JPH08103B2 - Alignment device for ophthalmic machine - Google Patents

Description

Detailed Description of the Invention

[0001] The present invention is for aligning the optical axis of an eye to be inspected, such as a refractometer, a fundus camera, or an off-salmometer, with the optical axis of the instrument (alignment in a narrow sense) or for working distance adjustment. The present invention relates to an alignment device for ophthalmic instruments. Hereinafter, in the present specification, unless otherwise specified, both “alignment in a narrow sense” and “working distance alignment” are simply referred to as “alignment”. Conventionally, as this type of device, a light emitting means for irradiating the anterior eye part such as the cornea or sclera of the eye to be inspected with a light beam at a predetermined angle, and when the ophthalmologic apparatus is aligned in a regular position, the irradiation The light flux is reflected by the anterior segment of the eye to be examined, and the reflected light is arranged at a position where the return light should be returned.The light receiving means receives the reflected light. When the light receiving means receives the reflected light, the alignment is completed. It was a device that gave a signal to inform the examiner. And in the conventional alignment apparatus, as a premise for determining the arrangement positions of the light emitting and light receiving means,
The shape of the anterior segment of the subject's eye that reflects the irradiation light has to be obtained for a certain model eye, and normally, for example, when the light is reflected by the cornea, the radius of curvature of the front surface of the cornea is 7.5 m / m to 7.
It was based on any one value of 8 m / m. Also, in order to improve the alignment accuracy, as a light emitting means,
A micro light source such as a light emitting diode is used, and the light from this light source is imaged on a pinhole by a relay optical system, and this pinhole is used as a secondary light source, and this secondary light source is on or near the cornea of the eye to be examined. To form an image on the
Further, a pinhole is also provided in the light receiving means, the pinhole is arranged at an optically conjugate position of the light receiving element, and an image forming means for forming an image of the reflected light from the cornea on the pinhole has been adopted.

However, the subject does not always have a cornea having the same shape as that of the model eye, and the eye refraction characteristics of the subject, for example, the curvature of the cornea in the farsighted eye and myopia. The radius often deviates from the numerical value of the model eye, which has led to a decrease in alignment detection accuracy. An even bigger drawback is
The conventional alignment apparatus does not consider the astigmatic element of the subject's eye at all. Generally, the human eye has an average ID even if it is measured as emmetropia in subjective or objective visual acuity measurement.
About 90% of people have physiological corneal astigmatism. This is because the radius of curvature of the vertical facet is smaller than the radius of curvature of the horizontal facet of the cornea. If the eye to be inspected is an astigmatic eye, about 80% of the astigmatic eye is due to corneal astigmatism, and therefore the difference in radius of curvature on each radial line of the cornea becomes larger. In the conventional alignment apparatus designed by considering the cornea due to the astigmatism characteristic of the eye to be examined as a certain spherical surface, the alignment accuracy has to be extremely low. Also, some of the conventional alignment devices
Four sets of the above-mentioned light emitting and receiving means are provided, two sets of which are arranged in a horizontal plane including the optical axis of the device, and the other two sets are arranged in a vertical plane including the optical axis, and further, each of the light receiving elements is arranged in the alignment display device. The four display means are provided in a positional relationship corresponding to, and the light receiving means is configured to turn on when the reflected light is received,
There is a device for instructing the examiner by the display state of the display means that the alignment is completed and the alignment direction, that is, the direction of moving the instrument up, down, left or right.

However, even in this alignment apparatus, the light emitting-light receiving means can only output a signal indicating whether or not the reflected light can be received, so that it is impossible to quantitatively output the movement amount. It was This inevitably causes the examiner to perform the alignment operation, and the examiner spends a great deal of alignment adjustment time.In addition, if the instrument is the original machine, that is, if it is a fundus camera, photographing of the fundus of the eye to be examined, refracting. If it is a meter, it is not possible to monitor the alignment state while performing refractive power measurement, if it is an off salmometer, while measuring the radius of curvature of the cornea, etc.
In some cases, the alignment may be incompletely measured, which causes a large error in the measurement result of the instrument. In particular, when the subject is a child, the fixation is difficult, and the measurement and alignment adjustments are repeated frequently, leading to an increase in the measurement time and the intervention of the accommodation power of the eye to be examined may cause an error in the measurement result in the future. It was linked to shortcomings. Especially in recent years many eye instruments have tended to automate the measurement, but the automation of alignment has not yet been realized, and even if the measurement itself is automated,
Because of that, even if automatic measurement is performed with the alignment incomplete, it is not possible to know the alignment defect,
There is a drawback that incorrect measurement values are regarded as correct measurement values.

The present invention is made in order to solve the drawbacks of the alignment apparatus in the conventional ophthalmologic apparatus, and the first object thereof is an alignment apparatus capable of quantitatively measuring the alignment amount in the non-imaging optical format. To provide. A second object of the present invention is to provide an automatic alignment apparatus capable of continuously measuring the alignment amount, digitizing and outputting the alignment adjustment amount, and automatically adjusting the alignment based on the output. . A third object of the present invention is to provide an alignment apparatus of a new type that can provide such an alignment apparatus at a relatively low cost and has high alignment amount detection accuracy. The structural features of the alignment apparatus according to the present invention for achieving the above object are a light source that emits an illumination light flux having a predetermined shape that is a reference for measurement in a plane, and an optical axis on the optical axis. For arranging a pinhole and a chief ray of the illumination light flux passing through the pinhole in parallel with the optical axis, and for forming an image of the light source in the vicinity of a tangent plane of the apex of the anterior segment of the eye to be examined. An illumination optical system having an optical member; a detection means for photoelectrically detecting reflected light of the illumination light flux from the anterior segment in a plane optically non-conjugated with the light source; A light source image corresponding to the light source from the reflected light; a change in shape and position of the light source image with respect to the light source; and a calculation unit that calculates an alignment amount of the apparatus based on the change in shape and position. To be done .

With the above construction, it is possible to measure a quantitative alignment amount in a non-imaging optical system, which is impossible with the conventional alignment apparatus, and the alignment is automatically adjusted based on this alignment amount. A new alignment that can be performed, and the alignment amount can always be measured while performing the original measurement, inspection, or recording of the ophthalmologic instrument having this alignment device, and the alignment can be continuously adjusted based on this result. A device can be provided. The principle of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic optical device diagram showing the basic principle of an alignment apparatus according to the present invention. Illumination optical axis O
_2, at least three point light sources P ₁₂ and P ₃ are arranged at predetermined intervals (P ₁ and P _{3 in} FIG. 1).
Only ₂ is shown). _The light fluxes emitted from ₁ , P ₂ and P ₃ pass through a pin PH arranged on the illumination optical axis O ₂ , are reflected by a reflecting mirror M, and then have a focus at the position of the pinhole PH. An illumination light flux I ₁ , which is parallel to the optical axis O ₁ of the device and its chief rays I ₁ , I ₂ , I ₃ by the image lens L,
The cornea C is irradiated with I ₂ and I ₃ . The light source images of the point light sources P ₁ P ₂ and P ₃ are formed on the tangent plane H that is in contact with the apex Oc of the cornea C by the imaging lens L. Further, a plane type detector Do is arranged in a plane with the optical axis O _{1 of the} apparatus, and in this detector Do, the imaging lens L functions as a relay lens and an optical conjugate image thereof is formed at a position D in the figure. There is. The conjugate detection surface D has an optically non-conjugated relationship with the pinhole PH. Here, the detection surface D is located ₁ from the cornea C in the direction of the optical axis O ₁ and is separated from the front surface of the imaging lens L by a distance d.

Further, in the present measurement principle, the point light source P ₁ ,
The advantages of forming the images of P ₂ and P _{3 on} the tangent plane H are as follows. That is, in general, when a parallel light beam is incident on the eye to be inspected, its light source image is focused on the macula fovea of the retina, which is the focal position of the eye to be emmetropic, so that a strong illumination light beam is emitted. Incident light may cause dazzling of the eye to be inspected or damage to the eye to be inspected when it is extremely large. In order to avoid this, a light source image is formed on the tangential plane, so that
As shown in, the light flux i after passing through the tangential plane H enters the cornea as a diffused light flux and goes to the focal point Fc of the cornea C. Then, the light is diffused as it enters the eye and is irradiated to the peripheral retina as diffused light, so that damage to the retina and glare can be prevented. In addition, the chief ray I of the illumination luminous flux i is always the optical axis O ₁
And the chief ray reaching the cornea C is also parallel,
The reflected light on the cornea becomes a reflected light flux as it emerges from the corneal focal point Fc, which is extremely convenient in terms of measurement principle.
FIG. 3 is a perspective view for explaining the first measurement principle of the present invention, and the illustration of the optical system after the conjugate detection surface D is omitted. Further, in the following description, the illumination luminous fluxes i ₁ , i
₂ and i ₃ all use their chief rays I ₁ , I ₂ , and I ₃ , and consider the X ₀ -Y ₀ Cartesian coordinate system having the origin at the device optical axis O ₁ in FIG. It is assumed that the cornea C is arranged so that its apex is in contact with the plane including this X ₀ -Y ₀ coordinate system. The cornea C, the _E optical centers (corneal apex) Oc to _{X 0} axis direction H, _{Y 0} in the axial direction are staggered _{E v,} and the radius of curvature r ₁ main meridian _{r 1} is _{X 0} The radius of curvature of the second main radial line r ₂ which is assumed to be arranged at an angle θ with respect to the axis is r ₂ . This _X 0 -Y ₀ coordinate-end optical axis _{O 1} position apart a distance I Te graduation now, the device optical axis O
_It is assumed that the Y orthogonal coordinate system having the origin O at ₁ is assumed and the detection plane D is arranged on this XY coordinate plane.

Now, as described above, the optical axis O _{1 is applied} to the cornea C.
When three light rays I ₁ and I ₂₃ parallel to are irradiated, these light rays are reflected by the cornea C, and the reflected light rays I ₁ , I, and I
₃ ′ reaches the conjugate detection surface D. Rays I ₁ , I ₂ , I ₃
The incident points incident on X ₀ − of U ₀ ( ₀ X ₁ , ₀
Y ₁ ), V ₀ ( ₀ , W ₀ ( ₀ X ₃ , ₀ Y ₃ ), and the positions on the XY coordinates of the reaching points of the reflected rays I ₁ ′, I ₂ ′, and D are U ( X ₁ , Y ₁ ), V (X ₂₂ ), W
(X ₃ , Y ₃ ) and define the following coefficient formulas for these 6 points.

[0008]

[Equation 1] Based on the above definition, between the point of incidence on the cornea and the point of projection on the detection surface

[0009]

[Equation 2] It is expressed by the equation. Here, 1 is the distance between the apex of the cornea and the detection surface D as described above, and r is the radius of curvature of the cornea. Here, the Katsuko formula of the above coefficient is defined as follows.

[0010]

(Equation 3) Here, p and q are A, B, C, and
If any one of D is taken, equation (2) becomes

[0011]

[Equation 4] Is represented as Where the root of the above quadratic equation is

[0012]

(Equation 5) Here, i = 1 and 2. In addition, as shown in FIG.

[0013]

(Equation 6) From the conjugate detection surface to the position of the distance I ′ from the arrival point U of the reflected light rays I ₁ ′, I ₂ ′ and I ₃ ′ to the detection surface D ′.
′ (X ₁ ′, Y ₁ ′,), V ′ (X ₂ ), W ′ (X
₃ ′, Y ₃ ′), the incident points U ₀ ( ₀ X ₁ , ₀ Y ₁ ), V _{0 of} I ₂ , I _{3 on} the X ₀ -Y ₀ coordinate plane.
Between ( ₀ X ( ₀ X ₃ , ₀ Y ₃ ), the same as the above formula (3),

[0014]

(Equation 7) Is established and its root

[0015]

(Equation 8) And Thus, the root λi of the above equations (4) and (4) '
From 1, λi '

[0016]

[Equation 9] Than this

[0017]

[Equation 10] You can ask for 1. Further, as can be seen from FIG. 1, 1-1 ′ = d′−d, and d and d ′ are known distances that can be predetermined in design. Therefore, the equation (5) is

[0018]

[Equation 11] Can be written. Further, from FIG. 1, the working distance, that is, the distance WD between the lens L and the cornea C is WD = 1 + d.

[0019]

(Equation 12) Can be obtained as By comparing the obtained working distance wd with the proper working distance peculiar to the ophthalmologic apparatus, it can be determined whether or not the apparatus is located at the normal working distance position, and the working distance wd and the normal working distance can be determined. By calculating the difference between and, it is possible to determine how much the ophthalmologic apparatus should be moved in the optical axis direction. Next, the corneal apex Oc is the optical axis O.
₁ and horizontally E _M, horizontal alignment amount for narrow alignment caused by E _V vertically offset alpha, the point light sources to determine the vertical alignment amount beta p
For example, the point light sources P ₁ , P ₂ , P ₃ are arranged so that the arrangement of ₁ , P ₂ , P ₃ is ₀ x ₁ + ₀ x ₂ + ₀ x ₃ = 0 ₀ y ₁ + 0y ₂ + 0y ₃ = 0} (7). Positive equation (3) ′ created by ₃ is designed in advance so that the center of gravity of the triangle coincides with the optical axis O ₁ , or a reflecting mirror perpendicular to the optical axis O ₁ is placed on the cornea C at this time. Based on the detection point on the detection surface D of (7)
The X ₀ -Y ₀ coordinate system and the XY coordinate system that satisfy the formula may be established, and the initial condition may be set.

By doing this, the light rays I ₁ ,
When I ₂ and I ₃ are made incident, the detection point U (X ₁ ,
Y ₁ ), V (X ₂ , Y ₂ ), W (X ₃ , Y alignment amounts α, β are respectively

[0021]

(Equation 13) Can be obtained as If there are n point light sources P, α and β can be expanded as follows. Ie

[0022]

[Equation 14] Becomes FIG. 4 is a perspective view for explaining the second measurement principle of the present invention. The same components as those of the first measurement principle described above are designated by the same reference numerals, and the description thereof will be omitted. The principle of this measurement is that even if a plane light flux from a linear light source is incident on a spherical or toric surface reflecting surface, the reflected light flux is still a plane light flux. It is based on the principle that only changes. Now, assume that linear light sources A and B as shown in FIG. The linear light sources A and B intersect each other at one point U, and their end points are V and W, respectively. The linear light source A is
The angle θ _{1 is} inclined with respect to the straight line Xp parallel to the X ₀ axis,
Further, it is assumed that the light source is inclined at an angle θ ₂ with respect to the linear light source B line Xp. The intersection angle between the two linear light sources A and B is θ.
If the light from the linear light sources A and B is projected and imaged on the X ₀ -Y ₀ coordinate plane so that its main optical axis is parallel to the device optical axis O ₁ , the principal rays from the light sources A and B are formed. The light is reflected by the film C and reaches the detection surface D which is optically non-conjugated with the linear light sources A and B. The cornea C of the linear light source A on the detection surface D
Let A'be the projection straight line by the reflection on the cornea C and B 'be the projection straight line by the reflection on the cornea C of the linear light source B. And the projection radiuses A ′ and B depending on the radius of curvature
The intersection of ′ changes to U ′, the end point of the projection line A ′ changes to V ′, the inclination changes to the angle of the X axis and θ ₁ ′, and the projection line B ′.
Has an end point of W ′ and an inclination with respect to the axis changes to θ ₂ ′. Also, the length of the linear light source A, that is, the point U and the end point V
Length ₀ l _A is the length between the intersection U'and end point _V'0 between
l is turned into _A, likewise linear light source length of B, that is the length ₀ l ₅ between the intersection U and end point W, the 'length _{0 l} B _between' intersection U'and end point W Is changing. Nθ ₁ = ₀
m _A , tan θ ₂ = ₀ m _B ′ tan θ ₁ ′ = ₀ m _A = ₀
If m _B ′,

[0023]

(Equation 15) And Here, the conjugate detection surface D is moved to D ′ and arranged at a distance of 1 ′ from the cornea C as in the first measurement principle described above.
Detection surface D of linear light sources A and B after this movement in this case
Also for the projected image on ′, a quadratic equation similar to the above equation (9)

[0024]

[Equation 16] Can be obtained as The above measurement principle is based on the projection straight lines A ′, B ′ by reflection on the cornea C of the linear light sources A, B.
The detection planes D and D'were used for the detection of A, and then these projection lines A are present only on both coordinate axes X and Y of the XY coordinate system.
Consider a method for determining'B '. For that purpose, as shown in FIG. 5, another linear light source C that intersects the opposite sides of the linear light sources A and B is assumed, and their intersections are V and W, respectively. The projected straight lines by the reflection of the cornea C on the XY coordinate system of these three linear light sources A, B, and C are designated as A'B 'and C', respectively. And the X-axis and the Y-axis and the projected straight line A
The intersection of ', B', and C'is detected. Let xa ₁ , xa ₂ and xa ₃ be the detection points on the X-axis, and ya ₁ , ya ₂ and ya ₃ on the Y-axis, the straight line determines the equation if it is any two of them. Because you can
The projection line A equation can be determined from the detection points ya ₁ and xa ₃ , and similarly, the equation of the projection line B ′ can be determined from the detection points xa ₁ and ya ₂ and the projection line C ′ can be determined from the detection points xa ₂ and ya _3. . From the respective equations of the projected straight lines A ', B'and C', these three straight lines A ', B'and C'
Intersection U'and V 'and it can coordinate calculation of W', than this U' length between _V'0 1 ', the length between U'and _{W'0 1}
′ B ′ can be obtained, and the slope tan θ ₁ ′ = 0 ^{m A} ′ can be calculated from the equation of the projection line ′, and the slope tan θ ₂ ′, = 0 ^{m B} ′ of the projection line B ′ can be calculated. Therefore, the working distance WD can be obtained by using the equation (12) from the above equation 9).

The optical axis O _{1 of the} apparatus and the apex Oc of the cornea C to be inspected
In the narrow sense of alignment, the coordinates of intersection points U, V and W of the linear light sources A, B and C are respectively U (0X ₁ , 0Y ₁ V
When (0X ₂ , 0Y ₂ ) and W (0X ₃ , 0Y ₃ ) are used, the alignment amounts α and β are calculated using the equations (7) and (8) from the same idea as the first principle. can do. In addition, solving the above (9), (9) ',
If it is difficult to find the roots φi and φi ′ due to the capability of the arithmetic processing unit, the respective equations of the projection lines A ′, B ′, and C ′ are obtained, and the three intersection points U are obtained based on these three equations. ′, V ′, W ′ coordinates are calculated, and the formulas (1) to (4) ′ described in the first measurement principle are applied to apply the formulas (3) and (3). ′ 'S two roots λi, λ
From i ′, the working distance WD is obtained by the equation (6), and the alignment amount α, by applying the equations (7) and (8) from the coordinate values of the three intersection points U ′, V ′, and W ′. β may be calculated. As explained above, according to the method of FIG.
As shown in FIG. 4, it is not necessary to detect the respective intersections and the end points i ′, j ′, k ′ of the projection straight lines A ′, B ′, but the two detectors intersect with each other instead of the planar detector. The detectors on the straight line can determine the projected straight lines A ′, B ′, C ′, and the intersections i ′, j ′, k ′ can be calculated from this, which is advantageous in the device configuration.

FIG. 6 is a perspective view for clarifying the third measurement principle of the present invention. This measurement principle is that when parallel plane light beams from two parallel linear light sources are incident on a spherical or toric surface-like reflecting surface, the parallelism of the reflected plane light beam from the reflecting surface is not impaired, but only at the pitch. This is based on the principle that the tilt angle of the plane light flux itself parallel to P changes. In the following description of the present principle, the same components as those of the above-mentioned first or second measurement principle are designated by the same reference numerals and the description thereof will be omitted. Now, light from a linear light source forming at least two parallel straight line groups L having a pitch P and intersecting the Xo axis at an inclination m is adjusted so that its chief ray is parallel to the optical axis O ₁ of the apparatus. When image-projected onto the Yo coordinate plane, this illumination light has a curved surface characteristic of the front surface of the cornea C, that is, if this cornea has a toric surface shape, the index radius R _{1 of} the first main radial line R ₁ thereof, The detection surface that is deflected and reflected according to the respective values of the radius of curvature R ₂ of the second main radial line R ₂ and the axial angle of the first main radial line and that is optically non-conjugated to the linear light source. D
Head to. The projected linear pattern L ′ on the detection surface D corresponding to the linear light source is changed to its pitch P ′ and its X-axis inclination is changed to M. When the distance between the detection surface D and the apex Oc of the cornea is 1, the inclination M of the projected straight line pattern L ′ is represented by the following equation.

[0027]

[Equation 17] Is. In the actual measurement, in order to measure the working distance WD from the change in the inclination and pitch of the parallel straight line group based on the expressions (13) and (14), the unknowns in the expressions (13) and (14) are R ₁ , Since there are three R ₂ and θ, it can be seen that the solution of the expressions 3) and (14) cannot be obtained only by changing one parallel straight line group. Therefore, in practice, it is necessary to know the inclination and pitch change of the two parallel straight line groups by combining with the other parallel straight line group. This structure is shown in FIG. Figure 7 is the slope _{m 1,} and two flat line group _{L 1} of Pitsu _{P 1,} the slope _{m 2,} are but disposed constituting the two parallel straight lines _{L 2} of the pitch _{P 2,} the light source And the ray bundle reflected by the cornea C to be inspected has two projection parallel straight line groups L ₁ ′ with an inclination of m ₁ ′ and pitch P ₁ ′ on the detection surface D and an inclination of 2 with pitch P ₂ ′. A group of projected parallel straight lines L ₂ ′ is formed. Since two sets of equations (13) and (14) are obtained respectively from these two sets of projection straight lines, a total of four equations are obtained, the unknown value θ of equations (13) and (14) is
R ₁ and R ₂ can be obtained. Secondary process (13),
If solving the equation (14) and obtaining R ₁ , R ₂ , and θ would lead to cost increase of the processing mechanism and increase of processing time in terms of arithmetic processing, the following intermediate arithmetic processing may be performed. .

FIG. 8 shows parallel straight line groups L ₁ and L ₂ formed by the linear light source of FIG. The slope of L ₁ is m ₁ , the pitch of P ₁ is L _{1, and} the slope of L ₂ is m ₂ , and the pitch is the same as in FIG. 7. Now, the distance from _one of the parallel straight line groups L ₁ L ₁₁ is e times as large as the pitch P _1.

[0029]

(Equation 18) think of. Also, the distance from one of the parallel straight line groups L ₂ L ₂₁

[0030]

[Formula 19] A virtual parallelogram UVWQ is formed, and x of these four vertices is formed.
-The virtual coordinates of the y coordinate system are U (ox ₁ , oy ₁ ), V
(Ox ₂ , oy ₂ ), W (ox ₃ , oyox ₄ , o
y ₄ ). FIG. 9 shows the parallel straight line groups L ₁ and L _{2 of} FIG.
Is a diagram showing projected parallel straight line groups L ₁ ′ and L ₂ ′ reflected by the cornea C and projected on the detection surface. This L ₁ ′ is tilted ′, pitch P ₂ ′, and L ₂ ′ is tilted m. ₂ ′ and pitch P ₂ ′ are the same as in FIG. This projected parallel straight line group may be detected by a plane type position sensor arranged on the detection surface D, but now, tentatively, only ξ in the X axis direction and η in the Y axis direction from the origin O of the XY coordinates. When Kenru thing at an intersection angle linear positive Chillon sensor S ₁ arranged on the X'-Y'coordinate axes intersecting at _gamma, S ₂ having an origin O'in that the translation, the linear sensor S ₁ is detected The projected parallel lines are detected at points a, b, c and d, and the linear sensor S ₂ is
Check the projected parallel straight lines at F, T, and J. Then, the equation of one L ₁₁ ′ of the projected parallel straight line group is calculated from the detection points B and F, and the equation of L ₂₁ ′ is calculated from the detection points C and G. Of Likewise detection point b, another one L ₁₂ of the projection parallel straight lines from ho _', the detection point D, L ₂₂ from Ji
It is possible to calculate the respective equations of ‘′ and the pitch P ₁ ′ of L ₁₁ ′ and L ₁₂ ′ as well as the pitch P ₂ ′ of ₁ ′ and L ₂₂ ′. Then, the same magnification e as that multiplied from L ₁₁ ′ to the pitch P in FIG.

[0031]

(Equation 20) A row quadrilateral U'V'W'C 'can be sought. The virtual coordinates in the xy coordinate system of the four vertices of this virtual parallelogram are U ′ (x ₁ , y ₁ ), V ′ (x ₂ , W ′.
(X ₃ , y ₃ ), Q '(x ₄ , y ₄ ), the reference quadrilateral UVWQ of FIG. 8 and the first projected parallelogram U'V of FIG.
'W'Q' correspond, and this change is exactly related to the curved surface characteristics of the cornea. Now, here, the same coefficients and equations as the above-mentioned equation (1) are defined for the virtual four points.

[0032]

[Equation 21] Here, i, j, and k are assumed to be j or k with respect to i. From four virtual points, 12 combinations are possible. Using the above equation (15a), R ₁ and R ₂ relating to the radii of the two main radial lines can be expressed by the following quadratic equation.

[0033]

[Equation 22] Here, the parenthesized expression of the above coefficient is defined as follows.

[0034]

(Equation 23) Here, if p and q are any of A, B, C, and D, then equation (15b) is

[0035]

[Equation 24] Is represented as 1 refers to the distance between the cornea C and the optical role detecting surface D as shown in FIG. Therefore, as shown in FIG. 7, the pitch P ₁ P ₂ ′ and the slopes m ₁ ′ and m ₂ ′ of the two sets of projected parallel straight line groups L ₁ ′ and L ₂ ′ are detected, and as shown in FIG. From the four vertices that form the projected virtual quadrilateral and form the parallelogram,
By solving the quadratic equation of equation (15),

[0036]

(Equation 25) You can ask. Here, similar to the first measurement principle, the detection surface D is moved from the cornea C to a position at a distance 1'to create the detection surface D '. As shown in FIG. 10, the second projected virtual parallelogram V ″ W ″ Q ″ formed by the group of projected parallel four lines L ₁ ″, L ₂ ″ on the detection plane D ′ is also the above (15a). Expression ~ Expression (15c) can be applied, and its root is

[0037]

(Equation 26) Then, from Ki and Ki ′, as in the above equation (5),

[0038]

[Equation 27] And the working distance WD is calculated from the same concept as the first measurement principle described above.

[0039]

[Equation 28] Is obtained. In FIGS. 8, 9 and 10 described above, the pitches P ₁ , P ₂ and P are used to find the virtual parallelogram.
₁ ′, P ₂ ′, P ₁ ″, and P ₂ ″ are multiplied by arbitrary numbers, g and h, respectively, but in reality, e = 1, g = 1, and a virtual parallelogram U ₀ V ₀ W ₀ Q, and U _{0'V 0'W 0} Write'Q' was used connexion operation can punished simplified. Moreover, although the coordinates of the vertices of the virtual parallelogram have been described using the x ₀ = y ₀ Cartesian coordinate system and the XY direct coordinate system, the oblique crossover X is arranged according to the arrangement of the linear sensors S ₁ and S _2. Considering the'-Y 'coordinate system, FIG.
X axis and X'axis intersect at an angle α, as shown in
′ Axis intersects at an angle β and origin O of the X′-Y ′ coordinate system
_{Since 2} is displaced from the origin O ₁ of the X-coordinate system by ξ in the X-axis direction and η in the Y-axis direction, at this time, X from the X′-Y ′ coordinate system is detected.
-The coordinate conversion to the Y coordinate system

[0040]

[Equation 29] From equation (15), Aij = (oxi-xi)-(oxj-xj) Substituting equation (19) into this, Aij = {(ox'isinα + oy'isinβ +
ξ)-(x'isinα + y'isinβ + ξ)}-
{(Ox'jsinα + oy'jsinβ + ξ)-(x
′ Jsinα−y′jsinβ + ξ)} = sinα
{(Ox'i-x'i)-(ox'j-x'j)} + s
inβ {oy'i-y'i)-(oy'j-y'j)}
= A'ijsin α + B'ijsin β (20
a) In addition, Bij = (oyi-yi)-(oyj-yj) and Bij = cosβ {(oy'i-y'i)-(oy'j
-Y'j)}-cosα {(ox'i-x'i)-(o
x'j-x'j)} = B'ijcosβ-A'ijco
sα (20b) Similarly, Cij = C'ijsinα + D'ijsinβ (20c) Dij = D'ijcosβ + C'ijcosα (20d). Here, [C, D,], [B, C], [A,
D] and [A, B], the (20a) to (20)
From the equation d), [C, D] = CijDik−DijCik = (C′ijsin α + D′ ijsin β) (D′ ik
ocsβ-C'ikcosα)-(D'ijcosβ-
C'ijcosα) (C'iksinα + D'iksi
nβ) = (sinαsinβ + cosαsinβ) [C
', D'] similarly, [B, C] = (sinαsinβ + sinβcosα)
[A ′, B ′] [A, D] = sin α cos β [A ′,
D ′] − sin α cos α [A ′, C ′] + sin βc
osβ [B ', D']-sinβ cosα [B ', C
′] [A, B] = sin αcos β + cos αsin
β] [A ′, B ′] Also, [B, C] − (A, D] = (sin αcos β + cos
αsinβ) {[B ', C']-[A ', D')} Therefore, the formula (15c) is

[0041]

[Equation 30] Therefore, the inside of {} is a quadratic equation of the same form as the equation (15c), and it can be seen that the quadratic equation of the equation (15c) is an invariant equation irrelevant to the way of taking the coordinate system. This means that in the arrangement of the two linear sensors as the detector, the degree of freedom of the arrangement is very large. That is, two linear sensors are X, Y
It does not need to be placed on the coordinate system and the orthogonal coordinate axis, and it means that it may be on the X′-Y ′ coordinate system. Even if the orthogonal accuracy of the linear sensor and the optical axis alignment are not taken into consideration,
It can be independent of measurement accuracy. Then, upon measurement, the parallel straight line group pattern L on the conjugate detection surface D
₁ ′, L ₂ ′ is an oblique coordinate system −X ′ axis of Y ′ coordinate, Y ′
Detected by the linear sensors S ₁ and S ₂ arranged on the axis, the virtual parallelogram U′V′W′Q ′ created from this detection is used as the first projected virtual parallelogram, and then the detection surface is D ′. To the position of the second projection virtual parallelogram U ″ at this time
V "W" Q "is created, and the first projected virtual parallelogram and the second
Based on the projected virtual parallelogram and its vertices U ′, V
Working distance WD from the coordinates of ', W', Q'and U ", V", W ", Q" using the above-mentioned equations (15) to (18)
Ask for. At this time, both parallelograms are considered as the coordinate system only for the oblique coordinate system X'-Y 'coordinate system which can be arbitrarily selected, and this oblique coordinate system X'-Y'.
Is an invariant that is irrelevant to the quadratic equation for the working distance WD calculation as described above, and according to the present invention, the linear sensors S ₁ and S ₂ are also assembled in terms of assembly. It has a very advantageous effect that no adjustment is required for maintenance.

Next, the calculation of the alignment amounts α and β will be described with reference to FIG. X ₀ − assumed at the light source position
Calculation of the alignment amounts α and β by the XY orthogonal system assumed for the Y ₀ orthogonal coordinate system and the detection surface position is performed with respect to the Y ₀ axis as follows.
A group L of parallel straight lines of the pitch P ₁ symmetrically arranged at the same angle γ
₁ and any one of the parallel straight line groups L ₂ having a pitch P ₂ of straight lines L ₁₁ and L ₂₁

[0043]

[Equation 31] It is set so as to coincide with the X ₀ axis and the Y ₀ axis. That is, if the reference virtual parallelogram is created by calculation so as to be symmetric with respect to the measurement O ₁ , the center of the reference virtual parallelogram coincides with the measurement optical axis O ₁ . Next, the cornea C is illuminated, and a group of projected parallel straight lines L ′ ₁ , projected onto the detection surface (X-coordinate system),
L' ₂ detected

[0044]

[Equation 32] From the coordinates of these four vertices, the horizontal alignment amount α and the vertical alignment amount β are expressed by the following equations.

[0045]

[Expression 33] When the measurement is performed in the oblique coordinate system x′-y ′, the initial virtual point is set to (ox
₁ , oy ₁ ) (ox ₂ + oy ₂ ) (ox ₃ ) (ox ₄ ,
oy ₄ ) Toki

[0046]

(Equation 34) The virtual points may be set so as to satisfy Then, the horizontal alignment amount α and the vertical alignment amount β are
Since each is given by the equation (22), if the equation (23) is converted by the equation (19),

[0047]

[Equation 35] Then, if the equation (22) is similarly converted by the equation (19),

[0048]

[Equation 36] Becomes α and β are the coordinates (ox in the oblique coordinate system of the initial virtual point (oxi, oyi) when the cornea C is not irradiated.
′ I, oy′i) and the coordinates (x ′ in the oblique coordinate system of the measurement coordinates when the cornea C is irradiated and measured on the detection surface D).
i, y'i), the (24), (25)
The following equation is obtained from the equation.

[0049]

(37)

This equation represents the alignment amount. As described above, according to the present measurement principle, the working distance can be calculated by an invariant equation irrelevant to the way of taking the coordinate system, but the oblique amount-orthogonal coordinate transformation is necessary in the alignment amount, and the formula (26) is used. However, if the calculation mechanism is complicated, the measurement coordinates (x ', y in the oblique coordinate system)
It is also possible to calculate the alignment amount by using the calculation formula (22) of the Cartesian coordinate system after the orthogonal coordinate conversion from ′) to the formula (19). As described above, according to the present measurement principle, the reference virtual parallel four-dimensional symmetry with respect to the optical axis O ₁ from the parallel straight line groups L ₁ and L ₂ of the light sources arranged at the light source position (X ₀ -Y ₀ coordinate system). ₀ -Y ₀ made by calculation in the coordinate system, then X-Y
If a first virtual parallelogram similar to the reference virtual parallelogram is created from the detection plane D projection parallel straight line groups L ₁ − and L ₂ − in the coordinate system by calculation, the four vertices of both virtual parallelograms will be obtained. The alignment amounts α and β can be calculated from the coordinates of, and the alignment amounts α and β can be calculated independently without knowing the working distance WD. This is extremely advantageous considering that alignment adjustment cannot be performed unless the conventional alignment device first adjusts the working distance, and the working distance calculation step and the alignment amount calculation step are parallel independently. This has the advantage that the calculation time can be greatly shortened because the process can be carried out. Further, the fact that the alignment amount can be quantitatively measured is a great feature peculiar to the present invention, which is not present in the conventional alignment apparatus.

[0051] Further, when creating the virtual parallelogram, the pitch of the straight lines belongs them straight to the straight line _{L 11, L 21} and n times, pulling parallel to the imaginary straight line to the slope of the straight line _{L 11, L 21} Although the virtual parallelogram was created by the above, the method of creating the virtual parallelogram is not limited to this.
To the straight line L ₁₁ as shown in FIG. 11, a virtual straight line l ₁₁ having the inclination angle beta, also creates a virtual straight line l ₂₁ having an inclination of angle α with respect to the straight line L _21, the created virtual straight line l
It goes without saying that the virtual parallelogram vwq may be created on the basis of ₁₁ 1 and l ₂₁ , and this does not change the measurement principle of the present application. FIG. 14 is a perspective view for explaining the fourth measurement principle of the present invention. The principle of this measurement is that when the light flux from a circular light source is reflected by a spherical surface, the reflected light flux becomes a circular light flux according to the radius of curvature of the reflecting surface, and when reflected by a toric surface, it is an elliptical light flux due to its curved surface characteristics. It is based on the principle that In describing the present measurement principle, the same components as those in the above-mentioned first measurement principle are designated by the same reference numerals and the description thereof will be omitted. Now, it is assumed that a light flux Fx from a circular light source having a predetermined radius R is projected and imaged on the Xo-Yo coordinate plane so that the optical axis O _{1 of the} apparatus and its main line are parallel to each other. The reflected light of the illumination light flux on the cornea C is the three elements of the curved surface characteristic of the cornea C, that is, the shape of the front surface of the cornea.
The radius of curvature _{r 1} of the main meridian _{r 1,} offset amount to the apparatus optical axis _{O 1} of the second main meridian _{r 2} songs _{r 2} and the first principal meridian axial θ further optical center Oc of _{r 1,} E _H, elliptical pattern FX 'to shadow formed on the detection surface D is deflected by the effect of E _V. The relation between the circular light source and the elliptical pattern FX ′ on the detection surface D is that the circular illumination light flux formed by the chief ray of the light flux FX from the circular light source is x ² + y ² = R ² ≡Constant [a ² ( 1) sin ² θ + b ² (1) cos ² θ) (x′−α) ² + [a ² (1) cos ² θ + b ² (1) sin ² θ] (y′−β) ² − [a ² ( 1) −b ² (1)] sin ² θ + a (1) b (1) · R ² = 0 (27)

[0052]

(38) The equation of Now the root of this equation

[0053]

[Formula 39] And Also, α and β in this equation are the cornea C
Xo-Yo coordinate system offset amount E _H between the apex O _o of _a quantity alignment is due to E _V are trying to measure the horizontal alignment amount alpha, vertical vertex Oc (also the optical center) of The fact that the alignment amount is defined as β is similar to the above-mentioned measurement principles. Now, similarly to the above-mentioned first principle, the detection surface D is placed at the position of the distance l'from the cornea C, and this is set as the detection surface D ', and the above equation (1) holds for the elliptical pattern at this time. Its roots

[0054]

(Equation 40) Then, from equations (28) and (28 '), the same as equation (5) above,

[0055]

[Formula 41] Can be obtained as 1 and the working distance WD can be calculated in the same way as the first principle.

[0056]

(Equation 42) You can ask for it as (30). Above (2
In equation (7), 1 can be stopped by equation (29), so
After all, since the unknowns in the equation (27) are five of r ₁ , r ₂ , θ, α, and β, five points of the projected ellipse pattern are detected and their coordinate values (Xi ′, Yi ′) (where i = 1 2, 3, 4 and 5) are substituted as the X ′ and Y ′ values of the equation (27),
By solving the five-dimensional simultaneous equations created by this, the detection surface D
Since the shape and the position on the XY coordinate system of the projected ellipse pattern can be determined, the alignment amount α,
β can be obtained. If a flat position sensor is used as the detector as shown in FIG. 14 or if the linear position sensor is rotated around the optical axis O ₁ , there is a problem in cost up and accuracy guarantee of the detector. Then, the following configuration may be adopted. That is, as shown in FIG. 15, if a circular light source and a single linear light source that intersects with the circular light source are used, the plane light flux from the linear light source is reflected by the cornea C as is apparent from the above-mentioned second principle, and the detection surface. When projected onto D, the linearity itself does not collapse even if the inclination changes, so by knowing this change in inclination, information on the curved surface characteristics of the cornea C can be obtained conversely. Then, the working distance and the alignment amount can be obtained by utilizing the curved surface characteristic.

Now, as shown in FIG. 15, the X of the linear light source is
If the inclination angle with the o-axis is a, and the inclination with respect to the X-axis of the projected linear pattern L _A ′ on the detection surface D corresponding to this linear light source is a ′, the following equation holds. [A (1) a-B (1) a ′] tan ² θ + [A (1) -B (1)] (1-a a ′) tan θ + [A (1) a′-B (1) a) = 0 …… (31) Here

[0058]

[Equation 43] Is. From this, four points U (o ₁ , y ₁ ) on the projection ellipse pattern are obtained by the linear position sensor 1x described on the X axis of the XY coordinate system and the linear position sensor ly arranged on the Y axis. , V (x ₁ , o), W (o, y ₂ ),
Q (x ₂ , o) 2 points on the shadow straight line pattern I (x ₃ , o),
If J (o, y ₃ ) is obtained, the corneal curved surface characteristic can be obtained. Further, as the arrangement of the linear sensors lx and ly, they may be obliquely arranged on the detection surface as described in the third principle. In this case, the above coordinate conversion formula

[0059]

[Equation 44] Should be used. Further, as shown in FIG. 15, two parallel linear sensors ₁ 1, ₂ ly may be used. At this time, the projected elliptical pattern Fx ′ is the detection point U,

[0060]

[Equation 45] A few examples of the alignment apparatus using the above-described measurement principle will be described below with reference to the drawings. 16
It is an optical layout drawing showing a 1st example of the present invention. Stand 1
An ophthalmologic device housing 2 movably supported in the front, back, left, right, and up and down directions incorporates a measurement optical system section 3 and an alignment optical system 4 of the present invention, which are responsible for the original measurement, inspection, or photographing of the ophthalmic device. There is. The measurement optical system 3 is, for example, a refractometer, an offsalmometer, or an optical system of a fundus camera. Alignment device 4
Are roughly divided into an illumination optical system 5, a measurement optical system 6, an arithmetic circuit 7, a display 8 and a casing drive unit 9 built in the gantry 1.
It consists of and. The configuration of the illumination optical system 5 is as follows. As the light source, light emitting diodes 10a and 10b that emit two infrared lights having different emission wavelengths are used. The light emitted from the light emitting diode 10a is reflected by the dichroic surface 11a of the dichroic prism 11, and the light emitted from the light emitting diode 10b passes through the dichroic surface 11a and passes through the condenser lens 12a.
Enter the aperture plate 13. FIG. 17 shows the aperture plate 13.
As shown in (a) to (d), one of the opening patterns conforming to each of the first to fourth measurement principles is formed. The aperture plate 13 in FIG. 17A is an example of the aperture plate when the first measurement principle is adopted. A large number of point openings 200 are arranged on the opening plate 13 along two axes orthogonal to each other. Fig. 14b Fig. 17 (b) shows an aperture plate when the second measurement principle is adopted. In this aperture plate 13, thick aperture straight lines 201a and 201b are arranged in parallel and The first straight line group openings 202a each having a set of three thin straight line openings orthogonal to both 201a and 201b, and the second straight line group openings 202b having the same configuration are arranged. At the intersection with 201a and 201b, the linear group opening 202
The a and 202b are cut. The straight line opening 201 formed of a thick straight line and the straight line group opening 202 formed of three thin lines are formed as the straight line openings so that they can be distinguished when detecting the projection patterns of the straight line openings. The invention is not limited to this aperture plate pattern. For example, the transmittances of the openings 201 and 202 may be made different, or only the thicknesses of the openings 201 and 202 may be changed. FIG. 17C is a diagram showing an example of an opening pattern formed on the aperture plate for adopting the above-described third measurement principle, and the aperture plate 13 has a linear aperture 2
The first parallel straight line opening group 203 and the first parallel straight line opening group 2 in which a plurality of 03a are arranged in parallel at the same pitch interval.
A second parallel linear aperture group 204 is formed by arranging a plurality of the linear apertures 03 and the linear apertures 204a whose arrangement directions are different from each other in parallel at the same pitch interval. The first and second parallel linear aperture groups have at least one reference linear aperture 203 having a thickness different from that of the linear apertures 203a and 204a.
03b and 204b are formed. The reason why the reference straight line openings 203b and 204b are provided is that which of the detection points is used when the projection pattern of these parallel straight line openings is detected by two linear type position sensors and the equation of the projection pattern is determined from the detection points. This is because it is easy to change which detection point should be used to calculate the equation.
A large number of linear openings are formed in order to average the projection patterns corresponding to these and increase the measurement accuracy.

FIG. 17D is a diagram showing an example of the opening pattern of the aperture plate when the fourth measurement principle is adopted. The aperture plate 13 has a circular aperture 205 and intersects it. Two parallel straight openings 206a, 206b
A group of parallel straight apertures 206 is formed. Here, two linear openings 206a and 206b are provided in parallel, for example, when two linear sensors detect the projection pattern of this opening pattern, the projected linear pattern corresponding to the linear opening 206a is Even if it is projected onto the intersection of the linear sensor of the book, another linear aperture 206b
This is because the projected straight line pattern corresponding to is always projected over two linear sensors, so that two points on the projected pattern can be detected and the equation of this projected pattern can be calculated. . As described above, according to each measurement principle, various aperture patterns can be adopted according to the measurement principle. However, in the following description of the present embodiment, the aperture plate 13 having the aperture pattern shown in FIG. 17B is incorporated. It will be described as being. That is, this aperture plate 13 acts as the above-mentioned linear light source. The light flux emitted from the aperture pattern of the aperture plate 13 passes through the pinhole 14 a of the pinhole plate 14 and enters the image formation auxiliary lens 15. The illumination light flux emitted from the image formation auxiliary lens 15 is tilted to the measurement optical axis O ₁ of the measurement optical system 6 to the small half mirror 1.
The light is reflected by 6 and enters the lens combination 17. The image forming lens 17 may be an independent one as an alignment device, or may be used also as an objective lens of the measurement optical unit 3 of an ophthalmologic apparatus incorporating this alignment device. The pinhole 14a is arranged at the combined focal position of both the image forming lens 17 and the image forming auxiliary lens 15. The illumination light flux emitted from the imaging lens 17 forms an image of the light source, that is, the aperture pattern of the aperture plate 13, on the image plane IS near the cornea C of the eye E to be examined.

The illumination light flux reflected by the cornea C passes through the imaging lens 17, and the illumination light flux is measured by the measurement optical section 3 of the ophthalmologic apparatus.
Optical axis O that splits the light beam to the
By ₁ part by傾設been half mirror 18 is reflected, the dichroic prism 11 and dichroic prism 19 having the same wavelength selective reflection and transmission characteristics, the first
It is divided into an optical path 20 and a second optical path 21. First optical path 20
Is composed of an auxiliary relay lens 22, a mirror 23, and a plane-parallel glass 24 for adjusting the optical optical path length. On the other hand, the second
The optical path 21 includes an auxiliary relay lens 25, a mirror 26, and an image rotator 27 that rotates an image, that is, a light beam by a predetermined angle around the optical axis of the second optical path. Then, the light fluxes of the first optical path 20 and the second optical path 21 are combined by the dichroic prism 28 having the same wavelength selective reflection / transmission specification as the dichroic prism 11. Then, the cornea reflected light flux emitted from the dichroic prism 28 is projected on the linear position sensor 29. As the linear position sensor 29, for example, a linear CCD
An array of (Charge Coupled Devices) is used. The linear sensor 29 is connected to the arithmetic circuit 7 described in detail later. An optical path length conversion member made of, for example, parallel flat glass, which is inserted and selected in the optical path by receiving a signal from the arithmetic circuit 7 between the dichroic prism 28 and the linear sensor 29 and drivingly controlling the detection surface switching circuit 30. 31 are arranged. The linear sensor 29 is
The optically conjugate image is the auxiliary relay lens 22 or 25.
When the optical path length conversion member 31 is projected from the optical path when the optical path length conversion member 31 is inserted into the optical path by the imaging lens 17 after being formed by the Are formed at positions D'in the figure, respectively. Further, these conjugate detection surfaces D and D'are located at positions which are not conjugate with the pinhole 14a of the illumination optical system.

Further, in front of the imaging lens 17, as a means for obtaining a reference projection pattern at the time of measurement, the optical axis O
The reflection sensor 32 having a reflection surface perpendicular to ₁ and capable of being inserted / removed in the measurement optical path is arranged, and this reflection mirror 32 is used to form a projection pattern having the same shape as the linear light source by the reflection light of the illumination light by this reflection mirror. 29, a reference projection pattern is created based on this, and if the value is stored in the memory of the arithmetic circuit, there may be an error with the design value when producing the opening pattern of the aperture plate 13 as the linear light source. Even if there is an error in assembling the aperture plate 13 into the illumination optical system 5, there is an advantage that a measurement error does not occur because a unique reference projection pattern can be used in the device 22. Next, the measuring operation of this embodiment will be described. First, how to create the reference projection pattern will be described. A holding stage (not shown) so that the reflecting mirror 32 is perpendicular to the optical axis O ₁ at a position where the eye to be inspected will normally be located, for example, for fixing the head of the subject of an ophthalmologic machine having this alignment device. Attach to the jaw receiving means, etc. Next, the optical path length conversion member 31 is inserted into the measurement optical path, and the light emitting diode 10a is turned on. The light flux emitted from the light emitting diode 10a is selectively transmitted through the aperture plate 13, and the aperture pattern of the aperture plate 13 is used as a linear light source,
The light emitted from this light source is illuminated by a focusing mirror 17 and a focusing auxiliary lens 15 so that its principal ray is parallel to the optical axis O ₁ and illuminates the reflecting mirror, and a linear light source image is formed on the image plane IS near the reflecting mirror. create. The reflected light from the reflecting mirror 32 enters the imaging lens through the same optical path as the illumination light. Then, the reflected light is reflected by the half mirror 18 by the imaging lens 17, is reflected by the dichroic surface of the dichroic prism 19, and is projected on the linear sensor 29 through the first optical path 20. This reference projection pattern P ₀ is shown by the solid line in FIG. Point linear sensor 29 intersects with the reference projection pattern or detection point _{0 S 0, 0 S 2,} 0 to detect the S _{3, 0} S _4.

Next, when the light emission is switched to the light emitting diode 10b, the light flux reflected by the reflecting mirror 32 of the linear light source by the aperture pattern of the aperture plate 13 by this light flux passes through the dichroic surface of the dichroic prism 19 and the second optical path 21. And is projected onto the linear sensor 29. Here, the light flux is rotated by the action of the image rotator 27 in the second optical path 21, and is incident on the linear sensor 29 as a reflected light flux equivalent to that when the linear sensor 29 is arranged at the position indicated by 29 'in FIG. The linear sensor detects the detection points ₀ S ₅ , ₀ S ₆ , ₀ S ₇ and ₀ S ₈ on this projection pattern.
Based on the equation of the projected straight line pattern 201′a from ₀ S ₁ and ₀ S ₆ , the straight line pattern 2 from the detection points ₀ S ₃ and ₀ S ₇
The equation of 01′b is projected from the detection point ₀ S ₄ to the projection pattern 20.
The equation of 2'a is obtained for the detection points ₀ S ₂ and ₀ S shadow pattern, respectively, and the intersections U ₀ , V ₀ , W ₀ , Q ₀ of the projection pattern are calculated based on these four equations, An XY coordinate system is defined with a straight line passing through the intersections U ₀ and W ₀ and a straight line passing through the intersections V ₀ and Q ₀ as the Y axis. And then this X-
The Y coordinate system is used as the coordinate system for measurement. Also intersection U
_The reference points are ₀ , V, W ₀ , and Q ₀ . And these X
-The Y coordinate system and the intersections U ₀ , W ₀ , and Q ₀ are stored in the memory circuit of the arithmetic circuit as the reference origin.

The ophthalmologic apparatus thus prepared is placed against the eye to be inspected, the measurement is performed by the same measurement procedure as described above, and the optical path length conversion member 31 is inserted into the optical path to detect the conjugate detection surface D. , The respective equations of the respective projected straight line patterns 201 ″ a, 201 ″ b, 02 ″ a, 202 ″ b of the first projected pattern P ₁ are obtained, and the intersection point U is obtained based on these four equations.
₁ , V ₁ , W ₁ , Q ₁ are obtained. The four points U ₁ , V ₁ ,
W ₁ Stores the coordinate values of the reference origins U ₀ , V ₀ , W ₀ , Q _{0 in} the XY coordinate system. Next, the optical path changing member 31 is moved out of the optical path, and the second projection pattern P ₂ is detected at the position of the conjugate detection surface D ′ by the same measurement procedure as described above. The intersection points U ₂ , V ₂ , W ₂ , and Q ₂ of the second throwing pattern are obtained from the detection points by the same procedure as described above, and the coordinate value of Y in the standard system is stored.
Then, between the above-mentioned reference origins U ₀ , V ₀ , W ₀ , Q ₀ and ₁ , V ₁ , W ₁ , Q _{1 of} the first projection pattern, (1)-
Equation (4) is applied and its root is λ. Next, the reference origin U ₀ ,
4 intersections of V ₀ , W ₀ , Q ₀ and the second projection pattern V ₂ ,
Similarly, the equations (1) to (4) are applied between W ₂ and Q ₂ to find the root λ. The working distance WD is calculated by the equation (6) from these λt ′ and λt ′. Further, between the reference origins U ₀ , V ₀ , W ₀ , Q ₀ and 4, V ₁ , W ₁ , Q _{1 of} the first projection pattern, n in the equation (8) ′ is n =
In the case of 4, the amount of applicable license is calculated. As described in the principle description, the calculation of the working distance and the alignment amount can be performed independently and in parallel by the arithmetic circuit 7.
The working distance adjustment amount and the alignment amount are displayed on the CRT display 33 as numerical values or figures, or are input to the housing drive unit 9 to automatically adjust the working distance and alignment.

FIG. 19 is a block diagram showing an example of the arithmetic circuit 7 for performing the above arithmetic processing. The linear position sensor 29 driven by the linear position sensor drive circuit 101 sends the detection output of the projected linear pattern to the signal line 102 by the light emission of the light emitting diode 10a driven by the drive circuit 100. Sign 1
Reference numeral 04 denotes an analog switch, which is a microprocessor 1
Controlled by 05. When the microprocessor 105 receives an interrupt by the scan start pulse 106 of the linear sensor from the drive circuit 101 that drives the linear sensor 29, it controls the analog switch 104 so that the output of the linear sensor 29 is sent to the A / D converter 107. Make it input. The A / D converter 107 is the drive circuit 1
The output of each element of the linear sensor read by the read pulse 108 from 01 is subjected to analog-to-digital conversion, and the converted digital value is supplied to the microprocessor. Here, the A / D converter 107 is 8 pits (1/25
Those having a resolution of about 6) and a conversion time faster than the linear sensor scanning frequency are selected. The microprocessor 105 reads the output of the linear sensor 29 converted into a digital value for each element, and stores it in a RAM (random
Data memory 1 including access memory)
Succeedingly memorized in 09. Accordingly, the data memory 109 stores digital values in order from the output from the first element of the linear sensor from a predetermined address. For example, if the linear sensor 29 has 1728 elements,
When 1728 data has been captured, the microprocessor 105 stops capturing more data and controls the drive circuit 100 to turn off the light emitting diode 10a which has been emitting light until now and cause the light emitting diode 10b to emit light. Then, the detection output of the linear sensor 29 is stored in the data memory 109 by the same drive as described above. Next, the microprocessor outputs the switching signal 120 of the detection surface switching circuit 30, drives the switching circuit 30, and drives the optical path length conversion member 31.
Is exited from the measurement optical path, and the same driving as described above is performed again to store all the detection data in the data memory 109. After that, the arithmetic circuit 112 in the microprocessor 105 performs the following processing based on the data written in the data memory 109. i The number of the element of the linear sensor at which the center position of the linear sensor output waveform by the linear projection pattern is located is detected. ii Calculate the equation of the projected straight line pattern from the detected position of i). iii From the equation, the position coordinates of the intersection of the projected patterns are obtained. iv Based on the coordinate value of the intersection point, the two roots λi and λi of the equations (1) to (4) ′ are obtained. The working distance is calculated from the equation (6) using the v 2 roots λi and λi ′. vi Alignment amount is calculated from the intersection point coordinate value. Each value obtained by the above processing is the CRT display 33.
Numerical value or figure is displayed by. Alternatively, the difference from the reference working distance stored in advance in the reference value setting circuit 121 is calculated as a vector value, that is, the amount and direction of movement of the device housing 2 is calculated by the arithmetic circuit 112, and the value is calculated as the housing drive unit. 9 is input to the drive control circuit 114 that controls the drive of the front-rear direction moving motor 117 to automatically adjust the working distance.

Similarly, the horizontal alignment amount α is supplied to the drive control circuit 115 of the horizontal movement motor 118, and the vertical alignment amount β is supplied to the vertical movement motor 119.
To the drive control circuit 116, and the alignment is automatically adjusted. FIG. 20 is an optical layout diagram showing a second embodiment of the present invention. The same or equivalent components as those of the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted. The aperture plate of the illumination optical system 5 of this embodiment is composed of two aperture plates 50 and 51, which are arranged on the reflection optical axis and the transmission optical axis of the dichroic prism 11, respectively. Further, as the light emitting light source, general incandescent light bulbs 52, 53 are used instead of the light emitting diode. The light beams emitted from the light sources 52 and 53 pass through the diffuser plate 54 and the infrared filter 55 that transmits only infrared light, and enter the aperture plates 50 and 51. In the aperture plate 51, only one aperture is formed for each aperture pattern of the aperture plate 13 shown in FIG. For example, referring to FIG. 17B, linear apertures 201a and 201b are formed in the aperture plate 50, and parallel linear group apertures 202a and 202b are formed in the aperture plate 51, respectively, and an image is formed through the pinhole 14a. An image is formed on the image plane IS near the cornea by the lens 17 and the auxiliary image forming lens 15, and the images are combined in this image plane. Further, the half mirror 56 combines the first optical path 20 and the second optical path 21 of the measurement optical system 6 and divides the cornea reflected light passing through the first optical path 20 into two so that the reflected light of the half mirror 53 is linear. The sensor 29 and the transmitted light are projected on the linear sensor 57, respectively. Similarly, the corneal reflected light that has passed through the second optical path 21 is divided into two by the huller mirror 57, and the reflected light of the half mirror 56 is projected on the linear sensor 57 and the transmitted light is projected on the linear sensor 29. Here, the two linear sensors 29 and 57 are the complementary rib relay lens 22 or 25, respectively.
And the imaging lens 17, the conjugate detection surface D or D '.
They are arranged so that they intersect each other.

When the light source 52 emits light, the emitted light is selectively transmitted by the aperture plate 50, reflected by the dichroic prism 11 and directed to the cornea. Then, the cornea reflected light passes through the optical image lens 17, the half mirror 18, and the first optical path 20, is divided into two by the half mirror 56, and is projected on the linear sensors 29 and 57, respectively. The linear sensor 29 is shown in FIG.
Detection points ₁ S ₁ and ₁ S ₂ of the linear sensor 57
₁ S ₃ Detect each. Next, when the light emission is switched to the light source 53, the emitted light is selectively transmitted through the aperture plate 51 and goes to the cornea C. The reflected light from the cornea C passes through the second optical path 21 and is similarly bisected by the half mirror 56, one of which is projected on the linear sensor 29, and the linear sensor 29 detects the detection point ₁ S ₅ ,
₁ S ₆ is detected. The other is projected on the linear sensor 57, and the sensor 57 detects the detection points ₁ S ₇ and ₁ S ₈ . Then, the equation of each projected straight line pattern is obtained from these eight detections _{, 1} S ₂ , ... ₁ S _8, and the four intersection points U ₁ W ₁ and Q ₁ are obtained. After that, the operation and the alignment amount can be obtained by the same measurement procedure as in the first embodiment. FIG. 21 is an optical layout drawing showing a third embodiment of the present invention, and FIG. 22 is an optical layout drawing showing a fourth embodiment of the present invention.

In the third and fourth embodiments, the above-mentioned first
Alternatively, the same or equivalent constituent elements as those of the second embodiment are designated by the same reference numerals and the description thereof will be omitted. In the third embodiment shown in FIG. 21, the linear sensor 29 is rotated by the pulse motor 300 controlled by the rotation drive control circuit 301 with the optical axis O ₁ as the rotation axis, and the linearr 29 is fixed and shown by a chain line. An example of rotating the image rotator 302 is shown. As a result, the same effect as the flat sensor can be obtained, so that even when a point light source is used for measurement as in the first measurement principle, it can be detected by one linear sensor. Further, when only the same-shaped light source is used in the fourth measurement principle, it is possible to detect with a single linear sensor in the same manner. In the fourth embodiment shown in FIG. 22, instead of arranging two linear sensors as detectors in parallel, the plane-parallel glass 303 is rotated about an axis perpendicular to the optical axis O ₁ as a rotation axis to shift the reflected light flux. This is an example in which a single linear sensor has the same operational effect as the parallel arrangement. In each of the embodiments described above, the aperture pattern formed on the aperture plate is used as the light source, but the present invention is not limited to this, and a reflection pattern that selectively reflects the illumination light flux from the light source. Needless to say, it may be used as a light source, and it goes without saying that a large number of minute light emitting elements may be arranged to directly form each pattern. The measurement principle of 1 is sufficiently practical.

Further, in order to obtain these light sources, the light beam emitted from one point light source is configured as if there are a plurality of light sources through a pyramid prism or a polygonal pyramid prism having a plurality of refracting surfaces. One linear light emitting element array or a mask pattern may be moved or rotated to virtually form a plurality of linear light emitting element arrays or a plurality of mask patterns as described in the above principle. Needless to say. Instead of the circular light source, one off-axis point light source or one off-axis point aperture may be rotated about the optical axis to form a circular light source.

[Brief description of drawings]

FIG. 1 is an optical layout diagram for illustrating the principle of the present invention,

FIG. 2 is a diagram showing a catadioptric state of illumination light to the cornea in the vicinity of the cornea,

FIG. 3 is a perspective view for explaining the first measurement principle of the present invention,

FIG. 4 is a perspective view for explaining a second measurement principle of the present invention,

FIG. 5 is a perspective view for explaining a second measurement principle of the present invention,

FIG. 6 is a perspective view showing the third measurement principle of the present invention,

FIG. 7 is a perspective view showing a third measurement principle of the present invention,

FIG. 8 is a schematic view showing a method for creating a virtual parallelogram from a projected pattern of the present invention,

FIG. 9 is a schematic view showing a method for creating a virtual parallelogram from a projected pattern according to the present invention;

FIG. 10 is a schematic view showing a method of creating a virtual parallelogram from a projected pattern of the present invention,

FIG. 11 is a schematic view showing a method for creating a virtual parallelogram from a projected pattern according to the present invention;

FIG. 12 is a diagram showing a relationship between a rectangular coordinate system and an oblique coordinate system,

FIG. 13 is a schematic view showing a method for creating a virtual parallelogram from a projected pattern of the present invention,

FIG. 14 is a perspective view for explaining a fourth measurement principle of the present invention,

FIG. 15 is a perspective view for explaining a fourth measurement principle of the present invention,

FIG. 16 is an optical layout diagram showing a first embodiment of the present invention,

17A to 17D are front views showing examples of aperture plates.

FIG. 18 is a schematic diagram showing a projection pattern detection method,

19 is a block diagram showing an example of the arithmetic circuit of FIG.

FIG. 20 is an optical layout diagram showing a second embodiment of the present invention,

FIG. 21 is an optical layout diagram showing a third embodiment of the present invention,

FIG. 22 is an optical layout diagram showing a fourth embodiment of the present invention. 5 ... Illumination optical system, 6 ... Measuring optical system, 10a, 10b
...... Light emitting diode, 14a ...... Pinhole, 17 ...
Imaging lens, 27, 302 ... Image rotator,
29, 57 ... Linear position sensor, 31 ... Optical path length conversion member, 52, 53 ... Light source, 55 ... Infrared filter, 303 ... Luminous flux shift means, 300 ... Pulse motor.

Claims (1)

[Claims] 1. A projection system for projecting a predetermined pattern image toward a cornea of an eye to be inspected, a light receiving section for photoelectrically detecting a corneal reflection pattern image formed by a light beam reflected by the cornea of the eye to be inspected, A calculation unit for calculating the geometric center of the corneal reflection pattern image from an equation indicating the shape of the corneal reflection pattern image based on the signal from the light receiving unit, and calculating the alignment amount of the device with respect to the eye to be examined. Alignment device for ophthalmic machines.