The computer 8 calculates the brightness distribution function PT (x, y) of the pattern template with reference to the memory (S613). The computer 8 obtains a two-dimensional Fourier transform FPT (u, v) of PT (x, y) (S615). Next, the computer 8 obtains OTmp (u, v) by multiplying the spatial frequency distribution OR (u, v) of the retinal image calculated from the wavefront and the spatial frequency distribution FPT (u, v) of the pattern (S617). .
OR (u, v) × FT (u, v) → OTmp (u, v) (23)
Next, the computer 8 performs two-dimensional inverse Fourier transform on OTmp (u, v) to obtain TmpIm (X, Y) (S619). The computer 8 acquires the maximum value of the absolute value of TmpIm (X, Y) and sets it as the pattern matching value _Pk (S621). Also, the computer 8 ends the pattern matching value calculation process, and proceeds to the process of step S517 in FIG.

(Comparative example)
FIG. 20 is a comparison diagram of images obtained by pattern optimization. (A) is no correction, (B) is a case where correction is made so that the aberration amount RMS is small (RMS optimization), and (C) is this embodiment. The case where it correct | amends by the pattern optimization in the form of is shown. 20A to 20C show (i) wavefront aberration, (ii) image simulation of Landolt's ring, (iii) fringe image simulation, and (iv) RMS, respectively. In the pattern optimization, RMS 0.095 is larger than RMS 0.089 in RMS optimization, but it can be understood by the observer that the image looks better as shown in (ii).

FIG. 23 is a block diagram illustrating the entirety of the fundus oculi observation device according to the third embodiment of the present invention. In FIG. 23, the cylinder lens 77 is not shown. In the light flux from the eye 60 to be examined, the wavefront distortion occurs between the fundus 61 and the pupil 62. Therefore, when a pupil conjugate point that is a pupil conjugate position is selected as the position of the deformable mirror 71 that corrects the wavefront, the position at which the reflected light from the reflection mirror 72 is incident on the deformable mirror 71 again is the pupil conjugate point. It becomes. Further, as shown in FIG. 23, the two lenses L11 and L12 are interposed between the deformable mirror 71 and the reflecting mirror 72 so that the direction of the image of the light re-entering the deformable mirror 71 is erect. To do. By making the direction of the image of the light re-entering the deformable mirror 71 upright, the amount of phase distortion at the same position of the light beam can be corrected by a single amount by the single deformable mirror 71. Then, the distance _{L A} between the reflecting mirror 72 and the deformable mirror 71, an amount corresponding to two lenses L11 and L12 is interposed increases.

FIG. 24 is a block diagram illustrating the entire fundus oculi observation device according to the fourth embodiment of the present invention. Therefore, the deformable mirror 71 is placed at the pupil conjugate point, and the position where the reflected light from the reflection mirror 72 is incident on the deformable mirror 71 again becomes the pupil conjugate point. In addition, as shown in FIG. 24, since the single lens L11 is interposed between the deformable mirror 71 and the reflecting mirror 72, the direction of the image of the light re-entering the deformable mirror 71 is reversed. With respect to centrally symmetric wavefront distortion, for example, distortion such as astigmatism, a single correction mirror 71 can effectively obtain a double correction amount. Then, the distance L _B between the reflecting mirror 72 and the deformable mirror 71, a size of one lens L11 is interposed.

FIG. 25 is a block diagram illustrating the entire fundus oculi observation device according to the fifth embodiment of the present invention. As shown in FIG. 25, in order to simplify the optical system, the deformable mirror 71 is arranged at a position close to the pupil conjugate point without interposing a lens between the deformable mirror 71 and the reflecting mirror 72. In the arrangement shown in FIG. 25, the direction of the re-incident light image is upright, so that a single correction mirror 71 can effectively obtain a double correction amount, and the distance L _C of the reflecting mirror 72 can be very short, displacement of the position of the position and the re-incident light of the light emitted to the reflecting mirror 72 of the deformable mirror 71 is very small, which is preferable.

  The fundus oculi observation device / system of the present invention includes a fundus oculi observation program for causing a computer to execute each procedure, a computer-readable recording medium recording the fundus oculi observation program, and a fundus observation program that can be loaded into an internal memory of the computer. The program product can be provided by a computer such as a server including the program.

  The optical characteristics of the eye 60 to be examined are obtained by the aberration measuring unit 81 using the anterior eye image and the fundus image obtained by the point image receiving optical system 5, but the present invention is not limited to this. Further, it can be configured so as to be obtained from wavefront measurement data including wavefront aberration from an appropriate optical system and apparatus. In the embodiment of the present invention, by appropriately arranging the distance L between the deformable mirror 71 and the reflecting mirror 72, when the deformable mirror 71 is reflected twice, the phase change is effectively about twice. Thus, sufficient aberration correction of the anterior eye image and the fundus image can be performed. As a result, a clear fundus image can be obtained in the photographing system.

  According to the embodiment of the present invention, an appropriate correction amount can be obtained by adjusting the correction amount of the wavefront aberration correction optical element so as to improve the quality of the fundus image. According to the embodiment of the present invention, it is possible to improve the image quality of the fundus image using the voltage change template for adjusting the correction amount of the wavefront aberration correcting optical element.

1 is a configuration block diagram illustrating an example of an entire fundus oculi observation device according to the present invention. In the block diagram of the deformable mirror 71, a single deformable mirror is shown. It is the format of the reference voltage value table which memorize | stores the reference voltage value of a voltage change. It is a table format of a concentric circle template. It is a table format of a symmetric template. It is a table format of an asymmetric template. This is a format of matching numerical data by template matching. It is a flowchart of the fundus observation in the first embodiment of the present invention. It is a flowchart explaining an example of the optimal selection norm of a voltage change template. It is a flowchart explaining the procedure which selects the type of a voltage change template. It is explanatory drawing about the best judgment by the change of MTF concerning the 2nd Embodiment of this invention. It is a flowchart of MTF optimization. It is a related figure of the distance from a macular and the spatial frequency of a cell. It is a flowchart of MTF (cf) calculation. It is a flowchart of pattern optimization. It is a flowchart about calculation of the pattern matching value _Pk . It is a figure explaining the relationship between the distance from a macula, and the magnitude | size of a cell. It is explanatory drawing of a pattern original image. It is explanatory drawing of pattern template image PT (x, y). It is a comparison figure of the image obtained by pattern optimization. It is explanatory drawing of a wavefront sensor. It is a principal part block diagram explaining arrangement | positioning of a deformable mirror and a reflective mirror. It is a block diagram explaining the whole fundus observation device in a 3rd embodiment of the present invention. It is a block diagram explaining the entirety of a fundus oculi observation device according to a fourth embodiment of the present invention. It is a block diagram explaining the entirety of a fundus oculi observation device according to a fifth embodiment of the present invention.

Explanation of symbols

2 Fundus illumination system (second illumination optical system)
3 Fundus observation system (image forming optical system)
31 Optical system for fundus image formation 32 Fundus image light receiving unit (CCD)
33 fundus image display unit 4 point image projection optical system 41 first light source unit 5 point image light receiving optical system 51 Hartmann plate 52 point image light receiving optical unit 6 voltage change template storage unit (DB: database)
8 Computer 9 Operation control unit 60 Eye to be examined (object)
61 Retina (fundus)
62 Cornea (Anterior Eye)
7 Compensation Optics 71 Variable Shape Mirror (Wavefront Aberration Correction Optical Element)
72 Reflection mirror (recursive optical system)
77 Cylinder Lens 8 Computer 81 Aberration Measuring Unit 82 Image Data Storage Unit 83 Compensation Amount Determination Unit 85 Voltage Change Template Selection Unit 86 Display Unit BS Beam Spiriter DM Dichroic Mirrors L1 to L12 Lens

Claims (9)

A wavefront aberration measuring unit that receives a light beam from an object and measures wavefront aberration;
An image forming optical system that receives a light from the object by at least twice acting a single wavefront aberration correcting optical element to form an image of the object;
A control unit that controls an aberration correction amount of the wavefront aberration correcting optical element based on the wavefront aberration measured by the wavefront aberration measuring unit;
An image forming apparatus with an aberration correction function. The object is the fundus of the eye to be examined;
And an illumination optical system for illuminating the fundus of the eye to be examined;
The image forming optical system is configured to form an image of the fundus of the eye to be examined;
The image forming apparatus with an aberration correction function according to claim 1. The wavefront aberration correcting optical element is composed of a deformable mirror;
A recursive optical system that reflects the light beam, which has been subjected to the first action by the wavefront aberration correcting optical element, to the wavefront aberration correcting optical element side again;
The image forming apparatus with an aberration correction function according to claim 2.   The recursive optical system is configured to return the light beam first reflected from the deformable mirror to the deformable mirror again, and is configured to have a substantially conjugate relationship with the eye to be examined in the deformable mirror. The image forming apparatus with an aberration correction function according to claim 3.   The recursive optical system returns the light beam first reflected from the deformable mirror to the deformable mirror again, and forms the erect image on the deformable mirror again at the first reflection position. The image forming apparatus with an aberration correction function according to claim 3 or claim 4 configured.   The wavefront aberration measuring unit includes a Hartmann optical element disposed at a position substantially conjugate with a pupil of an eye to be examined, and is formed such that a light receiving unit is disposed at a substantially focal position of the Hartmann optical element. The image forming apparatus with an aberration correction function according to any one of claims 1 to 5. Receiving the light beam from the object and measuring the wavefront aberration by the wavefront aberration measuring unit;
A wavefront correcting step of causing a single wavefront aberration correcting optical element to act on a light beam from the object at least twice;
Receiving a light beam from the object corrected in the wavefront correcting step by an image forming optical system;
Controlling the aberration correction amount of the wavefront aberration correcting optical element based on the wavefront aberration measured in the wavefront aberration measuring step;
An image forming method using an aberration correction optical element. Further, a voltage-change template storage unit for storing a plurality of types of voltage change templates for adjusting the wavefront aberration correcting optical element;
From the voltage-change template, and a voltage-change template selection unit for selecting the type of voltage change templates for correcting the wavefront aberration correcting optical element;
The control unit controls an aberration correction amount of the wavefront aberration correcting optical element according to the voltage change template selected by the voltage change template selection unit;
The image forming apparatus with an aberration correction function according to any one of claims 1 to 6 . The voltage change template storage unit includes a concentric template of the wavefront aberration correcting optical element, a symmetrical template in which a voltage change is set symmetrically with respect to a center or a desired axis of the wavefront aberration correcting optical element, and a voltage change being the wavefront aberration. Including at least one voltage change template of an asymmetric template set asymmetrically about the center or desired axis of the correction optical element;
The voltage change template selection unit selects a type of voltage change template for correcting the wavefront aberration correction optical element based on the determination of the wavefront aberration measured by the wavefront aberration measurement unit;
The image forming apparatus with an aberration correction function according to claim 8.

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