JPH06101B2 - Alignment device for ophthalmic machine - Google Patents

Description

The present invention relates to an alignment device for an ophthalmologic machine for performing alignment between an ophthalmologic machine such as an autorefractometer and a fundus camera and an eye to be inspected which is an inspection / treatment target.

Conventionally, many types of alignment devices for ophthalmologic machines are known. For example, an optical system for directly observing the eye to be examined laterally or obliquely sideways is provided, but this causes the position of the inspector during alignment to be relatively limited, and the working distance (working distance) and this There is a problem that it is difficult to improve the accuracy of alignment in the orthogonal direction. In another example, a plurality of target light beams are made incident on the cornea of the eye to be inspected from different directions, and a target image formed by the cornea is imaged and observed by a monitor television, but a target light beam is formed. There was a problem that the optical system to operate was complicated.

The present invention has been made in view of the above problems of the conventional alignment apparatus, and provides an alignment apparatus having an extremely simple index projection optical system and capable of performing alignment efficiently with high accuracy. With the goal.

The present invention, in order to achieve the above object, an index projection unit that projects an annular index on the cornea of the eye to be inspected, and a detection unit that electrically detects reflected images of the index by the cornea from at least two different directions. And a display unit for displaying alignment information based on the positional deviation between the reflection images detected by each of the detection units.

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

Example Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is an optical layout diagram and a block diagram of an electric system showing the present invention. The index plate 10 is formed with an annular slit 11 having a center on the optical axis A of the apparatus. Behind the slit 11, there is an index illuminating section including an annular light source 12 and a reflecting mirror 13. As shown in FIG. 2, the light from the slit 11 is reflected by the cornea C of the eye to be inspected to form an annular virtual image 11 '. The light from the virtual image 11 ′ is the index plate 10
Through the lenses 16 and 17 provided on the detectors 14 and 1,
5, respectively.

In the present embodiment, the detectors 14 and 15 are composed of area CCDs, and the detection signals thereof are sent to the video signal processing circuits 21 and 22 of the alignment detection system 20 and the detection signal coefficient circuits 31 and 32 of the corneal shape measuring system 30. Is output.

[Alignment detection]

The alignment detection system 30 in this embodiment is used for coarse alignment adjustment for capturing an eye to be inspected in the visual field of the apparatus. The detection signals from the respective detectors 14 and 15 are converted into video signals by the video processing circuits 21 and 22, and the video signals from both detectors are synthesized by the video signal synthesizing circuit 23, and a display composed of a CRT or a liquid crystal display is displayed. An image is displayed on the device 24, for example, as shown in FIG.

In FIG. 5, 11 a ″ indicates the index image by the detector 14, and 11 b ″ indicates the index image by the detector 15. When the alignment is incomplete, that is, when the working distance between the eye to be inspected and the apparatus is not within the regular distance, both images 11a ″ and 11b ″ are displayed as deviated, as shown in FIG. Further, when there is a deviation in the left-right and up-down directions in a plane perpendicular to the optical axis to be inspected, the center of the image is displayed with a deviation from the intersection Q of the reticle lines 40 formed on the display surface. The measurer views the images 11a ″, 11 on the display device 24.
While looking at b ″, the device housing is moved back and forth, left and right, and up and down so that both images are aligned and the center is substantially aligned with the intersection Q, as shown by the dotted line ∇ ″.

FIG. 6 shows another example of the display format. A signal corresponding to the upper half screen frame of the detector 14 is input from the video signal processing circuit 21 to the video synthesizing 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 input signals are combined in the video signal combining circuit 23 and are simultaneously displayed on the display device 24. In the display, when the working distance is incorrect, the images 11a ″ and 11b ″ are shifted from each other to the left and right. The misalignment in the left-right and up-down directions is displayed as the difference in the division ratio of the index images 11a ″ and 11b ″. The measurer moves the device back and forth, left and right, and up and down so that the separation index images 11a "and 11b" are aligned as indicated by the dotted line {circle over ()} and the center thereof is substantially aligned with the intersection Q.

[Corneal shape detection]

When the above rough alignment is completed, the detectors 14 and 15
The detection signal from is input to the coefficient circuits 31 and 32. The coefficient circuit 31, as shown in FIG.
Are scanned, and a binarized signal is obtained for each pixel with reference to a predetermined threshold level. The pixel on which the projection index image is projected outputs the signal “1”, and the pixel which is not projected outputs the signal “0”. Further, the address information E (x, y) of the pixel that outputs the signal "1" is detected.

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

The arithmetic circuit 33 determines the address information E of each index image 11 '.
For (x, y), the center point G of the index image is obtained by the following calculation. That is, from the address information E (x, y), the same _{x a} pixel pairs _E 1 having address, _{E 2} of _y a, _y from address _{b y a + y b / 2 =} 1 y p the determined _P 1 _{(x a} , ₁ y _p ) for the address. The same calculation is executed for the other pixel pairs having the same x address, the midpoint P _i (i = 1, 2, --n) is obtained, and the straight line P passing through these midpoints P _i is obtained. Next, from the address information E (x, y), a pixel pair E ₅ (x _e , y _e ) and E ₆ (x _f , y _e ) having the same y address, for example, y _e , is selected, and x _e + y _f / 2 = _i x _q is calculated and the middle point Q ₁ ( ₁ x _q , y _e )
Ask for. Similarly, the middle point Q _i (i = 1, 2, 3 −−−)
n) is obtained and a straight line passing through these midpoints Q _i is obtained. The center G of the index is determined from the intersection of these two calculated straight lines.

Next, the address information E (x, with the obtained center G as the center,
The radial radial distance P _i (FIG. 4) of y) is obtained in at least three directions by the following equation.

Pw _i (θ _i ) = R ₁ −R ₂ ) cos ₂ (θ _i −A) + R ₁ where R ₁ and R ₂ are radii of curvature of the cornea in two directions orthogonal to each other, and A is the main diameter of the cornea. Indicates the line axis angle. By solving the simultaneous equations of the three calculated equations, the radii of curvature R ₁ , R ₂ of the cornea and the main radial axis angle A can be obtained. The measurement results R ₁ , R ₂ , and A are digitally displayed on the display device 34.

If there is an error in the working distance, the projection magnification of the index projection image on the detectors 14 and 15 changes, which causes a measurement error. However, in the present invention, the center G of the index projection image is obtained, and when G has a predetermined address, that is, an address different from the address that should be located when the working distance is correct, the deviation amount is calculated. This shift amount and the 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 R ₁ , R ₂ , and A of the index image obtained by this calculation is calculated. Therefore, the device of the present invention does not require precise adjustment of the working distance. Further, if the detection surfaces of the detectors 14 and 15 are made sufficiently larger than the projected index image, the shape of the projected index image can be obtained even if there is some alignment error in the alignment in the left-right and up-down directions. It is possible.

In the present invention, the light source 12 may emit either visible light or invisible light (infrared light). Also slit 11
By observing the corneal reflection image 11 'of No. 1 by an anterior segment magnifying observation means (not shown), it is possible to know from the disturbance of the reflection image 11' whether or not there is an irregular astigmatism of the cornea to be examined. It is also possible to obtain the amount of irregular astigmatism by detecting this reflected image with the detectors 14 and 15. Further, in the example of FIG. 6, instead of using the anterior segment magnifying observation means, the detectors 14, 1 are used.
5 can also be used as an anterior segment observation means.

[Brief description of drawings]

FIG. 1 is a diagram showing a block diagram of an optical device and an electric system of an apparatus according to the present invention, FIG. 2 is an optical path diagram showing an optical path through which light from an index enters a detector, and FIG. 3 is a detection index image. FIG. 4 is a schematic diagram showing a method of obtaining a center, FIG. 4 is a schematic diagram showing a principle of obtaining a corneal shape, FIG. 5 is an explanatory diagram showing an example of a display system, and FIG. 6 is an explanatory diagram showing another example of the display system. Is. 11 ... Slit index, 16, 17 ... Lens, 14, 25 ... Detector, 20 ... Alignment system, 30 ... Corneal shape detection system.

Claims (2)

[Claims] 1. An index projection means for projecting an annular index onto the cornea of an eye to be inspected, a detection means for photoelectrically detecting reflection images of the index by the cornea from at least two different directions, and the detection means. An alignment device for an ophthalmologic machine, comprising: display means for displaying alignment information based on the positional deviation between the reflection images detected by the above. 2. The alignment apparatus for an ophthalmologic machine according to claim 1, wherein the display means superimposes and displays images of reflection images by the cornea of the index detected by each of the detection means.