JP2945092B2 - Eye refractometer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an eye refractometer used in, for example, an ophthalmic clinic.

2. Description of the Related Art Conventionally, a near-infrared light beam is incident on an eye refractometer from an eye-gaze direction of an eye to be examined via an eye refraction value measuring lens facing the eye to be examined, and a light beam reflected by the fundus is detected by a photoelectric sensor. There is known a device that receives light from above and performs refraction value measurement from the light receiving position. In this case, if the reflected light beam on the lens surface is received on the photoelectric sensor, it causes a measurement error.Therefore, a light shielding plate or the like is provided to remove the reflected light beam, or the lens surface is inclined with respect to the line of sight. In order to prevent the reflected light flux on the lens surface from being received by the photoelectric sensor, a device has been proposed.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, it is necessary to provide a light-shielding plate or the like, or it is preferable that aberration is interposed at the time of subjective measurement because the lens surface is inclined with respect to the line of sight. Absent. In addition, when a near-infrared light beam is incident from the line of sight of the eye to be examined, it is perceived as red by the macula, which may disturb and cause discomfort and hinder the measurement. It is not currently done.

SUMMARY OF THE INVENTION An object of the present invention is to provide an eye refractometer capable of removing a reflected light beam from a lens surface with a simple configuration and performing highly accurate measurement, and further not causing the subject to feel troublesome.

[Means for Solving the Problems] In order to achieve the above-mentioned object, in an eye refractometer according to the present invention, an eye refraction value measuring lens facing the eye to be inspected, and a measurement light beam whose center line is A projection optical system for projecting onto the eye to be examined so as to pass through a position decentered with respect to the optical axis of the eye refraction value measurement lens, and the eye refraction value measurement lens that reflects the measurement light beam reflected from the fundus of the eye to be examined. And a light receiving optical system that receives light on a photoelectric sensor via the light receiving element.

[Effect] The eye refractometer having the above-described configuration projects a light beam onto the subject's eye from a direction passing through a position decentered with respect to the optical axis of the lens via an eye refraction value measuring lens, and reflects the light from the fundus. The light beam is received on the photoelectric sensor via the eye refraction value measuring lens, and the refraction value is measured from the light receiving position.

[Example] The present invention will be described in detail based on an illustrated example.

FIG. 1 is a block diagram of an embodiment in which the present invention is applied to an objective ophthalmic refractometer, and emits a near-infrared light beam at a position slightly decentered from the optical axis 01 in the line of sight of the eye E to be examined. Point light source 1
Is located at a conjugate position with the standard fundus, and between the light source 1 and the subject's eye E is a lens 2 from the side close to the light source 1, a stop 3 having a central opening 3a as shown in FIG. A dichroic mirror 5 having a wavelength spectral characteristic of transmitting an infrared light beam and reflecting a visible light beam, and an objective lens 6 are arranged. On the optical axis 02 in the reflection direction of the perforated mirror 4, a third
As shown in the figure, an aperture 7 having six apertures, a lens 8,
As shown in FIG. 4, a separation prism 9 composed of six wedge prisms and a two-dimensional image pickup device 10 such as a CCD are arranged, while the optical axis 03 in the reflection direction of the dichroic mirror 5 is arranged.
A lens 11 movable in a direction along the optical axis 03 and an optotype 12 on which a cross mark is displayed as shown in FIG.

In the measurement of the refraction value, the light beam from the light source 1 travels on the optical path L1 indicated by the alternate long and short dash line in FIG. 1, and the lens 2, the aperture of the stop 3, the perforated mirror 4, the dichroic mirror 5, the objective lens 6
Through the center of the pupil Ep of the eye E to be projected onto the fundus Er. The reflected light flux from the fundus Er returns the same optical path,
After being reflected by the perforated mirror 4, the light is separated from the optical axis 02 by the separation prism 9 via the stop 7 and the lens 8, and six light beams as shown in FIG. A refraction value is calculated from the light beam position.

At the time of measurement, the visible light flux from the cross mark on the optotype 12 travels on the optical axis 03, is reflected by the dichroic mirror 5 via the lens 11, reaches the eye E via the objective lens 6, and The target is presented to E. In this case, by moving the lens 11 in the direction along the optical axis 03, it is possible to change the apparent distance of the optotype 12 and to guide the eye E to the far point.

The subject's eye E fixes the visual target by making the visual line direction coincide with the optical axis 01, but the optical path of the light beam from the light source 1 is fixed.
Since L1 does not coincide with the optical axis 01 which is the direction of the line of sight of the eye E, the eye E does not feel the luminous flux from the light source 1 annoyingly during measurement.

When the light beam from the light source 1 is incident on the objective lens 6, a part of the light beam is reflected by the objective lens 6, but since the light source 1 is arranged slightly eccentric from the optical axis 01, the reflected light beam The optical path L2 is as shown by the two-dot chain line in FIG.
Since it is different from L1, it is possible to prevent the light beam reflected by the objective lens 6 from being received on the image sensor 10.

FIG. 7 is a block diagram of a second embodiment in which the present invention is applied to a subjective and objective eye refractometer, and the same reference numerals as those in FIG. 1 denote the same members. A visual target 13 is provided far away from the apparatus for presentation to the subject's eye E. Dichroic mirror 14 that reflects near-infrared light at the same time, a subjective measurement lens that can be inserted and removed from the optical axis 04
15 are located. On the optical axis 05 slightly deviated from the direction in which the light beam is reflected by the dichroic mirror 14, a lens 16a and a small mirror 16b are provided. The optical member 16, the lens 17, and the imaging device 10 having such a prism action are arranged, and the lens 18 and the light source 1 are arranged on the optical axis 06 in the reflection direction of the small mirror 16b.

The visible light flux from the target 13 travels on the optical axis 04, and is presented to the eye E through the dichroic mirror 14 and the subjective measurement lens 15. In this state, the examiner exchanges the subjective measurement lens 15 so as to be suitable for the eye E, and performs the subjective refraction value measurement.

When performing an objective refraction value measurement, the light source 1 is turned on, and the light beam from the light source 1 is reflected by the small mirror 16b via the lens 18 and travels along the optical axis 05, and after passing through the lens 16a, the dichroic mirror 14 And reaches the eye E through the subjective measurement lens 15. The light flux reflected by the fundus Er returns along the same optical path, passes through the optical optical member 16 and the lens 17,
A light beam is projected on the upper surface, and a refraction value is measured from the positional relationship.

As in the first embodiment, a part of the light beam from the light source 1 is reflected when the light beam is incident on the subjective measurement lens 15,
The light flux from the light source 1 is slightly deviated from the optical axis 04 and enters the subjective measurement lens 15. Therefore, the subjective measurement lens 15
The reflected luminous flux does not return to the light source 1 in exactly the same way, and is not received on the image sensor 10. In addition, the subject's eye E
It does not give any discomfort that it is bothersome.

Note that the method of measuring the refraction value is not limited to the above-described embodiment as long as it uses a near-infrared light beam.

[Effects of the Invention] As described above, the eye refractometer according to the present invention transmits a luminous flux through a lens that is eccentric to the optical axis of an eye refraction value measurement lens facing the subject's eye through the lens. The configuration is simple because the projection light beam reflected by the lens is received on the photoelectric sensor by projecting it to the subject's eye and receiving the reflected light beam from the fundus on the photoelectric sensor via the lens and measuring the refraction value. The measurement accuracy is improved, and the luminous flux is incident from a direction passing through a position decentered with respect to the line of sight of the eye to be inspected.

[Brief description of the drawings]

The drawings show an embodiment of an eye refractometer according to the present invention. FIG. 1 is a block diagram of the first embodiment, FIGS. 2, 3 are front views of a diaphragm, and FIG. 4 is a front view of a separation prism. FIG. 5 is a front view of the optotype, FIG. 6 is an explanatory view of the reflected light beam on the image sensor, and FIG. 7 is a configuration diagram of the second embodiment. Reference numeral 1 is a light source, 3 is a stop, 4 is a perforated mirror, 5 and 14 are dichroic mirrors, 6 is an objective lens, 10 is an image sensor, 12 and 13 are targets, and 15 is a subjective measurement lens.

Claims (2)

(57) [Claims] A lens for measuring an eye refraction value directly facing an eye to be inspected, and a measurement light beam is applied to an eye to be inspected such that a center line thereof passes through a position decentered with respect to an optical axis of the lens for measuring an eye refraction value. An eye refractometer comprising: a projection optical system for projecting; and a light receiving optical system for receiving a reflected light beam of the measurement light beam from the fundus of the eye to be examined on a photoelectric sensor via the lens for measuring an eye refraction value. 2. The eye refractometer according to claim 1, wherein the lens for measuring an eye refraction value is a lens for measuring objective or subjective refraction.