JPS584530A - Position aligning apparatus for ophthalmic device - 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 a device for alignment.

In ophthalmological measurement instruments such as refractometers and ophthalmometers, it is necessary to accurately align the eye to be examined and the measurement device in order to improve measurement accuracy, and various devices for this purpose have been proposed. A simple device is known in which a pattern is projected onto the eye to be examined and the image of this pattern is observed by the cornea of the eye to be examined, but accurate alignment is difficult when the surroundings of the eye to be examined are dark. In addition, automatic tracking devices that photoelectrically detect the movement of the subject's eye and automatically track the measurement device, and devices that use infrared rays are known.
These devices have complicated and large-scale configurations, which is disadvantageous for making the entire measuring device compact. Therefore,
A simple and compact alignment device that can perform accurate alignment even when the surroundings of the eye to be examined is dark was developed in 1982.
It is known as No. 131703.

That is, this device includes a projection means for projecting a predetermined projection pattern onto the eye to be examined, an objective lens for observing the reflected image of the projection pattern on the cornea of the eye to be examined, and a predetermined position on the image side of the objective lens. a field stop provided near the objective lens, a light shielding member having two openings outside the optical axis of the objective lens; a reference chart board having a reference chart for positioning on the optical axis extension line of the objective lens; a reference chart board having a reference chart for positioning on the optical axis extension line of the objective lens; and a projection lens for projecting onto the field stop position.

However, when trying to improve the sensitivity of alignment with this device, increasing the distance between the apertures of the light shielding member will result in a shallower depth of focus (which will increase the sensitivity); Increasing the distance requires increasing the diameter of the objective lens, which is not desirable from the perspective of lens aberration.

The purpose of the present invention is to provide a simple and compact design that allows accurate alignment even when the surroundings of the eye to be examined are dark, and that increases alignment sensitivity while maintaining good aberrations without increasing the aperture of the objective lens. An object of the present invention is to provide an alignment device.

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a side view showing a schematic configuration of an embodiment in which the alignment device according to the present invention is used in an eye refractive power measuring device. It is installed in one piece. The optical path of the alignment device is branched from the optical path of the measuring device 2 by a beam splitter 11. This eye refractive power measuring device is based on the so-called horizontal method, and is described in detail in, for example, Japanese Patent Application Laid-Open No. 5E-I Jl 703 (1983), so a brief explanation will be given here.

The transmission optical axis width of the beam splitter 11 includes an image rotation prism 21 and the beam splitter 22, and the transmission optical path width of the beam splitter 22 includes an objective lens 23 and an aperture 24.
, and a light receiving member 25 is arranged. On the other hand, in the reflected optical path of the beam splitter 22, a rotating drum 28 having a slit-shaped opening, a projection lens 27 inside the rotating drum 28, and a point light source 26 that emits infrared rays are arranged. Therefore, the light beam from the point light source 26 is transmitted through the projection lens 21 to the slit of the rotating drum 28 and the beam splitter 22.
, the image rotation prism 21, and the beam splitter 11 to reach the eye EI.

Since the rotating drum 28 is rotated at a constant speed by a drive device (not shown), the rotation of the rotating drum 28 causes a linear light beam to scan the pupil of the eye E1 to be examined. As shown in the plan view of FIG. 2, the light receiving member 25 includes two light receiving elements 2 outside the optical axis.
51 and 252 are provided 5, by which the movement of reflected light from the fundus of the eye to be examined is observed. That is, depending on the refractive power of the eye E and the refractive power of the lens 23, whether the fundus of the eye E1 to be examined and the aperture 24 are conjugate or not, and if they are not conjugate, the amount of deviation is determined by the output of the two light receiving elements. This is obtained as a phase difference between the signals. For example, if the lens 23 is movable along the optical axis, the position of the lens 23 where the phase difference between the output signals of the two light-receiving elements becomes zero is the eye to be examined E.
1, and the above phase difference directly corresponds to the refractive power of the eye E. Therefore,
The refractive power of the eye E can be measured using these signals. However, as a prerequisite for this, the eye E to be examined and the eye refractive power measuring device must be accurately aligned.

Next, the alignment device 1 will be explained with reference to the plan view shown in FIG. Note that the beam splitters 11 and -7 and the reflecting mirror 12 shown in FIG. 1 are shown by broken lines in FIG. 3 for simplicity. Both of the two green filters 31a and 31b have a translucent part with only a crosshair as shown in FIG.
The green cross line is the projection pattern to the measuring device 20.
It is projected from a direction symmetrical to the optical axis O7. A virtual image of this crosshair pattern is formed by the cornea of the eye to be examined, and this virtual image is formed by a pair of first objective lenses 33 arranged symmetrically about the optical axis O8.
a, 33b and a pair of reflecting mirrors 34a.

Reflection surface Ra corresponding to each optical path of 34b.

A real image is formed at the position of the field stop 15 by the prism 35 having Rh and the second objective lens 14 . The second objective lens 14 is fixed so that its optical axis 02 is at the same position as the optical axis 01 of the measuring device 2, that is, in FIG. 3, it overlaps with the optical axis 01. Between the prism 35 and the second objective lens 14, as shown in FIG.
A reflecting mirror 37 is provided obliquely on the optical axis of the second objective lens 14 adjacent to the central light-shielding portion of the light-shielding diaphragm 36 . Chart board 3 illuminated by light source 38
As shown in FIG. 6, 9 is provided with light-transmitting portions of a cross chart 39a and a small circle chart 39b as alignment reference charts. It passes through the chart board 39 and the reflecting mirror 4
The light beam reflected at 0 passes through the projection lens 41 and reaches the reflecting mirror 3.
After being reflected by T and passing through the second objective lens 14, a cross chart 398 and a small circle chart 39b are placed at the field stop 15.
form an image of The center of the image of this cross chart is the second
It is precisely aligned with the optical axis of the objective lens 14. Therefore, at the position of the field stop 15, in addition to the two images of the crosshair pattern 31 & on the green filter 31, images of the cross chart 39a and the small circle chart 39b on the chart board 39 are formed at the center of the field of view. Ru. The examiner E2 observes these through the eyepiece 16.

Here, the two light beams forming the image of the crosshair pattern of the pair of green filters 318° 31b are the pair of first objective lenses 13a.

13b, a pair of reflecting mirrors 34a, 34b, prism 35
Since the crosshair patterns pass through a portion off the optical axis of the second objective lens 14 by the light-shielding diaphragm 36, when the entire apparatus is not located at a predetermined distance from the subject's eye, each pair of crosshair patterns always becomes a double image ( Each crosshair pattern 31a.

It is well known that the distance adjustment is performed by matching the double images (two images of each, that is, a total of four images) in the image forming apparatus 31b. When the distance adjustment is completed, the positional relationship between the images observed by the examiner E2 is usually as shown in FIG. 7, which is the image 39a', 39b' of the cross chart 39a and the small circle chart 39b, which serve as the reference chart for positioning. For,
The entire apparatus is moved left and right and up and down so that the images 31a' and 31b' of the crosshair pattern on the green filters 31a and 3Ib are positioned symmetrically with respect to the image 39a' of the cross chart, and each image is moved as shown in FIG. If the position of the eye is established, the alignment of the device 3 with respect to the eye to be examined is completed. In the observation field, the two crosshair 1<turn images 31a' and 31b' are green, and the cross chart image 39a' and the small circle chart image 39b' are white, so it is easy to distinguish between them. Extremely accurate positioning is possible because it is determined whether the three crosses are aligned in a straight line or not and whether the intervals between the crosshairs are symmetrical.

In this example, a pair of green filters and illumination light sources were provided on both sides of the optical axis of the second objective lens 14, and two crosshair patterns were projected onto the eye E, but only one crosshair pattern was projected. Alignment is possible even if it is made as follows. In this case, there is no image 31b' in FIG. 8, for example. In this case, the cross-hair pattern image 31a' is displayed on the chart board 39 in the completed positioning state.
By creating a new chart that matches the above, accurate positioning can be achieved. Of course, the image 398' of the cross chart 39a is the aligned green filter 31a.
The chart 39 overlaps with the image 31a' of the cross chart.
A may be formed eccentrically in advance.

Further, in the above embodiment, the first objective lenses 33a and 33b
and the second objective lens 14, but it is of course possible to use only one objective lens, and the light-shielding aperture 36
The reflecting mirror 31 obliquely installed adjacent to this may be placed in front of or behind the second objective lens 14 (as long as it is in the vicinity). It goes without saying that various images can be observed more easily by providing a screen at the position of the field stop 15.In this case as well, the periphery of the screen covers the substantial field of view. It functions as an aperture.

As described above, according to the present invention, although the configuration is simple,
A compact positioning device has been obtained that allows accurate positioning even when the surroundings of the subject's eye are dark, and that the objective lens does not require a large aperture, increasing sensitivity while maintaining good aberrations.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of an embodiment of the present invention used in an eye refractive power measuring device, FIG. 2 is a plan view of a light receiving member in the eye refractive power measuring device, and FIG. 3 is the same as that in FIG. A plan view of the embodiment, FIG. 4 is a plan view of the green filter in the embodiment of FIG. 3, FIG. 5 is a plan view of the light-shielding diaphragm in the embodiment of FIG. 3, and FIGS. FIG. 7 is a diagram showing the positional relationship of each image observed by the examiner when distance adjustment of the entire device is completed, and FIG. 8 is a diagram showing the positioning device and eye refractive power for the eye to be examined. FIG. 6 is a diagram showing the positional relationship of each image observed by the examiner when alignment of the measuring device is completed. [Explanation of symbols of main mold parts] Projection means-31a, 31b, 32a, 32b first
Objective lens... 33a, 33b second objective lens...
...14 Field stop...15 First reflective member...34a, 34b Second reflective member...35 Light shielding member...36 Third reflective member...37 Reference chart board... 39 Projection lens...41

Claims (1)

[Claims] a projection means for projecting a predetermined projection pattern onto the eye to be examined; and observing a reflected image of the projection pattern by the cornea of the eye to be examined;
The first and second objective lenses include a pair of objective lenses provided symmetrically with respect to the optical axis of the latter, a field stop provided at a predetermined position on the image side of the objective lens, and the first objective lens. a pair of first reflecting members provided symmetrically with respect to the optical axis to reflect the light flux from the first objective lens in the direction of the optical axis of the second objective lens; a second reflecting member provided on the optical axis for reflecting in a direction substantially along the optical axis of the second objective lens and toward the image side; and a second reflecting member near the second objective lens and the second reflecting member. a light shielding member provided on the image side of the member and having two openings outside the optical axis of the second objective lens; and a light shielding member at the center of the light shielding member and on the optical axis of the second objective lens. a third reflective member diagonally arranged substantially adjacent to each other; a reference chart plate having an alignment reference chart on the optical axis extension line of the second objective lens; and a projection lens that projects onto the optical axis of the second objective lens and onto the field stop position through the projection lens.