JP3452388B2 - Ophthalmic instruments - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment light projecting optical system which guides a cornea of an eye to be inspected, receives the reflected alignment light reflected by the cornea, and forms a light beam on the cornea. The present invention relates to an ophthalmic instrument provided with an alignment detection optical system that detects an alignment state with an apparatus main body. 2. Description of the Related Art Conventionally, as an ophthalmic instrument, detection of alignment of the apparatus main body with respect to an eye to be examined in the vertical and horizontal directions (detection of alignment in the XY directions) and detection of an appropriate working distance of the apparatus main body with respect to the eye to be inspected (alignment in the Z direction). Non-contact type tonometer provided with an alignment detection optical system for performing the above-mentioned detection. In this non-contact tonometer, an alignment operation is performed while observing the anterior segment of the subject's eye with a monitor, an eyepiece, or the like. The light receiving position of the detector is located within the allowable range and the light receiving amount exceeds the reference value, whereby the air pulse emitting means is driven to start emitting the air pulse to the cornea. In this conventional non-contact tonometer, deviation in the XY direction has a greater effect on the measurement accuracy of the tonometer than deviation in the Z direction. The deviation in the Z direction greatly affects the measurement accuracy of the tonometer. In consideration of this, the detection magnification of the alignment detection optical system is set to a high magnification in order to narrow the allowable range in the Z direction, and an aperture is installed immediately before the detector.
If the working distance to the main unit is slightly out of order,
The amount of light incident on the detector can be greatly changed with a small deviation from the proper working distance by greatly changing the image and restricting the alignment reflected light beam incident on the detector by the aperture. However, in the case of an ophthalmic instrument such as this non-contact tonometer, the measurement accuracy cannot be guaranteed unless the detection of the alignment of the apparatus body with the eye in the XY directions is strictly performed. However, if the detection magnification of the alignment detection optical system is increased, it is possible to avoid deviation in the Z direction due to the difference in the reflectance of the cornea, but the deviation in the alignment accuracy in the XY directions increases, and as a result, the measurement accuracy is further guaranteed. It will not be done. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to maintain the alignment accuracy of the apparatus main body with respect to the eye to be examined in the vertical and horizontal directions, and reduce the working distance detection accuracy due to the variation in reflectance of the eye. It is an object to provide an ophthalmic instrument that can be avoided. [0008] In order to achieve the object, the present invention, by receiving alignment reflected light from the cornea of the eye to be inspected, to determine the working distance between the eye to be inspected and the main body of the apparatus and the distance to the eye to be inspected. The alignment detection optical system for detecting the alignment state in the vertical and horizontal directions of the apparatus main body is composed of an optical system for detecting the working distance and an optical system for detecting the vertical and horizontal directions, and the detection magnification of the optical system for detecting the working distance is The gist of the present invention is that the magnification is higher than the detection magnification of the optical system for vertical and horizontal detection. In such a configuration, the alignment detecting optical system for receiving the alignment reflected light from the cornea of the eye to be inspected is composed of the working distance detecting optical system and the upper, lower, left and right direction detecting optical systems. The working distance from the subject's eye to the device body is detected by the working distance detecting optical system with a high magnification, and the alignment state of the device body with respect to the subject's eye in the up, down, left, and right directions is detected by the vertical, left, and right detecting optical system with a low detection magnification. . Next, an embodiment of an ophthalmic instrument according to the present invention will be described with reference to FIGS. FIGS. 1 to 3 show an embodiment of an ophthalmologic instrument according to the present invention. FIG. 1 is an explanatory view of an optical system in an observation state of an eye to be inspected.
FIG. 3 is an explanatory diagram of an optical system in an alignment detection state, and FIG. 3 is an explanatory diagram of an optical system in an intraocular pressure measurement state. 1 to 3, reference numeral 10 denotes a fixation target projecting optical system for projecting a fixation target for fixation onto the eye E, and reference numeral 20 denotes an anterior eye part for observing an anterior eye image including the eye E. Observation optics,
Reference numeral 30 denotes an alignment light projection optical system for projecting an alignment light beam onto the eye E to be inspected, and reference numeral 40 denotes an alignment observation optical system for observing a state of alignment between the visual axis O ′ of the eye E and the optical axis O of the anterior eye observation optical system 20. , 50 are the visual axis O ′ of the eye E and the device book
An optical system for vertical and horizontal detection (hereinafter, abbreviated as “first detection system”) for detecting the alignment with the optical axis O of the body , and 60 is the eye E
Working distance detecting optical system for detecting the operating distance of the alignment of the apparatus body relative (hereinafter, referred to as "second detection system".), 70
Reference numeral denotes a detection light receiving optical system that receives reflection of the corneal deformation detection light. The fixation target projection optical system 10 includes an LED 11 for emitting visible light, an aperture stop 12, a wavelength division filter 13 for transmitting visible light and reflecting near-infrared light, a collimator lens 14, a stop 15, and a half mirror. 16, a chamber window 17, and a spray nozzle 18. The chamber window 17 is a frame surrounding a supply device (for example, a cylinder member) for supplying an air pulse to the injection nozzle 18. As shown in FIG. 2, the visible light emitted from the LED 11 and passing through the aperture stop 12 and the wavelength division filter 13 is converted into a parallel light beam by the collimator lens 14, After being reflected by the half mirror 16 in the state of being
, And a diaphragm image is presented to the cornea C of the eye E through the inside of the ejection nozzle 18. The visible light reflected by the cornea C is set so that it is reflected by the objective lens 11 and is not guided to an optical member thereafter. The anterior eye observation optical system 20 includes an LED 2 for emitting infrared light for directly illuminating the eye E to be examined from the left and right.
1. a cover glass 22 fixed to the tip of the spray nozzle 18;
An objective lens 19 for reflecting visible light, a chamber window 17,
Half mirror 16, half mirror 23, total reflection mirror 2
4, a first imaging lens 25, a second imaging lens 26, a total reflection mirror 27, a half mirror 28, and a CCD camera 29. The infrared reflected light from the LED 21 reflected by the eye E passes through the cover glass 22 and passes through the objective lens 1.
9, the light is converted into a parallel light beam, transmitted through the chamber window 17 and the half mirror 16, reflected by the half mirror 23, reflected by the total reflection mirror 24, and further reflected by the first and second mirrors.
The light is condensed by the imaging lenses 25 and 26, and forms an image on a CCD camera 29 via a total reflection mirror 27 and a half mirror 28. When the distance between the main body of the apparatus and the cornea C is large, the second imaging lens 26 is moved in the direction of arrow A by a known means to perform focusing. The alignment light projection optical system 30 has an LED 31 for emitting near-infrared light, an aperture stop 32, a wavelength division filter 13, a collimator lens 14, a stop 15, a half mirror 16, a chamber window 17, and an injection nozzle 18. The near-infrared light emitted from the LED 31 passes through an aperture stop 32 and is reflected by a wavelength division filter 13 as shown in FIG. After being reflected by the half mirror 16 in the state described above, the light passes through the chamber window 17 and further passes through the inside of the ejection nozzle 18 to be examined.
And is reflected by this cornea C. The alignment observation optical system 40 includes a cover glass 22, an objective lens 19, a chamber window 17, a half mirror 16, a half mirror 23, a half mirror 41 inclined in a direction intersecting the half mirror 23, an imaging lens 42, A half mirror 28 and a CCD camera 29 are provided. The alignment reflected light beam reflected by the cornea C passes through the cover glass 22 and is converted into a parallel light beam by the objective lens 19, and the chamber window 17 and the half mirror 1
6. After being transmitted through the half mirror 23 and the half mirror 41 and guided to the image forming lens 42 and condensed by the image forming lens 42, the light is transmitted through the half mirror 28 and imaged on the CCD camera 29. The first detection system 50 has a low magnification (less than × 1.0).
Are used for monitoring the alignment between the visual axis O ′ and the optical axis O, and share the respective optical members of the alignment observation optical system 40 from the cover glass 22 to the half mirror 41.
Half mirror 5 provided with total reflection mirror 51a at the center
1, a half mirror 52, an imaging lens 53, an aperture 54, and a light receiving sensor 55, which are detected by the light receiving sensor 55
Alignment in the vertical and horizontal directions based on the amount of light
Means for detecting a match . The second detection system 60 has a high magnification (× 2.0 or more)
In the same manner as the first detection system 50, each of the optical members of the alignment observation optical system 40 from the cover glass 22 to the half mirror 41 is shared, and the half mirror 51, the half mirror 52 , Imaging lens 61, total reflection mirror 62, aperture 63, light receiving sensor 6
4 based on the amount of light detected by the light receiving sensor 64.
Means for detecting the matching of the working distance . The alignment reflected light beam reflected by the cornea C and guided to the half mirror 41
And is transmitted to the half mirror 52 through the peripheral portion of the half mirror 51. On the other hand, a part of the alignment reflected light beam guided to the half mirror 52 is reflected by the half mirror 52 and guided to the image forming lens 53, and then forms an image on the light receiving sensor 55 through the stop 54. Another part of the alignment reflected light beam guided to the half mirror 52 passes through the half mirror 52 and is guided to the imaging lens 61, is reflected by the total reflection mirror 62, passes through the diaphragm 63, and is received by the light receiving sensor 64. Is imaged. When the light receiving sensors 55 and 64 both determine that the alignment reflected light amount has reached a predetermined light amount or more, the alignment is completed, and based on this light amount detection, an air pulse is emitted from the injection nozzle 18. Inject automatically. Accordingly, the low-magnification first detection system 50 detects the alignment between the visual axis O and the optical axis O ', and the high-magnification second detection system 60 detects the working distance, thereby reflecting the cornea C. Measurement errors due to differences in rates can be reduced. Incidentally, the alignment light projection optical system 30
Each optical member from the LED 31 to the injection nozzle 18 is
As shown in FIG. 3, it functions as a detection light projection optical system that projects corneal deformation detection light toward the cornea C in order to optically detect the deformation of the cornea C due to the ejection of the air pulse from the ejection nozzle 18, Each optical member that guides the light reflected from the cornea C to the half mirror 41 constitutes a part of the detection light receiving optical system 70. A part of the detected reflected light guided from the cornea C, which is applanated by the injection of the air pulse, to the half mirror 41 is reflected toward the half mirror 51, and is reflected to the total reflection mirror 51a of the half mirror 51. The light is reflected and condensed on the image forming lens 71, and forms an image on the light receiving element 73 through the stop 72. In the light receiving element 73, the amount of light received by the light receiving element 73 increases with the start of the deformation of the cornea C. Therefore, based on the increase in the amount of light received due to the deformation of the cornea C, the intraocular pressure is measured according to a known procedure. On the other hand, the other part of the detected reflected light guided to the half mirror 41 is transmitted through the half mirror 41, guided to the image forming lens 42, and formed on the CCD camera 29 via the half mirror 28. The corneal deformation detection light imaged on the CCD camera 29 is displayed on a monitor (not shown) as an anterior segment image of the eye in an applanation state, and the subject can use the image to detect the eye to be examined in the applanation. The state can be confirmed, and it can be objectively confirmed whether or not the obtained intraocular pressure value is reliable. As described above, in the ophthalmologic instrument of the present invention, the alignment detecting optical system is constituted by the working distance detecting optical system and the vertical, horizontal, and lateral direction detecting optical systems. By setting the detection magnification of the distance detection optical system to be higher than the detection magnification of the vertical and horizontal direction detection optical system, the reflectance of the subject's eye varies while maintaining the alignment accuracy of the apparatus body with respect to the subject's eye in the vertical and horizontal directions. Therefore, it is possible to avoid a decrease in working distance detection accuracy due to the above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of an optical system in an eye observation state of an eye to be inspected, showing an ophthalmic instrument of the present invention. FIG. 2 is an explanatory diagram of an optical system in an alignment detection state. FIG. 3 is an explanatory diagram of an optical system in an intraocular pressure measurement state. [Description of Signs] C ... Cornea E ... Eye to be examined 50 ... Optical system 60 for detecting up, down, left and right directions ... Optical system for detecting working distance

Claims (1)

(57) [Claim 1] Alignment of the apparatus main body with respect to the working distance from the eye to be inspected to the apparatus main body and the eye by receiving alignment reflected light from the cornea of the eye to be inspected. The alignment detection optical system for detecting the state and the optical system for working distance detection and the optical system for vertical and horizontal detection, and the detection magnification of the optical system for working distance detection is the optical system for vertical and horizontal detection The magnification is higher than the detection magnification, and the working distance detecting optical system adjusts the working distance.
Means for detecting a combination, and the optical system for detecting up, down, left, right
Detecting the alignment of the alignment state in the vertical and horizontal directions
Ophthalmic instrument which is characterized that you have the means.