Apparatus, systems and methods for measuring the far point distance of the human eye

Abstract

This invention relates to the field of optical technology, specifically to a device for measuring the far point distance of the human eye. It includes a cylindrical housing containing a condenser lens and a light-shielding plate, spaced apart. The light-shielding plate has observation channels symmetrically arranged along the optical axis. A blocking plate, positioned along the optical axis between the condenser lens and the light-shielding plate, separates the observation channels. By using the blocking plate on the optical axis, interfering images can be eliminated, and when the optical axis is deflected, the imaging of one light source will show a significant deviation, making it easy to adjust the blocking plate.

Description

Technical Field

[0001] This invention relates to the field of optical technology, specifically to a device, system, and method for measuring the far point distance of the human eye. Background Technology

[0002] The widespread use of smartphones, computers and other smart devices has greatly impacted people's vision. Currently, the number of people with myopia and astigmatism has increased dramatically. Moreover, vision tests now generally require going to a professional optometry institution and using complex optometry equipment, which is not only time-consuming but also wasteful of resources. Existing portable testing devices can measure vision levels, but they require highly skilled operators, have many interfering factors, and are not conducive to obtaining accurate measurement results. Summary of the Invention

[0003] The purpose of this invention is to provide an apparatus, system, and method for measuring the distance to the far point of the human eye, in order to solve the technical problems mentioned in the background art.

[0004] To achieve the above objectives, this application provides a device for measuring the far point distance of the human eye, including a cylindrical shell, a condenser lens and a light shield inside the cylindrical shell, the condenser lens and the light shield being spaced apart, and the light shield having an observation channel symmetrical along the optical axis.

[0005] A shielding plate is placed along the optical axis between the condenser lens and the light shield to separate the observation channel.

[0006] By setting a shield on the optical axis, interference images can be removed, and when the optical axis is offset or tilted, the imaging of one side of the light source will show obvious deviation, making it easy to calibrate the optical axis.

[0007] Furthermore, the observation channel is a small hole or a slit.

[0008] Furthermore, the condenser lens is a concave lens or a group of concave lenses.

[0009] Furthermore, the distance between the observation channels is C, where 0 < C ≤ 5 mm.

[0010] This application also provides a system for measuring the distance to the far point of the human eye, including...

[0011] The display unit is used to display two targets.

[0012] The adjustment unit is used to move the visual target so that the image of the visual target on the fundus coincides with the optical axis;

[0013] The acquisition unit is used to acquire the distance B from the condenser lens to the light shield, the target movement information, and the entrance pupil width I;

[0014] The calculation unit is used to calculate the target movement distance G and the far point distance A of the human eye, where A = I * B / G.

[0015] Furthermore, the calculation unit calculates the target movement distance G based on the resolution of the display unit.

[0016] Furthermore, the calculation unit is also used to calculate the target movement distance G′ after the display unit rotates 90° and the far point distance A′ of the human eye, A′=I*B / G′, and to calculate the cylindrical lens refractive error and the spherical lens refractive error based on the far point distance A and A′ of the human eye.

[0017] This application also provides a method for measuring the distance to the far point of the human eye, including...

[0018] Two targets are displayed on a screen. The screen is rotated and the targets are moved so that the fundus image coincides with the optical axis. The distance B from the condenser to the shading plate, the target movement information, and the entrance pupil width I are obtained. The target movement distance G and the far point distance A of the human eye are calculated, where A = I * B / G.

[0019] Furthermore, the computing unit calculates the target movement distance G based on the resolution of the display screen.

[0020] This application also provides a system for measuring refractive errors of the human eye, characterized in that it includes a device for measuring the far point distance of the human eye;

[0021] It also includes a smart terminal with a display screen for displaying two targets, and the display screen also has adjustment unit icons for moving the targets;

[0022] The smart terminal is equipped with an acquisition unit for acquiring the distance B from the condenser lens to the light shield, the target movement information, and the entrance pupil width I;

[0023] The calculation unit is used to calculate the target movement distance G and the far point distance A of the human eye, A = I*B / G, and to calculate the target movement distance G′ and the far point distance A′ of the human eye after the display unit rotates 90°, A′ = I*B / G′, and to calculate the cylindrical lens refractive error and the spherical lens refractive error based on the far point distance A and A′ of the human eye. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the device for measuring the distance to the far point of the human eye according to the present invention;

[0025] Figure 2 This is an internal structural diagram of a device for measuring the distance to the far point of the human eye in another embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the connection between the device for measuring the far point distance of the human eye according to the present invention and a smart terminal;

[0027] Figure 4 This is an optical path diagram of the measurement process of this invention;

[0028] Figure 5 This is a schematic diagram of the target state during the measurement process of this invention;

[0029] Figure 6 This is a schematic diagram of the measurement process of the present invention without filtering out interference images;

[0030] Figure 7 This is a schematic diagram illustrating the measurement process of the present invention, where interference images are filtered out.

[0031] Figure 8 This is a schematic diagram of the tilted optical axis during the measurement process of this invention;

[0032] Figure 9 This is a schematic diagram of the standard optical axis in the measurement process of this invention;

[0033] The components include: cylindrical shell 1, condenser lens 2, light shield 3, observation channel 4, shielding plate 5, point light source 6, base plate 7, horizontal plate 8, display unit 110, adjustment unit 120, acquisition unit 130, and calculation unit 140. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to specific embodiments and the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the present invention.

[0038] Please see Figures 1-3 This embodiment provides a device for measuring the distance to the far point of the human eye, including a cylindrical shell 1. The cylindrical shell 1 is a hollow structure with openings at both ends in the axial direction. The cylindrical shell 1 serves to block interference from ambient light and to fix internal parts. It is best to use opaque and non-reflective materials to improve the clarity of the light source image.

[0039] The cylindrical shell 1 is equipped with a condenser lens 2 and a light shield 3. The function of the condenser lens 2 is to reduce the image and shorten the length of the cylindrical shell 1.

[0040] The condenser lens 2 and the light shield 3 are spaced apart. The light shield 3 has observation channels 4 symmetrically arranged along the optical axis. The distance between the observation channels is C, where 0 < C ≤ 2.2 mm. In principle, simply placing an obstruction can divide the pupil's field of view into two parts. However, since the size of human pupils varies, a frame needs to be added to the field of view. This means placing a single hole in the middle of the human eye, with a diameter of 2I. 2I is smaller than the average width of the pupil, but the field of view of a single hole is too large, so part of the middle needs to be blocked, resulting in a double hole. The distance between the inner sides of the two observation channels 4 needs to be greater than or equal to the thickness of the obstruction 5 mentioned below.

[0041] In use, the cylindrical housing 1 needs to be fixed to the smart terminal screen. The bottom of the cylindrical housing 1 can be fixed to the smart terminal screen by silicone suction, adhesive, buckles, or straps, allowing the observation system to rotate synchronously with the target. The condenser lens 2 is positioned close to one end of the smart terminal screen, with the observation channel 4 serving as the observation hole. The cylindrical housing 1 is then aligned with the target on the other end of the smart terminal screen, or with the point light source 6 at the other end of the cylindrical housing 1. Figure 2 As shown, the point light source 6 is mounted on the base plate 7 perpendicular to the optical axis. The base plate 7 is provided with an angle scale for measuring the rotation angle of the base plate. The base plate 7 is provided with a graduated horizontal plate 8 for measuring the moving distance of the point light source 6.

[0042] The farther the point light source is from the human eye during measurement, the more obvious the distance between the image and the optical axis becomes. However, the closer the point light source 6 is to the human eye, the easier the operation becomes. At this time, a condenser lens 2 needs to be added, which can greatly shorten the operation distance.

[0043] During measurement, the human eye cannot determine the position of the optical axis. At this time, a point light source needs to be added at a symmetrical position. The position where the two point images coincide is the optical axis. The far point of the human eye is conjugate with the fundus. When the point light source is not on the conjugate plane, it will form a diffuse circle on the fundus. Therefore, it is necessary to block the entrance pupil and leave a small hole (observation channel 4) at a specific width so that the point light source forms a point image.

[0044] When the optical axis is misaligned during measurement, the imaging distance increases, and interference images appear in the two observation channels 4. Therefore, this embodiment adds a shielding plate 5, which is positioned along the optical axis between the condenser lens 2 and the shielding plate 3 to separate the observation channels 4. This eliminates interference images, and when the optical axis is misaligned, the imaging of one light source will show a significant deviation, making it easier to adjust the optical axis. The thickness of the shielding plate 5 should be as small as possible. The shielding effect of the shielding plate 5 is referenced. Figure 6 and Figure 7 Reference diagram of the target state before and after tilting the optical axis. Figure 7 and Figure 8 A schematic diagram of the standard optical axis can be found in [the diagram]. Figure 9 .

[0045] In another embodiment of this application, the observation channel consists of two small holes, which can be replaced by double slits. The slits can increase the amount of light entering the eye, improve the observation effect, and enhance the clarity.

[0046] In another embodiment of this application, the condenser lens 2 can be replaced by the edges of two convex lenses instead of a concave lens, or by a combination of two or more concave lenses, or by a combination of two or more concave lenses and convex lenses. In short, any lens that can achieve the effect of reducing the image can be used instead. These combination methods are conventional techniques and will not be described in detail here. However, it is advisable to choose a lens with a small focal length for the condenser lens 2 to improve measurement accuracy.

[0047] This application also provides a system for measuring the far point distance of the human eye. This system can operate independently on smartphones, tablets, or other smart terminals or electronic devices with touchscreens. When used in conjunction with these devices, it measures the far point distance of the human eye and calculates the refractive error of the eye. The system includes:

[0048] Display unit 110 is used to display two targets; because the shape, size, brightness, etc. of the object are not conducive to observation, the object is replaced with a target formed by a point light source or a luminous object;

[0049] When using this method, it should be noted that the two targets can be patterns of any color and shape. When using this method, it is best to choose two patterns with the same shape but different colors to improve measurement accuracy, such as the cross shape used in this embodiment.

[0050] The adjustment unit 120 is used to move the visual target so that the image of the visual target on the fundus coincides with the optical axis; the display unit has an icon of the adjustment unit, which can be clicked to move the visual target.

[0051] The acquisition unit 130 is used to acquire the distance B from the condenser lens to the shading plate, the target movement information, and the entrance pupil width I (i.e., the standard distance between two targets); the target movement information includes the screen resolution and the diagonal inches.

[0052] The calculation unit 140 is used to calculate the target movement distance G and the far point distance A of the human eye, where A = I * B / G.

[0053] At any distance, the distance to the farthest point of an object parallel to the optical axis is determined by the optical path. Let A be the farthest point distance of the human eye, I be the entrance pupil width, B be the measured distance from the condenser to the diaphragm, and G be the target movement distance. The farthest point distance of the human eye can then be calculated using A = I * B / G. However, it is necessary to measure and calculate the distance B from the condenser to the diaphragm, the entrance pupil width I, and the target movement distance G.

[0054] Calculation process: Reference Figure 4 and Figure 5 As shown, Figure 4 For an ideal optical path diagram, Figure 5 To implement the optical path diagram; where the length of ac is the far point distance A of the human eye, cd is the entrance pupil width I, db is the distance B from the condenser to the shading plate, be is the target movement distance G, and G = number of spacing pixels * pixel side length; because ac and bd are parallel, and ed and ad coincide, △acd and △dbe are similar, so ac / cd = db / be, so ac = cd * db / be. Since cd and db are known, the length of ac can be calculated by measuring the length of be.

[0055] When a concave lens is used to shorten the optical path, the target's movement distance G is also shortened to G'. The magnification of the concave lens is β, G' = G * β, and the far point formula is A = I * B / G'.

[0056] During measurement, a gap C is left between the human eye and the slit. Since the human eye needs to be as close to the slit as possible, the distance C is very short and has a negligible impact on the result. Moreover, it is difficult to measure and can be ignored in the calculation.

[0057] It should be noted that the refractive interface of a cylindrical lens refractive error is a toric surface. Parallel light rays passing through the toric surface cannot form a focal point, but instead form two mutually orthogonal focal lines, one in front of the other. The gap between the focal lines is the degree of cylindrical lens refractive error, and the angle of the strong principal meridian is the axis of the cylindrical lens refractive error.

[0058] When the human eye has cylindrical refractive error, fixing gaze on a point light source will produce an irregular blurry image (with indistinct boundaries), and the refractive power will differ at different axes. Therefore, a second measurement is required. First, rotate the entire measurement system around the optical axis until the blurry image becomes regular (with clear horizontal or vertical boundaries). Perform the first measurement, recording the distance the point light source moved and the rotation angle. Then, at the angle measured in the first measurement, rotate the entire measurement system 90 degrees around the optical axis, performing a second measurement and recording the distance the point light source moved and the rotation angle. Compare the two measurement results. The result with the smaller absolute value of refractive power represents the spherical refractive error, the difference between the two results represents the cylindrical refractive error, and the angle corresponding to the result with the larger absolute value represents the cylindrical axis. The observation state of the target is referenced. Figure 5 ;

[0059] Therefore, the calculation unit is also used to calculate the target movement distance G′ after the display unit rotates 90° and the far point distance A′ of the human eye, A′=I*B / G′, and calculate the cylindrical lens refractive error and spherical lens refractive error based on the far point distance A and A′ of the human eye. The reciprocal of A is the refractive error.

[0060] This application also provides a method for measuring the distance to the far point of the human eye, including the following steps:

[0061] S1: Display two targets on the screen of a smart terminal, and fix the aforementioned device for measuring the distance to the far point of the human eye on the screen;

[0062] S2: Rotate the display screen and move the target to make the fundus image coincide with the optical axis, and obtain the distance B from the condenser lens to the light shield, the target movement information and the entrance pupil width I. The target movement information includes the resolution and pixel side length of the smart terminal's display screen.

[0063] S3: Calculate the target movement distance G and the far point distance A of the human eye, A = I * B / G. The target movement distance can be obtained by multiplying the target movement pixel of the smart terminal's display screen by the pixel side length.

[0064] This application also provides a system for measuring refractive errors of the human eye, including the aforementioned device for measuring the far point distance of the human eye;

[0065] It also includes a smart terminal, which can be a smartphone, iPad or other handheld terminal capable of running the detection system, and the screen size of the smart terminal can at least completely cover the bottom of the detection component.

[0066] The smart terminal has a display screen for displaying two targets, and the display screen also has adjustment unit icons for moving the targets;

[0067] The smart terminal is equipped with an acquisition unit for acquiring the distance B from the condenser lens to the light shield, the target movement information, and the entrance pupil width I;

[0068] The smart terminal also includes a computing unit for calculating the target movement distance G and the far point distance A of the human eye, where A = I * B / G; the computing unit is also used to calculate the target movement distance G′ after the display unit rotates 90° and the far point distance A′ of the human eye, where A′ = I * B / G′, and to calculate the cylindrical lens refractive error and the spherical lens refractive error based on the far point distance A and A′ of the human eye, where the reciprocal of A is the refractive error; and the refractive error is sent to the display screen for display.

[0069] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A system for measuring the distance to the far point of the human eye, characterized in that: It includes a cylindrical shell, inside which are a condenser lens and a light shield, which are spaced apart, and the light shield has an observation channel symmetrical along the optical axis. A shielding plate is placed along the optical axis between the condenser lens and the shielding plate to separate the observation channel; The display unit is used to display two targets. The adjustment unit is used to move the visual target so that the image of the visual target on the fundus coincides with the optical axis; The acquisition unit is used to acquire the distance B from the condenser lens to the light shield, the target movement information, and the entrance pupil width I; a computing unit for calculating the target movement distance G and the far point distance A of the human eye, A = I B / G.

2. The system for measuring the distance of the far point of the human eye according to claim 1, characterized in that: The calculation unit calculates the target movement distance G based on the resolution of the display unit.

3. The system for measuring the far point distance of the human eye according to claim 1, characterized in that: The computing unit is also used to calculate the distance G' of the target moving after the display unit rotates 90° and the distance A' of the far point of the human eye, A'=I B / G', and calculate the cylindrical refractive error and the spherical refractive error according to the distance A of the far point of the human eye and A'.

4. The system for measuring the far point distance of the human eye according to claim 1, characterized in that: The observation channel is a small hole or a slit.

5. The system for measuring the far point distance of the human eye according to claim 1, characterized in that: The condenser lens is a concave lens or a group of concave lenses.

6. The system for measuring the far point distance of the human eye according to claim 1, characterized in that: The distance C between the observation channels is 0 < C ≤ 5 mm.

7. A method for measuring the distance to the far point of the human eye, characterized in that: include Two targets are displayed on a screen. The targets are moved to make the fundus image coincide with the optical axis. The distance B from the condenser to the shading plate, the target movement information, and the entrance pupil width I are obtained. Calculate the target movement distance G and the far point distance A of the human eye, where A = I. B / G; Also includes A cylindrical shell, inside which are a condenser lens and a light shield, the condenser lens and the light shield are spaced apart, and the light shield has an observation channel symmetrical along the optical axis; A shielding plate is placed along the optical axis between the condenser lens and the light shield to separate the observation channel.

8. The method for measuring the far point distance of the human eye according to claim 7, characterized in that: The target movement distance G is calculated based on the display screen resolution.

9. A system for measuring refractive errors in the human eye, characterized in that: Includes the system for measuring the far point distance of the human eye as described in claim 1; It also includes a smart terminal with a display screen for displaying two targets, and the display screen also has adjustment unit icons for moving the targets; The smart terminal is equipped with an acquisition unit for acquiring the distance B from the condenser lens to the light shield, the target movement information, and the entrance pupil width I; The calculation unit is used to calculate the target movement distance G and the far point distance A of the human eye, where A=I B / G, and calculate the target movement distance G′ and the far point distance A′ of the human eye after the display unit rotates 90°, A′=I B / G′, and calculate the cylindrical lens refractive error and spherical lens refractive error based on the far point distances A and A′ of the human eye.

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