JP2014030573A - Device for objective measurement of refractive wavefront aberration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for objective measurement of refractive wavefront aberration in a smaller size at lower costs.SOLUTION: A device for objective measurement of refractive wavefront aberration comprises: an illumination optical system that has a light source 101 and irradiates the fundus of a subject eye 150 with illumination light; a wavefront measurement system having a Hartmann plate 122 that divides reflective luminous flux reflected from the fundus of a subject eye 150 into a plurality of luminous flux, and a first light receiving part 122 for receiving luminous flux divided by the Hartmann plate 121; an anterior eye illumination system for illuminating an anterior eye part of the subject eye 150; an anterior eye observation system having a second light receiving part 114 for receiving light reflected from the anterior eye part of the subject eye 150 that is illuminated by the anterior eye illumination system; and an image data output part 115 for outputting image data of an anterior eye image obtained by the anterior eye observation system. When the light source 101 is set in a range from -3D to -13D, a position of the fungus of the subject eye 150 is set to be substantially conjugate with the light source and a position of the exit pupil is set to be away from an image surface position.

Description

  The present invention relates to an objective refractive wavefront aberration measuring apparatus.

  A general objective refractive wavefront aberration measuring apparatus is known (see, for example, Patent Document 1).

JP 2012-75491 A

  The objective refractive wavefront aberration measuring apparatus includes a wavefront sensor optical system that detects the state of the wavefront of the reflected light from the eye to be detected in order to detect the state of refraction in the eye to be examined. The wavefront sensor optical system requires a diopter correction mechanism corresponding to the power change of the eye to be examined (the human eye to be measured). The diopter correction mechanism is a mechanism that adjusts the position of the focal point of the optical system by moving the optical component on the optical axis according to the power of the eye to be examined (that is, visual acuity). However, since the diopter correction mechanism requires a mechanism for moving the optical component, the optical system becomes large and the apparatus becomes expensive. In such a background, an object of the present invention is to provide an objective refractive wavefront aberration measuring apparatus that can be reduced in size and cost.

  The invention described in claim 1 includes an illumination optical system that includes a light source and irradiates illumination light to the fundus of the eye to be examined, a Hartmann plate that divides a reflected light beam reflected from the fundus of the eye to be examined into a plurality of light beams, and the Illuminated by a wavefront measurement system having a first light receiving unit that receives a divided light beam divided by a Hartmann plate, an anterior segment illumination system that illuminates the anterior segment of the subject's eye, and the anterior segment illumination system An anterior ocular segment observation system having a second light receiving unit that receives light reflected from the anterior ocular segment of the eye to be examined, and image data of an anterior ocular segment image obtained by the anterior ocular segment observation system are output. An image data output unit, and when the light source is between -3D and -13D, the fundus position of the eye to be examined is arranged substantially conjugate with the light source, and the exit pupil position is defined as an image plane position. This is an objective refractive wavefront aberration measuring device, which is arranged farther away.

  A second aspect of the invention is an objective refractive wavefront aberration measuring apparatus according to the first aspect of the invention, wherein the focal point of the illumination optical system is fixed. A third aspect of the invention is an objective refractive wavefront aberration measuring apparatus according to the first aspect of the invention, wherein the exit pupil position is disposed at a distance of 200 mm to 300 mm far from the image plane position. . A fourth aspect of the present invention is the objective refractive wavefront aberration measuring apparatus according to the first aspect of the present invention, wherein a working distance that is a distance from the apparatus main body to the eye to be examined is variable. .

  The present invention optimizes the position of the beam waist and the exit pupil position (aperture position) so that the pupil entrance diameter of the eye to be examined is an optimal (small and circular) value, and the difference in the power of the eye to be examined is achieved. Even if it exists, the change of the magnitude | size of the spot image used as the area | region observed is suppressed. That is, the present invention adjusts the beam waist position to the vicinity of the 0.0D fundus position by placing the light source position at approximately −10D position (−3D to −13D), and sets the exit pupil position to 200 mm far from the image plane position. The aperture position is determined so that the incident diameter at the pupil position of the human eye is reduced and the depth of focus is increased. By doing so, the change in the size of the spot image due to the Dioptor change of the human eye can be reduced. That is, even if there is a difference in the power of the eye to be examined, a change in the size of the spot image that becomes an observed region can be suppressed. Thereby, the diopter correction mechanism for coping with the change in the power of the eye to be examined can be omitted, and the apparatus can be reduced in size and cost.

  According to the present invention, it is possible to obtain an objective refractive wavefront aberration measuring apparatus that can be reduced in size and cost.

It is a block diagram of the objective refractive wavefront aberration measuring apparatus of an embodiment. It is a conceptual diagram explaining an optical system. It is a graph which shows the relationship between the position (D value) (horizontal axis) of a light source, and the distance (vertical axis) from an image surface to a waist. It is a conceptual diagram explaining a Gaussian beam. It is the photograph which image | photographed the cross section of the beam of illumination light. It is a conceptual diagram which shows the relationship between D value and a to-be-tested eye.

  FIG. 1 shows a block diagram of an embodiment using the invention. FIG. 2 is a conceptual diagram illustrating the optical system. FIG. 1 shows an objective refractive wavefront aberration measuring apparatus 100 according to the embodiment. The objective refractive wavefront aberration measuring apparatus 100 does not include a diopter correction mechanism, and the focus of the illumination optical system is fixed. For this reason, an optical system can be reduced in size simply and cost reduction can be achieved. Moreover, since it can be reduced in size, it can be easily mounted on a surgical microscope or a slit lamp.

(Illumination optics)
The objective refractive wavefront aberration measuring apparatus 100 includes an illumination optical system that irradiates illumination light to the fundus of the eye to be examined. Hereinafter, the illumination optical system will be described. The objective refractive wavefront aberration measuring apparatus 100 includes a light source 101 that emits measurement light applied to the fundus of the eye 150 to be examined. The light source 101 is a laser diode that emits infrared light having a wavelength of 830 nm. Reference numeral 102 denotes a lens system for adjusting the light flux from the light source 101. Although the lens system 102 is a simplified description, it is actually an optical system in which a plurality of lenses are combined. The same applies to other lens systems described later.

  Illumination light from the light source 101 is reflected upward by the dichroic mirror 107 through the polarization beam splitter 104, the optical aperture 105, and the lens system 106. The dichroic mirror 107 is set to reflect light having a wavelength of 830 nm and transmit light having a wavelength of 940 nm. Illumination light reflected upward by the dichroic mirror 107 is reflected by the dichroic mirror 109 via the objective lens 108 in the left direction (the direction of the eye 150 to be examined). The dichroic mirror 109 has a structure in which the direction of the eye of the subject is open, transmits visible light in a region where the wavelength is shorter than approximately 800 nm, and reflects infrared light that exceeds the wavelength of 800 nm. Has been. Illumination light reflected in the left direction in the figure by the dichroic mirror 109 is applied to the fundus of the eye 150 to be examined. The above is the illumination optical system.

  The illumination optical system is designed to satisfy the following conditions. First, the beam waist position is adjusted to the image plane position (0.0D) by bringing the position of the light source 101 to -3D to -13D. Hereinafter, the meaning of this numerical limitation will be described. First, FIG. 3 is a graph showing the relationship between the position of the light source (D value) (horizontal axis) and the distance from the image plane to the beam waist (vertical axis). FIG. 4 is a conceptual diagram illustrating a Gaussian beam. FIG. 5 is a photograph of a cross section of the illumination light beam. FIG. 6 is a conceptual diagram showing the relationship between the D value and the eye to be examined.

  What is required here is that the beam diameter of the illumination light is small (does not spread unnecessarily) in the range before and after the position shown in FIG. 6B, and the change in the size can be reduced. That is, when the diopter of the eye to be examined is different, the state of refraction inside the eye to be examined differs accordingly, so the state of the illumination light beam inside the eye to be examined is also affected, and the beam waist (the beam is the most The position of the squeezed part also changes. However, even if the position of the beam waist changes in the front and rear range centering on the position of FIG. 6B, if the change in the beam cross-sectional shape of the beam waist portion is small, the adverse effect due to the difference in diopter is suppressed. Can do. If the view is changed, even if the diopter correction mechanism is omitted, the disadvantages thereof can be suppressed.

By the way, it is preferable to focus the irradiation light on the image plane as much as possible (the position of the beam waist). From this point of view, when viewing FIG. 3, the position of the light source 101 is suitably about −13 or more in terms of the D value. (Below −13D, the position of the beam waist suddenly moves away from the image plane). On the other hand, from the model of FIG. 4, considering the divergence of the beam, it is W ₀ smaller is preferable, W ₀ is the divergence angle increases small, therefore the value of the appropriate W ₀ is required. Here, as is apparent from the model of FIG. 6, as the value approaches 0D, the value of W ₀ decreases and the beam divergence angle increases. Therefore, it is not appropriate to make the position of the light source captured by the D value so close to 0D. Therefore, it is appropriate that the upper limit of the position of the light source captured by the D value is about -3D.

This can be read from FIG. FIG. 5 shows the positions (A), (B), and (C) on the three optical axes in FIG. 6 (the horizontal direction in FIG. 5) and the position of the light source captured by the D value (the vertical direction in FIG. 5). A cross-sectional photograph of a beam of illumination light when the relationship with is changed. As is clear from the vertical cross-sectional photograph of FIG. 5, when the position of the light source is smaller than −5D, the distortion of the cross-sectional shape of the beam is small. It begins to be seen, and it becomes obvious when it reaches 0D. This is because the divergence angle of the beam is increased and the influence of the aberration of the optical system becomes obvious as W ₀ in the model of FIG. 4 is decreased. Since the distortion of the beam cross-sectional shape increases the error of the observed information, it is desirable that the distortion is as small as possible. From this, it is concluded that the upper limit of the position of the light source captured by the D value is about −3D.

  In addition, the position of the optical aperture 105 is adjusted so that the exit pupil position is 200 mm to 300 mm far from the image plane position (the direction behind the fundus). By doing so, even if there is a change (difference) in the diopter of the eye to be examined, the pupil incident diameter of the eye to be examined can be prevented from greatly deviating from the optimum (small and circular) value. The distance between the exit pupil position and the image plane position is optimally about 250 mm, but can be selected from a range of 200 mm to 300 mm.

  Of course, the setting of each parameter described above is set in consideration of the lens system. In FIG. 1, the explanatory line of the exit pupil and the luminous flux of the illumination light are exaggerated and do not match the aperture diameter of the optical aperture 105 in FIGS.

  As described above, the illumination optical system of this embodiment can reduce the beam diameter of illumination light (so as not to spread unnecessarily) in the range before and after the position shown in FIG. The change of can be suppressed. For this reason, the diopter correction mechanism can be omitted, and the simplification of the optical system, the miniaturization of the entire apparatus, and the cost reduction can be pursued. Since the fundus position of the eye to be examined is substantially conjugate with the light source when the light source is between -3D and -13D, and the exit pupil position is located far from the image plane position, the apparatus main body The working distance that is the distance from the eye to the subject eye can be made variable.

(Wavefront measurement system)
The objective refractive wavefront aberration measuring apparatus 100 includes a Hartmann plate that divides a reflected light beam reflected from the fundus of the eye to be examined into a plurality of light beams, and a first light receiving unit that receives the divided light beam divided by the Hartman plate. A wavefront measurement system is provided. Hereinafter, the wavefront measurement system will be described. Illumination light from the light source 101 reflected on the fundus of the eye 150 (hereinafter referred to as fundus reflection light) is reflected downward in the figure by the dichroic mirror 109, passes through the objective lens 108, and is then reflected by the dichroic mirror 107. Reflected in the right direction (the direction of the lens system 106). The fundus reflection light that has passed through the lens system 106 from the left to the right in the figure is separated by the polarization beam splitter 104, and a part of the polarization component (mainly a polarization component whose polarization plane is rotated at the fundus) is converted into the lens system. Reflected in the 120 direction. The light beam of the fundus reflected light reflected from the polarization beam splitter 104 in the direction of the lens system 120 is divided into a plurality of light beams by the Hartmann plate 121 and received by the light receiving unit 122. Here, the Hartmann plate 121 is in a conjugate relationship with the pupil of the eye 150 to be examined, and the light receiving unit 122 is configured by a CMOS image sensor. The light receiving unit 122 optically detects wavefront information of reflected light from the eye 150 to be examined. This wavefront information includes information relating to the refractive characteristics of the eye, and is used, for example, for examinations inside the eyeball and refractive surgery. Here, as will be described later, the objective lens 108 is shared with the anterior ocular segment observation system.

(Anterior segment illumination system)
The objective refractive wavefront aberration measuring apparatus 100 includes an anterior segment illumination system that illuminates the anterior segment of the eye to be examined. Hereinafter, the anterior segment illumination system will be described. The objective refractive wavefront aberration measuring apparatus 100 includes a light source 112 that constitutes an anterior ocular segment illumination system. The light source 112 is an LED that emits infrared light having a wavelength of 940 nm. Although not clearly shown in FIG. 1, the light sources 112 are disposed at two positions on both sides (left and right) below the dichroic mirror 109. The light source 112 irradiates the dichroic mirror 109 with illumination light, and is reflected light (infrared light). Is irradiated to the eye 150 to be examined.

(Anterior segment observation system)
It can be said that the objective refractive wavefront aberration measuring apparatus 100 includes an anterior ocular segment observation system having a light receiving unit that receives light reflected from the anterior ocular segment of the subject's eye illuminated by the anterior ocular segment illumination system. Hereinafter, the anterior ocular segment observation system will be described. Light having a wavelength of about 940 nm included in the illumination light irradiated to the eye 150 to be examined through the dichroic mirror 109 from the light source 112 is reflected by the anterior eye portion of the eye 150 to be examined (hereinafter, this reflected light is referred to as the anterior eye). 1 is reflected by the dichroic mirror 109 in the downward direction in FIG. The anterior ocular segment reflected light including light having a wavelength of 940 nm passes through the objective lens 108, further passes through the dichroic mirror 107, and reaches the lens system 113. The anterior segment reflected light that has passed through the lens system 113 is received by the light receiving unit 114. The light receiving unit 114 is a CCD sensor, and detects image data (that is, image data of the anterior segment) based on the anterior segment reflected light having a wavelength of 940 nm. Note that the reflected light in the visible band from the eye 150 passes through the dichroic mirror 109 in the right direction in the figure and passes outside the objective refractive wavefront aberration measuring apparatus 100.

(Image data output system)
The objective refractive wavefront aberration measuring apparatus 100 includes an image data output unit 115 that outputs image data of an anterior segment image obtained by the anterior segment observation system. In addition to the function of outputting the image data of the anterior segment obtained by the light receiving unit 114, the image data output unit 115 synthesizes the image data obtained by integrating the information of the wavefront aberration obtained by the light receiving unit 122 with the image of the anterior segment. And has a function of outputting it. For example, the wavefront information of the reflected light from the fundus is visually embedded in the image of the anterior eye part, and image data in which the wavefront information is displayed as color information is generated and output. In this case, an anterior eye image in which the state of the wavefront aberration can be visually grasped can be obtained due to a partial color difference. Therefore, the exact pupil center can be used as the origin of wavefront aberration display. The objective refractive wavefront aberration measuring apparatus 100 can measure the corneal shape by attaching a placido plate (not shown), which is a corneal shape measuring member, but the image data output unit 115 can measure the corneal shape. It has a function of outputting shape data and wavefront information in conjunction with each other. Thus, various diagnoses can be made by combining and displaying image data of an anterior segment image, corneal shape data, wavefront aberration information, and the like. The placido ring plate is a light guide plate, and light from a plurality of (for example, 36) LED light sources provided on the periphery of the placido plate propagates in the placido, and light diffuses in the direction of the eye at the placido ring portion. That part has been diffusion processed to make it easier. Further, the image data output unit 115 captures the influence when the dichroic mirror 109 is rotated or the objective refractive wavefront aberration measuring apparatus 100 is tilted, and the wavefront data measured by the wavefront measuring system is taken into account. The coordinate axis is changed, and data conversion is performed so that appropriate wavefront data can be obtained.

(Dichroic mirror rotation control / detection system)
The objective refractive wavefront aberration measuring apparatus 100 includes a dichroic mirror rotation control / detection unit 116 that controls / detects the rotation of the dichroic mirror 109. The dichroic mirror 109 has a structure that can be swung left and right around the direction toward the eye 150 to be examined. This drive is performed by a drive motor and a gear mechanism not shown in FIG. The dichroic mirror rotation control / detection unit 116 controls the drive motor. The rotation angle of the dichroic mirror 109 is detected by a rotary encoder (not shown), and the information is fed back to the dichroic mirror rotation control / detection unit 116. The rotation angle information is sent to the image data output unit 115. A structure in which the dichroic mirror 109 is manually rotated is also possible.

(Tilt angle detection system of objective refraction wavefront aberration measuring device)
The objective refraction wavefront aberration measuring apparatus 100 includes an inclination angle detection unit 117. As will be described later, the objective refractive wavefront aberration measuring apparatus 100 is arranged obliquely below the eye to be examined, and is configured to perform measurement from obliquely below the eye to be examined. At this time, since measurement is not performed from the front, in order to obtain appropriate wavefront information, it is necessary to convert the coordinate system of the wavefront information based on the tilted angle (elevation angle). The tilt angle detection unit 117 includes a tilt angle sensor that detects the tilt angle of the objective refractive wavefront aberration measuring apparatus 100, and outputs tilt angle information to the image data output unit 115 based on the output. The image data output unit 115 converts the coordinate system of the wavefront information detected by the wavefront measurement system based on the tilt angle information, and generates wavefront data in which an error when measuring from the tilted position is corrected.

(Advantages, other)
The objective refractive wavefront aberration measuring apparatus 100 can be mounted on a surgical microscope, a slit lamp, or the like. The objective refractive wavefront aberration measuring apparatus 100 can observe the anterior segment image in addition to the detection of the wavefront aberration from the eye to be examined.
(1) Positioning of the objective refractive wavefront aberration measuring apparatus can be easily performed.
(2) The eye movement can be fed back to the wavefront data (by image processing).
(3) The objective refractive wavefront aberration measuring apparatus can be rotated in accordance with the eye movement.
(4) By using the anterior ocular segment image as a guide image, it can be combined with an apparatus whose visual field cannot be confirmed.
(5) The degree of freedom of the combination position when combining with other devices is high.
(6) The corneal shape can be measured by adding a platide plate.
In addition, it is possible to measure off-axis aberrations by configuring the mounting arm for mounting the polygonal refractive wavefront aberration measuring apparatus so as to be rotatable. Further, since it can be used with an elevation angle (tilt angle), the progressive lens can be evaluated by measuring the wavefront at various tilt angles. In addition, it can be combined with a refractometer, a handheld, and a head mount. In addition, since it is an integrated unit structure, it is effective when measuring children, and it is effective to wear a handheld structure and the spectacles that have been completed, and measure the wavefront during the action to evaluate the spectacles. A head mount structure that can be performed is possible. In addition, because it is small and lightweight, it is easy to handle, and by mounting it alone on the slit lamp stage, the off-axis refraction and aberration in the horizontal direction (up to about 40 degrees) and the off-axis amount in the vertical direction Easy to measure (important in preventing myopia).

  The present invention can be used for an objective refractive wavefront aberration measuring apparatus provided with an anterior ocular segment observation system.

  DESCRIPTION OF SYMBOLS 100 ... Objective refractive wave aberration measuring apparatus, 101 ... Light source, 102 ... Lens system, 104 ... Polarizing beam splitter, 105 ... Optical aperture, 106 ... Lens system, 107 ... Dichroic mirror, 108 ... Objective lens, 109 ... Dichroic mirror , 112 ... light source, 113 ... lens system, 114 ... light receiving part, 115 ... image data output part, 116 ... dichroic mirror rotation control / detection part, 117 ... tilt angle detection part, 150 ... eye to be examined, 120 ... lens system, 121 ... Hartmann plate, 122 ... light receiving part.

Claims (4)

An illumination optical system that includes a light source and irradiates the fundus of the eye to be examined; and
A wavefront measuring system having a Hartmann plate that divides a reflected light beam reflected from the fundus of the eye to be examined into a plurality of light beams, and a first light receiving unit that receives the divided light beam divided by the Hartmann plate;
An anterior ocular segment illumination system for illuminating the anterior segment of the subject eye;
An anterior ocular segment observation system having a second light receiving unit that receives light reflected from the anterior ocular segment of the eye to be examined illuminated by the anterior ocular segment illumination system;
An image data output unit that outputs image data of an anterior segment image obtained by the anterior segment observation system;
When the light source is between -3D and -13D, the fundus position of the eye to be examined is arranged so as to be substantially conjugate with the light source,
An objective refractive wavefront aberration measuring apparatus, wherein an exit pupil position is arranged far from an image plane position.   2. The objective refractive wavefront aberration measuring apparatus according to claim 1, wherein a focal point of the illumination optical system is fixed.   2. The objective refractive wavefront aberration measuring apparatus according to claim 1, wherein the exit pupil position is disposed at a distance of 200 mm to 300 mm far from the image plane position.   The objective refractive wavefront aberration measuring apparatus according to claim 1, wherein a working distance that is a distance from the apparatus main body to the eye to be examined is variable.

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