JPS6141570B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an eye refractometer.
In particular, the invention relates to an aiming device in an eye refractometer.

Eye refractometers are used to objectively measure the corrected refractive power of the eye to be examined, by projecting a target onto the fundus of the eye through the pupil of the eye to be examined, and measuring the focusing state of the target image formed on the retina of the eye to be examined. The refractive power of the eye to be examined is measured as the necessary corrective refractive power based on the position of the target when the target image is clearly formed on the retina. During this measurement, a aiming optical system is provided in order to properly maintain the distance between the corneal vertex of the eye to be examined and the objective lens, that is, the working distance, and to align the optical axis of the eye to be examined with the measurement optical axis.

This aiming optical system observes the anterior segment of the eye to be examined from a direction forming a fixed angle, usually an angle of 9°, within the same horizontal plane as the measurement optical system, and uses a means such as a split prism to set an objective to the eye to be examined. This allows you to check the proper working distance of the lens. In addition, in order to confirm the alignment of the optical axis, on the premise that an appropriate working distance is maintained,
A method is used in which the index line of the aiming system is aligned with the center of the pupil of the eye to be examined.

In infrared eye refractometers, where aiming and measurement are performed using near-infrared light or infrared light, the resolution of the night vision device is not sufficient, so the split image matching method has a certain degree of error in working distance. is unavoidable. Since the aiming optical system has an angle with respect to the measuring optical system, an error in this working distance causes an alignment error between the optical axis of the eye to be examined and the optical axis of the measuring optical system. This alignment error between the optical axis of the eye to be examined and the optical axis for measurement is undesirable because it causes an error especially in astigmatism measurement due to the aberration of the eyeball optical system. In particular, in an infrared eye refractometer, since the pupil of the eye to be examined is open, a certain degree of deviation between the optical axis of the eye to be examined and the optical axis for measurement will not cause any special abnormality in the target image in the fundus, and alignment errors can be avoided. It cannot be detected during measurement.

If we consider the effects of working distance error and optical axis alignment error on the measurement results, we can see that an error of about 5 mm in working distance, for example, is approximately 5 mm for a 10 day opter.
Approximately for 0.5 day opter and 5 day opter
Although it only appears as a measurement error of 0.12 dayopter, the error in astigmatism measurement due to optical axis alignment error is significant. Therefore, it is particularly desirable to provide an aiming device that can eliminate optical axis alignment errors.

Therefore, the main object of the present invention is to provide an aiming device for an eye refractometer that can align the optical axis of the eye to be examined and the measurement optical axis with sufficient accuracy.

It is best to perform the measurement along the optical axis of the eye to be examined and the optical axis of the measurement. For this purpose, a half mirror may be placed on the measurement optical axis, and an aiming optical system may be placed on the reflection optical axis of this half mirror. However, placing a half mirror in the measurement optical system in this way leads to a loss of light intensity, and especially in the case of an infrared eye refractometer, there is not enough light capacity for both the measurement optical system and the aiming optical system, so this is not practical. It is not possible to adopt a suitable arrangement.

Therefore, in the present invention, in order to reliably eliminate the alignment error of the optical axis without using means such as a half mirror, the optical axis of the measuring optical system and the aiming optical system are An index projection device is provided that projects an index line onto the anterior segment of the subject's eye in a plane that is substantially orthogonal to the subject's eye, and the aiming optical system is provided with an index line that extends in a direction that is approximately orthogonal to the index line of the index projection device. The alignment of the optical axis is confirmed by the relative position of the eye to the subject's eye. In other words, if the index projection device is installed in a vertical plane that includes the optical axis of the measurement optical system and projects a vertical index, the optical axis will be horizontal depending on the relative position of this index and the iris of the eye to be examined. A directional alignment is obtained, and a horizontal index provided on the aiming optics provides a vertical alignment of the optical axis.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The infrared eye refractometer shown in the figure is
It has a measurement optical system A, a projection optical system B, an aiming optical system C, and an index projection system D, and the measurement optical system A includes an image rotator 4 having a known configuration consisting of an objective lens 1, a triangular prism 2, and a plane mirror 3; It has a perforated prism 5 and an imaging lens 6, and light passing through the imaging lens 6 forms an image on the photocathode of an imaging tube 7. The projection optical system B has a near-infrared light source 8, a condenser lens 9, a target plate 10, and a projection lens 11. It is reflected along the image rotator 4 and the objective lens 1, and is projected onto the eye E to be examined, forming a target image on the fundus of the eye. The light from the target image in the fundus of the eye is
The light enters the measuring optical system A through the pupil of the eye E to be examined, forms an image on the photocathode of the image pickup tube 7, and a target image is displayed on the television 13 as a visible image.

The aiming optical system C has an optical axis 15 that is in the same horizontal plane as the optical axis 12 of the measurement optical system A and intersects with the optical axis 12 at a point 14 in front of the objective lens 1. At the rear of the objective lens 1, there is a lens 16, a split prism 17, and a lens 1.
8, 19, an aperture plate 20, and an imaging lens 21 are arranged, and the light passing through the lens 21 forms an image on the photocathode of the imaging tube 22.

The index projection system D has an optical axis 23 that lies in the same vertical plane as the optical axis 12 of the measurement optical system A and intersects the optical axis 12 at a point 14, and includes a near-infrared light source 24,
It has a condenser lens 25, an index plate 26, a reflection mirror 27, and projection lenses 28 and 29. On the index plate 26, index lines, in this example, two parallel lines symmetrical with the optical axis in between, are drawn, and these index lines are examined as two vertical dark lines as shown in FIG. 4a. Projected to the anterior segment of the eye.

In the aiming optical system C, two horizontal index lines as shown in FIG. 4b are drawn symmetrically with respect to the optical axis at appropriate positions, for example, on the focal plane of the split prism 17. Therefore, when using this eye refractometer, first adjust the working distance between the eye E and the objective lens 1 so that the split images of the anterior segment of the eye obtained by the split prism match. Then, move the device horizontally to position it so that the two dark lines projected onto the anterior segment of the subject's eye sandwich the iris of the subject's eye, then move the device vertically to position the aiming optical system. The two horizontal index lines are positioned so that they sandwich the iris of the eye to be examined. Thereby, the optical axis 12 of the measurement optical system A can be accurately matched with the optical axis of the eye E to be examined.

As described above, in the present invention, an index line is projected onto the anterior segment of the subject's eye in a plane that is substantially orthogonal to a plane including the optical axis of the measurement optical system and the optical axis of the aiming optical system, and Since the system is equipped with index lines that run in a direction approximately perpendicular to this projection index line, by determining the positional relationship between these index lines and a suitable part of the anterior segment of the subject's eye, such as the iris, the optical axis of the measurement optical system can be adjusted. It is possible to accurately obtain alignment between the eye and the optical axis of the eye to be examined. Further, this means for alignment does not involve loss of light quantity in the measurement and aiming optical system, and can be applied to an infrared eye refractometer with a small margin of light quantity to obtain a great effect.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view of the optical system arrangement of an infrared eye refractometer showing an embodiment of the present invention, Fig. 2 is a plan view of the optical system, Fig. 3 is a side view, and Fig. 4 a is a projection of an index. FIG. 4b is a diagram showing an example of an index projected by the system, and FIG. 4b is a diagram showing an example of an index provided in the aiming optical system. A...Measurement optical system, B...Projection optical system, C...
Aiming optical system, D... Index projection system, 1... Objective lens, 5... Perforated prism, 7, 22... Image pickup tube, 10... Target plate, 17... Split prism, 26... Index plate .

Claims (1)

[Scope of Claims] 1. A projection optical system for projecting a target through the pupil of the eye to be examined, and a measurement optical system for measuring the in-focus state of the target image formed on the retina of the eye to be examined through the pupil of the eye to be examined. and an aiming optical system that has an optical axis that intersects with the optical axis of the measurement optical system and determines the alignment between the optical axis of the eye to be examined and the optical axis of the measurement optical system using corneal reflected light, An index projection device is provided that projects an index line onto the anterior segment of the subject's eye in a plane substantially orthogonal to a plane including the optical axis of the measurement optical system and the optical axis of the aiming optical system, and the aiming optical system An aiming device characterized by having an index line in a direction substantially perpendicular to the index line of the index projection device. 2. In the above item 1, the projection of the target and the index is performed using infrared light, and the measurement optical system and the aiming optical system have a night vision device for observing the image using the infrared light. aiming device. 3. In the first or second paragraph, each of the index line of the index projection device and the index line of the aiming optical system is arranged symmetrically with respect to the respective optical axis.
An aiming device that consists of two lines that intersect with each other, and aims by inserting the iris of the subject's eye between two lines that intersect with each other. 4. In any one of Items 1 to 3 above, the aiming optical system is arranged laterally in a horizontal plane with respect to the measuring optical system, and the index projection device is arranged vertically downward. Aiming device.