JPH03173526A - Ophthalmic device - Google Patents

Abstract

PURPOSE:To enable detecting the position of a subject eye with simple constitution by projecting a light beam to the cornea of the subject eye from a direction inclined relative to an optical axis and receiving a beam reflected at the cornea with a photoelectric sensor via a spot opening. CONSTITUTION:An illuminant 2 and a projection diaphragm 3 are arranged on an optical axis P1 forming an angle of theta with the optical axis P0 of a measurement optical system 1 opposing a subject eye E, and a small spot opening 4 is positioned at an optical axis P2 forming an angle of theta with the optical axis P0 on the same plane as the optical axes P0 and P1. A circular photoelectric sensor 5 comprising a single element is provided at a certain distance from the spot opening 4. A light beam emitted from the illuminant 2 passes through the projection diaphragm 3 and is projected to the cornea Ec of the subject eye E. The beam reflected at the cornea advances along the optical axis 2 and is received by the photoelectric sensor 5 via the spot opening 4, when the subject eye E is at the predetermined position. If the subject eye E is off the predetermined position in the direction of the optical axis P0 or in a direction perpendicular thereto, the beam reflected at the cornea does not pass the spot opening 4. It is possible, therefore, to detect whether the subject eye E is at the predetermined position on the basis of the light receiving amount of the photoelectric sensor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ophthalmological apparatus equipped with an optical system for detecting the position of an eye to be examined.

[Prior Art] Conventionally, the alignment of an ophthalmological apparatus with respect to the eye to be examined in the optical axis direction and its vertical direction has been performed using methods such as those disclosed in Japanese Patent Application Laid-open No. 128937/1983 or Japanese Patent Application Laid-Open No. 58-97340. It is possible to receive the corneal reflected light flux in two directions inclined to the optical axis of the device and use the deviation of the receiving position, or
As disclosed in Japanese Patent No.-6532, etc., a thick corneal reflected light beam is received in the optical axis direction of the device, and the shift or blur of the light receiving position is used.

[Problems to be Solved by the Invention] However, when receiving the corneal reflected image in two directions, the configuration of the light receiving optical system of the ophthalmological device becomes complicated. Design constraints are imposed on ophthalmological devices in order to share optical paths with other optical systems of the device.

An object of the present invention is to provide an ophthalmologic apparatus that is easy to configure and can detect the position of the eye to be examined with almost no design restrictions.

[Means for Solving the Problems] In order to achieve the above object, the ophthalmological apparatus according to the present invention includes a projection optical system that projects a light beam onto the cornea of the eye to be examined from a direction inclined to the optical axis of the apparatus. , a light receiving optical system including a small spot aperture arranged in a direction symmetrical to the direction in which the light beam is projected with respect to the optical axis, and a photoelectric sensor spaced apart from the spot aperture; This method is characterized in that the position of the eye to be examined is detected by the output of a photoelectric sensor.

[Operation] The ophthalmological apparatus having the above-mentioned configuration projects a light beam onto the cornea of the eye to be examined from a direction inclined to the optical axis, and receives the reflected light beam from the cornea with a photoelectric sensor through a spot aperture. Detects the position of

[Example] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows an optical system for detecting the position of the eye to be examined according to the first embodiment, and an optical axis P1 that forms an angle θ with the optical axis PO of the measurement optical system 1 facing the eye E to be examined includes a light source 2 and a light emitting light. A diaphragm 3 is placed facing the eye E, and a small spot aperture 4 is placed on the other optical axis P2, which is on the same plane as the optical axes Po and pi and forms an angle θ with the optical axis PO, and a small spot aperture 4 is placed behind it. A circular photoelectric sensor 5 made of a single element as shown in FIG. 2 is arranged at a constant distance from the spot aperture 4. As shown in FIG.

The light beam emitted from the light source 2 passes through the projection diaphragm 3 and is projected onto the cornea Ec of the eye E, and when the eye E is in a predetermined position, the light beam reflected from the cornea travels on the optical axis P2 and forms a spot. The light passes through the aperture 4 and is received by the photoelectric sensor 5.

When the eye E to be examined deviates from the predetermined position in the direction of the optical axis PO or in a direction perpendicular thereto, the corneal reflected light beam no longer passes through the spot aperture 4. Alternatively, even if a part of the luminous flux passes through the spot aperture 4, it is not received by the photoelectric sensor 5 which is located away from the spot aperture 4. This means that it can be detected based on the amount.

FIG. 2 shows an optical system for detecting the position of the eye E according to another embodiment, in which a light source 2 and a lens 6 are arranged on the optical axis P1, a lens 7 and a small spot aperture 4 are arranged on the optical axis P2. As shown in FIG. 4, a photoelectric sensor 8 composed of four elements 8a to 8d is arranged behind the spot aperture 4 and spaced apart from the spot aperture 4 by a certain distance.

The light beam emitted from the light source 2 is projected onto the cornea Ec via the lens 6, and the corneal reflected light beam is reflected in the direction of the optical axis P2 when the eye E is in a predetermined position, passes through the lens 7, and passes through the spot aperture 4. Each element 8a to 8d of the photoelectric sensor 8 receives light as shown in FIG. The actions of the spot aperture 4 and the photoelectric sensor 8 arranged on the optical axis P2 are the same as in the first embodiment, and the outputs of the four elements 8a to 8d of the photoelectric sensor 8 are equal, and when the output is above a certain level, In this case, it can be determined that the eye E to be examined is at a predetermined position.

The reason why the photoelectric sensor 8 is composed of four elements 8a to 8d is because when the photoelectric sensor is composed of one element as in the first embodiment, the difference in the eye to be examined E is determined by individual differences in corneal reflectance.
This is because there is a risk that the position of the object may be erroneously detected.

[Effects of the Invention] As explained above, the ophthalmological apparatus according to the present invention projects a light beam onto the subject's eye from a direction oblique to the optical axis, and reflects the corneal light beam only in one direction oblique to the optical axis. Since the position of the eye to be examined is detected by receiving light, the configuration is easy.
Furthermore, there are no design restrictions.

[Brief explanation of the drawing]

The drawings show an embodiment of the ophthalmological apparatus according to the present invention, in which FIG. 1 is a configuration diagram of the optical system for detecting the position of the eye to be examined, FIGS. 2 and 4 are front views of the photoelectric sensor, and FIG. 3 is another embodiment. FIG. 5, which is a configuration diagram of an example detection optical system, is an explanatory diagram of a corneal reflection image on a photoelectric sensor. Reference numeral 1 is a measurement optical system, 2 is a light source, 3 is a projection diaphragm, 4 is a spot aperture, 5.8 is a photoelectric sensor, and 6.7 is a lens.

Claims (1)

[Claims] 1. A projection optical system that projects a light beam onto the cornea of the eye to be examined from a direction inclined to the optical axis of the device, and a small aperture spot arranged in a direction symmetrical to the direction in which the light beam is projected with respect to the optical axis. An ophthalmologic apparatus comprising: an aperture; and a light-receiving optical system including a photoelectric sensor spaced apart behind the spot aperture, and detecting the position of the eye to be examined based on the output of the photoelectric sensor.