JPS6219146A - Alignment apparatus for ophthalmic machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alignment device for an ophthalmological machine for aligning an ophthalmological machine such as an autorefractometer or a fundus camera with an eye to be examined or treated.

Conventionally, many types of alignment devices for ophthalmic machines are known. For example, an optical system is installed to directly observe the eye to be examined from the side or diagonally from the side, but this relatively limits the position of the examiner during alignment, and also limits the working distance. There has been a problem in that it is difficult to increase the accuracy of alignment in orthogonal directions. In other examples, a plurality of target light beams are made incident on the cornea of the subject's eye from different directions, and the target image formed by the cornea is captured and observed on a monitor television. There was a problem in that the optical system used was complicated.

The present invention has been made in view of the above-mentioned problems of conventional alignment devices, and an object of the present invention is to provide an alignment device that has an extremely simple target projection optical system and can perform alignment efficiently with high precision. With the goal.

In order to achieve the above object, the present invention provides a method of applying
an index projection means for projecting one index; two detection means for detecting the reflected image of the index by the cornea from two different directions; and a positional shift between the reflected images detected by each of the detection means. and display means for displaying alignment information based on the alignment information.

Therefore, the alignment device according to the present invention has an extremely simple target projection system and can efficiently perform alignment of an ophthalmological machine with high accuracy.

Example Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 is an optical layout diagram and a block diagram of an electrical system showing the present invention. An annular slit 11 having a center on the optical axis A of the device is formed in the index plate 10 . Behind this slit 11 is an annular light source 12 and a reflecting mirror 13.
There is an index illumination section consisting of. The light from slit 11 is
As shown in FIG. 2, the light is reflected by the cornea C of the eye to be examined, creating a toric virtual image 11'. The light from this virtual image 11' passes through lenses 16 and 17 provided on the index plate 10 to the detector 1.
4.15, respectively.

In this embodiment, the detector 14.15 is composed of an area type CCD, and its detection signal is sent to the video signal processing circuit 21.22 of the alignment detection system 20 and the detection signal counting circuit 31.32 of the corneal topography measurement system 30. Output.

[Alignment detection]

The alignment detection system 30 in this embodiment is used for coarse alignment adjustment to capture the eye to be examined within the field of view of the apparatus. The detection signals from each detector 14.15 are converted into video signals by video processing circuits 21.22, and the video signals from both detectors are combined by a video signal synthesis circuit 23, and then displayed on a CRT or liquid crystal display. For example, an image is displayed on the device 24 as shown in FIG.

In FIG. 5, lla" indicates the index image obtained by the detector 14, and llb' indicates the index image obtained by the detector 15. When the alignment is incomplete, that is, the working distance between the eye to be examined and the device is the normal distance. 5, the images 11a' and 11b' are displayed shifted.Furthermore, when there is a shift in the horizontal and vertical directions within the plane perpendicular to the optical axis, the images is displayed with the center of the image 11a', ll
While looking at b', move the device casing back and forth, left and right, and up and down so that both images match and their centers approximately coincide with the intersection Q, as shown by the dotted line opening'.

FIG. 6 shows another example of the display format, in which a signal corresponding to the screen frame of the upper half of the detector 14 is inputted from the video signal processing circuit 21 to the video synthesis circuit 23. on the other hand,
A signal corresponding to the lower half screen frame of the detector 15 is input from the video signal processing circuit 22 . Both human power signals are combined in a video signal combining circuit 23 and displayed simultaneously on a display device 24. In this display, when the working distance is inappropriate, the images 11a' and 11b' are shifted from each other in the left and right directions. In addition, the alignment deviation in the horizontal, vertical, and vertical directions is displayed as a difference in the division of the index images 11a' and llb''. The device is moved back and forth, left and right, and up and down so that the center of the intersection substantially coincides with the intersection point Q.

[Cornea shape detection]

When the rough alignment described above is completed, the detectors 14 and 15
The detection signals from the counters are input to counting circuits 31 and 32. The counting circuit 31, as shown in FIG.
is scanned to obtain a binarized signal for each pixel based on a predetermined threshold level. A pixel on which a projection index image is projected outputs a signal "1", and a pixel on which the projection index image is not projected outputs a signal "0". Further, address information E (xSy) of the pixel that outputs the signal "1" is detected.

Similarly, the counting circuit 32 detects address information of the pixel onto which the projection index image is projected based on the detection output of the detector 15. The address information detected by the counting circuits 31 and 32 are both input to the arithmetic circuit 33.

The arithmetic circuit 33 calculates each address information E of the index image 11'.
For (x, y), perform the following calculation to find the center point G of the index image. That is, from the address information E (x, y), 5 of the pixel pairs E l and E 2 having the same address Xa
'Find y, 10yb/2-1y, from address aSybP
Find the address of +(xa N +yp ). Similar operations are performed for other pairs of pixels with the same X address,
Find the midpoints P, (1-1, 2, --n), and set these midpoints P
Find a straight line P that passes through . Next, address information E (x, y)
Pixel pair E5 (
Xll, ye) and E6 (Xr, y,) are selected, and xe+yr/2=+xq is calculated to find the midpoint Q+(+Xq, ye). Similarly, midpoints Q, (i=l, 2.3---n) are found, and straight line intersections passing through these midpoints Q1 are found. The center G of the index is determined from the intersection of these two straight lines P and Q.

Next, address information E (x
, y) in at least three directions using the following equation.

Pw+(θ+) =(R,-R2) cos 2(θ,-
8) +R1 Here, R1 and R2 are the radii of curvature of the cornea in two mutually orthogonal directions, and A indicates the main axis axis angle of the cornea. By solving the simultaneous equations of the three calculated equations, the radii of curvature R1 and R2 of the cornea and the main radial axis angle A can be determined. The measurement results R1, R2, and A are digitally displayed on the display device 34.

If there is an error in the working distance, the projection magnification of the target projected image onto the detector 14, 15 will change, resulting in a measurement error. However, in the present invention, the center G of the index projection image is determined, and when G takes a predetermined address, that is, a different address from the address at which it should be located at the correct working distance, the amount of deviation is calculated. This amount of shift and lens 16.
From the magnification of 17, the size of the index image when the device is located at the normal working distance is calculated. The address information R1, R21, A of the index image obtained by this calculation is calculated. Therefore, in the apparatus of the present invention, it is not necessary to precisely adjust the working distance. Also,
If the detection surfaces of the detectors 14 and 15 are made sufficiently larger than the projected target image, the alignment in the horizontal and vertical directions can be measured because the shape of the projected target image can be determined even if there is some alignment error. be.

In the present invention, the light source 12 may emit either visible light or invisible light (infrared light). Furthermore, by observing the corneal reflection image 11' of the slit 11 with an anterior segment magnification observation means (not shown), it is possible to determine whether there is irregular astigmatism in the cornea to be examined from the disturbance of the reflection image 11'. It is also possible to determine the amount of irregular astigmatism by detecting this reflected image with the detectors 14 and 15. Furthermore, in the example of FIG. 6, instead of using the anterior segment magnification observation means, the detector 14.1
5 can also be used as an anterior segment observation means.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the optical device and electrical system of the device according to the present invention, Fig. 2 is an optical path diagram showing the optical path of light from the index entering the detector, and Fig. 3 is a diagram showing the optical path of the detected index image. A schematic diagram showing the method of determining the center, FIG. 4 is a schematic diagram showing the principle of determining the corneal shape, FIG. 5 is an explanatory diagram showing an example of a display method, and FIG. 6 is an explanatory diagram showing another example of the display method. It is. 11... Slit index, 16.17... Lens, 14.25... Detector, 20... Alignment system, 30... Corneal shape detection system. Figure 5 Figure 6

Claims (2)

[Claims] (1) An index projection means for projecting one index onto the cornea of the eye to be examined; two detection means for detecting the reflected image of the index by the cornea from two different directions; and display means for displaying alignment information based on the mutual positional deviation between the reflected images. (2) The alignment device for an ophthalmic machine according to claim (1), wherein the display means displays images of cornea-reflected images of the indices detected by each of the detection means in a superimposed manner.