Continuous variable optometry optical system and portable subjective optometry

Abstract

The application discloses a continuous zooming optometry optical system, which comprises a negative spherical thin lens L1, a positive spherical thin lens L2 and a negative spherical thin lens L3 arranged in sequence on the same optical axis, the negative spherical thin lens L1 is arranged along the optical axis, the optical center of the negative spherical thin lens L3 is located at the image-side focal point of the positive spherical thin lens L2, the optical power of the negative spherical thin lens L1 is the optical power of the positive spherical thin lens L2 is the optical power of the negative spherical thin lens L3 satisfies the following relationship, and the application further discloses a portable subjective optometry instrument comprising the continuous zooming optometry optical system. The application can accurately simulate the optometry process of the plug-in sheet optometry, the optometry process is fast, the optometry result is accurate, and the optometry and lens matching time can be greatly shortened.

Description

Technical Field

[0001] This invention relates to an optometry optical system and an optometer, and particularly to a portable continuous optical zoom subjective optometer. Background Technology

[0002] Refractive errors of the eye (myopia, hyperopia, astigmatism, presbyopia, anisometropia) are common eye diseases, all characterized by decreased vision and blurred vision, affecting daily life, work, and study. Currently, the best and most widely accepted method for correcting refractive errors is wearing eyeglasses. Therefore, it is essential to examine the eye with the refractive error using a specialized optometry instrument to determine the nature and degree of the error, and to use the examination results to guide the prescription of eyeglasses.

[0003] A subjective refractometer is an refractometer based on the subjective refraction method. It uses a series of corrective lenses and, with the cooperation of the test subject, prescribes glasses based on the test subject's subjective feeling of visual improvement, making the test subject feel that they can see clearly, accurately, comfortably, and for a long time.

[0004] Common subjective refraction devices mainly include trial lens refraction equipment and comprehensive refraction equipment. Trial lens refraction equipment mainly includes a trial lens box and a visual acuity chart. During the refraction, the visual acuity chart is placed five meters in front of the eye being tested, the pupil of the eye being tested is kept in a natural state (without dilation), and a trial frame is worn. The trial lens is inserted into the trial frame, which ensures that the distance between the trial lens and the apex of the cornea of ​​the eye being tested is equal to the generally accepted distance between the eyes when wearing eyeglasses. The trial lens is added or removed, and the most suitable lens is determined based on the improvement of the subject's vision while observing the visual acuity chart. This refraction method has simple equipment, is easy to operate, and provides accurate and reliable results. It is also an indispensable final step in the prescription process after obtaining results from all other refraction devices, making it irreplaceable. Its disadvantages are that manual lens changing during the refraction process is cumbersome, requires an experienced optometrist, and is time-consuming and inefficient.

[0005] A comprehensive phoropter is an ophthalmic instrument that integrates refractive error examination and visual function examination. It houses almost all trial lenses in a single rotating system, making lens selection quick and easy by simply rotating the system's wheels. However, the accuracy of the refraction is susceptible to several factors: the instrument's large size can induce near-sensitivity accommodation in the patient; the instrument's shape and design limit the eye-to-lens distance and the patient's head position during the refraction process; fine-tuning astigmatism and axis using cross-cylinder lenses is cumbersome and time-consuming, requiring repeated question-and-answer communication between the optometrist and the patient, slowing down the refraction process and reducing accuracy. Therefore, the test results still need to be reviewed and adjusted using trial lenses, and the final result of the trial lens refraction is used as the prescription for glasses. Furthermore, the instrument is expensive, complex in structure, inconvenient to move, and requires an experienced optometrist to operate.

[0006] Additionally, Chinese invention patent application number 201310207478.7, entitled "A Subjective Optometrist and Optometry Method," discloses a method for obtaining the spherical and cylindrical power of the tested eye by observing the clarity of a target. Chinese invention patent application number 201610094759.X, entitled "A Subjective Optometrist Device and Subjective Optometry Method," discloses a method to address the low accuracy of refraction results caused by the inaccurate judgment of clarity versus blurriness when observing a target in the aforementioned optometrists. These two types of refractometers are actually improvements on the optotype of the BaDa refractometer, which consists of a single refractive lens and a movable optotype. They add the function of measuring astigmatism and a reference object. However, since these improvements cannot change the objective existence of the depth of field (focal depth) of the refractive lens, nor can they effectively control the accommodation produced by the test subject (i.e., the test subject will almost always produce accommodation when the optotype is near), and the change in the position of the optotype causes changes in the convergence and divergence of the light from the optotype, which also changes the accommodation stimulation of the test subject's eye, the measurement accuracy will not be improved.

[0007] Ji Minsheng, Dai Zhixia. Design Principles and Clinical Applications of Optometrists. Journal of Huazhong University of Science and Technology (Medical Edition), 1978. This paper introduces a subjective optometry system. The spherical optical system of this system is a simple Galilean telescope. The composite focal length (diopter) of the entire spherical optical system is changed by altering the position of the telescope's objective lens. The system is simple, compact, and portable. However, because changing the objective lens position not only changes the composite focal length (diopter), but also the positions of the object-side principal point and image-side principal point of the composite system, the composite system cannot function as a thin lens, nor can it maintain the universally accepted lens-to-eye distance required for lens fitting between the posterior principal point and the corneal apex of the tested eye. This does not meet the basic conditions for optometry and lens fitting, resulting in significant measurement errors.

[0008] In summary, the results obtained by existing subjective refractometers, except for those with insert lenses, can only provide initial data for eyeglass prescription. All of these results must be reviewed and adjusted by insert lenses, and the final adjustment result of the insert lenses should be used as the prescription for eyeglasses. Summary of the Invention

[0009] To address the shortcomings of the existing technology, this invention provides a continuous zoom refraction optical system and a portable subjective refractometer, overcoming the problems that existing subjective refractometers either measure accurately but not quickly, or measure quickly but not accurately, and that a single refractometer cannot obtain refraction measurement results quickly and accurately.

[0010] The technical solution of this invention is as follows: A continuous zoom refraction optical system includes a spherical negative thin lens L1, a spherical positive thin lens L2, and a spherical negative thin lens L3 arranged sequentially along the optical axis. The spherical negative thin lens L1 is movable along the optical axis, and the optical center of the spherical negative thin lens L3 is located at the image-side focal point of the spherical positive thin lens L2. The optical power of the spherical negative thin lens L1 is [missing information]. The optical power of the spherical thin lens L2 is: The optical power of the spherical negative thin lens L3 is: Satisfy the following relationship

[0011]

[0012] Furthermore, the optical power of the spherical thin lens L2 is... The range is +3D to +25D.

[0013] Furthermore, the optical power of the spherical negative thin lens L3 is... The range is -25D to -3D.

[0014] Furthermore, the spherical negative thin lens L1 is a single optical lens or a combination of multiple optical lenses, the spherical positive thin lens L2 is a single optical lens or a combination of multiple optical lenses, and the spherical negative thin lens L3 is a single optical lens or a combination of multiple optical lenses.

[0015] Furthermore, in order to meet the requirements of astigmatism detection, the spherical negative thin lens L3 is provided with a rotatable negative cylindrical thin lens L4 and a negative cylindrical thin lens L5 of the same sign on the side opposite to the spherical positive thin lens L2. The rotation axes of the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 are coaxial with the optical axis, the lens axes of the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 intersect at the optical axis, and the lens axes of the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 are both perpendicular to the optical axis.

[0016] Furthermore, the optical power of both the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 is -3D cylinder.

[0017] A portable subjective refractometer includes the aforementioned continuous zoom refraction optical system, zoom adjustment device, optical power display device, and eye contact device. The zoom adjustment device is used to drive the spherical negative thin lens L1 to move along the optical axis. The optical power display device is used to display the overall optical power of the continuous zoom refraction optical system according to the position of the spherical negative thin lens L1 on the optical axis. The eye contact device is used to maintain the distance between the eye being tested and the spherical negative thin lens L3.

[0018] Further, the device includes an optometry instrument body, wherein the spherical positive thin lens L2 and the spherical negative thin lens L3 are fixedly disposed on the optometry instrument body, the spherical negative thin lens L3 is located at the end of the optometry instrument body, the optometry instrument body is provided with a movable frame, the spherical negative thin lens L1 is fixed to the movable frame, the zoom adjustment device is disposed on the optometry instrument body for driving the movable frame to move along the optometry instrument body so that the spherical negative thin lens L1 moves along the optical axis, the optical power display device includes an optical power pointer and an optical power indicator, the optical power pointer and the optical power indicator are respectively connected to the movable frame and the optometry instrument body, the position of the optical power pointer on the optical power indicator changes when the movable frame moves, and the eye contact device is disposed at the end of the optometry instrument body.

[0019] A portable subjective refractometer includes the aforementioned continuous zoom refraction optical system, a zoom adjustment device, an optical power display device, an astigmatism adjustment device, an astigmatism display device, and an eye-connecting device. The zoom adjustment device is used to drive the spherical negative thin lens L1 to move along the optical axis. The optical power display device is used to display the overall optical power of the continuous zoom refraction optical system based on the position of the spherical negative thin lens L1 on the optical axis. The astigmatism adjustment device is used to drive the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 to rotate to change the position of the negative cylindrical thin lens. The angle between the lens axes of L4 and the negative cylindrical thin lens L5 and / or the angle bisector of the angle between the lens axes of L4 and L5 in the circumferential direction of the optical axis, the astigmatism display device is used to display the astigmatism degree according to the angle between the lens axes of L4 and L5 and the astigmatism angle according to the angle bisector of the angle between the lens axes of L4 and L5 in the circumferential direction of the optical axis, and the eye contact device is used to maintain the distance between the eye being tested and the spherical negative thin lens L3.

[0020] Further, the device includes an optometry instrument body, with the spherical positive thin lens L2 fixedly mounted on the optometry instrument body. The optometry instrument body has a movable frame, and the spherical negative thin lens L1 is fixed to the movable frame. A zoom adjustment device is disposed on the optometry instrument body to drive the movable frame to move along the optometry instrument body, causing the spherical negative thin lens L1 to move along the optical axis. The optical power display device includes an optical power pointer and an optical power indicator, which are respectively connected to the movable frame and the optometry instrument body. When the movable frame moves, it changes the position of the optical power pointer on the optical power indicator. The astigmatism adjustment device includes a sleeve and a coaxial reversing mechanism, with the sleeve rotatably mounted on the optometry instrument body. At the end of the sleeve, the rotation axis of the sleeve is coaxial with the optical axis. The spherical negative thin lens L3, the negative cylindrical thin lens L4, and the negative cylindrical thin lens L5 are disposed inside the sleeve. The coaxial reversal mechanism is disposed on the sleeve. The astigmatism display device includes an angle pointer, an angle indicator, an astigmatism pointer, and an astigmatism indicator. The angle pointer and the angle indicator are respectively connected to the sleeve and the optometry instrument body. When the sleeve rotates, it changes the position of the angle pointer on the angle indicator. The coaxial reversal mechanism drives the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 to rotate in opposite directions at the same speed and simultaneously drives the astigmatism pointer to change the position of the astigmatism indicator on the astigmatism indicator. The eye contact device is disposed at the end of the sleeve.

[0021] Furthermore, it includes an old-vision target, which is positioned 30 to 50 cm in front of the side of the spherical positive thin lens L2 facing the spherical negative thin lens L1.

[0022] The advantages of the technical solution provided by this invention are as follows:

[0023] This invention provides a continuous optical zoom system that can accurately simulate the refraction process of trial lens refraction. Continuous and rapid zoom is achieved by moving the spherical negative thin lens L1 and rotating the negative cylindrical thin lenses L4 and L5. This system replaces the trial lenses with fixed value intervals used in trial lens refraction and comprehensive refraction instruments. During refraction, there is no need for the tedious and time-consuming operations of manually or mechanically changing lenses or finely adjusting the astigmatism power and astigmatism axis with cross cylindrical lenses, nor is it necessary to use a computerized refraction instrument.

[0024] Portable subjective refractometers employing a continuous optical zoom system offer rapid and continuous optical zoom capabilities and accurate synchronous readings. This allows for quick and precise examination of refractive errors. By configuring presbyopia targets, presbyopic refractive errors can also be detected quickly and conveniently. The continuous zoom prevents overcorrection or undercorrection of refractive errors that can occur with trial lens refraction and comprehensive refractometers due to the interval between lens powers. This enables rapid and accurate refraction with a single refractometer, improving the efficiency and quality of optometry and lens fitting, and meeting the needs of hospitals and optometry / lens fitting facilities at all levels for rapid and accurate refraction.

[0025] Portable subjective refractometers utilize only three optical lenses and simple mechanical devices, requiring no power supply or other facilities. The instruments are inexpensive, small, lightweight, portable, and easy to operate. They can be used quickly and accurately in general locations, even outdoors (observing objects up to 5 meters away). When used with a lens fitting kit, they can be used quickly and accurately in a standard optometry room, significantly reducing equipment and costs. Portable subjective refractometers are operated independently by the patient; the optometrist only needs to provide appropriate guidance and perform final adjustments and verifications. This low level of expertise required of optometrists makes them suitable for various groups requiring vision checks, screenings, and monitoring.

[0026] When used, a portable subjective refractometer can observe a vision chart or other objects 5 meters away, just like a lens refractometer. It is direct and natural, and easily accepted by the test subjects, especially children and adolescents. It also does not pose the risk of light hazards that may exist with other automatic refractometers.

[0027] This portable subjective refractometer allows for convenient fogging refraction, overcoming the problems of large changes in the optical power of the fogging lens affecting the fogging effect and the hassle of repeatedly adjusting the spherical lens optical power wheel in a comprehensive refractometer. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the continuous zoom optometry optical system of Example 1.

[0029] Figure 2 This is a schematic diagram of the optical principle of the continuous zoom optometry optical system in Example 1.

[0030] Figure 3 This is a schematic diagram of the structure of a portable subjective refractometer based on the continuous zoom refractometer optical system of Embodiment 1.

[0031] Figure 4 This is a schematic diagram of the continuous zoom optometry optical system of Example 2.

[0032] Figure 5This is a schematic diagram of the structure of a portable subjective refractometer based on the continuous zoom refractometer optical system of Embodiment 2. Detailed Implementation

[0033] The present invention will be further described below with reference to embodiments. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. After reading this description, any modifications of this description in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0034] Example 1, such as Figure 1 As shown, the continuous zoom refraction optical system involved in this embodiment includes a spherical negative thin lens L1, a spherical positive thin lens L2, and a spherical negative thin lens L3 arranged sequentially along the optical axis. The spherical negative thin lens L1 can move along the optical axis, that is, it can move closer to or further away from the spherical positive thin lens L2 along the optical axis. The optical center of the spherical negative thin lens L3 is located at the image-side focal point of the spherical positive thin lens L2. The optical power of the spherical negative thin lens L1 is... The optical power of the spherical thin lens L2 is The optical power of the spherical negative thin lens L3 is Satisfy the following relationship

[0035]

[0036] The optical power of the spherical thin lens L2 is The range is +3D to +25D, and the optical power of the spherical negative thin lens L3 is... The range is -25D to -3D, and the specific range can be determined according to the required optical power (refractive power) measurement range.

[0037] For the aforementioned continuous zoom refraction optical system, without considering the spherical negative thin lens L3, the structural optics principle of the system is as follows: Figure 2 The spherical negative thin lens L1 is spherical system I, and the spherical positive thin lens L2 is spherical system II. The object-side principal points and image-side principal points of spherical system I and spherical system II are H1, H′1 and H2, H′2, respectively; their principal foci are F1, F′1 and F2, F′2, respectively; and their focal lengths are f1, f′1 and f2, f′2, respectively. The optical spacing between the two systems is... d represents the distance between the image-side principal point H′1 of spherical system I and the object-side principal point H2 of spherical system II. The position of the image-side principal point H′2 of spherical system II is used to determine the position of the image-side principal point H′ of the composite system. X′ H express.

[0038] Then, the focal lengths f and f′ of the composite system of spherical system I and spherical system II, and the positions X′ of the object-side principal point and the image-side principal point are given. H X HThe distance between the object principal point and the image principal point They are respectively represented as

[0039]

[0040]

[0041]

[0042]

[0043]

[0044] The principal point H of the synthetic system is not shown in the figure.

[0045] It is evident that the focal lengths f and f′ of the synthesized system, the positions of the object-side principal point H and the image-side principal point H′, and the distance between them are determined by the focal lengths f1 and f2 of spherical system I and spherical system II, the optical gap Δ between the two systems, and the distance d from the image-side principal point H′1 of spherical system I to the object-side principal point H2 of spherical system II. When the optical power of the synthesized system changes with Δ, the positions of its object-side principal point H and image-side principal point H′ also change. It cannot function as a thin lens, and the position of the image-side principal point cannot remain constant. Therefore, arbitrarily selecting spherical system I and spherical system II to construct a coaxial optical zoom system cannot meet the design requirements of an optometer.

[0046] In fact, in this embodiment, the optical power of the spherical negative thin lens L1 is... The optical power of the spherical thin lens L2 is satisfy

[0047]

[0048] That is, f′1=f2, at which point d=Δ and X′ H =f′2, the principal point position of the image side of the composite system can remain unchanged. Substituting f′1 = f2 into the formula for the focal length f′ of the composite system, we can obtain...

[0049]

[0050] This indicates that the image-side focal length f′ of the composite system is inversely proportional to d only, meaning that f′ is uniquely determined by the value of d, and its range of variation is also uniquely determined by the value of d. Substituting f′1 = f2 into the distance between the object-side principal point and the image-side principal point of the composite system... The formula can be obtained

[0051]

[0052] This indicates that the distance between the object-side principal point and the image-side principal point of the synthesis system is exactly equal to the d-value, which uniquely determines the focal length variation and range of the synthesis system. Therefore, if the d-value can be kept sufficiently small within a certain zoom range (i.e., the d-value is sufficiently small relative to the distance of the eye chart, typically 5 meters), then the synthesis system is equivalent to a thin lens relative to the eye chart or other objects 5 meters away.

[0053] The optical power of the system consisting of a spherical negative thin lens L1 and a spherical positive thin lens L2 is

[0054]

[0055] According to the selected The optical power value of the system consisting of the spherical negative thin lens L1 and the spherical positive thin lens L2 can be determined by the above formula.

[0056] Pick but Therefore, a negative spherical thin lens L3 with negative optical power is placed at the image-side focal plane of spherical system II (i.e., at the image-side focal point of the positive spherical thin lens L2). The optical power of the negative spherical thin lens L3 is... Then the optical power of the combined system of the three thin lenses is:

[0057]

[0058] The image-side principal point of the synthesized system remains unchanged, still located at the image-side principal point of the spherical system II. Based on the above two equations, the range of change and the zero-value location of the optical power of the synthesized system can be determined by varying the d-value.

[0059] In summary, this continuous zoom refraction optical system meets all the requirements of the simulated lens refraction process and the requirements for wearing eyeglasses. These requirements specifically include:

[0060] 1. Since all trial lenses used in the trial lens refraction process and the lenses of the eyeglasses worn in the frame are thin lenses, the optical zoom system must be equivalent to a thin lens within the measurement range required by the refractometer.

[0061] 2. Since the lens-to-eye distance between any trial lens inserted into the frame and the vertex of the lens membrane being measured remains constant during trial lens refraction, meaning that the position of the principal point on the image side is the same after any trial lens is inserted into the frame, the position of the principal point on the image side must remain unchanged when the optical zoom system zooms arbitrarily within the measurement range required by the refractometer.

[0062] It should be noted that the spherical negative thin lens L1, spherical positive thin lens L2, and spherical negative thin lens L3 shown in the illustrations of the continuous zoom optometry optical system of the above embodiments are all single optical lenses, but are not limited thereto. The spherical negative thin lens L1, spherical positive thin lens L2, and spherical negative thin lens L3 can each be selected as single optical lenses or composed of a combination of multiple optical lenses.

[0063] A specific portable subjective optometry device structure based on the continuous zoom optometry optical system of the above embodiments is as follows: Figure 3 As shown, the refractometer includes a main body and a continuous zoom refraction optical system. The mechanical structure of the refractometer mainly includes a front lens barrel 11 and a rear lens barrel 13. A movable frame 8, which houses a spherical negative thin lens L1 9, is installed inside the front lens barrel 11 and can move along its inner wall to ensure that the optical axis of the spherical negative thin lens L1 9 is coaxial with the front lens barrel 11. At the same time, an axial groove can be opened on the wall of the front lens barrel 11 to cooperate with the movable frame 8, so that the movement of the movable frame 8 is along the axial direction of the front lens barrel 11, which is the optical axis of the spherical negative thin lens L1 9.

[0064] Spherical positive thin lens L2 12 and spherical negative thin lens L3 14 are fixed to the front end (far eye end) and the rear end (near eye end) of the rear lens barrel 13, respectively. The optical axes of spherical positive thin lens L2 12 and spherical negative thin lens L3 14 are coaxial with the rear lens barrel 13. The distance between the optical centers of spherical positive thin lens L2 12 and spherical negative thin lens L3 14 is the image-side focal length of spherical positive thin lens L2 12. The front end of the rear lens barrel 13 is inserted into the rear end (near eye end) of the front lens barrel 11 to achieve coaxial engagement between the front lens barrel 11 and the rear lens barrel 13, and is fixed with a set nut 30. A protective glass frame 2 with a protective glass 1 is screwed onto the front end (far eye end) of the front lens barrel 11 to protect the spherical negative thin lens L1 9.

[0065] The front lens barrel 11 is also equipped with a zoom adjustment device and an optical power display device. The zoom adjustment device is used to drive the movable lens frame 8 to move, that is, to drive the spherical negative thin lens L1 9 to move along the optical axis. The optical power display device is used to display the overall optical power of the continuous zoom refraction optical system based on the position of the spherical negative thin lens L1 on the optical axis.

[0066] Specifically, the zoom adjustment device uses a line drive method that is easy to maintain, and the optical power display device uses a pointer movement indication method. Two or three long slots are formed axially on the front lens barrel 11, allowing the transmission line fastening screw 34 and the optical power pointer fixing screw 7, which are fixed to the movable lens frame 8, to move synchronously with the movable lens frame 8 within the long slots. The transmission line fastening screw 34 is connected to the mechanical transmission system, which includes a first line drive driven wheel 37 fixed to the front bracket 4, a line drive driving wheel 35 fixed to the base 36, and a second line drive driven wheel 33 fixed to the rear bracket 32. Their transmission lines are fastened to the transmission line fastening screw 34. The front bracket 4 and the rear bracket are fixed to the front lens barrel 11 by the front bracket screw 3 and the rear bracket screw 31, respectively, and the base 36 is fixed to the front bracket 4 and the rear bracket 32.

[0067] The optical power pointer 6 is fixed to the optical power pointer fixing screw 7. An optical power indicator 5 is fixed on one side of the moving slot of the optical power pointer fixing screw 7 on the front lens barrel 11, and a protective shell 10 covers the optical power indicator 5. During refraction, rotating the linear drive wheel 35 moves the spherical negative thin lens L1 9 within the front lens barrel 11, simultaneously moving the optical power pointer 6. The optical power of the continuous zoom refraction optical system is displayed by the change in the position of the optical power pointer 6 on the optical power indicator 5.

[0068] To ensure a consistent eye-to-lens distance during refraction, this refractometer is designed with an eye-connecting device, namely an eye-connecting ring 15. The eye-connecting ring 15 is screwed onto the end of the rear lens barrel 13. During refraction, the eye being tested is placed close to the eye-connecting ring 15, ensuring that the eye-to-lens distance remains at the recognized distance. In addition, a cover plate (not shown) that can rotate around the rear lens barrel 13 is provided at the end of the rear lens barrel 13 to cover the untested eye during refraction.

[0069] The refraction method using the portable subjective refractometer in this embodiment is as follows: The optometrist instructs the subject to hold the refractometer in their left hand, place the eye to be tested close to the eye protection ring 15 of the refractometer, cover the other eye, and observe a vision chart or other object 5 meters away. The optometrist then rotates the linear drive wheel 35 with their right hand until the image is clearly visible. At this point, the optical power reading on the optical power indicator 5, aligned with the optical power pointer 6, is the spherical optical power value of the eye being tested. This process is repeated three times, and the average value is taken. The same procedure is then repeated for the other eye.

[0070] For the detection of presbyopic refractive errors, the presbyopic target 39 can be inserted into the presbyopic target socket 38, which is located on the front bracket 4. It should be noted that this is only a schematic diagram of how to fix the presbyopic target 39; the presbyopic target 39 can also be fixed to the refractometer body in other ways. Based on the principle of prioritizing the comfort of the test subject in the empirical method of presbyopia measurement, and considering the requirement that the general reading distance is 40 cm and clear vision should be possible within a ±5 cm range, and taking into account that the reading of general physiological presbyopia is between 0.5D and 3.5D, and that the principal point of this refractometer is at the object-side focal point of the spherical negative thin lens L1 9, the presbyopic target 39 of this refractometer does not need to move with the spherical negative thin lens L1 9. Its position can be fixed approximately 30-50 cm in front of the spherical positive thin lens L2 12. Place the eye being tested close to the eye shield 15 and operate as described above until the presbyopic target 39 is seen most clearly. At this point, the optical power value on the optical power indicator 5 is the degree of presbyopic refractive error of the eye being tested.

[0071] Example 2, as Figure 4 As shown, the continuous zoom optometry optical system in this embodiment adds a cylindrical continuous optical zoom system to the system described in Embodiment 1. The cylindrical continuous optical zoom system includes a negative cylindrical thin lens L4 and a negative cylindrical thin lens L5. The negative cylindrical thin lenses L4 and L5 are closely attached to the side of the spherical negative thin lens L3 facing away from the spherical positive thin lens L2. The negative cylindrical thin lenses L4 and L5 are rotatable, and their rotation axes are coaxial with the optical axis of the continuous zoom optometry optical system in Embodiment 1. The intersection of the lens axes of the negative cylindrical thin lenses L4 and L5 is located on the optical axis, and both lens axes are perpendicular to the optical axis. Rotation of the negative cylindrical thin lenses L4 and L5 can directly change the angle between their lens axes, or they can rotate synchronously without changing the angle between their lens axes, only changing the circumferential position of their lens axes on the optical axis. According to Thomson's formula for a system combining two identical cylindrical thin lenses, the astigmatic reading C, the spherical reading D, and the astigmatic axis β of the cylindrical combining system are determined by the angle α (α < 90°) between the axes of the two cylindrical thin lenses and the diopter values ​​A and B of the two cylindrical thin lenses.

[0072] C 2 =A 2 +B 2 +2ABcos2α

[0073]

[0074]

[0075] In this embodiment, both cylindrical thin lenses are negative cylindrical lenses, and the optical power of both negative cylindrical thin lenses L4 and L5 is -3D cylinder.

[0076] C = -6cosα

[0077]

[0078]

[0079] When the angle α between the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 varies between 0° and 90°, the astigmatism reading C of the cylindrical continuous optical zoom system will vary between -6D cylinder and 0D cylinder, satisfying the measurement range that the optometry instrument must meet for astigmatism, and the astigmatic axis is the angle bisector of the angle between the two axes. Since the two negative cylindrical lenses can rotate synchronously around the optical axis without changing the angle between the two axes, the requirement of 0° to 180° for astigmatism axis measurement can be met.

[0080] A specific portable subjective optometry device structure based on the continuous zoom optometry optical system of the above embodiments is as follows: Figure 5 As shown, the front lens barrel 11 and its internal structure (including the spherical negative thin lens L1 9), zoom adjustment device, and optical power display device are the same as in Embodiment 1, and will not be described again. This embodiment also includes a negative cylindrical thin lens L4 25, a negative cylindrical thin lens L5 24, an astigmatism adjustment device, and an astigmatism display device. The astigmatism adjustment device includes a sleeve 29 and a coaxial reversing mechanism. Specifically, a spherical positive thin lens L2 12 is fixedly installed at the front end of the rear lens barrel 13 and coaxially fixed to the rear end of the front lens barrel 11. A rotatable sleeve 29 is coaxially sleeved at the end of the rear lens barrel 13. A clamping ring 16 is fitted on the sleeve 29, and a sleeve tensioning ring 26 is provided at the end of the rear lens barrel 13. The clamping ring 16 is threadedly connected to the sleeve tensioning ring 26, so that the sleeve 29 is tightly attached to the sleeve fixing seat 21 fixed on the rear lens barrel 13, so that the sleeve 29 can rotate around the optical axis (the axis of the rear lens barrel 13) without axial movement. A circumferential dial is provided on the clamping ring 16 as an angle indicator (astigmatism axial angle), and an indicator line is provided on the sleeve 29 as an angle pointer. The two together constitute the part of the astigmatism display device used to display the astigmatism axial angle. The rotation of the sleeve 29 changes the position of the angle pointer on the angle indicator, thereby obtaining the astigmatism axial angle.

[0081] A rotatable front lens frame 28 and a rear lens frame 22 are coaxially arranged inside the sleeve 29. The spherical negative thin lens L3 12 and the negative cylindrical thin lens L4 25 are closely connected and fixed together inside the front lens frame 28. The negative cylindrical thin lens L5 24 is fixed inside the rear lens frame 22. The axes of the spherical negative thin lens L3 14, the negative cylindrical thin lens L4 25 and the negative cylindrical thin lens L5 24 are all coaxial with the sleeve 29. That is, the spherical negative thin lens L1 9, the spherical positive thin lens L2 12, the spherical negative thin lens L3 14, the negative cylindrical thin lens L4 25 and the negative cylindrical thin lens L5 24 are on the same optical axis, and the negative cylindrical thin lens L4 25 and the negative cylindrical thin lens L5 24 can rotate around the optical axis. The coaxial reversing mechanism includes a small bevel gear 17, a first large bevel gear 23, and a second large bevel gear 27. The first large bevel gear 23 and the second large bevel gear 27 are mounted together in a sleeve and positioned by a clamping nut 20. The first large bevel gear 23 and the second large bevel gear 27 are rotatably connected to the sleeve 29. The front lens frame 28 is fixed in the shaft hole of the first large bevel gear 23, and the rear lens frame 22 is fixed in the shaft hole of the second large bevel gear 27. The small bevel gear 17 is radially mounted on the sleeve 29 via a gear fixing seat 19 and meshes with both the first large bevel gear 23 and the second large bevel gear 27. When the small bevel gear 17 is rotated, the first large bevel gear 23 and the second large bevel gear 27 can drive the front lens frame 28 and the rear lens frame 22 to rotate synchronously in opposite directions, thereby changing the included angle α between the lens axes of the negative cylindrical thin lens L4 25 and the negative cylindrical thin lens L5 24, but without changing the direction of the angle bisector, i.e., without changing the astigmatic axis. The dial 18, which rotates synchronously with the small bevel gear 17, is engraved with an astigmatism indicator on its circumference. An indicator line engraved on the sleeve 29 serves as an astigmatism pointer (which can be the same indicator line as the angle pointer). Together, they constitute the part of the astigmatism display device used to display the astigmatism. The rotation of the small bevel gear 17 changes the position of the astigmatism pointer on the astigmatism indicator, thereby obtaining the astigmatism.

[0082] The refraction method using the portable subjective refractometer in this embodiment is as follows:

[0083] I. Determination of spherical refractive errors (myopia, hyperopia, presbyopia)

[0084] Rotate the small bevel gear 17 until the zero point of the astigmatism scale C on the astigmatism indicator is aligned with the indicator line on the sleeve 29. At this point, the optical system consisting of the negative cylindrical thin lens L4 25 and the negative cylindrical thin lens L5 24 has no astigmatism. The remaining measurement steps are the same as in Example 1.

[0085] II. Astigmatism Measurement

[0086] The spherical refractive error of the tested eye is determined using the above method. If the visual acuity of the tested eye is less than 0.7–0.8, astigmatism may be considered. Rotate the small bevel gear 17 until the astigmatism scale C shows 0.5D or 1.0D, resulting in 0.5D or 1.0D astigmatism in the combined system of negative cylindrical thin lenses L4 25 and L5 24. At this point, the visual acuity chart becomes blurry. Rotate the sleeve 29. If the tested eye feels blurry at any position, it indicates that the tested eye has no astigmatism, and the visual acuity improvement is not expected; this may be due to other reasons in the tested eye. If the visual acuity chart is relatively clear at a certain position, but blurry at other positions, it suggests that the tested eye has astigmatism. Further rotate the small bevel gear 17 to adjust the astigmatism power and slightly rotate the linear drive wheel 35 to adjust the spherical refractive power until the visual acuity chart is most clearly visible. At this time, the astigmatism value indicated by the astigmatism pointer on the astigmatism indicator is the astigmatism value of the tested eye, and the value indicated by the angle pointer on the clamping ring 16 is the astigmatic axis of the tested eye. At this time, the absolute value of the spherical refractive power value minus half of the astigmatism value is the spherical refractive power of the tested eye.

[0087] Based on the fact that the meridians of maximum and minimum refractive power in regular astigmatism are perpendicular to each other and the conversion relationship between the two axes, for any regular astigmatism, there is always one axis with a negative astigmatism power. Therefore, the measurement range of this optometry instrument actually covers the measurement range of -6D to 6D that the optometry instrument must meet, and also meets the current practice of using negative cylindrical lenses for astigmatism prescription.

[0088] The portable subjective refractometer described in the above embodiment was tested and compared with both trial-and-error refraction and cycloplegic refraction. A difference of 0.5D or less was considered basically acceptable, and a difference greater than 0.5D was considered significantly different. All tests were performed independently by the subjects under the guidance of an optometrist, and the testing time for each eye was within 2 minutes. The test results are as follows.

[0089]

[0090] The above results show that this refractometer provides fast and accurate refraction. Compared with lens-based refraction, its complete consistency rate is 95.8%, and its basic consistency rate is 100%. This indicates that the continuous zoom optical system used in this invention reliably and accurately simulates the lens-based refraction process, verifying that the system design is correct and feasible, and that the operation of its mechanical system and the accuracy of its readings are reliable, achieving the design expectations. The lower consistency rate compared to cycloplegic refraction is due to two factors: firstly, the measurement error of the refractometer itself, and secondly, the subjective judgment error of the optometrist during cycloplegic refraction.

Claims

1. A continuous zoom optometry optical system, characterized in that, The system includes a spherical negative thin lens L1, a spherical positive thin lens L2, and a spherical negative thin lens L3 arranged sequentially along the optical axis. The spherical negative thin lens L1 is movable along the optical axis. The optical center of the spherical negative thin lens L3 is located at the image-side focal point of the spherical positive thin lens L2. The optical power of the spherical negative thin lens L1 is [missing value]. The optical power of the spherical thin lens L2 is The optical power of the spherical negative thin lens L3 is , , , Satisfy the following relationship .

2. The continuous zoom optometry optical system according to claim 1, characterized in that, The optical power of the spherical thin lens L2 is: The range is +3D to +25D.

3. The continuous zoom optometry optical system according to claim 2, characterized in that, The optical power of the spherical negative thin lens L3 is: The range is -25D to -3D.

4. The continuous zoom optometry optical system according to claim 1, characterized in that, The spherical negative thin lens L1 is a single optical lens or a combination of multiple optical lenses, the spherical positive thin lens L2 is a single optical lens or a combination of multiple optical lenses, and the spherical negative thin lens L3 is a single optical lens or a combination of multiple optical lenses.

5. The continuous zoom optometry optical system according to claim 1, characterized in that, On the side of the spherical negative thin lens L3 facing away from the spherical positive thin lens L2, there are rotatable negative cylindrical thin lenses L4 and L5 of the same sign. The rotation axes of the negative cylindrical thin lenses L4 and L5 are coaxial with the optical axis. The intersection of the lens axes of the negative cylindrical thin lenses L4 and L5 is located on the optical axis. The lens axes of the negative cylindrical thin lenses L4 and L5 are both perpendicular to the optical axis.

6. The continuous zoom optometry optical system according to claim 5, characterized in that, Both the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 have an optical power of -3D cylinder.

7. A portable subjective refractometer, characterized in that, The system includes a continuous zoom refraction optical system, a zoom adjustment device, an optical power display device, and an eye-connecting device as described in any one of claims 1 to 4. The zoom adjustment device is used to drive the spherical negative thin lens L1 to move along the optical axis. The optical power display device is used to display the overall optical power of the continuous zoom refraction optical system according to the position of the spherical negative thin lens L1 on the optical axis. The eye-connecting device is used to maintain the distance between the eye being tested and the spherical negative thin lens L3.

8. The portable subjective refractometer according to claim 7, characterized in that, The device includes an optometry instrument body, a spherical positive thin lens L2 and a spherical negative thin lens L3 fixedly mounted on the optometry instrument body, the spherical negative thin lens L3 located at the end of the optometry instrument body, a movable frame provided on the optometry instrument body, the spherical negative thin lens L1 fixed to the movable frame, a zoom adjustment device disposed on the optometry instrument body for driving the movable frame to move along the optometry instrument body so that the spherical negative thin lens L1 moves along the optical axis, a power display device including a power pointer and a power indicator, the power pointer and the power indicator being respectively connected to the movable frame and the optometry instrument body, the power pointer changing the position of the power pointer on the power indicator when the movable frame moves, and an eye contact device disposed at the end of the optometry instrument body.

9. A portable subjective refractometer, characterized in that, The system includes the continuous zoom refraction optical system, zoom adjustment device, optical power display device, astigmatism adjustment device, astigmatism display device, and eye contact device as described in claim 5 or 6. The zoom adjustment device drives the spherical negative thin lens L1 to move along the optical axis. The optical power display device displays the overall optical power of the continuous zoom refraction optical system based on the position of the spherical negative thin lens L1 on the optical axis. The astigmatism adjustment device drives the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 to rotate, thereby changing the position of the negative cylindrical thin lens L4. The astigmatism display device is used to display the astigmatism degree based on the lens axis angle between the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 and / or the angle bisector of the angle between the lens axes of the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 in the circumferential direction of the optical axis. The astigmatism angle is displayed based on the angle bisector of the angle between the lens axes of the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 in the circumferential direction of the optical axis. The eye contact device is used to maintain the distance between the eye being tested and the spherical negative thin lens L3.

10. The portable subjective refractometer according to claim 9, characterized in that, The system includes an optometry instrument body, a spherical positive thin lens L2 fixedly mounted on the optometry instrument body, a movable frame on the optometry instrument body, a spherical negative thin lens L1 fixed to the movable frame, a zoom adjustment device mounted on the optometry instrument body for driving the movable frame to move along the optometry instrument body, causing the spherical negative thin lens L1 to move along the optical axis, a power display device including a power pointer and a power indicator, the power pointer and the power indicator being respectively connected to the movable frame and the optometry instrument body, the power pointer changing the position of the power pointer on the power indicator when the movable frame moves, and an astigmatism adjustment device including a sleeve and a coaxial reversing mechanism, the sleeve being rotatably mounted at the end of the optometry instrument body. At the end, the rotation axis of the sleeve is coaxial with the optical axis. The spherical negative thin lens L3, the negative cylindrical thin lens L4, and the negative cylindrical thin lens L5 are disposed inside the sleeve. The coaxial reversal mechanism is disposed on the sleeve. The astigmatism display device includes an angle pointer, an angle indicator, an astigmatism pointer, and an astigmatism indicator. The angle pointer and the angle indicator are respectively connected to the sleeve and the optometry instrument body. When the sleeve rotates, it changes the position of the angle pointer on the angle indicator. The coaxial reversal mechanism drives the negative cylindrical thin lens L4 and the negative cylindrical thin lens L5 to rotate in opposite directions at the same speed and simultaneously drives the astigmatism pointer to change the position of the astigmatism indicator on the astigmatism indicator. The eye contact device is disposed at the end of the sleeve.

11. The portable subjective refractometer according to claim 7 or 9, characterized in that, It includes an old-vision target, which is positioned 30 to 50 cm in front of the side of the spherical positive thin lens L2 facing the spherical negative thin lens L1.

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