Portable vision detection device

Abstract

The utility model provides a portable vision detection device, which relates to the technical field of ophthalmological optical instruments and comprises an outer cylinder, and a laser speckle component and a cam zoom lens component are arranged in the outer cylinder. The laser speckle assembly comprises a laser source, a beam expanding lens, a diffuse reflection disc driven by a motor to rotate, a slit, a view field segmentation reversing system and a third prism rotating in the radial direction, all of which are arranged in sequence. Wherein the laser source emits laser, laser speckles are formed after the laser passes through the diffuse reflection disc, the slit is formed in one side of the motor and corresponds to the laser speckles in position, the view field segmentation reversing system, the third prism and the slit are coaxially arranged, and diffraction fringes are formed after the laser speckles pass through the slit. The diffraction fringes are changed into two groups of fringes with opposite movement directions after passing through the view field segmentation inversion system, and the two groups of fringes reach the cam zoom lens assembly after passing through the third prism rotating in the radial direction and finally reach the fundus retina. The portable vision detection device provided by the utility model is small in size and light in weight.

Description

Technical Field

[0001] The utility model belongs to the technical field of ophthalmic optical instruments, and particularly relates to a portable vision detection device. Background Art

[0002] With the prevalence of electronic products, people's outdoor activity time has significantly decreased, while the time spent using their eyes at close range has increased significantly. Coupled with the fact that most people use their eyes improperly, myopia has become a global epidemic. If patients can regularly perform self-refraction tests to understand recent changes in their refractive power, they can adjust their eye habits in a timely manner and seek targeted professional help. This will greatly benefit the patient's refractive error and correction. However, due to the complexity and professional nature of current ophthalmic equipment, optometry cannot be completed at home. Instead, it must be performed using a professional ophthalmometer and requires the participation of an optometrist, which brings difficulties to vision assessment.

[0003] In the prior art, the Chinese utility model patent application number CN202322942395.4 provides an ophthalmic testing device. By setting structures such as a grid plate and a frame, the size of the "E" in each row on the eye chart is different. When the frame moves to the position corresponding to a row of "E" characters, under the control of the control module body, a certain "E" in this row is randomly selected, and several LED light modules corresponding to the size of the "E" character are lit, so that the subject can see the corresponding "E" character clearly according to the light source. Compared with the prior art, by lighting the light source corresponding to the position of the "E" character on the back of the eye chart, the subject can easily see the corresponding "E" character, and there will be no problem of inaccurate indication or blocking the "E" character, which is convenient for vision testing. The ophthalmic testing device provided by this patent is easy to use, but it cannot obtain a specific refractive power;

[0004] Hospital eye examinations are accurate but not timely enough. Smart eye examination equipment, such as the hipee smart eye examination device, already exists on the market, but they are still relatively expensive and have some problems in use, making them not widely used among the general public. Some eye examination equipment can only detect myopia and hyperopia but cannot measure astigmatism. If a patient has both myopia and astigmatism, multiple devices will need to be used for testing, or they will eventually need to go to a hospital or eyewear store for a comprehensive vision test, which is complicated and time-consuming.

[0005] In addition to the accuracy and price of optometry, size is also a factor people consider when choosing optometry equipment. If the optometry equipment is bulky and takes up a lot of space, it will be inconvenient to carry when going out and will not be able to complete real-time vision testing.

[0006] Adolescents' eyes are in a critical period of growth and development. Real-time, efficient refractive power testing not only facilitates timely targeted treatment and correction, and the replacement of more suitable glasses, but also provides guidance for rationally managing eye use and behavioral habits, ultimately protecting our eyes. Therefore, there is an urgent need for a portable vision testing device that is easy to use and highly effective. Utility Model Content

[0007] The utility model aims to solve the problems existing in the prior art and provides a portable vision detection device. The portable vision detection device is simple, reliable, easy to use, and can complete the detection of myopia, hyperopia, and astigmatism.

[0008] In order to achieve the above purpose, the technical solution adopted by the present utility model is as follows:

[0009] A portable vision detection device comprising

[0010] an outer cylinder, wherein a laser speckle assembly and a cam zoom lens assembly are disposed in the outer cylinder;

[0011] The laser speckle assembly includes a laser source, a beam expander, a diffuse reflection disk, a slit, a field of view splitting and inverting system, and a radially rotating third prism which are arranged in sequence;

[0012] The diffuse reflection disk is driven by a motor to rotate around its own central axis;

[0013] The third prism rotates the incident light beam;

[0014] The laser source emits a laser, which forms a laser speckle after passing through a diffuse reflection disk. A slit is provided on one side of the motor and corresponds to the position of the laser speckle. The field of view splitting and inverting system and the third prism are coaxially arranged with the slit. The laser speckle forms diffraction stripes after passing through the slit. The diffraction stripes become two groups of stripes with opposite movement directions after passing through the field of view splitting and inverting system. The two groups of stripes pass through the radially rotating third prism and reach the cam zoom lens assembly, and finally reach the fundus retina.

[0015] Furthermore, it also includes a second right-angle prism, which is arranged between the third prism and the cam zoom lens assembly.

[0016] Furthermore, it also includes a first right-angle prism, which is arranged between the beam expander and the diffuse reflection disk; the laser source is arranged on the central axis of the outer cylinder, and the laser source emits laser light, which changes the light path through the first right-angle prism to one side of the diffuse reflection disk, forming a laser speckle. The laser speckle passes through the slit, the field of view splitting and inverting system, and the third prism in sequence, and is reflected to the central axis through the second right-angle prism and reaches the cam zoom lens assembly.

[0017] Furthermore, the laser source is arranged on the upper side or the lower side of the outer cylinder, and the position of the beam expander corresponds to the position of the laser source. The laser source emits laser light, which is irradiated on one side of the diffuse reflection disk to form a laser speckle. The laser speckle passes through the slit, the field of view splitting inverted system, and the third prism in sequence, and is reflected to the central axis by the second right-angle prism and reaches the cam zoom lens assembly.

[0018] Furthermore, it also includes an inner cylinder, which is arranged in the outer cylinder, the laser speckle assembly is arranged in the inner cylinder, and the inner cylinder is fixedly connected to the cam zoom lens assembly.

[0019] Furthermore, it also includes a lens seat, which is threadedly connected to the inner cylinder, and the laser source, beam expander, first right-angle prism, field of view splitting inverted system, third prism, and second right-angle prism are respectively arranged on the lens seat.

[0020] Furthermore, it also includes a motor base, which is arranged in the inner cylinder; the motor base includes a first bracket and a first fixing member, the first fixing member is parallel plates arranged opposite to each other, the motor is horizontally arranged between the parallel plates, and a slit is provided on the first bracket.

[0021] Furthermore, the cam zoom lens assembly includes a front fixed lens group, a zoom lens group, a compensation lens group, and a rear fixed lens group. The zoom lens group and the compensation lens group together constitute an equivalent concave lens, and the front fixed lens group and the rear fixed lens group are both convex lenses.

[0022] Furthermore, it also includes a zoom group barrel, a compensation group barrel, and a cam; the zoom group lens is installed in the zoom group barrel, and the compensation group lens is installed in the compensation group barrel; the cam includes an inner cam and an outer cam, the inner cam is mounted on the zoom group barrel and the compensation group barrel, and the outer cam is rotatably mounted on the inner cam, the inner cam is provided with a linear guide groove, and the side wall of the outer cam is provided with a zoom guide groove and a compensation guide groove.

[0023] Furthermore, it also includes a zoom motor and gears; a zoom group pin is fixed on the zoom group barrel, and the zoom group pin passes through the linear guide groove of the inner cam and the zoom guide groove of the outer cam; a compensation group pin is fixed on the compensation group barrel, and the compensation group pin passes through the linear guide groove of the inner cam and the compensation guide groove of the outer cam; the zoom motor drives the outer cam to rotate through the gears, and the outer cam drives the zoom group pin to move in the zoom guide groove and the compensation group pin to move in the compensation guide groove, thereby driving the zoom group lens and the compensation group lens to move along the optical axis, thereby completing continuous zoom of the optical system.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The portable vision testing device provided by this utility model is based on the principle of laser speckle optometry. By adjusting the focal length of the cam zoom lens assembly to change the imaging pattern of laser speckle on the human retina, it helps the subject to judge their own eye vision. It is simple and reliable, and does not require the patient to distinguish the clarity of the image.

[0026] 2. The utility model is provided with a third prism, which can measure not only myopia and hyperopia, but also astigmatism, and is easy to use;

[0027] 3. The vision detection device provided by the utility model has a compact structure, small size, light weight and is easy to carry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic structural diagram of a portable vision detection device according to an embodiment of the present invention;

[0029] Figure 2 This is a light path diagram in the embodiment provided by the utility model;

[0030] Figure 3 This is a schematic structural diagram of the inner and outer cams in the embodiment provided by the present utility model.

[0031] In the figure, 1. outer cylinder; 2. laser source; 3. beam expander; 4. first right-angle prism; 5. diffuse reflection disk; 6. slit; 7. field-splitting inverting system; 8. third prism; 9. second right-angle prism; 10. motor; 11. inner cylinder; 12. lens holder; 13. motor holder; 14. front fixed lens group; 15. zoom lens group; 16. compensation lens group; 17. rear fixed lens group; 18. outer cam; 19. zoom guide groove; 20. compensation guide groove. DETAILED DESCRIPTION

[0032] Laser is a near-coherent light. When laser is projected onto a rough surface or a surface with an uneven refractive index distribution, the human eye can see a granular speckle distribution. Laser speckle refers to this type of speckle pattern, which carries relevant information about the rough surface.

[0033] The laser speckle phenomenon, combined with a zoom system, can be used to detect the degree of refraction in the human eye. If a coherent source is observed in a circular area on the edge of a slowly rotating diffuse reflector 5, a moving speckle pattern is generated on the patient's retina. The speed of the speckle pattern is determined by the distance between the plane of the diffuse reflector 5 and the focal plane of the eye. In myopia, the speckle pattern moves in the same direction as the rotation of the ground glass disk 2; in hyperopia, the opposite movement is observed. If the point light source is axially adjusted until it is conjugate with the retinal plane, the speckle pattern will not move in any direction regardless of the speed or axial position of the diffuse reflector 5. This is the basic principle of laser speckle optometry. Specifically, when the ciliary muscle is in a relaxed state and the diffuse reflector 5 is stationary, laser speckle is visible to emmetropes, hyperopes, and myopes, but the speckle particle size varies significantly. When the diffuse reflector 5 is in motion, the speckle pattern moves in different directions for emmetropes, hyperopes, and myopes. Using laser speckle to measure the refractive power of the human eye is a relatively accurate way of optometry.

[0034] like Figure 1-3 As shown, the portable vision detection device provided by the present invention includes:

[0035] An outer cylinder 1, wherein a laser speckle assembly and a cam zoom lens assembly are provided in the outer cylinder 1;

[0036] The laser speckle assembly includes a laser source 2, a beam expander 3, a diffuse reflection disk 5, a slit 6, a field of view splitting and inverting system 7, and a radially rotating third prism 8, which are arranged in sequence; the diffuse reflection disk 5 is driven by a motor 10 to rotate around its own central axis; and the third prism 8 rotates the incident light beam.

[0037] Among them, the laser source 2 emits a laser, and the laser forms a laser speckle after passing through the diffuse reflection disk 5. The slit 6 is arranged on one side of the motor 10 and corresponds to the position of the laser speckle. Setting the slit 6 on one side of the motor 10 can reasonably utilize the internal space of the outer cylinder 1, and the structure is compact, thereby reducing the volume of the vision detection device.

[0038] The field of view splitting and inverting system 7 and the third prism 8 are coaxially arranged with the slit 6. The laser speckle forms diffraction stripes after passing through the slit 6. The diffraction stripes are transformed into two groups of stripes with opposite movement directions after passing through the field of view splitting and inverting system 7. The two groups of stripes pass through the radially rotating third prism 8 and reach the cam zoom lens assembly, and finally reach the fundus retina.

[0039] As for laser source 2, considering that high-power lasers can damage the human eye, only a micro-power laser source 2 can be used. Specifically, a helium-neon laser can be used. The helium-neon laser emits 0.5-1mW of laser light. The laser speckle produced by this helium-neon laser is classified as a surface light source, and the power entering the eye is classified as Class I laser, which will not cause damage to the eye. Even considering that unexpected situations such as damage to the helium-neon laser may prevent the laser from producing speckle, the laser light emitted by the helium-neon laser after passing through optical devices such as the beam expander 3 and entering the eye is still a Class II laser. Short-term direct viewing will not cause damage to the eyes, and people will instinctively avoid it, ensuring absolute eye safety.

[0040] like Figure 2 As shown, the beam expander 3 can, on the one hand, expand the laser beam emitted by the laser source 2, so as to facilitate the division of the field of view after forming speckles through the diffuse reflection disk 5, and on the other hand, reduce the energy of the laser beam to prevent damage to the eyes.

[0041] The diffuse reflector 5 can be any object with a rough surface, specifically a frosted glass disk. To prevent significant laser light loss from the frosted glass disk while maintaining structural rigidity, its thickness should be within a reasonable range, typically 1 mm to 5 mm. Because a micropower laser source 2 is used, a 2 mm thick frosted glass disk is preferably used to minimize laser power loss while effectively generating distinct laser speckle patterns.

[0042] The field of view splitting inverting system 7 is formed by coupling a first prism and a second prism, which can be a square prism and a trapezoidal prism. The first prism and the second prism have different refractive indices. When the light path enters from one end, it will be reflected multiple times inside the coupled prism, and the emitted light will be divided into two parts, upper and lower parts.

[0043] To rotate the incident light beam, the third prism 8 can be a radially rotating dove prism or a pair of radially rotating triangular prisms. A dove prism is preferred due to its simple structure. The dove prism has the following optical characteristic: when it rotates by an angle α about its optical axis, the reflected image rotates by 2α in the same direction. Therefore, a 45° rotation of the dove prism rotates the reflected image by 90°, enabling detection of astigmatism along all meridians.

[0044] In order to make this design more convenient, the light path needs to be refracted and reflected to reduce the structural volume. In addition, since this device is an optical precision instrument, multiple reflections on the silver surface and glass surface of the plane mirror will produce more interfering stray light and aberrations, so a plane mirror cannot be used and a prism must be used. Therefore, a second right-angle prism 9 can be used to refract and reflect the light path. The second right-angle prism 9 is arranged between the third prism and the cam zoom lens assembly.

[0045] In a specific embodiment, the laser source 2 is arranged on the upper side or the lower side of the outer cylinder 1, and the position of the beam expander 3 corresponds to the position of the laser source 2. The laser source 2 emits a laser, which is irradiated on one side of the diffuse reflection disk 5 to form a laser speckle. The laser speckle passes through the slit 6, the field of view splitting and inverting system 7, and the third prism 8 in sequence, and is reflected to the central axis by the second right-angle prism 9 and reaches the cam zoom lens assembly.

[0046] In another embodiment, a first right-angle prism 4 is further included, and the first right-angle prism 4 is arranged between the beam expander 3 and the diffuse reflection disk 5. The laser source 2 is arranged on the central axis of the outer cylinder 1. The laser source 2 emits a laser, and the optical path is changed by the first right-angle prism 4 to one side of the diffuse reflection disk 5, thereby forming a laser speckle. The laser speckle passes through the slit 6, the field of view splitting and inverting system 7, and the third prism 8 in sequence, and is then reflected to the central axis by the second right-angle prism 9 and reaches the cam zoom lens assembly.

[0047] The portable vision detection device further includes an inner cylinder 11 disposed in the outer cylinder 1 , the laser speckle assembly is disposed in the inner cylinder 11 , and the inner cylinder 11 is fixedly connected to the cam zoom lens assembly.

[0048] It also includes a lens seat 12, which is threadedly connected to the inner cylinder 11. The laser source 2, beam expander 3, first right-angle prism 4, field of view splitting and inverting system 7, third prism 8, and second right-angle prism 9 are respectively arranged on the lens seat 12.

[0049] In order to rationally utilize the space of the inner cylinder 11, a motor base 13 is also included, which is arranged in the inner cylinder 11; the motor base 13 includes a first bracket and a first fixing member, the first fixing member is a parallel plate arranged opposite to each other, and the motor 10 is horizontally arranged between the parallel plates. A slit 6 is provided on the first bracket, and specifically, the first bracket itself may include a narrow and elongated slit hole, and the laser speckle is formed into diffraction stripes through the slit 6.

[0050] Another key design feature of this device is the cam zoom lens assembly, which directly impacts the accuracy and repeatability of visual acuity measurement. This assembly achieves a clear and stable image by changing the positions of several lens groups. The cam zoom lens assembly includes a front fixed lens group 14, a zoom lens group 15, a compensating lens group 16, and a rear fixed lens group 17. The zoom lens group 15 and the compensating lens group 16 form an equivalent concave lens, while both the front fixed lens group 14 and the rear fixed lens group 17 are convex lenses. By separating the zoom lens group 15 and the compensating lens group 16 into two parts, which together form an equivalent concave lens, the weight of the concave lens can be reduced and the strength of the concave lens can be increased.

[0051] The vision detection device is designed based on a mechanical compensation zoom system, which only uses mechanical means to achieve the relative movement of the zoom group and the compensation group. The movement requirement is that the sum of the changes in the conjugate distances of the object and image is equal to zero, so that the object and image can be kept stable. In order to achieve this, the portable vision detection device also includes a zoom group barrel, a compensation group barrel, a cam, a zoom motor and a gear; the zoom group lens 15 and the compensation group lens 16 are respectively installed in the zoom group barrel and the compensation group barrel; the cam includes an outer cam 18 and an inner cam, the outer cam 18 is rotatably mounted on the inner cam, and the inner cam is mounted on the zoom group barrel and the compensation group barrel, and the zoom group barrel and the compensation group lens A zoom group pin and a compensation group pin are fixed on the barrel respectively; the side wall of the outer cam 18 is provided with a zoom guide groove 19 processed according to the curve of the outer cam 18 of the zoom group, and a compensation guide groove 20 processed according to the curve of the outer cam 18 of the compensation group; the zoom group pin passes through the linear guide groove of the inner cam and the zoom guide groove 19 of the outer cam 18, and the compensation group pin passes through the linear guide groove of the inner cam and the compensation guide groove 20 of the outer cam 18; the zoom motor drives the outer cam 18 to rotate through the gear, and the outer cam 18 drives the zoom group pin and the compensation group pin to move in the guide grooves of the outer cam 18 and the inner cam, thereby driving the zoom group lens 15 and the compensation group lens 16 to make corresponding movements along the optical axis, completing continuous zoom of the optical system.

[0052] Similar to the method of correcting myopia with glasses, this device also corrects vision through a zoom lens group until the patient sees a fixed laser spot. The focal length value at this moment is output and converted into the eye's diopter value. The conversion formula is as follows:

[0053]

[0054] Where D represents the diopter and f represents the real-time focal length of the lens.

[0055] In summary, the parameters of the cam zoom lens assembly are set as shown in Table 1:

[0056] Table 1 Cam zoom lens assembly parameters

[0057]

[0058] When the focal length f is 50mm, D = 1 / d = 1 / 0.05 = 20D = 2000 degrees; when the focal length f is 400mm, it is equivalent to parallel light entering the human eye, which can be approximately considered to be 0 degrees. Using formula (1-1) and the requirement that the object-image distance is the same, the motion trajectory of the compensation lens group 16 can be calculated. A MATLAB mathematical model is further established to obtain the motion trajectory fitting function of the zoom lens group 15 and the compensation lens group 16:

[0059]

[0060] Wherein, q1 is the rotation angle of the cam tube 12, y1 is the moving distance of the zoom group, and y2 is the moving distance of the compensation group.

[0061] The horizontal movement of the zoom lens group 15 and the compensation lens group 16 is controlled by rotating the external cam 18. Figure 3 As shown in the figure, a schematic diagram of the outer cam 18 is provided with a zoom guide groove 19 and a compensation guide groove 20. The lift angle of the zoom lens group 15 refers to the angle between the side of the zoom guide groove 19 and the vertical line. Similarly, the lift angle of the compensation lens group 16 refers to the angle between the side of the compensation guide groove 20 and the vertical line. The range of the lift angle is affected by the torque of the zoom motor and the friction coefficient of the contact surface. The larger the friction coefficient, the smaller the range. The larger the lift angle, the negative effect is that it greatly increases the load on the zoom motor and increases the friction between the zoom group pin and the zoom guide groove 19, and the friction between the compensation group pin and the compensation guide groove 20. Increasing the width of the curved groove 13 (i.e., extending the curve as much as possible in length) can reduce the curve lift angle or pressure angle, but this will cause the cam structure rigidity to decrease significantly, which is not conducive to ensuring design accuracy. Too small a width will make the lift angle too large, which is also disadvantageous. Therefore, taking various factors into comprehensive consideration, the zoom lens group with a 15° rise angle and the compensation lens group with a 16° rise angle are selected between 15° and 30°.

[0062] like Figure 2 As shown, the working principle of the portable vision detection device is:

[0063] A helium-neon laser emits a 0.5-1 mW laser beam, which is expanded by a beam expander 3. The laser beam is then reflected by a first right-angle prism 4 and irradiated onto a diffuse reflector 5. After passing through the diffuse reflector 5, the laser light forms a laser speckle pattern that moves in one direction. This moving speckle pattern then passes through a slit 6, forming diffraction fringes that move in a certain direction. These fringes then pass through a field-of-view splitting and inverting system 7, consisting of two prisms, where they are divided into two sets of fringes moving in opposite directions, upper and lower. These two sets of fringes then pass through a radially rotatable third prism 8 and are reflected by a second right-angle prism 9 before reaching a cam zoom lens assembly and ultimately the retina. For myopia and hyperopia, when the laser focus is centered on the retina, the eye perceives two stationary fringes, upper and lower. If the focus is not centered, the patient sees two sets of fringes moving in opposite directions. The cam zoom lens assembly can then be adjusted until the patient can see the two stationary fringes. For the measurement of astigmatism, the third prism 8 needs to be activated. The third prism 8 can change the meridian angle between 0 and 180 degrees to measure the two extreme values ​​of the refractive power of the astigmatism eye on the corneal meridian, and the difference is the astigmatism degree.

[0064] In principle, the portable vision testing device provided by the utility model is based on the principle of laser speckle optometry. It changes the imaging pattern of laser speckle on the human retina by adjusting the focal length of the cam zoom lens assembly, thereby helping the subject to judge his or her own eye vision. It is simple and reliable, and does not require the patient to distinguish the clarity of the image. In addition to measuring myopia and hyperopia, it can also measure astigmatism, making it easy to use.

[0065] In terms of specific structure, the vision detection device provided by the present invention deflects the light path through the first right-angle prism 4 and / or the second right-angle prism 9, so that the laser can pass through the diffuse reflection disk 5, the slit 6, the field of view splitting inverting system 7 and the third prism 8, and can further deflect the light path to near the central axis so that the light path passes through the cam zoom lens assembly, which can reasonably utilize the internal space of the outer cylinder 1; the slit 6 is set on one side of the motor 10, and the structure is compact; the magnification lens group 15 and the compensation lens group 16 are also divided into two parts, and the magnification lens group 15 and the compensation lens group 16 together form an equivalent concave lens, which can reduce weight and improve strength; in summary, the vision detection device provided by the present design has a compact structure, light weight, and is portable, which is convenient for the viewer to complete real-time vision detection.

[0066] Finally, it should be noted that the above content is only used to illustrate the technical solution of the utility model, rather than to limit the scope of protection of the utility model. Simple modifications or equivalent replacements of the technical solution of the utility model by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the utility model.

Claims

1. A portable vision testing device, characterized in that: include an outer cylinder, wherein a laser speckle assembly and a cam zoom lens assembly are disposed in the outer cylinder; The laser speckle assembly includes a laser source, a beam expander, a diffuse reflection disk, a slit, a field of view splitting and inverting system, and a radially rotating third prism which are arranged in sequence; The diffuse reflection disk is driven by a motor to rotate around its own central axis; The third prism rotates the incident light beam; The laser source emits a laser, which forms a laser speckle after passing through a diffuse reflection disk. A slit is provided on one side of the motor and corresponds to the position of the laser speckle. The field of view splitting and inverting system and the third prism are coaxially arranged with the slit. The laser speckle forms diffraction stripes after passing through the slit. The diffraction stripes become two groups of stripes with opposite movement directions after passing through the field of view splitting and inverting system. The two groups of stripes pass through the radially rotating third prism and reach the cam zoom lens assembly, and finally reach the fundus retina.

2. The portable vision testing device according to claim 1, wherein: It also includes a second right-angle prism, which is arranged between the third prism and the cam zoom lens assembly.

3. The portable vision testing device according to claim 2, characterized in that: The optical system further includes a first right-angle prism, which is arranged between the beam expander and the diffuse reflection disk; the laser source is arranged on the central axis of the outer cylinder, and the laser source emits a laser, which changes the optical path through the first right-angle prism to one side of the diffuse reflection disk, forming a laser speckle. The laser speckle passes through the slit, the field of view splitting and inverting system, and the third prism in sequence, and is reflected to the central axis by the second right-angle prism and reaches the cam zoom lens assembly.

4. The portable vision testing device according to claim 2, wherein: The laser source is arranged on the upper side or the lower side of the outer cylinder, and the position of the beam expander corresponds to the position of the laser source. The laser source emits laser light, which is irradiated on one side of the diffuse reflection disk to form laser speckles. The laser speckles pass through the slit, the field of view splitting and inverting system, and the third prism in sequence, and are reflected to the central axis by the second right-angle prism and reach the cam zoom lens assembly.

5. The portable vision testing device according to claim 3, characterized in that: It also includes an inner cylinder, which is arranged in the outer cylinder. The laser speckle assembly is arranged in the inner cylinder, and the inner cylinder is fixedly connected to the cam zoom lens assembly.

6. The portable vision testing device according to claim 5, characterized in that: It also includes a lens seat, which is threadedly connected to the inner cylinder. The laser source, beam expander, first right-angle prism, field of view splitting and inverting system, third prism and second right-angle prism are respectively arranged on the lens seat.

7. The portable vision testing device according to claim 5, characterized in that: It also includes a motor base, which is arranged in the inner cylinder; the motor base includes a first bracket and a first fixing member, the first fixing member is parallel plates arranged opposite to each other, the motor is horizontally arranged between the parallel plates, and a slit is provided on the first bracket.

8. The portable vision testing device according to claim 1, wherein: The cam zoom lens assembly includes a front fixed lens group, a zoom lens group, a compensation lens group, and a rear fixed lens group. The zoom lens group and the compensation lens group together form an equivalent concave lens, and the front fixed lens group and the rear fixed lens group are both convex lenses.

9. The portable vision testing device according to claim 8, characterized in that: It also includes a zoom group barrel, a compensation group barrel, and a cam; the zoom group lens is installed in the zoom group barrel, and the compensation group lens is installed in the compensation group barrel; the cam includes an inner cam and an outer cam, the inner cam is sleeved on the zoom group barrel and the compensation group barrel, and the outer cam is rotatably sleeved on the inner cam, the inner cam is provided with a linear guide groove, and the side wall of the outer cam is provided with a zoom guide groove and a compensation guide groove.

10. The portable vision testing device according to claim 9, characterized in that: It also includes a zoom motor and gears; a zoom group pin is fixed on the zoom group barrel, and the zoom group pin passes through the linear guide groove of the inner cam and the zoom guide groove of the outer cam; a compensation group pin is fixed on the compensation group barrel, and the compensation group pin passes through the linear guide groove of the inner cam and the compensation guide groove of the outer cam; the zoom motor drives the outer cam to rotate through the gears, and the outer cam drives the zoom group pin to move in the zoom guide groove and the compensation group pin to move in the compensation guide groove, thereby driving the zoom group lens and the compensation group lens to move along the optical axis, thereby completing continuous zoom of the optical system.

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