CN112697395A

CN112697395A - Method and device for measuring vision degree value

Info

Publication number: CN112697395A
Application number: CN202011310054.XA
Authority: CN
Inventors: 吴洁明; 包锡锋; 吴冠洲; 徐艳; 胡鹏程; 张嘉; 俞菊英
Original assignee: JIANGSU NORTH HUGUANG OPTICS ELECTRONICS CO Ltd
Current assignee: JIANGSU NORTH HUGUANG OPTICS ELECTRONICS CO Ltd
Priority date: 2020-11-20
Filing date: 2020-11-20
Publication date: 2021-04-23

Abstract

The invention discloses a method and a device for measuring a vision value, and belongs to the technical field of photoelectric measurement. The method and the device for measuring the vision value mainly apply the technology of automatically tracking the image surface of the CCD camera to measure the displacement of the last image surface of the optical system relative to the focus of the image space, and according to the formula between the vision value and the displacement:

the digital signal of the grating ruler is adopted to establish computer program and numerical control software and hardware, and the automatic detection and calibration of the ocular vision value of the product to be detected are realized.

Description

Method and device for measuring vision degree value

Technical Field

The invention relates to the technical field of photoelectric measurement, in particular to a method and a device for measuring a vision value.

Background

On the assembly line of telescope mass production, the visual degree value and the visual degree scope of the eyepiece of telescope are detected or are markd to the visual degree section of thick bamboo commonly used, receive the restriction of people's eye fatigue, and artifical measuring speed is slow moreover, the error is big, can not adapt to the quick production operation of assembly line, for this reason we have designed an instrument that can automatic tracking image plane realize automatic measure visual degree, automatic display visual degree value and have replaced artifical the detection.

In the digital image display of the CCD camera, the positional relationship between the imaging CCD photosurfaces after the light beam enters the CCD camera objective lens is as shown in fig. 1,

if the parallel light enters the CCD camera objective and the object space position is infinite, the imaging position is on the focal point of the objective, such as the F' position of the figure, namely the ideal position where the CCD photosensitive surface is supposed to be, and the photosensitive signal is converted into a digital display signal; if the object space position is at the point P instead of the parallel light entering the CCD camera lens, the focal point of the lens is not the clearest image surface at the position P' after being imaged by the camera lens. It can be seen that the image position changes by x' from parallel light to non-parallel light, where parallel light is 0 diopter; the convergent light is the front visibility; the divergent light is the negative diopter;

the technology of automatically tracking the image plane in the modern technology is mature, wherein one mode is to use the photosensitive surface of the CCD to track the clearest image plane, and the CCD photosensitive surface can automatically track the clearest image plane on the optical axis and stay at the position of the clearest image plane regardless of whether parallel light enters the objective lens of the CCD camera or not. This is of course achieved with corresponding hardware drives, displacement sensors, and control of software program models. The technology for automatically tracking the image surface position controls the driving mechanism through a computer program, so that the photosensitive surface of the CCD can also move back and forth along the direction of the guide rail along with the driving mechanism, namely the photosensitive surface of the CCD moves back and forth along the direction of the optical axis until the clearest image surface is found, and the photosensitive surface of the CCD can stop at the clearest image surface position. The principle of the method for automatically tracking the clearest image surface position is as follows:

focusing is a key technology for ensuring that images recorded by the photosensitive device obtain a clear effect. The focusing mechanism adjusts the distance between the camera lens and the photosensitive device, so that the image plane is the surface of the photosensitive device. The automatic focusing is that the lens is moved back and forth to a corresponding position by a focusing mechanism according to the distance of a shot object, so that the shot object is automatically and clearly imaged. Before discussing the auto-focus problem of digital cameras, it is necessary to present an optical imaging system model. A typical optical imaging system model is given in fig. 2 below:

where P is a point on the subject and P' is an image formed by P. The lens which can not generate aberration during imaging has two characteristics:

1. the energy of the object point P and the energy of the image point P' are in a certain proportional relation, and the intensity of the point light source is increased according to a certain proportion, so that the lens can be regarded as a two-dimensional linear system;

2. the positional relationship of the object point P and its image point P' can be expressed as the equation:

f is the focal length of the lens, and u and v are the object distance and the image distance respectively;

s, f, D are collectively referred to as imaging parameters, with vector e;

e represents:

e＝(s,f,D)。

if the camera system can not focus accurately, the image formed by the object point P is a light spot P', and the shape of the light spot P is the same as that of the aperture of the camera system; if the object point P is in focus, the size of the imaging spot is minimal. If the aperture of the camera is circular, when the point light source can not be focused accurately, a fuzzy circle P' with the radius of R is formed on the image sensor, and the brightness inside the circle is uniform while the brightness outside the circle is zero. R may be represented as:

for a discrete image, the blur radius is: σ ═ cR (σ is in units of pixel points), c > 0, a camera constant, determined during camera calibration. At different lens positions, there are:

when the object distance is changed, the focal length is not changed, and the position where a clear image is obtained is changed accordingly, i.e., S is changed. There are two ways of adjustment:

1. the lens position is changed to achieve the aim of clear imaging, but the change of magnification can be caused;

and 2, determining s by N, and adjusting the position of the object plane along the optical axis to enable the object plane to reach the object distance required by the design, so that the method is mainly used for precision instruments. To obtain a clear image, P and P "are completely overlapped, and the optical imaging system is in focus, which can be realized by an automatic focusing technique.

The key to all-digital autofocus is to determine the point spread function PSF of the image. If P is not in full focus, it will form a blurred image P "on the image sensor. Let the incident energy of P be unit energy 1, then P "is the impact response of the system to unit energy, i.e. the point spread function PSF of the camera system, and is denoted as ha (x, y), and q is defined as 2R/D; according to the theorem of similar triangles:

by

To obtain

Substitution to obtain

Thus, the fuzzy circle radius R is:

obviously, R is a function with respect to the object distance u and the camera parameter e, denoted as R (e, u). Thus, the point spread function PSF of the system can be obtained

The Fourier transform form is as follows:

wherein, J₁The first order Bessel function is that of the first order,

in addition to the PSF determination methods described above, there are other methods to determine the PSF of the system. Firstly, an input image is divided into a plurality of image blocks, the image blocks are divided into different sets according to different boundary information of lines, then a two-dimensional point spread function PSF of the whole image is deduced according to a step response function of each set, and finally a restored image is reconstructed according to the obtained PSF, so that a clear focusing image is obtained. The implementation of this method is given in fig. 3 below.

Disclosure of Invention

The invention aims to provide a method and a device for measuring a vision value, which realize automatic measurement of the vision value by utilizing an automatic tracking technology of an image surface.

In order to solve the above technical problems, the present invention provides a method for measuring a diopter, which is based on a functional relation between a displacement x' of an objective lens image focus of a detection system relative to an actual image surface position of an optical system to be measured and a diopter SD:

firstly, x 'is obtained by measurement, then SD can be obtained, wherein f and f' are the object space focal length and the image space of the detection systemThe focal length, which is a known value and is equal, x 'is the distance that the actual image plane deviates from the image-side focal point F'.

Optionally, x 'is a displacement x' of a position of a clearest image plane and a focal length position of an objective lens of the detection system, which is automatically tracked by using a photosensitive surface of the CCD camera, and an SD value is obtained by calculation.

Optionally, the image plane displacement x' is measured by a grating ruler or other high-precision displacement sensors, and the motor mechanism is controlled by control software programmed by a point spread function PSF to drive the CCD photosensitive surface to move, so as to realize automatic detection and display of the vision value SD.

The invention also provides a device for measuring the vision value, which comprises an illumination light source, a product tool, a detection system and an operation display system, wherein the illumination light source consists of a central point light source and other uniform surface light sources; the product tool has the function of azimuth pitching fine adjustment; the detection system consists of a CCD camera objective, a CCD device, a precise displacement guide rail and a grating ruler, wherein the CCD is arranged on the precise displacement guide rail; further comprising, based on the functional relationship:

and control software compiled by a point spread function PSF required by the photosensitive surface of the CCD device to automatically track the image surface; the control software has a friendly human-computer interface, and the operation parameters are input through the interface, so that parameter setting, action instruction control, data and image display are realized, and all modules are controlled to run coordinately; the operation display system is composed of an industrial computer, a control module, an image processing module, a driver, an operation display module and the like, an industrial personal computer is used as a host, interfaces between the modules and the host are communicated, the CCD is moved along the direction of an optical axis through program control, and the vision value SD is displayed.

Optionally, the CCD camera lens is a high-definition, distortion-free fixed-focus imaging lens with a focal length of 50mm and a caliber of 40 mm; the CCD adopts a 500W pixel camera; the visibility recognition or calibration range is: the distance between the corresponding object space and the focus is-16.66 to 10mm, and the guide rail travel is more than 26.66 mm.

Optionally, the used hill-climbing search method program and the corresponding grating ruler control the motion of the CCD photosensitive surface to automatically track the image surface, and the precision of the object distance is 0.12mm, and the precision of the guide rail is less than 0.12mm, so that the visibility recognition precision can be realized: 0.05D.

Optionally, a guide rail parameter stroke of 35mm and a grating ruler corresponding to the precision are selected, and corresponding parameter setting of a hill climbing search method program is configured, so that the minimum displacement of 0.01mm and the precision of 0.005mm are realized

The invention provides a method and a device for measuring a vision value, which mainly apply the technology of automatically tracking an image surface of a CCD camera to measure the displacement of the actual image surface position of a measured optical system relative to an image focus, and according to a formula between the vision value and the displacement:

the automatic detection instrument adopts a grating ruler and a CCD (charge coupled device) to carry out signal acquisition, adopts program control as a judgment basis, and adopts a motor and a guide rail to execute signal feedback.

Drawings

FIG. 1 is a schematic diagram of the positional relationship between the imaging of the camera lens and the CCD photosurface provided by the invention;

FIG. 2 is a model of an optical imaging system provided by the present invention;

FIG. 3 is a flow chart of a search implementation of image contrast provided by the present invention;

figure 4 is a diagram of the composition and layout of the complete device provided by the present invention,

wherein: 1 an illumination light source; 2, product tooling; 3, detecting a system; 4 operating the display system;

FIG. 5 is a pattern of illumination sources provided by the present invention;

FIG. 6 is a block diagram of a detection system provided by the present invention;

FIG. 7 is a block diagram of an operation display system provided by the present invention;

FIG. 8 is an interface of control software provided by the present invention;

FIG. 9 is a schematic diagram of a hill-climbing search method provided by the present invention;

fig. 10 is a flowchart of the rough and fine combined hill-climbing search algorithm provided by the present invention.

Detailed Description

The method and apparatus for measuring a visual acuity value according to the present invention will be described in detail with reference to the accompanying drawings and embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

The automatic measurement of the visual degree value of the optical system implemented by the invention is based on the functional relation between the image surface movement amount and the visual degree, and the visual degree value can be calculated by measuring the image surface movement amount. As shown in fig. 1, the formula between the axial displacement x' of the CCD photosurface and the vision value SD of the product to be measured is based on the focal length of the CCD camera objective and the clearest image plane automatically tracked by the CCD camera:

corresponding software and hardware are configured to realize automatic measurement of the vision value of the emergent light beam of the optical system, wherein f' is the focal length of an objective lens of the CCD camera, is measured and recorded by the system and is a known value; and x' is the displacement of the incident beam in non-parallel state to the focus of the CCD camera lens via the image forming plane of the camera lens.

When the focal length of the camera system is fixed, the movement x' of the CCD photosensitive surface relative to the focal plane is measured, and then the vision value of the product can be obtained.

The technology of automatically tracking the image surface is applied to the technical effect of the visibility measurement: the speed is fast, the precision is high, the manpower is saved, and the requirement in mass production can be met.

The automatic detection device for the visibility value, as shown in the following fig. 4, comprises an illumination light source 1 and a product tool2. The detection system 3 and the operation display system 4 further comprise a function relation based:

and control software programmed with the point spread function PSF as described above.

Wherein, the constitution function of product frock 2: as shown in fig. 4, the tooling is customized according to the actual product, and has the function of azimuth pitching fine adjustment.

The illumination light source 1 includes contents and functions thereof: the illumination source shown in fig. 5 is composed of a central point light source and the rest of uniform surface light sources. The uniform surface light source provides illumination for the division of the eyepiece, and the central point light source provides indicating laser for the rough alignment of the optical axis and the detection of the product.

Composition and function of the detection system 3: the detection system 3 shown in fig. 6 is composed of an objective lens, a CCD, a precision displacement guide rail and a grating ruler (or the like for recording displacement). The objective lens can also be a high-definition and distortion-free fixed-focus imaging lens, the focal length can be 50mm, the caliber can be 40mm and the like, and a matched CCD objective lens can be selected according to the actual product to be detected; the CCD component can be 500W pixel.

Composition and function of the operation display system 4: the operation display system 4 shown in fig. 7 is composed of an industrial computer, a control module, an image processing module, a driver, an operation display module, and the like, and an industrial personal computer is used as a host, and interfaces between the modules and the host are communicated to realize parameter setting and action instruction control.

Functions of the control software 5: the interface of the control software 5 shown in fig. 8 has a friendly man-machine interface, and through the interface, the operation parameters, the display data and the images can be input, so that the modules are controlled to operate in a coordinated manner, and the control software enables the test equipment to be intelligent.

The device for automatically detecting the visibility value in the present embodiment includes, in addition to the above-mentioned illumination light source 1, the product to be detected and product fixture 2, the detection system 3, and the operation display system 4, a function-based relation:

and control software programmed with the point spread function PSF as described above, the operation of the whole set of devices is as follows: the light beam coming out from the eyepiece of the product to be detected enters the CCD camera objective of the detection system 3 after the parallel light emitted by the illumination light source 1 passes through the product to be detected on the product tool 2, is received by the CCD photosensitive surface, then is converted into a digital signal and is transmitted to a computer, whether the clearest image is seen or not is judged by software, then a driving signal instruction is made, the motor mechanism drives the CCD photosensitive surface to move on a guide rail, the automatic tracking search of the whole set of device on the actual image surface is completed, the displacement with the focal length of the objective is finally measured, and the final vision value result is automatically displayed.

When parallel light beams enter the objective lens of the CCD camera, the photosensitive surface of the CCD stays on the focal plane of the objective lens of the camera, the position of the photosensitive surface of the CCD in the direction of the guide rail can be set at the moment, and the computer program can record the value of the grating ruler as an initial state; placing the tested product again, requiring the tested equipment, the CCD camera objective lens and the CCD photosensitive surface to be coaxial, enabling the illumination light source to enter the tested product, emitting out from the eyepiece direction, possibly still being parallel light, or not being parallel light, driving a motor mechanism according to control software compiled by a point spread function PSF, driving the photosensitive surface of the CCD device to automatically track the image surface position, recording the position value of the CCD photosensitive surface in the guide rail direction again by a grating ruler, calculating the relative movement amount, and enabling the program to be based on a function relation formula:

and calculating to display the measured vision value. The measuring mechanism comprises a grating ruler (or a displacement sensor or a stepping motor for recording steps), records the displacement of the CCD photosensitive surface and transmits a data signal to a computer, the driving mechanism consists of a motor and a guide rail, the actual imaging position is found on the premise that the camera lens and the CCD photosensitive surface are coaxial, the computer program calculates according to the obtained information, and the vision value is displayed on the operation display system 4.

In addition, the derivation process of the functional relation of the displacement of the image plane and the visibility is as follows:

as shown in the position relation between the CCD camera lens imaging and the CCD photosensitive surface in figure 1, the tested equipment, the CCD camera lens and the CCD photosensitive surface are coaxial, the CCD photosensitive surface can move in the axial direction to form an image surface adjustable camera system with the CCD camera lens, and the object image emitted by the tested equipment is shot in real time.

When the measured visibility is zero, the light beam entering the camera system through the measured equipment is parallel light, and at the moment, if the CCD photosensitive surface is moved to the position of the focal plane of the camera system, the clearest image can be formed. When the detected visibility is not zero, the light beam entering the camera system converges (the visibility is a positive value) or diverges (the visibility is a negative value), taking the convergence situation as an example, a point P 'behind an image focal plane is imaged, the point P' corresponds to a point P of an object point in front of an object focal plane, and at the moment, if the system needs to form the clearest image, the CCD photosensitive surface is moved to the plane where the point P 'is located from the focal plane, and the movement amount is x'; it is clear that the value of x' is related to the degree of convergence or divergence of the beam, reflecting the magnitude of the degree of visibility.

The same relation between the vision SD of the tested device and the shift x 'of the CCD photosensitive surface can be obtained by Newton's formula. According to the newton equation:

x·x'＝f·f'

and geometric relationship

x＝L-p₂+f'

Can obtain the product

Note that SD equals 1/L, and the close distance P2 between the exit pupil of the device under test and the CCD camera objective is omitted, resulting in

Wherein f' is the focal length of the camera system and has the unit of mm. X' is obtained by conversion of the formula (2).

Example one

The following describes a specific set of methods and apparatus for automatically detecting a visual acuity value, which are implemented based on the principles of the present invention, and are mainly used for the visual acuity recognition range of the eyepiece of an optical system: -5 to +5D, or zero of visibility detection and calibration. The automatic detection device for the visibility value is based on a formula according to the imaging relation of a CCD camera lens and the position relation between CCD photosurfaces as shown in figure 1:

a set of hardware and software to configure. According to this formula, the change x' of the imaging position after passing through the CCD camera objective lens is measured, and the visual value (degree of divergence or convergence), that is, the visual value of the objective lens, can be calculated. The CCD photosensitive surface can automatically track the image surface position of the CCD camera lens by the complete device, so that the image surface deviates from the focal length of the lens and is the displacement x'.

The device for automatically detecting the visibility value, as shown in fig. 4, comprises an illumination light source 1, a product tool 2, a detection system 3, an operation display system 4, and a function-based relational expression:

The lighting source 1 includes the following contents and functions: the illumination light source is composed of a point light source at the center and other uniform surface light sources, and is composed as shown in fig. 5. The uniform surface light source provides illumination for the division of the eyepiece, and the central point light source provides indicating laser for the rough alignment of the optical axis and the detection of the product.

The product tool 2 has the following composition functions: the tool is customized according to an actual product and has the function of azimuth pitching fine adjustment.

The detection system 3 comprises the following components and functions: the detection system shown in fig. 6 is composed of an objective lens, a CCD, a precision displacement guide rail and a grating scale. Wherein, the objective lens is a high-definition and distortion-free fixed-focus imaging lens with a focal length of 50mm and a caliber of 40 mm; the CCD adopts a 500W pixel camera; the grating ruler is used for measuring the displacement x' of the CCD photosensitive surface relative to the focal plane on the precise guide rail, and the vision value of the product can be obtained because the focal length of the camera system is fixed to be 50 mm.

Visibility recognition range of the present embodiment: -5 to +5D, corresponding to x-16.66 to 10mm, the guide travel needs to be > 26.66 mm; visibility recognition accuracy: 0.05D, corresponding to x of 0.12mm, and the precision of the guide rail is required to be less than 0.12 mm. The CCD is arranged on the precise displacement guide rail and moves along the direction of the optical axis through program control. The guide rail parameter stroke is 35mm, the minimum displacement is 0.01mm, and the precision is 0.005 mm.

The composition and function of the operation display system 4 are as follows: the operation display system shown in fig. 7 is composed of an industrial computer, a control module, an image processing module, a driver, an operation display module and the like, and an industrial personal computer is used as a host, and interfaces between the modules and the host are communicated to realize parameter setting and action instruction control.

The functions of the control software 5 are as follows: the interface of the control software 5 in fig. 8 is a friendly man-machine interface, through which the operation parameters, the display data and the images can be input to control the modules to operate coordinately, and the control software makes the testing device intelligent.

The program configured in the apparatus for automatically detecting a visual value of this embodiment is a hill-climbing search method for automatic focusing, and the search method is based on: the ideal sharpness evaluation function curve has a single peak, the peak position corresponds to the best focus position, and the evaluation curves are monotonically decreased on both sides of the peak. The search process is illustrated in fig. 9, where the arrow points to indicate the direction of the search.

When focusing is started, setting a focusing search direction and a larger step value, continuously acquiring two images in the same direction, processing the acquired images by the system, comparing two evaluation values if the calculated image definition evaluation values are R1 and R2, and if R1 is greater than R2, indicating that the climbing stage is in the stage and the search direction is correct, continuing to search in the direction; if R1< R2 indicates that the search direction is wrong, the focusing search direction should be changed and the search is continued. When the evaluation value of the image is smaller than that of the previous image for the first time, it is indicated that the focus position has passed, the search direction should be changed, and the search step size should be reduced. And repeating the steps, finally determining the optimal imaging position, and finishing the focusing search process.

The hill climbing search method is simple in principle and highest in feasibility in practical application, and therefore, the hill climbing search method is widely applied to engineering. However, the hill-climbing search method may be affected by a local extreme of the evaluation function curve, which may result in a decrease in focusing accuracy and even a failure in focusing. Therefore, it is necessary to improve the hill climbing method to reduce the interference of local extremum and improve the focusing accuracy.

The conventional hill climbing method determines a search direction by comparing sharpness evaluation values of a current frame and a previous frame. However, due to noise interference, the sharpness evaluation function curve is not an ideal smooth curve but has a plurality of local extrema, and the conventional hill climbing method is easy to fall into the local extrema and cannot search the focus position. Aiming at the problem, the hill climbing method is correspondingly improved, and a rough and fine combined two-section fast hill climbing search algorithm is provided. In the coarse adjustment stage, the vicinity of the focus position is searched by using a large step size of a Brenner function, and in the fine adjustment stage, the focus position is searched by using a small step size of a lifting wavelet transform function. When a searching process starts, continuously acquiring three images in the same direction, and performing definition evaluation by adopting a Brenner function, assuming that the calculated definition evaluation values are R1, R2 and R3 respectively, if R1< R2< R3, indicating that the focusing position is approaching, the searching direction is correct, and continuing to search in the direction; if R1R 2R 3 shows that the searching direction is opposite, the reverse searching is needed, and the searching step length is changed to be 3/4 in each reverse searching; if the conditions of R1> R2 and R2< R3 occur, the search should be continued under the influence of local noise; if the condition of R1< R2 and R2> R3 occurs, the focusing position is indicated to be passed, the focusing position is searched backwards, the fine adjustment stage is entered, the lifting wavelet transform function is adopted to carry out definition evaluation, the initial step size of the fine adjustment stage is about 1/3 of the step size of the coarse adjustment stage, the steps are repeated, and the searching step size is changed into 3/4 every time the searching direction is changed. Similarly, when the case of R1< R2 and R2> R3 occurs again, it is described that the focusing position has passed, and the search should be carried back, and the second fine adjustment stage is entered, and the step size becomes 1/3 of this step size until the case of R1< R2 and R2> R3 occurs, and the focusing ends. The focusing flow chart of the rough and fine combined hill climbing search algorithm is shown in fig. 10, wherein the variable Count represents the times of occurrence of R1< R2 and R2> R3.

The embodiment can realize that: 1) the system automatically focuses and looks for images, has automatic identification capability and does not need manual triggering; 2) the recognition success rate is not lower than 99.9%, and the time for recognizing a single eyepiece is not longer than 10 s; 3) the function of information input and reading is provided; therefore, the defect of manual detection is avoided, manpower is saved, and the production line can be fast, accurate and convenient.

The invention is created according to the formula:

and the automatic image surface tracking principle and the digital transmission of the image surface displacement signal are applied, the displacement x' of the image surface can be automatically measured, and the automatic detection of the vision value is realized through the calculation, the control and the display of a numerical control program. Of course, the method and principle of the invention can be used to manufacture digital optical bench and measure parameters of various optical systems such as parallax error.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims

1. A method for measuring a vision value is characterized in that according to a functional relation between a displacement x' of an objective lens image focus of a detection system relative to an actual image surface position of an optical system to be measured and a vision SD:

the SD can be obtained by measuring x ', wherein F and F' are the object focal length and the image focal length of the detection system, are known values, and are equal, and x 'is the distance of the image plane from the image focal point F'.

2. The method according to claim 1, wherein x 'is a displacement x' of the most clear image plane position and the focal length position of the objective lens of the detection system automatically tracked by the photosensitive surface of the CCD camera, and the SD value is calculated.

3. The method according to claim 2, wherein the image plane displacement x' is measured by a grating ruler or other high-precision displacement sensor, and the control software programmed by the point spread function PSF controls the motor mechanism to drive the CCD photosensitive surface to move, so as to realize the automatic detection and display of the vision value SD.

4. A device for the method for measuring the diopter value according to any one of claims 1 to 3, which is characterized by comprising an illumination light source, a product tool, a detection system and an operation display system, wherein the illumination light source consists of a central point light source and other uniform surface light sources, the uniform surface light sources provide illumination for an eyepiece division, and the central point light source provides indicating laser for roughly aligning the optical axis of the product with the detection; the product tool has the function of azimuth pitching fine adjustment; the detection system consists of a CCD camera objective, a CCD device, a precise displacement guide rail and a grating ruler, wherein the CCD is arranged on the precise displacement guide rail; further comprising, based on the functional relationship:

5. The device for measuring the diopter value according to the claim 4, wherein the CCD camera lens is a high-definition and distortion-free fixed-focus imaging lens, the focal length is 50mm, and the caliber is 40 mm; the CCD adopts a 500W pixel camera; the visibility recognition or calibration range is: the distance between the corresponding object space and the focus is-16.66 to 10mm, and the guide rail travel is more than 26.66 mm.

6. The device for measuring the visibility value according to claim 4 or 5, wherein the used hill-climbing search method program and the corresponding grating ruler are used for controlling the CCD photosensitive surface to automatically track the motion of the image surface, so that the visibility recognition precision can be realized when the precision of the object space distance is 0.12mm and the precision of the guide rail is less than 0.12 mm: 0.05D.

7. The apparatus for measuring a visual acuity value as claimed in claim 5, wherein the guide parameter travel of 35mm and the grating ruler corresponding to the precision are selected, and the corresponding parameter settings of the hill-climbing search method program are configured to achieve the minimum displacement of 0.01mm and the precision of 0.005 mm.