TW202033985A - Method and apparatus for measurement of a characteristic of an optical system - Google Patents

Abstract

Disclosed embodiments may include a device, system and method for providing a low cost device that can measure refractive errors very accurately via attachment to a smart phone. A disclosed device may use ambient light or a light source in simulating the cross cylinder procedure that optometrists use by utilizing the inverse Shack-Hartman technique. The optical device may include an array of lens lets and pinholes that will force the user to effectively focus at different depths. Using an optical device, in conjunction with a smart phone, the user first changes the angle of the axis until he/she sees a cross pattern (the vertical and horizontal lines are equally spaced). The user adjusts the display, typically using the controls on the smartphone, to make the lines come together and overlap, which corresponds to bringing the view into sharp focus, thus determining the appropriate optical prescription for the user.

Description

Method and device for measuring characteristics of optical system

This is a utility model application based on the Partial Continuation (CIP) of U.S. Patent Application 16/276,302 filed on February 14, 2019, and claims the priority of U.S. Patent Application 16/276,302, which is requested on October 17, 2016 The priority of the provisional patent application 62/409,276 filed is the CIP of the US patent application 15/491,557 filed on April 19, 2017. This application also claims the rights and priority of provisional patent application 62/813,488 filed on March 4, 2019. Related applications are incorporated herein by reference and become a part of this application.

If there is any conflict between the invention disclosure in the utility model application and the disclosure in the related application, the disclosure in the utility model shall prevail. In addition, the inventor incorporates by reference hard copies or electronic files of any and all patents, patent applications, and other documents cited or mentioned in this application.

This application includes material protected by copyright and/or trademark. The copyright and trademark owners do not object to any faxed public fax copy that appears in the Patent and Trademark Office files or records, but reserves all copyright and trademark rights in other respects.

The present invention generally relates to optometry and the evaluation of refractive errors of the human eye. More specifically, the present invention relates to the use of self-refraction for handheld consumer devices.

The disclosed embodiment can measure the refractive characteristics of the optical system by simulating the cross cylinder process used by the optometrist in the clinical environment. The optical system defined herein is not limited to the human eye and mechanical system, where refractive measurement can determine refractive errors. The disclosed embodiments may include extensions and improvements to the method described in Pamplona et al.'s published patent application US2013/0027668A1, which discloses a low-cost device that can use a smartphone as a light source to measure refractive errors. However, the methods and devices described in the prior art are limited to an optical system composed of a single multi-lens array or pinhole array, and are neither as accurate and easy to use as the embodiments described herein, nor are they economical. Therefore, there is a need in the art for a new system and method that can measure the refractive characteristics of an optical system using a ubiquitous smartphone.

The system and method disclosed in the present invention include the method of using the reverse Shack-Hartmann technology to simulate or replicate the cross cylinder inspection of the optometrist. The disclosed systems and methods include various improvements, such as the accuracy and usability of the reverse Shack-Hartmann technique. The light input of the disclosed device can originate from a smartphone, personal electronic device or other optical system, where the user will see through the other end of the device two parallel lines (such as a green and a certain distance d) separated by a specific distance d (see Figure 1). One red). These lines can be generated from the screen of a smartphone. With the high resolution provided by today’s smartphones (for example, the iPhone 6 has a screen resolution of 326 dpi, which corresponds to a pixel interval of about 78 microns), if entities such as the focal plane or human retina are used, the optical displacement or error can be measured. High-resolution measurement. After the light passes through the optical system, two lines are formed on the imaging plane (see Figures 1 and 2), and in a specific embodiment, due to the expected coma in the described system, as shown in Figure 3. The two lines have "tails". The coma or coma aberration in the optical system is the inherent aberration of some optical designs, or it is caused by the distortion of the lens or other parts (causing off-axis point sources such as the pixels that form lines). Causes a tail like a comet (coma). Specifically, coma can be defined as the change in magnification on the entrance pupil. In refractive or diffractive optical systems, especially in optical systems that image images in a wide spectral range, coma can be a function of wavelength, in which case it is a form of chromatic aberration.

As shown in Figure 4, if the imaging system or the eye is tested for refractive errors, these lines will not be focused and separate. The imaging plane can be the retina of the eye or the sensor of a CCD camera. By changing the distance d between the two lines on the smartphone (see Figure 1), until the user feels a distance of zero or close to zero (see "Aligned Lines" in Figures 3 and 4), it is possible to evaluate whether there is flexion. The light is not right.

The distance between the small lens and the smartphone screen is D, which is equal to the focal length of each small lens. Therefore, after the incident light passes through the small lens, it becomes collimated and focused on the focal plane of the lens under test. If there is refractive error, as shown in Figure 4A, the red and green lines are separated on the imaging plane. If the distance d is changed by moving these lines on the screen, the position of the two lines on the imaging plane will also change. When two lines overlap on the imaging plane, the refractive error can be evaluated by the amount of change in the distance d.

The following detailed description is directed to certain specific embodiments of the present invention. However, the present invention can be embodied in many different ways defined and covered by the scope of rights and its equivalents. In this description, reference is made to the drawings, in which the same parts are always denoted by the same reference numerals.

Unless otherwise stated in this specification or the scope of rights, all terms used in the specification and the scope of rights shall have the meanings usually assigned to these terms by those skilled in the art.

Unless the context clearly requires otherwise, throughout the specification and the scope of rights, the words "including", "including", etc. should be understood as inclusive rather than exclusive or exhaustive meanings; that is, in a certain sense "including but not limited to". Words using the singular or plural number also include the plural or singular number respectively. In addition, when used in this application, the words "herein", "above", "below" and words of similar meaning shall refer to this application as a whole, rather than any specific part of this application.

The disclosed embodiments of the present invention can use the reverse Shack-Hartmann method and the process of simulating a cross cylinder, and many optometrists use this process to improve the accuracy of refractive errors.

The methods used by optometrists to accurately measure the refractive error of the patient include: Initially, the optometrist will make a rough estimate of the refractive error of the patient, and use a cross cylinder or equivalently to use Jackson's cross cylinder (Jackson's cross cylinder) to be accurate Determine the axis and the amplitude of astigmatism. Using this method, the optometrist first uses other refractive methods (such as automatic refractive measurement or retinoscopy) to estimate the prescription. Then, the optometrist uses this prescription as a baseline and adds a pure cylindrical lens with zero equivalent spherical lens and 2C cylindrical power. Therefore, the power of the lens on one axis (the power of the lens) is +C, and the power on the other axis perpendicular to the first axis is -C. The optometrist first aligns the axis of prescription estimation with the meridian with 0 optical power. Then, the optometrist flips the lens and changes the polarity of the lens on each meridian, or equivalently changes the axis of the cylinder by 90 degrees. If the initial axis is correct, the patient will not notice any difference and the degree of blur will be the same. If the patient notices the difference, the patient chooses the position (axis) where the best image is seen. Then, the optometrist rotates the correction lens by 5 degrees toward the axis that provides the best quality image. Repeat the process until the patient does not notice any difference. The above is the way to determine the axis with high precision. Then, the optometrist will fine-tune the astigmatism power and use the new axis to set the lens group. The cross cylinder used is the same as before, but now, the astigmatism axis and the cross cylinder The main meridian is parallel. The optometrist flips the cross cylinder according to the patient's direction (the position is the least blurred), and changes the optical power of the correction cylinder until the patient does not notice any difference, and corrects the two positions of the cross cylinder Both feel the same degree of blur.

In the disclosed embodiment, a simple inverse Shack-Hartmann implementation is used to measure refractive error, and the user observes two lines on the screen of a smartphone such as a smartphone through the optical system as shown in FIG. 1. Then, the user observes through the refraction device and changes the distance between the two lines on the screen until the two lines overlap. Then, the user moves or adjusts the device to continue to the next meridian, and then two lines are displayed to the user. The above process adds a corrective lens in front of the simulated eye and/or the camera until the image is formed clear.

According to the conventional reverse Shack-Hartmann method, the optical system can be a microlens array and/or a pinhole array, and the distance from the optical system to the mobile phone screen is defined as D.

As shown in Figure 2, the user will see two lines (one red and one green) on the screen when operating the disclosed device. The function of putting the lines together through the disclosed device operation is called or defined as "alignment", and the lines appear together and/or overlap at the end of the process. Whether the user can move the minimum distance of the line is limited by the resolution of the phone (ie, the pixel distance c) and the distance between the screen and the optical system D. When the user changes the distance on the phone, it will change the angle of incident light entering the imaging system (see Figure 4). The minimum change θmin of the incident angle to the imaging system can be calculated according to the following formula:

By knowing the distance d and distance D of the two lines on the screen of the mobile phone, the incident angle can be calculated. Calculate the refractive error P from the angle of incidence θ with the diopter (m-1) (diopter). Therefore, the required corrected diopter P can be calculated using the following equation:

Where, d'is the distance between the two beams of light on the lens of the imaging system or the size of the exit pupil, as shown in Fig. 4B.

Therefore, the resolution of the detected refractive error in the system shown in Figure 4B is:

This formula assumes that these lines exactly overlap in the center of the imaging plane. For example, if the primitive distance c is 0.78 μm, the entrance pupil size d'of the imaging system is 1.5 mm, and the focal length is 10 cm, the minimum refractive error can be detected to be about 1 diopter.

By using a pair of parallel lines, the described measurement occurs one meridian at a time. In order to measure different meridians by the camera or the human eye, the angle of the parallel line must be changed relative to the direction of the human eye. On different meridians, the need to align the space between the lines on the phone screen may be different, because the optical power on each meridian will change due to astigmatism, which can be rotated around the center of each line or around the center of the pattern Line to change the angle of the line, thereby changing the angle of the measured meridian (see Figure 5A and Figure 5B). Referring to Fig. 5B, in order to have representative points on all meridians, at least one rotation around the center of the pattern is required, otherwise the meridian corresponding to the initial meridian plus 90 degrees cannot be measured. When the line rotates around the center of the pattern, the optical element should also follow the rotation of the line. This can be done by rotating the optical element to match the rotation of the pattern or by rotating the entire display (mobile phone). Another method is to use more optical elements (microlenses, pinholes, etc.). In this case, the pattern will rotate on the phone and use different small lenses or pinholes to collimate the light, which may cause crosstalk The occurrence of confuses users.

Using the technique described herein, the disclosed embodiment using the reverse Shack-Hartmann technique simulates the cross cylinder process used by optometrists. Through the improvement of the reverse Shack-Hartmann method disclosed herein, the disclosed embodiments are made possible. As in the Shack-Hartmann technique discussed above, the disclosed optical device may include an array of small lenses and/or pinholes used with the light source. Using the disclosed optical device in combination with a smart phone can simulate the above-mentioned cross cylinder lens process.

In a disclosed embodiment, as shown in FIG. 9, the screen of the smart phone displays four lines and two pairs of parallel lines at the same time. Two pairs of parallel lines are perpendicular to each other, and the spacing of each pair of lines is always the same. When a user looks at the screen of a smartphone through an optical device, he will see two pairs of parallel lines, a total of four lines. The user's perception of the line distance in a pair of lines depends on the diopter of his eyes on the meridian perpendicular to the line and the line distance on the mobile phone. If the user has an astigmatism error, unless the measured meridian is 45 degrees away from the axis of the astigmatism error, the distance of each pair of lines will be different (the green circles in Figure 12 indicate the two meridians being measured). When the spacing of each pair of lines is different, the user rotates the pattern on the screen to continuously change the measured meridian angle until the user sees two crossed crosses, as shown in Figure 9 (each pair of lines are equidistant). The user uses the controls on the smartphone to adjust the line spacing between each pair of lines, so that the lines merge and overlap, so that the focus of the view is clear.

As shown in FIG. 12A, the process and the situation observed by the user in each step are displayed graphically. The blue line represents the degree of refractive error (y-axis) at each meridian (x-axis). In this particular example, the refractive error of a 0-sphere-2 cylinder with an axis of 25 is used. When the user rotates the pattern on the mobile phone screen, it effectively moves the red circle in FIG. 12A horizontally, which corresponds to the meridian under test. As shown in Figure 12B, the lines rotate around their centers on the screen, but the user sees the distance of the lines change. The red squares are always 90 degrees apart. When two meridians under test have the same optical power (they are at the same angle as the green circle in Figure 12A), the axis can be defined. When he or she sees the equal spacing of each pair of lines, the user knows that the two meridians to be measured have the same optical power (see Figure 12B). It is worth mentioning that in this process, the distance between each pair of lines is equal, and at this point it is therefore determined that the measured meridian is at ±45 degrees from the axis.

Then, the user changes the optical power of the equivalent spherical lens until each pair of lines seen overlaps. If there is a red line and a green line on each pair, the user sees the overlapped line as a yellow cross. The change of the equivalent spherical lens will change the distance of each pair of lines at the same time. When the lines overlap, the equivalent spherical lens can be inferred from the line distance on the screen. If the user cannot see the cross, you can repeat this step and the previous step until you see the yellow cross (that is, the red and green lines overlap). At the end of this measurement, the astigmatism axis and equivalent spherical lens are also determined.

The next step is to determine the optical power of the axis of astigmatism error (ie the cylinder). Compared with the rotation of the previous step, at the beginning of this stage, the app or the user rotates the pattern on the phone by 45 degrees, so , One pair is parallel to the astigmatism axis, and the second pair is perpendicular to the astigmatism axis. The user changes the optical power of the cylindrical lens by changing the spacing of each pair of lines until a yellow cross is formed as before, or equivalently, until the gray circle and the black circle in Figure 12A coincide with each other, which is determined by the last measurement The optical power of the cylinder.

In summary, the following steps sometimes use the disclosure of the present invention to measure the user's refractive error: 1. The user looks at the four lines on the phone screen by looking at the device on the smartphone screen, as shown in Figure 9; 2. Rotate the cross pattern on the device until the distance between the two lines of each pair of lines (red and green) is the same; 3. Change the equivalent spherical lens power by changing the distance between the lines until the user sees the yellow cross or as close as possible. 4. Repeat steps 2 and 3 until the user sees a yellow cross in the middle of the field of view; 5. Rotate the pattern by 45 degrees to measure the meridian optical power with minimum and maximum optical power; 6. Change the optical power of the cylindrical lens, that is, the amplitude of the sine wave in Figure 12A, until the user sees the yellow cross.

The advantage of the disclosed method is that the measurement is simultaneously performed on two meridians separated by 90 degrees. Therefore, when measuring on both meridians, the eyes are in the same state. Therefore, since the estimation of the cylinder and the axis will have smaller errors, it is expected that the refractive error can be measured more accurately or at least can produce better visual acuity measurements. Because this method avoids astigmatism errors caused by adaptive fluctuations (such as dark focus changes, instrumental myopia, etc.), because the measurement required to estimate the magnitude and axis of the aberration is performed simultaneously.

In order to realize this cross cylinder method, compared with the prior art, the reverse Shack-Hartmann device as shown in FIGS. 4A and 4B needs some improvement. First, the device should be able to process multiple meridians at the same time. Therefore, at least two pairs of small lenses (four small lenses in total) are required. In this case, the light that should have passed through a specific small lens will pass through another small lens, and The user is confused by creating multiple images. The effect shown in Figure 6 is called crosstalk. One way to reduce crosstalk is to increase the distance between the two small lenses, as shown in Figure 8, or include a baffle between the two small lenses to increase the resolution (larger d'), but the emitted light The pupil will also become larger. Because the human pupil is usually 3 to 6mm (1.5mm in a very bright environment and 8mm in a very light environment), in terms of the human eye, in addition to reducing the field of view, it also makes the alignment of the device very sensitive. . In addition, by moving a row of primitives at the same time, so that the overlap surrounds the center instead of precisely at the center, the resolution of the device can be increased by 2 times. Because when the resolution of the device exactly matches the user's refractive error, the lines can overlap in the center of the imaging plane. Finally, we deliberately introduce coma (coma/comma) into our system to help users make decisions. In this case, when the two lines touch slightly on the imaging plane, the two lines will align -Let the user not see the black line between the green line and the red line, and/or the two lines touch slightly to form a yellow line (the red line and the green line overlap), as shown in Figure 3.

Therefore, when the user is subjectively testing the method, an ideal device needs to have a small exit pupil/large field of view, low crosstalk, and high resolution that allows the user to easily determine the alignment of the lines.

Definition of subsystem

To solve the above problems, the following subsystems can be used: a demagnification subsystem including a single concave lens, which can greatly improve the resolution, as shown in Figure 7; the four lenses are 2mm thick and 6mm apart (center to center). Reduce crosstalk (for one lens with less light passing through the second lens, and the resulting image is relatively far away) and defocus problems (small hole thickness 2mm). A slit-shaped shutter can be used in the lens to further improve the usability of the optical system with higher refractive errors. These dimensions are taken as examples, but the invention is not limited to these parameters; the exit pupil is reduced and the field of view is improved during the magnification stage, and crosstalk is further reduced and coma is introduced to improve the user experience.

Finally, a slit shutter can be used in front of the lens of the optical system under test to increase the depth of field. This minimizes the blur observed by people with high refractive errors, due to the small holes in one direction, and at the same time the light attenuation is much less compared to pinholes.

As shown in Figure 7, the concept of zooming is shown, which can improve the effective resolution of the mobile phone screen. In order to improve the resolution, a subsystem consisting of a concave lens is introduced, which creates a new virtual image smaller than the original image. If the distance between the concave lens with focal length f and the image is L, the change in distance from the optical axis h will be converted into distance h', so the effective pixel density will increase to increase the linear pixel density, and the zoom factor DM = h / h', given by the following formula:

Therefore, by increasing the distance from the screen or reducing the focal length of the lens, the zoom factor can be increased. It can improve the effective resolution of the screen, and is not limited to other applications of this device. For example, it can also be used to increase the resolution of VR headsets. The virtual image is formed behind the concave lens (toward the screen) at a distance of L/DM, and the linear image The effect of increasing the element density by DM times, or equivalently reducing the minimum element distance by DM times.

As shown in Figure 8, optional lenses can be added to the lens array to allow transmission of other information, instructions and patterns. In this setup, four small lenses are used to avoid rotation/crosstalk/defocus (the four small lenses are at a relatively long distance), and there is a fifth optional small lens in the center of the array to allow other The optical image is presented to the user. Other optical images can be used to control adjustment or send user visual information and/or instructions. The size of the four small lenses can be 2x4 mm to act as a small shutter and reduce crosstalk. The light intended to pass through one lens is poorly coupled with the lens oriented perpendicular to the original lens. As mentioned at the beginning of this article, using small lenses in pairs (see 1, 2, 3, and 4 in Figure 8) produces two collimated beams. Because the light guided through lenses 1 and 2 cannot be well coupled to lenses 3 and 4 due to their shape, crosstalk is reduced, and vice versa. Therefore, the small lenses are 6 mm apart to reduce crosstalk.

Figure 9 shows the usage and inspection results of the lens. In order to check the validity of the test results, if the system correctly estimates the refractive characteristics of the user's eyes or the device under test, all four small lenses can be used at the same time, as in the cross cylinder method. The line spacing on the screen is set based on the result and the meridian being measured. If the result is correct, the user will see a cross. For example, the result shows that the cylindrical lens is at θ degrees, and to inspect the cylindrical lens, a pair of lenses is set to measure at θ degrees, and the second pair is set at θ+90 with 180 degrees as the modulus.

If you need to measure the equivalent spherical lens, you can measure with 180 degrees as the modulus at θ+45 and 180 degrees as the modulus at θ-45. On these two meridians, if the estimation of refractive error is correct, the optical power of the tested lens should be equal to the equivalent spherical lens. If the user sees 4 lines, the test result is incorrect (see the incorrect result indicated in Figure 9). If the user sees a cross, the result is valid (see Figure 9 for the correct result indicated). In this way, the results can be experimentally verified by measuring two meridians at the same time.

Using four small lenses that are relatively far from each other and the optional 5th lens can reduce crosstalk and avoid any mechanical rotation, and any meridian can be measured. At the same time, the fifth lens can be used to provide necessary stimuli to control the user’s adaptation and project other useful information to it. The disadvantage is that the exit pupil is large and the field of view is small. The next subsystem will solve this problem.

As shown in Figure 10, it is the optical system of the exit pupil reduction, crosstalk reduction and coma sensor. The introduced coma helps to improve the usability of the optical system. This subsystem has three purposes. The main purpose is to reduce the exit pupil, thereby increasing the field of view. Secondly, since the crosstalk image is out of the user's field of vision, the crosstalk perceived by the user can be further reduced. Finally, this setting introduces coma, making the lines easier to see and align (see the thick line effect shown in Figure 2).

This set or disclosed configuration includes a convex lens having a focal length f1 and a concave lens having a focal length f2. Both lenses share the same focal plane. The input in this system is the output of the lenslet array, so two collimated beams. To facilitate the analysis of this subsystem, it should be assumed that the two beams are parallel to the optical axis. The convex lens focuses two parallel beams. This brings the two beams closer together, thereby reducing the exit pupil. Before they reach the focal point, the concave lens intervenes and the two beams become parallel and closer again. The reduction of the exit pupil (d/d’) is equal to the ratio of the focal lengths of the two lenses (f1/f2). This has the effect of reducing crosstalk (the concave lens acts as a beam expander and increases the angular separation between the main beam and the beam due to crosstalk). The second side effect of this system is coma induction, because the edge of the spherical lens is used and converted, which will produce coma introduced by the collimated beam. As shown in Figure 3, this resulted in a sharp line with a fading tail. Makes it easier to find the line and can be aligned objectively. Ideally, the user will place the two threads very close together so that they can see a light yellow thread without gaps (see Figure 3). The disadvantage of this system is that the resolution is greatly reduced. Two phenomena cause the resolution to decrease: (1) The distance of parallel beams is reduced, which directly affects the resolution; (2) For the same pixel movement, the angle of incidence of the eye will change greatly, resulting in a lower resolution.

As shown in Fig. 11, it is the overall disclosed system, including the description of the overall system and optical components. The previous subsystem implements Figures 7, 8, and 10 as a complete optical system, which can include: a concave lens to reduce the minimum refractive error; a lens array to collimate the virtual image created by the concave lens and the convex lens of the third subsystem straight. Compared with using a separate optical element, this customized/complex optical element can increase the transmittance by approximately 8.6%, significantly reducing manufacturing costs; and the second concave lens prepares light for the imaging system.

Therefore, the light from the display screen of the mobile phone first passes through the first concave lens to improve the effective resolution. The light is then collimated parallel by a small convex lens off-axis to the entire system, and then through another convex lens, then a concave lens to reduce the exit pupil and reduce crosstalk. In order to perform calibrated measurements, the equipment should be initially calibrated. This can be done with a camera focused at infinity (simulating frontal eyes). Then, create human error by adding a prescription lens from the audition kit in front of the camera. Then, move the lines until they touch, and record the displacement in the induced ametropia. This allows the displacement to determine the refractive error.

In another embodiment of the present invention, as shown in FIG. 14, a pair of colored lenses and a slit of each lens mounted on the rotating mount can be used to replace the complex lens and the reduction stage. Tinted lenses act as filters to eliminate crosstalk, one lens can be dyed red, and the second lens can be dyed green. Therefore, the light emitted from the green line cannot pass through the red lens, and vice versa. There is a slit behind each lens that acts as a shutter and increases the depth of field. Similarly, the use of slits does not greatly reduce the transmission intensity. In this embodiment, no magnification stage is required because the exit pupil is only determined by the distance between the two slits, and crosstalk is eliminated by using a colored lens. In order to measure the meridian at different angles, the lens and the slit are rotated together using a rotating mount, and as the screen rotates, the rotation can be performed manually by the user or by a motor. When the user enters the next meridian, the application can automatically rotate the rotating mount.

Mechanical tolerance analysis

If the entire system is translated parallel to the screen in a first-order approximation, the error in the refractive error evaluation will be minimal. The only effect is that the user will not see symmetrical lines around the center of their field of view, and the intensity will be reduced. Next, each subsystem will be analyzed separately, with emphasis on lateral displacement. By converting the lateral tolerance to an angle (shown at the end of this section), the inclination can be easily calculated.

a. Shrink

The scaling is derived from:

The position and size of the virtual image are

中的縮倍

以及虛擬影像的大小

發生變化。Therefore, the change of ΔL will cause the position of the virtual image

Zoom in

And the size of the virtual image

Changes.

The change of the virtual image size will directly cause the calibration offset, the change of the zoom will directly affect the resolution of the system, and the change of the position will affect the performance of the following subsystems. On DM, the resolution is limited by c (pixel interval):

Therefore, if the zoom ratio is 3, the sensitivity of the device is reduced by 9 times. As far as tolerances are concerned, high zoom is beneficial. It is even better to have a long focal length. It is preferable to use a longer length to achieve a large magnification.

b. Parallel beam creation

改變我們對光焦度的測量。If the light source is not completely at the focal point of the small lens, the light beam behind the small lens will diverge or converge, resulting in deviation and changing the measurement result. Therefore, will pass

Change our measurement of optical power.

According to this formula, the change in optical power caused by the zoom can be calculated as:

This change adds to the deviation due to the change in zoom and reduces the overall effect.

c. Amplification stage

主導因素是縮倍階段的橫向變化，主要是兩線（2h’）之間的距離變化。高度變化會引起測量光焦度的偏差。對於低解析度，由於縮倍的變化而導致的解析度變化非常重要，尤其是對於屈光不正的人。例如縮倍倍率等於3，線之間的距離等於18 mm，凹透鏡距螢幕的距離等於30mm的設計。This stage does not depend on the previous stage. It only reduces the distance between the two beams. If the distance between the two lenses is not correct, a deviation will occur in the refraction measurement. Again the first-order approximation is

The dominant factor is the lateral change in the shrinking stage, mainly the change in the distance between the two lines (2h'). Altitude changes can cause deviations in the measured optical power. For low resolution, the change in resolution due to changes in zoom is very important, especially for people with refractive errors. For example, the magnification ratio is equal to 3, the distance between the lines is equal to 18 mm, and the distance between the concave lens and the screen is equal to 30 mm.

Tilt can be converted to lateral displacement (at least in a first-order approximation). If the lens is tilted around the center, the focus is only on the zoom stage (this is the stage with the tightest tolerance), one side of the lens is closer to the screen and the other side is further away, and the net effect is zero. If the lens is tilted at an angle, only one side moves, and the length change is ΔL≈2hΔθ. The angle will be converted to a power deviation as shown below:

ΔP=-14.4Δθ(radian)=-0.25Δθ(angle).

Further embodiments include current devices and methods that include a lens-based diopter that is connected to a smartphone and used with a smartphone application, thereby allowing accurate measurement of the refractive error of the optical system. In the case where the measured optical system is the human eye, an example of such a device is EyeQue Corp's Personal Vision Tracker (PVT) (patent publication US20170215724A1, which is incorporated herein in its entirety by reference).

The working principle of PVT is to project a defined geometric pattern image onto the user's retina, allowing the user to control one side of the image properties to achieve a clear goal, and then measure the parameters of the image to infer the required user optics Correction of the system (such as their eyes). For example, the image can be on the screen of a smartphone to which the optical device is attached. In addition, an example of an image can be a set of parallel lines of different colors (such as red and green). When the image is transmitted through an optical device, the user adjusts the perceived distance between the lines on the screen to make them reach the final position, such as They appear in well-defined relationships (such as overlap). The relationship between the distance between the lines and the perceived overlap corresponds to the user's refractive error.

As shown in FIG. 15, it is an example of this embodiment.

As shown in Figure 15, the measurement accuracy of the method and device is limited by the resolution of the mobile phone. In today's smartphones, the pixel density (resolution measured in pixels per inch, ppi) is about 326. There are phones with higher resolution (the most common is around 570ppi) and phones with lower resolution (lower than 250ppi). 326ppi mobile phones allow 0.25D accuracy in the range of -10D and +8D. In most cases, this level of accuracy is sufficient, but may be limited (especially for lower resolution phones). In addition, this method requires a display to control the distance between the lines.

As an alternative to this device and method, the present invention proposes the following embodiments for measuring refractive index. An optical system (see the system shown in FIG. 15) is used to present a display showing geometric images (for example, parallel lines are one green and one red) to the user. Then, the user controls the geometric representation of the image through the measuring optical system. In the embodiment of the present invention, the control is accomplished by modifying the distance between the display and the first lens. In another embodiment of the present invention, the control is accomplished by modifying the focal length of the lens at the end of the optical system of the device, for example, by using a variable focal length lens, a zoom lens or a liquid lens. The user modifies the image through the measuring optical system to achieve specific geometric goals, such as line overlap. Then the system parameters (whether the distance offset or the adjusted focal length of the lens) are recorded and correlated with the required optical correction of the system under test. An example of the system under test may be the user's eyes. The association can be completed by artificial intelligence (such as a neural network) through calibration, curve/function fitting, analysis or numerical calculation, for example.

As shown in Figure 16, it is an explanation of the public measurement principle. At the nominal position of the display of the first lens of the device, the lines presented on the display appear to overlap the focal plane of the measured optical system (for example, the retina of the eye). When the display is shifted away from the optical system under test, as the focal point (the point where these lines intersect) moves away from the device, the lines seem to move further and further away from each other in the same direction. When the display is translated toward the first lens, the lines separate to the other direction and the focus moves toward the device.

As shown in FIG. 17, the embodiment of the present invention uses image modification based on a linear translation mechanism.

The optical refractor may include a reduced magnification lens L1 and two colored lenses L2 (green) and L3 (red). Adjacent to L2 and L3 are slits, which allow red and green light to pass through, respectively. The resolution of the device can be determined by the incremental distance of the two principal rays of the slit from the first lens to the screen.

As shown in 18, it is the power-distance relationship in the disclosed embodiment. It should be noted that the dependency relationship is not the expected linear relationship. The slope of the curve determines the resolution. In the current situation, the expected average resolution is about 2.5D/mm (100μm corresponds to 0.25D). When the angular sentence Ψ of the two lines is reduced, the resolution of the device can be improved by changing the nominal distance between the lines or by increasing the focal length of the first lens. The resolution of the device is equal to 1/tan(Ψ) Proportionally.

As shown in FIG. 19, it is another embodiment of the present invention, in which the first lens is replaced by a variable focal length lens. In this embodiment, the focal length of the first lens is changed so that the lines on the display overlap in the focal plane of the measured optical system (for example, the retina of the human eye). Figure 19 also shows the ray tracing of the nominal lens power and the other two possible powers. The higher power of the first lens (shorter absolute focal length, in the example positive power) will be farther away The two line focal points where the devices intersect correspond to each other, while the lower optical power (longer absolute focal length, in this case, the more negative optical power) corresponds to the line closer to the intersection of the device.

Since the modification mechanism has nothing to do with the actual distance between the lines, the display can have a variety of options, such as: screens (including smartphone screens), LED light strips (including lines composed of diffusers and color filters) , A translucent panel with backlight, and a mask light box that illuminates the desired pattern for transmission.

In order to measure the astigmatism of the measured optical system (such as the eye), the device can be rotated to pass through different meridians, and the resultant data of the required correction of the optical power can be used to calculate the focal point (sphere) and astigmatism ( Column and axis) refractive error.

Alternatively, as shown in FIGS. 20A, 20B, and 20C, the display, the colored lens, and the slit can be relatively rotated instead of the entire device.

In an embodiment of the present invention, the translation element moves the display along the optical axis, and a single rotating element allows the slit and colored lens on the eyepiece and the display to be rotated in series through different meridians (Figure 20A). In another proposed embodiment of the present invention, rotation is achieved by implementing two rotating elements, one rotating element on the display and the other rotating element for the slit and the colored lens (Figure 20B). In this embodiment, special attention needs to be paid to the synchronization between the rotating elements. In another embodiment of the present invention, the rotation of the display is accomplished by a digital device, wherein the display is an electronic screen. In this case, the rotation of the slit and the colored lens is completed by the rotating element (see Figure 20C).

Both linear translation elements and rotating elements can have various manifestations, including, for example, fully manual control, fully automatic or electronic control, and any combination thereof. The proposed embodiment can be implemented in monocular or binocular form. In the embodiment of the present invention, the device will be connected to a smart phone or other Bluetooth-enabled computing device to transmit data to perform calculation and analysis on the computing device, or to enable the data to be transmitted to the cloud for calculation and analysis. This connection can also be used to control different aspects of the device, such as the rotation and translation of corresponding elements.

The above detailed description of the embodiments of the present invention is not intended to be exhaustive or to limit the present invention to the precise form disclosed above. Although specific embodiments and examples of the present invention have been described above for illustrative purposes, as those skilled in the relevant art will recognize, various equivalent modifications can be made within the scope of the present invention. Although the steps are presented in a given order, alternative embodiments may execute the step routines in a different order. The teachings of the invention provided herein can be applied to other systems, not just the system described herein. The various embodiments described herein can be combined to provide other embodiments. Based on the detailed description, these and other changes can be made to the present invention.

All of the above references and US patents and applications are incorporated herein by reference. If necessary, various aspects of the present invention can be modified to adopt the systems, functions, and concepts of the various patents and applications mentioned above to provide yet another embodiment of the present invention.

Based on the above detailed description, these and other changes can be made to the present invention. In general, unless the above detailed description clearly defines terms, these terms used in the following claims should not be construed as limiting the present invention to the specific embodiments disclosed in the specification. Therefore, the actual scope of the present invention covers the disclosed embodiments and all equivalent ways of practicing or implementing the present invention under the scope of the rights.

Although certain aspects of the invention are presented below in the form of certain claims, the inventors have contemplated various aspects of the invention in the form of any number of claims.

The disclosed embodiments may include the following items: 1. A method for measuring refractive errors in an optical system (300) using the first lens (200), the second lens and the display (112), the method includes the following steps: Set the second lens near the optical system; set the first lens in the line of sight of the second lens; set the display in the line of sight of the first lens; change the distance from the first lens to the display until as observed by the optical system The marks on the display are aligned; the spherical error of the optical system is obtained by changing the distance of the display. 2. The method of item 1, wherein the first lens comprises a zoom lens. 3. The method of item 2, wherein the second lens includes a first colored lens and a second colored lens. 4. The method of item 3, wherein the second lens defines two slits. 5. The method of item 4, wherein the mark transmitted from the second lens to the optical system includes a first color and a second color. 6. The method of item 1, wherein the mark on the display includes a first symbol and a second symbol. 7. The method of item 6, wherein the first and second symbols are vertical and horizontal colored lines, respectively. 8. The method of item 7, in which the colored lines are red and green. 9. The method of item 1, wherein the display can include one selected from the following group: (screen (including smart phone screen)), LED light strip (including a line composed of diffusers and color filters) , A translucent panel with backlight, and a light box that illuminates the mask that transmits the mark. 10. The method of item 1, further comprising the following steps: in response to the changing projection on the screen and using the measured distance of the second lens, rotating the second lens through different meridians along the optical axis, and measuring the position of the second lens The distance of movement on each meridian to obtain further refractive errors of the optical system. 11. The method of item 1, further comprising the following steps: rotating the display synchronously with the second lens passing through different meridians along the optical axis, and measuring the movement distance of the second lens on each meridian, and using the measured second lens The distance to get further refractive error of the optical system. 12. A method for measuring refractive errors in the optical system (300) using the first lens, the second lens and the display (112), the method includes the following steps: Set the second lens near the optical system; set the first lens in the line of sight of the second lens; where the first lens is a zoom lens; set the display in the line of sight of the first lens; change the focal length from the first lens, Until the mark on the display is aligned as observed by the optical system; the spherical error of the optical system is obtained by using the changed focal length of the first lens. 13. The system for measuring refractive errors in the optical system (300), including a first lens, a second lens and a display, the system including: A second lens set in the vicinity of the optical system; a first lens set in the line of sight of the second lens; a display set in the line of sight of the first lens; the display has an adjustable connector from the first lens, the The adjusting connector has a device for adjusting the length until the mark on the display is aligned as observed by the optical system; the distance change of the display is used as a variable to obtain the spherical error of the optical system. 14. The system for measuring refractive errors in the optical system (300), including a first lens, a second lens and a display (112), the system including: A second lens arranged near the optical system; a first lens arranged in the line of sight of the second lens; wherein the first lens is a zoom lens; a display arranged in the line of sight of the first lens; a device for measuring the focal length change of the first lens, It is used to align the mark on the display observed by the optical system; the focal distance change of the first lens is used as a variable to obtain the spherical error of the optical system.

These and other aspects of the present invention will become apparent by reading the following detailed description in conjunction with the accompanying drawings. 100: smart phone 110: Smartphone screen 112: display 200: optical system 210: focal plane 220: imaging plane 230: convex lens 240: concave lens 300: Eye/imaging system 400: Optical axis 500: lens 600: Complex lens L1: Reduce lens L2: colored lens or second lens L3: colored lens or another second lens

The patent or application file contains at least one colored drawing. The Patent Office will provide a copy of this patent or patent application publication with color drawings on request and necessary fees. Figure 1 depicts a schematic diagram of the overall configuration of the disclosed system, in which the light source is a smartphone screen, and also depicts the effect of moving a line of a pixel of size c. Figure 2 depicts a schematic diagram of what a user may see when operating the disclosed device using a line without coma. Fig. 3 depicts a schematic diagram of what the user may see when operating the disclosed device due to the deliberate use of coma aberration in the optical system with thick lines that are not uniformly widened. Figure 4A depicts a schematic diagram of an embodiment of the reverse Shack Hartmann technique in an initial position. FIG. 4B depicts a schematic diagram of an implementation of the reverse Shack Hartmann technique that has moved one image element. Figure 5A depicts a patterned display used as the input of the optical system, using the rotation of the line around the center to measure different meridians. FIG. 5B depicts a patterned display used as the input of the optical system, using a line around the center of the screen to rotate and measure different meridians. FIG. 6 depicts a schematic diagram of using the complex lens of FIG. 8 to simulate crosstalk at the imaging plane using the reverse Shack-Hartmann technique. Figure 7 depicts a schematic diagram of the reduction phase. Figure 8 depicts a lens array, which can add lenses, and where the lens array can use other information, instructions, and pattern diagrams. Figure 9 depicts a schematic diagram of the inverse Shack-Hartmann method used to verify prescriptions and result descriptions. Figure 10 depicts a schematic diagram of the exit pupil reduction system so that the exit pupil is smaller than the entrance pupil of the imaging system. Fig. 11 depicts a schematic diagram of an embodiment disclosed in the present invention based on the contents of Figs. 4, 7, 8 and 10. Figure 12A depicts a graphical representation used by the inverse Shack-Hartmann technique, in which the disclosed embodiment can simulate a cross-cylinder process schematic for accurately estimating refractive error and lens characteristics. FIG. 12B depicts the graphical representation of the user's perception and a schematic diagram of the state on the mobile phone screen at the five points shown in FIG. 12A. FIG. 13 depicts a schematic drawing of the concave lens and the convex lens used in the drawings. FIG. 14 depicts a schematic diagram of an embodiment of the second disclosure. Figure 15 depicts a schematic diagram of a disclosed embodiment. FIG. 16 depicts a schematic diagram of the measurement concept of the disclosed embodiment. Figure 17 depicts a schematic diagram of a disclosed embodiment using a linear translation mechanism based on image modification. Figure 18 depicts a schematic diagram of the corrected optical power [D] relative to the nominal [mm] translational offset. Figure 19 depicts an alternative embodiment where the first lens is replaced by a variable focal length lens. Figures 20A, 20B, and 20C depict a schematic diagram of a disclosed embodiment in which a translation element moves the display along the optical axis.

Claims (14)

A method for measuring refractive error using a first lens, a second lens and a display in an optical system, the method comprising the following steps: a. Set the second lens near the optical system; b. Set the first lens in the line of sight of the second lens; c. Set the display in the line of sight of the first lens; d. Change the distance from the first lens to the display until the optical system observes the alignment of the marks on the display; e. Obtain the spherical error of the optical system by changing the distance of the display. The method according to claim 1, wherein the first lens includes a reduction lens. The method according to claim 2, wherein the second lens includes a first colored lens and a second colored lens. The method according to claim 3, wherein the second lens defines two slits. The method according to claim 4, wherein the mark transmitted from the second lens to the optical system includes a first color and a second color. The method according to claim 1, wherein the mark on the display includes a first symbol and a second symbol. The method according to claim 6, wherein the first and second symbols are vertical and horizontal colored lines, respectively. The method described in claim 7, wherein the colored lines are red and green. The method according to claim 1, wherein the display includes one selected from the following group: a screen (including a smartphone screen), an LED light strip (including a line composed of a diffuser and a color filter) ), a translucent board with backlight, a light box that illuminates the marking mask. The method described in claim 1 of the scope of the patent application further includes the following steps: in response to the measured distance of the second lens using the varying projection on the screen, rotating the second lens through a different lens along the optical axis And measure the moving distance of the second lens on each meridian to obtain further refractive errors of the optical system. The method according to claim 1, further comprising the following steps: rotating the display synchronously with the rotation of the second lens along the optical axis through different meridians, and measuring the movement of the second lens on each meridian And measure the distance of the second lens to obtain further refractive error of the optical system. A method for measuring refractive errors in an optical system using a first lens, a second lens and a display, the method comprising the following steps: a. Set the second lens near the optical system; b. Set the first lens in the line of sight of the second lens; wherein the first lens is a zoom lens; c. Set the display in the line of sight of the first lens; d. Change the focal length of the first lens until the optical system observes that the marks on the display are aligned; e. Use the changed focal length of the first lens to obtain the spherical error of the optical system. A system for measuring ametropia in an optical system, comprising a first lens, a second lens and a display, the system comprising: a. The second lens arranged near the optical system; b. The first lens arranged in the line of sight of the second lens; c. The display set in the line of sight of the first lens; d. The display has an adjustable connector from the first lens, and the adjustable connector has a device for adjusting the length until the optical system observes the alignment of the marks on the display; e. The varying distance of the display is used as a variable to obtain the spherical error of the optical system. A system for measuring refractive errors in an optical system, comprising a first lens, a second lens and a display, the system comprising: a. The second lens arranged near the optical system; b. The first lens arranged in the line of sight of the second lens; wherein the first lens is a zoom lens; c. The display set in the line of sight of the first lens; d. A device for measuring the change in the focal length of the first lens, which is used to align the optical system to observe the marks on the display; e. The focal length change distance of the first lens is used as a variable to obtain the spherical error of the optical system.

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