JPS6240568Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a curvature radius measuring device that optically measures the radius of curvature of a test object such as a cornea or a lens, and in particular, the present invention relates to a curvature radius measuring device that optically measures the radius of curvature of a test object such as a cornea or a lens. Regarding optical systems.

When trying to measure the radius of curvature of the cornea of a human eye, the cornea may include a toric surface, and in such cases, the radius of curvature indicating the maximum and minimum of the toric surface and its direction (principal axis direction) and need to be measured. As a premise, it is necessary to align the measuring device and the cornea.

Conventionally, indicators such as a ring-shaped light beam or a large number of light spots arranged on the circumference are projected onto the subject, and alignment in the vertical plane is performed based on the position of the reflected image on the corneal surface. I was getting used to it. In addition, if the eye to be examined is a toric surface, the measuring device can be rotated to determine the maximum or minimum interval between the reflected images (or the length of the long axis and short axis of the ellipse when a ring beam is projected onto the eye to be examined). It was necessary to match the direction (direction of the main radius) with a predetermined direction. Therefore, the measuring device was rotated so that the maximum and minimum intervals (or the direction of image flow) of the reflected images overlapped with the crosshairs on the reticle. That is, in the conventional apparatus, the measuring apparatus was aligned in the vertical plane and in the direction of the main meridian depending on the position and shape of the reflected image. Therefore,
Although various efforts have been made, none have been able to satisfy the speed and accuracy of positioning.

The purpose of the present invention is to provide a radius of curvature measurement device that
An object of the present invention is to provide an alignment optical system that can perform alignment quickly and accurately. The present invention was developed in view of the fact that the drawbacks of the conventional method were caused by aligning the eye to be examined and the measuring device based on the position and shape of the reflected image. The present invention provides an alignment optical system for a radius of curvature measuring device that can perform alignment using a matching formula.

The present invention will be described below based on embodiments shown in the drawings.

In FIG. 1, the optical axes _Oa of a pair of projection optical systems having light sources 1a, 1b, pinholes 2a, 2b, and collimator lenses 3a, 3b form an angle θ symmetrically with the optical axis O1 of the objective lens 4. , Ob is provided. In addition, the second
As is clear from the figure, the light sources 1c, 1d and the pinhole 2 also form an angle θ symmetrically with the optical axis O ₁ in a plane that includes the optical axis and is perpendicular to the plane of the paper in FIG. 1.
A pair of optical axes Oc and Od are provided for a pair of projection optical systems having collimator lenses 3c and 3d, and the point where the optical axes Oc and Od intersect with the optical axis _O1 is the optical axis. Each projection optical system is provided around the optical axis _O1 so that Oa and Ob also intersect.

An anti-transmissive mirror 5 is provided behind the objective lens 4, and separates the light incident on the objective lens 4 into a measurement optical system (transmission) and an alignment optical system (reflection). First, the measurement optical system after passing through the anti-transmission mirror 5 will be explained. The aperture 6 is provided at the back focal position of the objective lens 4. The lens 7 is arranged so that its front focal position coincides with the position of the aperture 6, and the lenses 4, 7 and the aperture 6 form a so-called telecentric optical system. lens 7
A reflector 8 is installed behind the 90
The light is bent once and guided to the light receiving element 9. The light receiving element 9 is provided at the focal point of the lens 7, and is an element such as a position sensor that outputs a signal according to the position of a point image formed on the surface.

Next, the positioning optical system after reflecting the anti-transmissive mirror 5 will be explained. The aperture 10 is provided at the back focal position of the objective lens 4. A bonded prism 11 is provided behind the aperture 10.
In this prism 11, the bonding surface 11a is approximately
It is constructed as a dichroic mirror that rises at around 550 nm. One of the prisms has a roof reflecting mirror 11b whose ridgeline is parallel to the dichroic mirror 11a, and the other prism has a plane mirror 11c parallel to the dichroic mirror 11a. The size of the dichroic mirror 11a is as follows:
It must be such that the optical axis separated at 1a is bent by 90 degrees at the roof reflector 11b and the plane mirror 11c, and includes the positions where they meet again. A lens 12 whose front focal point is above the aperture 10 is provided behind the prism 11. That is, as in the case of the measurement optical system, the lenses 4 and 12 and the aperture 10
A telecentric optical system is formed by this. A focusing plate 13 is provided at the rear focal position of the lens 12, and therefore the focusing plate 13 is located at a position equivalent to that of the light receiving element 9. Focus plate 13
are provided with crosshairs intersecting at the optical axis, one of the crosses being in the plane of the paper and the other at right angles to the plane of the paper. An eyepiece lens 14 is provided behind the focus plate 13.

With such an optical system, the light sources 1a to 1
The light flux from d passes through pinholes 2a to 2d, is made into a parallel light flux by collimator lenses 3a to 3d, and is then projected onto the subject's eye _E1 along optical axes Oa to Od. After the reflected light from the corneal surface of the eye _E1 to be examined enters the objective lens 4, it is separated by the anti-transmissive mirror 5 into reflected light and transmitted light. The transmitted light passes through an aperture 6, a lens 7, and a reflecting mirror 8 before reaching a light receiving element 9. In this example, a telecentric optical system is used, so
Even if the positioning of the objective lens 4 in the optical axis direction is not very strict, the principal ray after passing through the lens 7 will be parallel to the optical axis, so the light receiving element 9 will be able to detect the position of the principal ray, that is, the pinhole image. When the image is out of focus, the effect of out-of-focus can be removed by detecting the brightest position (corresponding to the center of the out-of-focus circle) as the coordinate position of the pinhole image. A well-known element such as a position sensor can be used as the light-receiving element 9, and the inter-image distance can be determined from a signal output from the light-receiving element 9 according to the coordinates. In this example, the inter-image distance is determined photoelectrically, but any method such as an optical reading method may be used.

Now, the light reflected by the anti-transmissive mirror 5 passes through the aperture 10 and enters the prism 11. The light incident on the prism 11 is separated by the dichroic mirror 11a into two wavelength ranges with the wavelength (550 nm) as the boundary, one of which is transmitted and the other is reflected. The light transmitted through the dichroic mirror 11a is reflected by the roof reflector 1.
1b, and is also reflected by the dichroic mirror 11a.
The light reflected by the plane mirror 11c is reflected again by the 2
The two lights are matched by a dichroic mirror 11a. Therefore, the image of the light reflected by the roof mirror 11b and the image of the light reflected by the plane mirror 11c are reversed left and right. The light emitted from the prism 11 forms an image on the focus plate 13 by a lens. The examiner E ₂ observes the focusing plate 13 through the eyepiece 14 .

Now, the alignment (focusing) of the eye to be examined E ₁ and the device 100 in the optical axis O ₁ direction has been completed;
Consider a case where the vertex of the eye E ₁ to be examined has not yet been aligned with the extension of the optical axis O ₁ of the apparatus 100 (optical axis alignment), and the cornea of the eye E ₁ to be examined has a spherical surface. Then, when all the alignments are completed, images 2a' to 2d' of bright spots corresponding to the pinholes 2a to 2d are formed on the reticle 13 around the optical axis as shown in FIG. If the optical axis alignment is not completed, the reflected images on the roof reflector 11b and the plane mirror 11c of the prism 11 are reversed left and right, so that images of eight bright spots as shown in FIG. 3 are formed on the focus plate 13. do. Moreover, the bonding surface of the prism 11 is the dichroic mirror 11a as described above.
Therefore, for example, the black dot in Figure 3 looks blue, and the white dot looks red. When the alignment (optical axis alignment) is completed by moving the device 100 in the direction orthogonal to the optical axis O ₁ with respect to the eye E ₁ to be examined, the images of the eight bright spots will become the corresponding blue color as shown in FIG. The red and red statues overlap to form four white statues. At this time, the four images overlap the crosshair.
Interval h ₁ , h ₂ between images generated by a pair of projection optical systems
As is well known, corresponds to the direction of the radial line in the plane of FIG. 1 and the radius of curvature in the direction perpendicular thereto. Assume that the cornea of the eye E ₁ to be examined is spherical, so h ₁ = h ₂ .

Next, consider the case where the cornea of the eye _E1 to be examined is a toric surface. Similarly to the above, the eye to be examined E ₁ and the device 1
00 means that focusing has been completed, but optical axis alignment has not been completed, and furthermore, the main diameter line is not within the paper plane of FIG. 1. Then, eight images as shown in FIG. 5 will be generated on the focus plate 13. In other words, the reflected image on the cornea is affected by the torsion on the toric surface and the different curvatures in the circumferential direction, so that the quadrilateral connecting four points of the same color does not form a square as shown in Figure 3, but instead forms a 5th square. As shown in the figure, it is diamond-shaped, and the diagonal direction is 0° or
The angle will be other than 90°. Therefore, when the optical axes of the eye _E1 to be examined and the apparatus 100 are aligned, images of blue and red bright spots are arranged alternately as shown in FIG. Conversely, the scattered images shown in Figure 5 are the 6th image.
The optical axes are aligned by moving the device 100 in a direction perpendicular to the optical axis _O1 so that the optical axes are lined up regularly as shown in the figure. After that, if the device is rotated around the optical axis _O1 so that the four white images are superimposed on the crosshairs, the direction of the principal axis of the toric surface will match the direction of projection of the pinhole by the projection optical system. become. The rotation angle of the device 100 at this time corresponds to the direction of the main axis of the toric surface, and the distance h between the bright spot image 2a' corresponding to the pinhole 2a and the bright spot image 2b' corresponding to the pinhole 2b ₁ is the radius of curvature on one main meridian, and similarly the distance h ₂ between images 2c' and 2d'
is the radius of curvature of the other main radius.

The operating procedure for the device 100 is shown in FIG.
The optical axis may be rotated to form the structure as shown in FIG. 8, and then the optical axis may be aligned and the operation may be performed as shown in FIG.

As can be seen from the above explanation, the radius of curvature does not need to be determined based on the output of the light receiving element 9,
If a scale is marked on the cross line 3, the radius of curvature can be read visually, so in that case members 6, 7, 8, and 9 are not needed. Further, in cases where a scale is not marked on the crosshair, the crosshair is not necessarily necessary. Of course, in that case, another device for reading the interval is required. Furthermore, in order to make it easier to confirm the match, in the above example, the roof reflector 1
The image passing through the optical path of the plane mirror 1b and the image passing through the optical path of the plane mirror 11c are separated by color.
The dichroic mirror 11a is used as the bonding surface of the dichroic mirror 11a, but it is not necessarily necessary to use different colors, and it is sufficient if the dichroic mirror 11a is a light splitter. In that case, images of the same color will be matched.

Further, the prism 11 can be formed of separate optical members having different functions. That is,
The prism 11 functionally includes a light splitter 11a for separating optical paths, and a roof reflector arranged so that one of the optical paths separated by the light splitter 11a has a ridge line parallel to the light splitter 11a. 11b, and a light splitter 11 in the other optical path separated by the light splitter 11a.
a plane mirror 11c disposed parallel to a, and a light combiner 11a disposed parallel to the light splitter 11a to combine optical paths at the intersecting position of the reflection optical axes of the plane mirror 11c and the roof reflector 11b. It is composed of.

As described above, according to the alignment optical system of the present invention, the apparatus and the object to be inspected can be aligned using a matching method, so that alignment can be performed quickly and accurately.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention;
The figures are a view from direction A in Fig. 1, Fig. 3, and Fig. 4.
, FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are field views showing reflected images of bright spots, respectively. Explanation of symbols of main parts, 1a to 1d...Light source (bright spot), 5...Anti-transmitting mirror, 9...Photoelectric element, 11
... Prism, 11a... Dichroic mirror, 11b... Roof reflector, 11c... Plane mirror,
E... Eye to be examined, E ₁ ... Eye of examiner.

Claims (1)

[Claims for Utility Model Registration] A positioning optical system for aligning a radius of curvature measuring device, which projects an index onto the object and measures the radius of curvature from the appearance of a reflecting mirror, with respect to the object. a light splitter for separating the optical path incident on the device; a roof reflector disposed so that one of the optical paths separated by the light splitter has a ridge line parallel to the light splitter; a plane mirror disposed parallel to the light splitter in the other optical path separated by the light splitter, and a position where the reflection optical axes of the plane mirror and the roof reflector intersect;
and a light combiner arranged parallel to the light splitter to combine optical paths.