JP2018068838A - Optical measurement device of eyeball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical measurement device of an eyeball which improves accuracy of optical measurement as compared with a case where correction corresponding to an incident state on a light receiving surface receiving a light beam is not performed.SOLUTION: An optical measurement device 1 of an eyeball comprises: a light irradiation system 21 for irradiating an anterior chamber 13 of an eyeball 10 of a subject with a light beam 28; a light reception system 22 having a light receiving surface 35a of a light receiver 35 for receiving the light beam 28 having passed through the anterior chamber 13 of the eyeball 10; and an incident state measurement system 23 which is provided between the eyeball 10 and the light irradiation system 21 so as to be able to receive at least a part of the light beam 28 having passed through the anterior chamber 13 of the eyeball 10 and has a light receiving surface 51a of a light receiver 51 capable of measuring an incident position of the light beam 28.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical measurement device for an eyeball.

  Patent Document 1 includes means for projecting laser light, a light receiving unit disposed coaxially with the light projecting unit, and a mirror disposed parallel to the optical axis at a predetermined distance from the optical axis. This mirror is used to let light pass through a predetermined part of the eyeball, characterized in that the vertical line at the center of the mirror is arranged so that it intersects the straight line connecting the light projecting part and the light receiving part at the center. An eye measurement positioning tool is described.

Japanese Patent Laid-Open No. 2002-570

  By the way, when measuring the eyeball by irradiating the eyeball of the measurement subject with the polarization-controlled light beam and receiving the light beam emitted from the eyeball across the anterior chamber, the state of the eyeball of the measurement subject If the incident state with respect to the light receiving surface that receives the light beam changes in accordance with the change of, there is a possibility that the accuracy of the optical measurement is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an eyeball optical measurement device in which the accuracy of optical measurement is improved as compared with a case where correction corresponding to an incident state on a light receiving surface that receives a light beam is not performed.

According to the first aspect of the present invention, a light irradiating unit that irradiates a light beam toward the anterior chamber of the eyeball of the measurement subject, and a first light receiving unit that receives the light beam that has passed through the anterior chamber of the eyeball. A light receiving means having a surface, and provided between the eyeball and the light receiving means so as to be able to receive at least part of the light beam that has passed through the anterior chamber of the eyeball, and the incident position of the light beam can be measured An optical measurement device for an eyeball comprising a measuring means having a second light receiving surface.
According to a second aspect of the present invention, a signal output from the light receiving unit is made to correspond to an incident state on the first light receiving surface based on an incident position on the second light receiving surface measured by the measuring unit. The eyeball optical measurement device according to claim 1, further comprising correction means for correcting the eyeball.
The invention according to claim 3 is a correction for correcting an incident state of a light beam on the first light receiving surface of the light receiving means based on an incident position on the second light receiving surface measured by the measuring means. The eyeball optical measurement device according to claim 1, further comprising: means.
According to a fourth aspect of the present invention, the measuring means is provided between the eyeball and the light receiving means so as to be able to receive at least part of the light that has passed through the eyeball, and an optical path length from the eyeball is The eyeball optical measurement device according to claim 1, further comprising a third light receiving surface different from the second light receiving surface.
According to a fifth aspect of the present invention, the signal output from the light receiving means is generated based on the incident position on the second light receiving surface and the incident position on the third light receiving surface measured by the measuring means. 5. The eyeball optical measurement device according to claim 4, further comprising correction means for correcting the light in accordance with an incident position and an incident angle on one light receiving surface.
According to a sixth aspect of the present invention, the first light receiving surface of the light receiving means is based on the incident position on the second light receiving surface and the incident position on the third light receiving surface measured by the measuring means. 5. The eyeball optical measurement device according to claim 4, further comprising correction means for correcting an incident position and an incident angle of the light beam on the eyeball.
The invention according to claim 7 is the optical measurement apparatus for an eyeball according to claim 1, wherein the incident position of the first light receiving surface of the light receiving means can be measured.
According to an eighth aspect of the present invention, a signal from the light receiving means is based on an incident position of the light receiving means on the first light receiving surface and an incident position of the measuring means on the second light receiving surface. The eyeball optical measurement device according to claim 7, further comprising correction means for correcting the output in accordance with an incident position and an incident angle on the first light receiving surface.
The invention according to claim 9 is based on the incident position of the light receiving means on the first light receiving surface and the incident position of the measuring means on the second light receiving surface. The eyeball optical measurement device according to claim 7, further comprising correction means for correcting an incident position and an incident angle of the light beam on one light receiving surface.

According to the first aspect of the present invention, the accuracy of optical measurement is improved as compared with the case where the correction corresponding to the incident state on the light receiving surface is not performed.
According to the second aspect of the present invention, no means for adjusting the optical system is required as compared with the case where the signal output is not corrected.
According to the third aspect of the present invention, it is not necessary to consider the in-plane variation of the light receiving sensitivity of the first light receiving surface as compared with the case where the incident state of the light beam is not corrected.
According to the fourth aspect of the present invention, information relating to the incident angle of the light beam can be easily obtained as compared with the case where the third light receiving surface is not provided.
According to the fifth and sixth aspects of the invention, the accuracy of optical measurement is further improved as compared with the case where correction is performed without corresponding to the incident angle.
According to the seventh aspect of the present invention, the number of light receiving surfaces provided in the measuring means is reduced as compared with the case where the first light receiving surface cannot measure the incident position.
According to the eighth and ninth aspects of the invention, the measurement accuracy of the incident position on the first light receiving surface is improved as compared with the case where the first light receiving surface cannot measure the incident position.

It is a figure which shows an example of a structure of the optical measuring device with which 1st Embodiment is applied. It is a figure explaining the method to measure the rotation angle (optical rotation) of the polarization plane by the optically active substance contained in the aqueous humor in the anterior chamber with the optical measurement device. It is a figure explaining the incident state to the light receiver of the light beam which passed the anterior chamber of the eyeball in the case where an incident state measurement system is not provided. It is a figure explaining the incident state measurement system in a 1st embodiment. (A) is a figure explaining the light beam which passes the assumed optical path, (b) is a figure explaining the light beam which deviated from the assumed optical path, (c) demonstrates the method of measuring an incident state. FIG. It is an example of the look-up table for correct | amending the output signal of a light receiver. (A) is a correction value lookup table for the incident position, and (b) is a correction value lookup table for the incident angle. It is a figure explaining the modification of an incident state measurement system. (A) is an incident state measurement system to which the first embodiment is applied, (b) is a modification, and (c) is another modification. It is a figure explaining the incident state measurement system which measures an incident position. (A) is an incident state measuring system using a beam splitter, and (b) is an incident state measuring system using a mirror. It is a figure explaining the optical measuring device of the eyeball to which a 2nd embodiment is applied.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the accompanying drawings, in order to clarify the relationship between the eyeball and the optical path, the eyeball is shown larger than other members (such as an optical system described later). Hereinafter, the optical measurement device for the eyeball is referred to as an optical measurement device.

[First Embodiment]
<Optical measurement device 1>
FIG. 1 is a diagram illustrating an example of a configuration of an optical measurement device 1 to which the first exemplary embodiment is applied. The optical measuring device 1 is disposed so as to be pressed against the face of the person to be measured (subject), and passes (transmits) the light beam 28 so as to cross the anterior chamber 13 of the eyeball 10. The aqueous humor in the chamber 13 is optically measured. Note that the eyeball 10 shown in FIG. 1 is the right eye.

This optical measuring device 1 uses the optical system 20 used for optical measurement of the aqueous humor in the anterior chamber 13 of the eyeball 10 of the measurement subject, the control unit 60 that controls the optical system 20, and the optical system 20. The calculation part 70 which calculates the characteristic of aqueous humor based on measured measurement data is provided.
The control unit 60 includes a correction unit 61 that corrects the signal output (measurement data) from the light receiver 35 corresponding to the incident state of the light beam 28 on the light receiving surface 35a of the light receiver 35 in the optical system 20. .
Here, the light receiving surface 35a of the light receiver 35 is an example of a first light receiving surface, and the correction unit 61 is an example of a correction unit.
In addition, although the optical measuring device 1 is provided with the holding part holding the optical system 20 grade | etc., Description about a holding part is abbreviate | omitted. The holding unit may hold all or a part of the control unit 60 and the calculation unit 70 in addition to the optical system 20.

(Eyeball 10)
First, the eyeball 10 will be described.
As shown in FIG. 1, the eyeball 10 has a substantially spherical outer shape, and has a glass body 11 in the center. A crystalline lens 12 serving as a lens is embedded in a part of the glass body 11. There is an anterior chamber 13 outside the lens 12, and a cornea 14 outside. The peripheral portion of the crystalline lens 12 is surrounded by an iris, and the center is the pupil 15. The glass body 11 is covered with a retina 16 except for a portion in contact with the crystalline lens 12.
That is, the anterior chamber 13 is an area surrounded by the cornea 14 and the crystalline lens 12 and protrudes from a spherical shape to a convex shape. The anterior chamber 13 is filled with aqueous humor.

  As shown in FIG. 1, the vertical direction of the person being measured is in the x direction with the upper side being positive, the z direction with the direction in which the light beam 28 emitted from the eyeball 10 travels is positive, the x direction, and the z direction being orthogonal. The direction away from the measurer is the positive y direction.

The characteristics of the aqueous humor measured by the optical measuring device 1 to which the first embodiment is applied are the rotation angle (optical rotation) of the vibration direction (polarization plane) of linearly polarized light by the optically active substance contained in the aqueous humor. Degree α _M ), a color absorption degree for circularly polarized light (circular dichroism), and the like. In this specification, the polarization plane of linearly polarized light refers to a plane in which an electric field vibrates in linearly polarized light.
Hereinafter, as an example, the description will be made assuming that the concentration of the optically active substance is calculated from the rotation angle (rotation angle α _M ) of the polarization plane of linearly polarized light by the optically active substance contained in the aqueous humor.

(Optical system 20)
The optical system 20 includes a light irradiation system 21 that irradiates the anterior chamber 13 of the eyeball 10 with a light beam 28, a light receiving system 22 that receives light that has passed through the anterior chamber 13, and an incident state measurement system 23.
Here, the light irradiation system 21 is an example of a light irradiation unit, the light receiving system 22 is an example of a light receiving unit, and the incident state measurement system 23 is an example of a measuring unit.

The light irradiation system 21 includes a light source 25, a polarizer 27, and a mirror 29.
The light source 25 irradiates beam-shaped light (light beam 28) toward the anterior chamber 13 of the eyeball 10. The light source 25 may be a light source with a narrow wavelength width such as a laser, or may be a light source with a wide wavelength width such as a light emitting diode (LED) or a lamp. Further, a plurality of LEDs, lamps or lasers may be provided. The wavelength width should be narrow. And it is good to use a some wavelength.
The polarizer 27 is, for example, a Nicol prism, a total reflection type Glan-Thompson prism, a Glan-Taylor prism, a Glan laser prism, or the like. Pass the linearly polarized light of the surface.
The mirror 29 reflects the light beam that has passed through the polarizer 27 and bends the optical path.

The light receiving system 22 includes a compensator 31, an analyzer 33, and a light receiver 35. The light receiving system 22 does not use a mirror that bends the optical path.
The compensator 31 is a magneto-optical element such as a Faraday rotator using a garnet or the like, and rotates the polarization plane of linearly polarized light by a magnetic field.
The analyzer 33 is a member similar to the polarizer 27 and allows linearly polarized light having a predetermined polarization plane of the light beam 28 to pass therethrough.
The light receiver 35 is a light receiving element (photodetector) having a light receiving surface 35a formed of a silicon diode or the like, and outputs an output signal (voltage signal) corresponding to the intensity of the received light beam 28. It is assumed that the light receiving surface 35a of the light receiver 35 is 10 mm × 10 mm or the like and is larger than the diameter of the light beam 28 to be received. That is, the light beam 28 enters a part of the light receiving surface 35 a of the light receiver 35.
The light receiver 35 is a light receiving element that places importance on sensitivity, and does not have a function of detecting (measuring) the incident position of the light beam 28.

The incident state measurement system 23 includes beam splitters 41 and 42 that split the light beam 28 and light receivers 51 and 52 that receive the light beam 28 split by the beam splitters 41 and 42. The light receivers 51 and 52 have light receiving surfaces 51a and 52a, respectively.
The beam splitters 41 and 42 split one light beam into a plurality of light beams. The beam splitters 41 and 42 may be a cube type in which the inclined surfaces of two right-angle prisms are joined via an optical thin film, or may be a plate type in which an optical thin film is provided on one surface. The beam splitters 41 and 42 are preferably those that do not affect the polarization state of the passing light beam. The ratio at which the beam splitters 41 and 42 split the light beam may not be 1: 1.
The light receivers 51 and 52 only need to identify the incident position of the incident light beam on the light receiving surfaces 51a and 52a. The light receivers 51 and 52 are image sensors such as CCD and CMOS, for example, and have a plurality of light receiving cells (pixels) arranged in two dimensions. Therefore, in the light receivers 51 and 52, the incident position of the light beam is detected by the position (coordinates) of the light receiving cell on the respective light receiving surfaces 51a and 52a.

An outline of the optical path of the light beam 28 in the optical system 20 will be described. The optical path in the incident state measurement system 23 will be described later.
The light beam 28 emitted from the light source 25 toward the anterior chamber 13 of the eyeball 10 passes through the polarizer 27, is bent by the mirror 29, and passes through the anterior chamber 13 of the eyeball 10.
The light beam 28 that has passed through the anterior chamber 13 of the eyeball 10 is split by the beam splitter 41 of the incident state measurement system 23. One light beam 28 divided by the beam splitter 41 passes through the compensator 31 and the analyzer 33 in the light receiving system 22 and enters the light receiver 35.

(Control unit 60)
The control unit 60 is configured as a computer including a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), I / O Port (I / O Port), and the like. It may be operated by software or may be configured by hardware such as an analog electronic circuit.
The control unit 60 controls the light source 25, the compensator 31, the light receiver 35, and the like in the optical system 20. In addition, the control unit 60 outputs measurement data such as the wavelength λ of the light beam used for measurement, the rotation angle of the compensator 31, and an output signal acquired from the light receiver 35 to the calculation unit 70.
The correction unit 61 in the control unit 60 outputs the output signal of the light receiver 35 corresponding to the incident state of the light beam 28 on the light receiving surface 35a of the light receiver 35 in the light receiving system 22 measured by the incident state measuring system 23. (Voltage signal) is corrected. The correction will be described later.

(Calculation unit 70)
The calculation unit 70 is configured similarly to the control unit 60. Then, based on the measurement data acquired from the control unit 60, the characteristics of the aqueous humor are calculated.
Note that the control unit 60 may also serve as the calculation unit 70.

<Optical measurement of aqueous humor>
Next, an example of calculating the concentration of the optically active substance contained in the aqueous humor in the anterior chamber 13 using the optical measurement device 1 will be described. Here, the glucose concentration is calculated as the optically active substance.

(Background for measuring glucose concentration in aqueous humor)
First, the background for measuring the glucose concentration of aqueous humor will be described.
Autologous blood glucose measurement is recommended for type 1 diabetic patients and type 2 diabetic patients (subjects) who need insulin treatment. In self blood glucose measurement, in order to precisely control blood sugar, the person to be measured himself / herself measures his / her blood sugar level at home and the like.
Currently available self-blood glucose measuring instruments puncture a fingertip or the like with an injection needle, collect a small amount of blood, and measure the glucose concentration in the blood. Autologous blood glucose measurement is often recommended after every meal or before going to bed, and is required to be performed once to several times a day. In particular, intensified insulin treatment requires many more measurements.
For this reason, the invasive blood glucose measurement method using a puncture-type self blood glucose meter tends to cause a decrease in incentive for the subject's self blood glucose measurement due to pain caused by pain when blood is collected (during blood collection). . This may make it difficult to treat diabetes effectively.

Therefore, development of a non-invasive blood glucose level measurement method that does not require puncture is being promoted instead of an invasive blood glucose level measurement method such as puncture.
As a non-invasive blood glucose level measuring method, near infrared spectroscopy, photoacoustic spectroscopy, a method using optical rotation, and the like are being studied. In these methods, the blood glucose level is estimated from the glucose concentration.
Near-infrared spectroscopy and photoacoustic spectroscopy detect a light absorption spectrum and acoustic vibration in blood in a finger blood vessel. However, there are cellular substances such as red blood cells and white blood cells in the blood. For this reason, it is greatly affected by light scattering. Furthermore, in addition to blood in blood vessels, it is affected by surrounding tissues. Therefore, these methods require detection of a signal related to glucose concentration from a signal involving a huge number of substances such as proteins and amino acids, and it is difficult to separate the signals.

On the other hand, the aqueous humor in the anterior chamber 13 is almost the same component as serum and contains protein, glucose, ascorbic acid and the like. However, unlike aqueous blood, aqueous humor does not contain cellular substances such as red blood cells and white blood cells, and is less affected by light scattering. Therefore, aqueous humor is suitable for optical measurement of glucose concentration.
Proteins, glucose, ascorbic acid and the like contained in aqueous humor are optically active substances and have optical activity.
Therefore, the optical measuring device 1 to which the first embodiment is applied optically measures the concentration of the optically active substance containing glucose from the aqueous humor using the optical rotation.
In addition, since aqueous humor is a tissue fluid for transporting glucose, the glucose concentration of aqueous humor is considered to correlate with the glucose concentration in blood. In the measurement using rabbits, it is reported that the time required for transporting glucose from blood to aqueous humor (transport delay time) is within 10 minutes.

(Optical path setting)
Now, in the technique of optically measuring the concentration of an optically active substance such as glucose contained in aqueous humor, the following two optical paths can be set.
One is different from the first embodiment shown in FIG. 1 in that light is incident on the eyeball 10 along an angle near the vertical, that is, the front-rear direction, and the interface between the cornea 14 and aqueous humor or the chamber. This is an optical path that reflects light at the interface between water and the crystalline lens 12 and receives (detects) the reflected light. The other is, as in the first embodiment shown in FIG. 1, injecting light at an angle intersecting the front-rear direction, specifically, an angle close to parallel to the eyeball 10, and It is an optical path for receiving (detecting) light that has passed across.

  As in the former case, there is a possibility that light may reach the retina 16 through an optical path that allows light to enter the eyeball 10 at an angle close to perpendicular. In particular, when a highly coherent laser is used as the light source 25, light having a high energy density reaches the retina 16, and the retina 16 may be adversely affected depending on the length of irradiation time.

On the other hand, in the optical path in which light is incident at an angle close to parallel to the eyeball 10 like the latter, the light passes through the cornea 14 so as to cross the anterior chamber 13, and the light that has passed through the aqueous humor is transmitted. Receives (detects) light. For this reason, it is suppressed that light reaches the retina 16.
The rotation angle (optical rotation) of the polarization plane by the optically active substance depends on the optical path length. The longer the optical path length, the higher the optical rotation. Therefore, the light path length is set long by allowing light to pass across the anterior chamber 13.

(Calculation of optically active substance concentration)
FIG. 2 is a diagram for explaining a method of measuring the rotation angle (optical rotation) of the polarization plane by the optically active substance contained in the aqueous humor in the anterior chamber 13 by the optical measurement device 1. Here, for ease of explanation, the light beam 28 is not bent and the description of the mirror 29 is omitted.
Further, the description of the incident state measurement system 23 is omitted in order to explain the concentration calculation of the optically active substance.
In addition, an arrow in a circle indicates the state of polarization viewed from the traveling direction of light between the light source 25, the polarizer 27, the anterior chamber 13, the compensator 31, the analyzer 33, and the light receiver 35 shown in FIG. Is shown.

The light source 25 emits light having a random polarization plane. The polarizer 27 passes linearly polarized light having a predetermined polarization plane. In FIG. 2, as an example, linearly polarized light having a polarization plane parallel to the paper surface passes.
The plane of polarization of the linearly polarized light that has passed through the polarizer 27 is rotated by the optically active substance contained in the aqueous humor in the anterior chamber 13. In FIG. 2, the plane of polarization rotates by an angle α _M (optical rotation α _M ).

Next, the polarization plane rotated by the optically active substance contained in the aqueous humor in the anterior chamber 13 is returned to the original by the compensator 31. When the compensator 31 is a magneto-optical element such as a Faraday element, the polarization plane of the light beam 28 passing through the compensator 31 is rotated by applying a magnetic field to the compensator 31.
The light receiver 35 receives the linearly polarized light that has passed through the analyzer 33 and converts it into an output signal (output voltage) corresponding to the intensity of the light beam 28.
The output signal (output voltage) is output by the correction unit 61 in the control unit 60 based on the incident state of the light beam 28 on the light receiving surface 35a of the light receiver 35 in the light receiving system 22 measured by the incident state measuring system 23. It is corrected.

Here, an example of a method for measuring the optical rotation α _M by the optical system 20 will be described.
First, in a state where the light beam 28 emitted from the light source 25 does not pass through the anterior chamber 13, light reception is performed using the optical system 20 including the light source 25, the polarizer 27, the compensator 31, the analyzer 33, and the light receiver 35. The compensator 31 and the analyzer 33 are set so that the output signal (output voltage) from the detector 35 is minimized. In the example shown in FIG. 2, in a state where the light beam 28 does not pass through the anterior chamber 13, the polarization plane of linearly polarized light that has passed through the polarizer 27 is orthogonal to the polarization plane that passes through the analyzer 33.

Next, the light beam 28 passes through the anterior chamber 13. Then, the polarization plane of the light beam 28 is rotated by the optically active substance contained in the aqueous humor in the anterior chamber 13. For this reason, the output signal (output voltage) from the light receiver 35 deviates from the minimum value. Therefore, the polarization plane is rotated by applying a magnetic field to the compensator 31 so that the output signal from the light receiver 35 is minimized. That is, the polarization plane of the light beam 28 emitted from the compensator 31 is orthogonal to the polarization plane passing through the analyzer 33.
The angle of the polarization plane rotated by the compensator 31 corresponds to the optical rotation α _M generated by the optically active substance contained in the aqueous humor. Here, the relationship between the magnitude of the magnetic field applied to the compensator 31 and the angle of the rotated polarization plane is known in advance. Therefore, the optical rotation α _M can be determined from the magnitude of the magnetic field applied to the compensator 31.

Specifically, light beams 28 having a plurality of wavelengths λ (wavelengths λ ₁ , λ ₂ , λ ₃ ,...) Are incident on the aqueous humor in the anterior chamber 13 from the light source 25, and the optical rotation α _{M is applied to} each. (Optical rotations α _M1 , α _M2 , α _M3 ,...) Are obtained. A set of the wavelength λ and the optical rotation α _M is taken into the calculation unit 70, and the concentration of the optically active substance to be obtained is calculated.
The concentration of the optically active substance calculated by the calculating unit 70 may be displayed on a display unit (not shown) provided in the optical measurement device 1 or via an output unit (not shown) provided in the optical measurement device 1. May be output to another terminal device (not shown) such as a PC (Personal Computer).

In addition, the aqueous humor includes a plurality of optically active substances as described above. Therefore, the measured optical rotation α _M is the sum of the optical rotation α _M by each of the plurality of optically active substances. Therefore, it is necessary to calculate the concentration of the optically active substance (here, glucose) to be obtained from the measured optical rotation α _M. The calculation of the concentration of the optically active substance to be obtained may be performed by using a known method as disclosed in, for example, Japanese Patent Application Laid-Open No. 09-138231, and the description thereof is omitted here.

  In FIG. 2, it is assumed that the polarization plane of the polarizer 27 and the polarization plane before passing through the analyzer 33 are both parallel to the paper surface. However, in the state where the light emitted from the light source 25 does not pass through the anterior chamber 13, when the plane of polarization is rotated by the compensator 31, the plane of polarization before passing through the analyzer 33 is inclined from a plane parallel to the paper surface. It may be. That is, the compensator 31 and the analyzer 33 may be set so that the output signal (signal voltage) from the light receiver 35 is minimized when light does not pass through the aqueous humor in the anterior chamber 13.

Furthermore, here has been described the example using the compensator 31 as a method for determining the optical rotation alpha _M, may be obtained optical rotation alpha _M outside compensator 31. Furthermore, although the orthogonal polarizer method (however, the compensator 31 is used), which is the most basic measurement method for measuring the rotation angle (rotation angle α _M ) of the polarization plane, is shown here, the rotation analyzer method and Faraday modulation are used. Other measurement methods such as the optical delay modulation method and the optical delay modulation method may be applied.

(Relationship between eyeball 10 and light receiver 35)
Next, the relationship between the eyeball 10 and the light receiver 35 will be described.
FIG. 3 is a diagram for explaining an incident state of the light beam 28 that has passed through the anterior chamber 13 of the eyeball 10 to the light receiver 35 when the incident state measurement system 23 is not provided. FIG. 3 shows a light beam 28 _I and a light beam 28 _II as an example of the light beam 28. In addition, when not distinguishing these, it describes with the light beam 28. FIG. Note that FIG. 3 shows FIG. 1 rotated 180 ° in the drawing.
The light beam 28 _I is a light beam that passes through the optical path assumed when the optical system 20 is set, and is positioned on the light receiving surface 35 a of the light receiver 35 by the xy coordinates (x _I , y _I ). It is incident on the (coordinate position) at an angle θ _I (in FIG. 3, it is expressed as coordinates (x _I , y _I , θ _I )). On the other hand, the light beam 28 _II is a light beam that passes through an optical path that deviates from the optical path (assumed optical path) through which the light beam 28 _I passes. The light receiving surface 35 a has xy coordinates (x _II , y _II ) is incident at an angle θ _II (coordinate position (x _II , y _II , θ _II ) in FIG. 3).

The light path 28 deviates from the optical path assumed when the optical system 20 is set (the optical path through which the light beam 28 _I passes) (the optical path through which the light beam 28 _II passes). This is because the optical path fluctuates due to biological vibration such as pulsation or a change in the state of the cornea 14.
In FIG. 3, the light beam 28 _I and the light beam 28 _II are described as having the same position of the cornea 14 from which they are emitted and changing due to a change in the state of the cornea 14. The optical path also varies depending on the position where 28 enters the cornea 14 and the state of the cornea 14 at the incident position.

The light receiver 35 has different output signals (output voltages) depending on the coordinate position where the light beam 28 is incident on the light receiving surface 35a. That is, the light receiving surface 35a of the light receiver 35 has variations (in-plane distribution) in light receiving sensitivity within the light receiving surface 35a. The reflectance at the light receiving surface 35a depends on the incident angle. The reflectance at the light receiving surface 35a includes not only the reflectance at the surface of the light receiving element such as a silicon diode but also the reflectance at the front and back surfaces of a protective member such as a glass plate covering the surface of the light receiving element.
Therefore, if the output signal (output voltage) of the light receiver 35 is used for the calculation of the characteristics of the aqueous humor in the anterior chamber 13 as it is, the measurement accuracy is impaired.
Therefore, in the first embodiment, the incident state (incident position, incident angle) of the light beam 28 incident on the light receiving surface 35a of the light receiver 35 is measured, and the output signal (output voltage) of the light receiver 35 is incident. Therefore, the measurement accuracy related to the aqueous humor in the anterior chamber 13 of the eyeball 10 of the measurement subject is improved.

FIG. 4 is a diagram for explaining the incident state measurement system 23 in the first embodiment. 4A is a diagram for explaining the light beam 28 _I passing through the assumed optical path, FIG. 4B is a diagram for explaining the light beam 28 _II off the assumed optical path, and FIG. It is a figure explaining the method to measure an incident state.
FIG. 4C connects point A, which is the emission point of the light beam 28 (light beams 28 _I , 28 _II ) on the cornea 14 of the eyeball 10, and point O, which is the center of the light receiving surface 35 a of the light receiver 35. Expressed in xyz coordinates with the direction as the z direction. The light receiving surface 35a of the light receiver 35 is set to z = 0. In addition to the xyz coordinates, the coordinates (x, y, z, θ) including the incident angle θ with respect to the xy plane are used.
Here, in order to describe the incident state measurement system 23, the eyeball 10, the light receiver 35 in the incident state measurement system 23, and the light receiving system 22 are shown, and the description of other configurations is omitted.

As described above, the incident state measurement system 23 includes the beam splitters 41 and 42 and the light receivers 51 and 52.
First, description will be given of light beam 28 _I that passes through the optical path which is assumed when setting the optical system 20. In the following description, a symbol (−0, −1, etc.) is attached to each optical path through which the light beam 28 _I passes.

As shown in FIG. 4A, it is assumed that the light beam 28 _I- 0 is emitted from a point A in the cornea 14 of the eyeball 10.
The light beam 28 _I- 0 is split by the beam splitter 41 into a light beam 28 _I -1 reflected by the reflection surface of the beam splitter 41 and a light beam 28 _I -2 passing through this reflection surface. It is assumed that the light beam 28 _I -2 is incident on the point O at the center of the light receiving surface 35a of the light receiver 35 at a light receiving angle θ _I of 0 °. The center O point of the light receiver 35 is (0, 0, 0) in the xyz coordinates. That is, x _I = 0, y _I = 0, and z _I = 0. Therefore, the light beam 28 _I -2 is incident on the point O (coordinates ((x, y, z, θ) = (0, 0, 0, 0))) in FIG.
The reflecting surface of the beam splitter 41 is assumed to be set to 45 ° with respect to the light beam 28 _I- 0. Then, the light beam 28 _I −1 is bent at 90 ° with respect to the light beam 28 _I- 0.

Next, the light beam 28 _I -1 is split by the beam splitter 42 into a light beam 28 _I- 11 reflected by the reflecting surface of the beam splitter 42 and a light beam 28 _I- 12 passing through the reflecting surface. .
It is assumed that the reflection surface of the beam splitter 42 is set to 45 ° with respect to the light beam 28 _I −1. Then, the light beam 28 _I- 11 is bent at 90 ° with respect to the light beam 28 _I -1.

It is assumed that the light beam 28 _I- 11 is received at the center O ′ point of the light receiving surface 51 a of the light receiver 51 at an incident angle θ _C1 of 0 °. Here, the light receiving surface 51a is represented by x′y ′ coordinates. The x ′ axis is parallel to the x axis, and the y ′ axis is parallel to the y axis. The central O ′ point is (0, 0) in the x′y ′ coordinate.
In this case, the optical path from the point A to the center O ′ point of the light receiver 51 (the optical paths of the light beam 28 _I- 0, the light beam 28 _I- 1, and the light beam 28 _I- 11) is reflected by the reflecting surface. If the light receiver 51 is shifted so that the x′y ′ coordinate and the xy coordinate are overlapped in order without overlapping, the light beam 28 _I− 11 is moved to the O ′ point (coordinate (( x, y, z, θ) = (0, 0, Z _C1 , 0)) where Z _C1 is the optical path length from point A to the center O ′ point of the light receiving surface 51a ( The sum of the optical path lengths of the light beam 28 _I- 0, the light beam 28 _I- 1, and the light beam 28 _I- 11) is subtracted from the distance between the AOs, where z = Z _C1 This corresponds to the position of the surface 51a.

Similarly, it is assumed that the light beam 28 _I- 12 is incident on the center O ″ point of the light receiving surface 52a of the light receiving device 52 at an incident angle θ _C2 of 0 °. The x ″ axis is parallel to the x axis, the y ″ axis is parallel to the y axis, and the central O ″ point is (0, 0) in the x ″ y ″ coordinate. .
In this case, the optical path from the point A to the center O ″ point of the light receiver 52 (the optical paths of the light beam 28 _I- 0, the light beam 28 _I- 1 and the light beam 28 _I- 12) is reflected by the reflecting surface. If the light receiver 52 is shifted so that the x ″ y ″ coordinates overlap with the xy coordinates in order without overlapping, the light beam 28 _I- 12 will have the O ″ point (coordinates (( x, y, z, θ) = (0, 0, Z _C2 , 0))). Z _C2 is the optical path length from the point A to the center O ″ point of the light receiving surface 52a (the sum of the optical path lengths of the light beam 28 _I- 0, the light beam 28 _I- 1, and the light beam 28 _I- 12). ) Is subtracted from the distance between AOs, where z = Z _C2 corresponds to the position of the light receiving surface 52a.

Next, the light beam 28 _II passing through the optical path deviating from the assumed optical path will be described with reference to FIG. In the following, a description will be given with reference (−0, −1, etc.) for each optical path through which the light beam 28 _II passes.
As shown in FIG. 4B, it is assumed that the light beam 28 _II- 0 is emitted from a point A in the cornea 14 of the eyeball 10. The light beam 28 _II- 0 travels in a different direction from the light beam 28 _I- 0.
The light beam 28 _II- 0 is split by the beam splitter 41 into a light beam 28 _II- 1 reflected by the reflection surface of the beam splitter 41 and a light beam 28 _II- 2 passing through this reflection surface.
Since the light beam 28 _II- 0 does not enter at 45 ° with respect to the reflection surface of the beam splitter 41, the light beam 28 _II- 1 is in the direction of the reflection angle corresponding to the incident angle to the reflection surface of the beam splitter 41. move on.
On the other hand, the light beam 28 _II -2 is incident on the point B of the light receiving surface 35 a of the light receiver 35 at an incident angle θ _II . The point B is (x _II , y _II , z _II ) in the xyz coordinates. Z ₁₁ is 0. That is, the light beam 28 _II -2 is incident on the point B (coordinates ((x, y, z, θ) = (x _II , y _II , 0 _, θ _II )) in FIG. 4C). Become.

Next, the light beam 28 _II -1 is split by the beam splitter 42 into a light beam 28 _II -11 reflected by the reflecting surface of the beam splitter 42 and a light beam 28 _II -12 passing through this reflecting surface. .
Since the light beam 28 _II -1 does not enter at 45 ° with respect to the reflection surface of the beam splitter 42, the light beam 28 _II -11 is in the direction of the reflection angle corresponding to the incident angle to the reflection surface of the beam splitter 42. move on. And it injects into C1 point of the light-receiving surface 51a in the light receiver 51 by incident angle (theta) _C1 . The C1 point is (x _C1 , y _C1 ) in the x′y ′ coordinate.
In this case, the optical paths from the point A to the point C1 of the light receiver 51 (the optical paths of the light beam 28 _II- 0, the light beam 28 _II- 1 and the light beam 28 _II- 11) are not reflected on the reflecting surface in order. When the light receiver 51 is shifted so that the x′y ′ coordinate and the xy coordinate overlap with each other on the z axis, as shown in FIG. 4C, the light beam 28 _II -11 is obtained as shown in FIG. It is incident on the C1 point (coordinates ((x, y, z, θ) = (x _C1 , y _C1, Z _C1 , θ _C1 )).

Similarly, the light beam 28 _II -12 is incident on the point C2 of the light receiver 52 at an incident angle θ _C2 . The C2 point is (x _C2 , y _C2 ) in the x ″ y ″ coordinate.
In this case, the light path from the point A to the point C2 of the light receiving surface 52a of the light receiver 52 (each light path of the light beam 28 _II- 0, the light beam 28 _II- 1, and the light beam 28 _II- 12) is reflected on the reflecting surface. When the light receiver 52 is shifted so that the x ″ y ″ coordinates overlap the xy coordinates in order without being reflected, the light beam 28 _II -12 is moved to the point C2 (coordinates (( x, y, z, θ) = (x _C2 , y _C2, Z _C2 , θ _C2 ))).

Note that refraction at the interface between the beam splitters 41 and 42 and the air with respect to the light beam 28 _II is ignored. From the coordinates of point B, the influence of refraction at the interface between the beam splitters 41 and 42 and air is obtained. Therefore, an optical path may be obtained in consideration of refraction.

Next, a method for calculating the xyz coordinates (x _II , y _II , 0) of the light receiving surface 35a of the light receiver 35 of the light beam 28 _{II in} the light receiver 35 and the incident angle θ _II with respect to the light receiving surface 35a of the light receiver 35 will be described. To do.
Point A is the exit point of the light beam 28 _II in the cornea 14 of the eyeball 10. However, point A is unknown because it is not fixed. On the other hand, the light receivers 51 and 52 are imaging elements such as a CCD and a CMOS, and have light receiving surfaces 51a and 52a each composed of a plurality of light receiving cells (pixels) arranged two-dimensionally. Therefore, the xy coordinates on which the light beam 28 _II is incident are measured by the light receiving surfaces 51a and 52b. Then, the light beam 28 _II (light beam 28 _II -11) is incident on the light receiving surface 51a at a point C1 (x _C1 , y _C1 ), and the light beam 28 _II (light beam 28 _II -12) is incident on the light receiving surface 52a. The C2 point (x _C2 , y _C2 ) to be measured is measured. The light receiving surface 35a is provided at z = 0, the light receiving surface 51a is provided at z = Z _C1 , and the light receiving surface 52a is provided at z = Z _C2 .
Therefore, since the xyz coordinates for the light beam _{28 II (x C1, y C1} , Z C1) xyz coordinates _{(x C2, y C2, Z} C2), the light-receiving surface 35a of the photodetector 35 is a light beam _{28 II} enters The xy coordinates (x _II , y _II ) and the incident angle θ _II with respect to the light receiving surface 35a are calculated.
Therefore, the output signal (signal voltage) from the light receiver 35 may be corrected based on the xy coordinates (x _II , y _II ) of the light receiving surface 35a and the incident angle θ _II with respect to the light receiving surface 35a.

FIG. 5 is an example of a look-up table for correcting the output signal of the light receiver 35. 5A is a lookup table for the correction value k (x, y) with respect to the incident position (x, y), and FIG. 5B is a lookup table for the correction value m (θ) with respect to the incident angle θ. is there.
The correction value k (x, y) for the incident position (x, y) is a value reflecting the sensitivity distribution in the light receiving surface when light is incident perpendicularly to the light receiving surface 35a of the light receiver 35. Therefore, the correction value k (x, y) for the incident position (x, y) is not dependent on the incident angle θ. In FIG. 5A, correction values k (x, y) are values x1, x2,..., Xn,... Which are values for x, and values y1, y2,. The matrix is shown in FIG. Here, n and m are integers of 1 or more.

The correction value m (θ) for the incident angle θ is a reflection coefficient for the incident angle θ of the light receiving surface 35a of the light receiver 35. In FIG. 5B, θ1, θ2,..., Θl,. Here, l is an integer of 1 or more. The reflection coefficient does not depend on the incident position (x, y) of the light receiving surface 35a in the light receiver 35. Therefore, the correction value m (θ) for the incident angle θ is assumed to be a function of the incident angle θ.
The lookup table for the correction value k (x, y) for the incident position (x, y) and the lookup table for the correction value m (θ) for the incident angle θ are, for example, a correction unit provided in the control unit 60. 61.

The correction unit 61 obtains a correction value k (x _II , y _II ) corresponding to the incident position (x _II , y _II ) of the light receiving surface 35a in the light receiver 35 from the look-up table shown in FIG. Further, the correction value m (θ _II ) corresponding to the incident angle θ _II is obtained from the lookup table shown in FIG. If x _II and y _II are not present in the lookup table of FIG. 5A, the correction values k (x, y) of the x and y coordinates closest to x _II and y _II may be used. Further, due to the linear _{interpolation,} x _II, the correction value _k (x _{II, y} II) corresponding to the _{y II} may be calculated.
Similarly, when there is no incident angle θ _II in the lookup table of FIG. 5B, the correction value m (θ) of θ closest to θ _II may be used. Further, due to the linear interpolation, may calculate the correction value m (theta _II) corresponding to theta _II.
Then, a corrected output signal (signal voltage) is obtained by multiplying the output signal (signal voltage) of the light receiver 35 by the correction value k (x _II , y _II ) and the correction value m (θ _II ).

  By doing in this way, the correction | amendment corresponding to the incident state to the light receiver 35 is made, and the precision of the measurement regarding a to-be-measured person's aqueous humor improves.

FIG. 6 is a diagram for explaining a modification of the incident state measurement system 23. 6A shows an incident state measurement system 23 to which the first embodiment described in FIGS. 1, 4A, and 4B is applied. FIG. 6B shows a modified example. (C) is another modification. Here, the description of the eyeball 10 and the light receiver 35 is omitted. The light beam 28 _I traveling along the assumed optical path and the light beam 28 _II traveling off the deviated optical path will be described without being divided, so they are referred to as the light beam 28. In the following description, a symbol (−0, −1, etc.) is attached to each optical path through which the light beam 28 passes. Moreover, the same number is attached | subjected to the member which has the same function.

In the modified example of FIG. 6B, the incident state measurement system 23 includes beam splitters 41 and 43 and light receivers 53 and 54. Each of the light receivers 53 and 54 is an image pickup device such as a CCD or a CMOS, and has light receiving surfaces 53a and 54a each composed of a plurality of light receiving cells (pixels) arranged two-dimensionally. The number of beam splitters and light receivers is the same as the incident state measurement system 23 to which the first embodiment of FIG. 6A is applied, but the optical paths are different.
The light beam 28-0 emitted from the point A of the cornea 14 of the eyeball 10 (see FIGS. 4A and 4B) is reflected by the beam splitter 41 on the reflecting surface of the beam splitter 41. And the light beam 28-2 that has passed through the reflecting surface.
The light beam 28-1 is incident on the light receiving surface 53 a of the light receiver 53.

The light beam 28-2 is split by the beam splitter 43 into a light beam 28-21 reflected by the reflecting surface of the beam splitter 43 and a light beam 28-22 that has passed through the reflecting surface.
The light beam 28-21 is incident on the light receiving surface 54a of the light receiver 54.
The light beam 28-22 is incident on a light receiving surface 35a of a light receiver 35 (not shown).

  Even if it does in this way, if each distance from the A point to the optical receiver 35, the optical receiver 53, and the optical receiver 54 is varied, the state shown in FIG. Therefore, the incident state (incident position, incident angle) on the light receiving surface 35a of the light receiver 35 is measured.

In this modification, since two beam splitters 41 and 43 are arranged in the optical path from the point A of the cornea 14 of the eyeball 10 to the light receiver 35 (see FIGS. 4A and 4B), The amount of light reaching the light receiver 35 is reduced as compared to the incident state measurement system 23 to which the first embodiment is applied.
The light receiving surface 53a is another example of the second light receiving surface, and the light receiving surface 54a is another example of the third light receiving surface.

  In another modification of FIG. 6C, the incident state measurement system 23 includes a beam splitter 42, a mirror 44, and light receivers 51 and 55. Each of the light receivers 51 and 55 is an image sensor such as a CCD or a CMOS, for example, and has light receiving surfaces 51a and 55a each composed of a plurality of light receiving cells (pixels) arranged two-dimensionally. The mirror 44 is configured to be retractable, and retracts (moves) from the optical path when measurement of an incident state (incident position and incident angle) on the light receiver 35 is not performed.

An optical path when the incident state measurement system 23 is used will be described.
The light beam 28-0 emitted from the point A of the cornea 14 of the eyeball 10 (see FIGS. 4A and 4B) is reflected by the mirror 44 to become a light beam 28-3. The light beam 28-3 is split by the beam splitter 42 into a light beam 28-31 reflected by the reflection surface of the beam splitter 42 and a light beam 28-32 passing through this reflection surface.
The light beam 28-31 is incident on the light receiving surface 51 a of the light receiver 51.
The light beam 28-32 is incident on the light receiving surface 55 a of the light receiver 55.

Even if it does in this way, if each distance from the A point to the optical receiver 35, the optical receiver 52, and the optical receiver 55 differs, it will be in the state described in FIG.4 (c). Therefore, the incident state (incident position, incident angle) to the light receiver 35 is measured.
The light receiving surface 55a is another example of the third light receiving surface.

In another modification of FIG. 6C, when the mirror 44 does not measure the incident state (incident position, incident angle) on the light receiver 35, it is retracted from the optical path. As a result, when the eyeball 10 is optically measured, the light emitted from the cornea 14 of the eyeball 10 is shown in the beam splitter of the incident state measurement system 23 (FIG. 6A). Incident without passing through the beam splitter 41) or the like. Therefore, a decrease in the amount of light and a change in the polarization state due to the insertion of the beam splitter are suppressed.
The retraction of the mirror 44 may be configured to move (shift) in a direction intersecting the optical path, or may be configured to repel.
In another modification, the mirror 44 is retracted from the optical path, but the incident state measurement system 23 may be retracted from the optical path.

In the above, the light receiver 35 is a light receiving element (photodetector) such as a silicon diode that outputs an output signal (voltage signal) corresponding to the intensity of the received light beam. For this reason, the function of measuring (detecting) the incident position is not provided.
On the other hand, each of the light receivers 51, 52, 53, 54, and 55 is an image sensor such as a CCD or a CMOS, and the light receiving surfaces 51a, 52a, and 53a of a plurality of light receiving cells (pixels) arranged in two dimensions. , 54a, 55a, and the incident position is detected by the position of the light receiving cell (pixel).
However, if the light receiver 35 is an image sensor such as a CCD or CMOS and has light receiving surfaces 35a of a plurality of light receiving cells (pixels) arranged two-dimensionally, the incident position (FIG. 4A) (X _II , y _II )) is detected by the position of the light receiving cell (pixel).
Therefore, it is not necessary to use the beam splitter 42 and the light receiver 51 in FIG. 6A (the same applies to FIGS. 4A and 4B). Similarly, in FIG. 6B, it is not necessary to use the beam splitter 41 and the light receiver 53 (or the beam splitter 43 and the light receiver 54). Further, it is not necessary to use the beam splitter 42 and the light receiver 51 in FIG.

In the above description, the incident position (x, y) and the incident angle θ are measured as the incident state on the light receiving surface 35a of the light receiver 35 and corrected for each. However, when the range of the incident angle θ is narrow and the difference in the correction value m (θ) is small within the range, no correction for the incident angle θ is required. That is, the incident state is only the incident position.
FIG. 7 is a diagram illustrating an incident state measurement system 23 that measures an incident position (x, y). 7A shows the incident state measurement system 23 using the beam splitter 41, and FIG. 7B shows the incident state measurement system 23 using the mirror 44. Here, the description of the eyeball 10 and the light receiver 35 is omitted. Since the light beam 28 _I traveling along the assumed optical path and the light beam 28 _II traveling off the deviated optical path are not divided, they are referred to as the light beam 28. In the following description, a symbol (−0, −1, etc.) is attached to each optical path through which the light beam 28 passes. Moreover, the same number is attached | subjected to the member which has the same function.
Here, it is assumed that the light receiver 35 is a light receiving element (photodetector) such as a silicon diode on the light receiving surface 35a that does not have a function of detecting (measuring) the incident position.

The incident state measurement system 23 using the beam splitter 41 shown in FIG. 7A includes a beam splitter 41 and a detector 56.
The light beam 28-0 emitted from the point A in the cornea 14 of the eyeball 10 (see FIGS. 4A and 4B) is reflected by the beam splitter 41 on the reflecting surface of the beam splitter 41. And the light beam 28-2 that has passed through the reflecting surface.
The light beam 28-1 is incident on the light receiving surface 56 a of the light receiver 56.
The light beam 28-2 is incident on a light receiving surface 35a of a light receiver 35 (not shown).

  Here, if the optical path length of the light beam 28-1 is equal to the optical path length of the light beam 28-2, the incident position of the light beam 28-1 on the light receiving surface 56a becomes the light beam 28-2 to the light receiver 35. Is the incident position. The optical path length of the light beam 28-1 is a distance from the branch point of the light beam 28-0 (to the light beam 28-1 and the light beam 28-2) in the beam splitter 41 to the light receiving surface 56a. The optical path length of the light beam 28-2 is the distance from the branch point of the light beam 28-0 (to the light beam 28-1 and the light beam 28-2) in the beam splitter 41 to the light receiving surface 35a.

The incident state measurement system 23 using the mirror 44 shown in FIG. 7B includes a mirror 44 and a detector 56. The mirror 44 is configured to be retractable, and is retracted from the optical path when the incident state (incident position) to the light receiver 35 is not measured. The retreat may be configured to move (shift) in a direction intersecting the optical path, or may be configured to repel.
An optical path when the incident state measurement system 23 is used will be described.
The light beam 28-0 emitted from the point A of the cornea 14 of the eyeball 10 (see FIGS. 4A and 4B) is reflected by the mirror 44 to become a light beam 28-3.
The light beam 28-3 is incident on the light receiving surface 56a of the light receiver 56.
When the mirror 44 is retracted, the light beam 28-0 is incident on the light receiving surface 35a of the light receiver 35.
When the incident position (x, y) on the light receiving surface 35a of the light receiver 35 is corrected as shown in FIGS. 7A and 7B, the correction value k (x) shown in FIG. , Y) may be used.

If the point A (see FIGS. 4A and 4B) of the cornea 14 of the eyeball 10 is known, the structure shown in FIGS. 7A and 7B is applied to the light receiving surface 35a of the light receiver 35. Is also measured. In this case, it is not necessary to make the optical path length of the light beam 28-1 equal to the optical path length of the light beam 28-2.
Here, the light receiving surface 56a of the light receiver 56 is another example of the second light receiving surface.

[Second Embodiment]
In the first embodiment, the measurement data is corrected using the lookup table for the incident state (incidence position, incident angle) measured by the incident state measurement system 23.
In the second embodiment, based on the incident state (incident position, incident angle) measured by the incident state measuring system 23, the light is incident on the predetermined incident position of the light receiver 35 at the predetermined incident angle. Next, the optical path is corrected.

  FIG. 8 is a diagram illustrating an optical measurement apparatus 1 for an eyeball to which the second embodiment is applied. Here, in order to explain the difference from the optical measurement apparatus 1 for the eyeball to which the first embodiment is applied, in the optical system 20 (see FIG. 1) of the optical measurement apparatus 1 for the eyeball 10, the light irradiation system 21 ( 1 shows a mirror 29, an incident state measurement system 23, and a light receiver 35 of a light receiving system 22 (see FIG. 1). Other configurations are the same as those of the first embodiment shown in FIG.

Here, a light beam 28 _I passing through an optical path (predetermined optical path) assumed when the optical system 20 is set and a light beam 28 _II passing through an optical path deviating from the assumed optical path are shown. The incident position (x, y) of the light beam 28 _{I on} the light receiver 35 has coordinates (x _I (0), y _I (0)), and the incident angle θ is θ _I (0).

Here, it is assumed that the light beam 28 is the light beam 28 _II . Then, the incident state measurement system 23 measures an incident position (x, y) on the light receiver 35 as coordinates (x _II , y _II ) and an incident angle as an incident angle θ _II .
Then, the correction unit 61 in the controller 60, the angle (incident angle) with respect to the light beam _{28 II} mirror 29, and, by adjusting the incident angle and the incident position with respect to the light beam _{28 II} of the light-receiving surface 35a of the photodetector 35 The light beam 28 _II is brought into the state of the light beam 28 _I. That is, the incident position (x, y) of the light beam 28 _{II on} the light receiving surface 35 a of the light receiver 35 is set as coordinates (x _II (0), y _II (0)), and the incident angle θ is set as θ _II (0). .

The mirror 29 is preferably made of, for example, MEMS (Micro Electro Mechanical Systems) or the like and can change the incident angle with respect to the light beam 28 by moving the reflecting surface.
The light receiver 35 is preferably mounted on a four-axis stage that can move in the xy direction and that has a variable inclination angle η in the xy direction. For example, based on the incident position (x, y), and sets the position of the xy direction, based on the incident angle theta, by setting the inclination angle eta _y tilt angle eta _x and y direction of the x-direction of the stage Good.
By doing so, the output signal (signal voltage) is not affected by the distribution of the light receiving sensitivity in the light receiving surface 35a of the light receiver 35 in the xy plane and the incident angle θ.

  Note that the modifications described in the first embodiment may be applied to the second embodiment. In the second embodiment, the incident angle described in the first embodiment may not be measured.

Furthermore, in the eyeball optical measurement device 1 according to the first embodiment and the second embodiment, the light passes through the cornea 14 of the eyeball 10 to the aqueous humor of the anterior chamber 13, and the aqueous humor It was assumed that the concentration of glucose, which is an optically active substance contained in, was calculated.
This eyeball optical measurement device 1 can be applied to the calculation of the concentration of other optically active substances contained in aqueous humor. Furthermore, the concentration of a plurality of optically active substances contained in aqueous humor can be calculated separately.

  The eyeball optical measurement device 1 can also be applied to the case where light is passed through a plurality of members having different optical characteristics such as birefringence and optical rotation and the concentration of the optically active substance contained therein is calculated.

  The present disclosure is not limited to the above embodiment, and can be implemented in various forms without departing from the gist of the present disclosure.

DESCRIPTION OF SYMBOLS 1 ... Eye measuring device, 10 ... Eyeball, 11 ... Glass body, 12 ... Lens, 13 ... Anterior chamber, 14 ... Cornea, 15 ... Pupil, 16 ... Retina, 20 ... Optical system, 21 ... Light irradiation system, DESCRIPTION OF SYMBOLS 22 ... Light receiving system, 23 ... Incident state measurement system, 25 ... Light source, 27 ... Polarizer, 28 ... Light beam, 31 ... Compensator, 33 ... Analyzer, 35 ... Light receiver, 41, 42, 43 ... Beam splitter, 44 ... Mirror, 51, 52, 53, 54, 55 ... Light receiver, 60 ... Control unit, 61 ... Correction unit, 70 ... Calculation unit, α _M ... Optical rotation, θ ... Incident angle, λ ... Wavelength

Claims (9)

A light irradiation means for irradiating a light beam toward the anterior chamber of the subject's eyeball;
A light receiving means having a first light receiving surface for receiving a light beam that has passed through the anterior chamber of the eyeball;
A second light receiving surface is provided between the eyeball and the light receiving means so as to be capable of receiving at least a part of the light beam that has passed through the anterior chamber of the eyeball and capable of measuring an incident position of the light beam. An optical measurement device for an eyeball comprising a measuring means.   Compensating means for correcting the signal output from the light receiving means in accordance with the incident state on the first light receiving surface based on the incident position on the second light receiving surface measured by the measuring means. The optical measurement apparatus for an eyeball according to claim 1, wherein   The correction means which correct | amends the incident state of the light beam to the said 1st light-receiving surface of the said light-receiving means based on the incident position to the said 2nd light-receiving surface which the said measurement means measured. Item 5. The eyeball optical measurement device according to Item 1.   The measuring means is provided between the eyeball and the light receiving means so as to be able to receive at least part of the light that has passed through the eyeball, and a third optical path length from the eyeball is different from that of the second light receiving surface. The eyeball optical measurement device according to claim 1, further comprising: a light receiving surface.   Based on the incident position on the second light receiving surface and the incident position on the third light receiving surface measured by the measuring means, the signal output from the light receiving means is input to the first light receiving surface and The eyeball optical measurement device according to claim 4, further comprising a correction unit configured to perform correction according to an incident angle.   Based on the incident position on the second light receiving surface and the incident position on the third light receiving surface measured by the measuring means, the light beam incident position and incident on the first light receiving surface of the light receiving means. 5. The eyeball optical measurement device according to claim 4, further comprising correction means for correcting the angle.   The eyeball optical measurement device according to claim 1, wherein an incident position of the first light receiving surface of the light receiving unit can be measured.   Based on the incident position of the light receiving means on the first light receiving surface and the incident position of the measuring means on the second light receiving surface, the signal output from the light receiving means is sent to the first light receiving surface. The eyeball optical measurement device according to claim 7, further comprising a correction unit configured to perform correction in accordance with an incident position and an incident angle.   Based on the incident position of the light receiving unit on the first light receiving surface and the incident position of the measuring unit on the second light receiving surface, the light beam on the first light receiving surface of the light receiving unit The eyeball optical measurement device according to claim 7, further comprising correction means for correcting an incident position and an incident angle.

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