Automated optical measurement system for near eye displays and method thereof
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Patents
- Current Assignee / Owner
- CHROMA ATE INC
- Filing Date
- 2023-06-20
- Publication Date
- 2026-08-01
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Optical Automation Measurement System and Method for Near-Eye Display Devices The present invention relates to an optical automation measurement system and method for near-eye display devices, especially a detection device for wearable near-eye display devices such as AR, VR, MR, and XR, and particularly relates to the testing of optical characteristics. The development of near-eye display devices (abbreviated as NED) has become increasingly mature, and their acceptance in the market has also been increasing. For example, wearable devices such as augmented reality (AR), virtual reality (VR), and mixed reality (MR) have gradually become popular. However, the optical characteristic quality testing of near-eye display devices has always been a pain point for major manufacturers. The main reason is that in order to accommodate different vision conditions of wearers (such as myopia, hyperopia, or normal vision), near-eye display devices allow different diopters to be set for display. Therefore, optical characteristic testing under different diopter conditions is an indispensable part of quality testing, but this directly increases the complexity of detection. In the traditional detection method, under different diopter conditions, manual focusing is first performed, and then various optical characteristics are tested. However, the traditional manual method has high uncertainty, consumes human resources, is costly, and has poor efficiency. In addition, the patent document WO2022204029 uses a commercially available photographic lens with an electric focusing function. However, since this commercially available lens is not specifically designed for near-eye display devices, it cannot fully meet the requirements and related display characteristics of near-eye display devices. The imaging quality may not be ideal, and the accuracy of the measurement results may also be questionable. Moreover, in terms of hardware design, integrating the commercially available lens into the test equipment will result in a large overall volume, and some additional installation components must be added, resulting in high construction costs and directly affecting the detection efficiency. The main objective of the present invention is to provide an optical automation measurement system and method for near-eye display devices to replace or simulate manual imaging quality detection of near-eye display devices. For the projected images under different diopter conditions, a measurement instrument that mimics the human eye can achieve rapid automatic focusing, thus significantly improving the test efficiency and obtaining excellent optical image quality. To achieve the above object, an optical automation measurement system for a near-eye display device of the present invention mainly includes an imaging module, an image sensing module, a displacement generation module, and a controller. The imaging module is used to connect to the near-eye display device; the image sensing module is connected to the imaging module; and the displacement generation module is adapted to displace the image sensing module in at least one dimensional direction; the controller is electrically connected to the near-eye display device, the image sensing module, and the displacement generation module. Among them, the controller controls the near-eye display device to display a specific pattern; the controller controls the image sensing module to capture the specific pattern to obtain at least one focused image; the controller controls the displacement generation module according to the focused image to drive the image sensing module to approach or move away from the imaging module for focusing. To achieve the foregoing object, an optical automation measurement method for a near-eye display device of the present invention mainly includes the following steps: First, the controller controls the near-eye display device to display a specific pattern; furthermore, the controller controls the displacement generation module to drive the image sensing module to approach or move away from the imaging module, and controls the image sensing module to respectively capture the specific pattern to obtain a plurality of focused images; wherein, the imaging module is located between the near-eye display device and the image sensing module; the controller performs focusing according to the plurality of focused images; then, the controller controls the measurement of the optical characteristics of the near-eye display device. Accordingly, when detecting the optical characteristics of the present invention, the focusing means adopted is to move the image sensing module while capturing the specific pattern displayed by the near-eye display device, and to locate the focusing position by comparing the captured results (focused images). However, this mechanism can achieve fast automatic focusing, and can be applied to any diopter condition, and can be applied to all types of near-eye display devices, and can greatly improve the detection efficiency and detection accuracy. On the other hand, since the moving member for performing focusing is the image sensing module, and after the image passes through the imaging module, the focal length range of imaging can be significantly reduced, so the moving stroke distance for the image sensing module to automatically focus can be greatly shortened; and because the image sensing module is small in volume and light in weight, the displacement generation module can be miniaturized, and the overall volume of the measurement system can be more compact. Furthermore, the present invention can adopt a dedicated imaging module designed for the near-eye display device, so excellent optical image quality can be obtained during the entire test stage, which is beneficial to improving the detection quality and detection efficiency. . Before the optical automation measurement system and method for the near-eye display device of the present invention are described in detail in this embodiment, it should be particularly noted that in the following description, similar elements will be represented by the same element symbols. Furthermore, the drawings of the present invention are only for illustrative purposes, and they are not necessarily drawn to scale, and not all details may be presented in the drawings. First, it should be noted that the near-eye display device D of this embodiment is described by taking an AR glasses as an example. However, the present invention is not limited thereto, and other near-eye display devices such as VR, MR, and XR can also be applied to the present invention. Please refer to FIG. 1, FIG. 2A, and FIG. 2B simultaneously. FIG. 1 is a schematic diagram of a system according to an embodiment of the present invention, FIG. 2A is a schematic diagram of an optical path according to an embodiment of the present invention, and FIG. 2B is a system architecture diagram according to an embodiment of the present invention. As shown in the figures, this embodiment mainly includes an imaging module 2, an image sensing module 3, a displacement generating module 4, and a controller 5. One end of the imaging module 2 is used to face the near-eye display device D, and the other end is adjacent to the image sensing module 3; the displacement generating module 4 is used to carry the image sensing module 3 and is adapted to displace the image sensing module 3 in at least one dimensional direction; the controller 5 is electrically connected to the near-eye display device D, the image sensing module 3, and the displacement generating module 4. Furthermore, the imaging module 2 can be composed of optical components such as a macro lens, a baffle, an aperture component, and an eyepiece. It should be particularly noted that the imaging module 2 of the present invention is a dedicated lens module, which is specially configured according to the optical characteristics of different objects to be measured (i.e., the near-eye display device D). For example, a dedicated imaging module 2 designed for AR glasses or VR glasses, and even dedicated imaging modules 2 can be designed for near-eye display devices D of different manufacturers. However, the imaging module 2 of this embodiment is an optical lens module specially designed for AR glasses. Further explanation, since the display in the AR glasses is configured to present information only in a small part of the user's field of view (FOV), most of the imaging module 2 customized for measuring the AR glasses display is a small angular field of view (for example, ±20 degrees). However, VR glasses are completely opposite. Since the display in VR glasses is usually configured to fill the user's field of view as much as possible to immerse the user, a relatively large angle is usually selected for the field of view. Accordingly, the present invention adopts a dedicated imaging module 2 according to the optical characteristics of different objects to be measured (i.e., the near-eye display device D). Therefore, excellent optical image quality can be obtained during the entire test stage, which is beneficial to improving the detection quality and detection efficiency, and the volume of the entire system can also be further reduced. In addition, the image sensing module 3 may include a CCD or CMOS sensor for simply capturing images and related measuring instruments for detecting optical characteristics, such as a photometer and a colorimeter. Moreover, the displacement generating module 4 of this embodiment mainly includes an actuator 41, a carriage 42, and a guide rod 43. The image sensing module 3 is disposed on the carriage 42, and the carriage 42 is slidably disposed on the guide rod 43, and the actuator 41 is power-connected to the carriage 42. Accordingly, the actuator 41 can drive the carriage 42 to slide back and forth. However, since the focal length range of the image has been significantly reduced after passing through the imaging module 2, for different cases of extreme diopters, the sliding range of the carriage 42 is only between 2 and 5 centimeters. Therefore, the volume of the displacement generating module 4 can be quite compact. The controller 5 of this embodiment can be a desktop computer, a notebook computer, a tablet computer, an industrial computer, a server, or other computer devices with data processing functions; the controller 5 is electrically connected to the near-eye display device D, the image sensing module 3, and the displacement generating module 5, and controls the operation of these components. The following describes the operation process of this embodiment. Please refer to FIG. 3 together, which is a measurement flowchart of an embodiment of the present invention. First, the near-eye display device D (AR glasses) is installed in front of the eyepiece of the imaging module 2. Then, the controller 5 sets the initial position of the displacement generating module 4, also known as zeroing the position, that is, step S100. Next, in step S110, the controller 5 controls the near-eye display device D to display a specific pattern Ps, and this specific pattern Ps is associated with the subsequent focusing comparison technical solution, which will be described in detail later. In step S120, the controller 5 first controls the image sensing module 3 to capture the specific pattern Ps to obtain a focused image Pa. Next, in step S130, the contrast analysis focusing method and the MTF value analysis focusing method are provided below. In the contrast analysis focusing method, the specific pattern Ps includes a plurality of black and white stripes, and the controller 5 calculates the contrast ratio of the captured focused image Pa. The calculation formula is contrast ratio = (Lmax - Lmin) / (Lmax + Lmin); where Lmax is the maximum brightness value in the focused image Pa, and Lmin is the minimum brightness value in the focused image Pa. In step S140, the controller 5 determines whether the calculated contrast ratio value has reached the value after optimal focusing. If the best focus value has not been reached, step S150 is performed, that is, the controller 5 controls the displacement generation module 4 to drive the image sensing module 3 to approach or move away from the imaging module 2, and then re-acquires the focused image Pa and calculates its contrast, that is, steps S120, S130, S140, and S150 are repeated. If the contrast value has reached the best focus value, the focusing procedure is completed, and step S160 is continued, that is, the controller 5 controls the relevant measuring instruments to measure the optical characteristics of the near-eye display device D, including but not limited to imaging quality, color brightness, viewing distance (AID), virtual image distance (VID), and binocular diopter, etc. On the other hand, in the MTF numerical analysis focusing method, the specific pattern includes a high-contrast slanted edge pattern, but is not limited to this pattern, and other patterns that can exhibit high contrast can also be applicable, such as a cross pattern. The controller 5 calculates the MTF (Modulation Transfer Function) value of the captured focused image Pa. The calculation formula is MTF = M* / M, where M is the contrast of the specific pattern Ps, and M* is the contrast of the focused image Pa. As for the focusing method, as described in the previous contrast analysis focusing method, steps S120, S130, S140, and S150 are repeated until the MTF value of the focused image Pa has reached the best focus value. It is worth mentioning that in the contrast analysis focusing method, the pitch period of the projected black and white stripes needs to be changed for different spatial frequencies; while in the MTF numerical analysis focusing method, only the slanted edge stripes with a fixed pitch need to be projected, and any spatial frequency can be selected for calculation. More simply, the MTF numerical analysis focusing method has the advantage of generating arbitrary spatial frequency values with a single calculation compared to the contrast analysis focusing method, so it can be more flexible in application. In addition, the following variant is provided in this embodiment. Please first refer to FIG. 4A, which is a focusing curve diagram using contrast analysis according to an embodiment of the present invention. Among them, the controller 5 controls the displacement generation module 4 to drive the image sensing module 3 to move at different positions, which can be a step-by-step movement, and a plurality of focused images Pa are obtained. The controller 5 calculates the contrast ratio of the plurality of focused images and obtains a focusing curve; the controller 5 finds the peak value of the focusing curve, which is the best focusing position. Then, the controller 5 controls the displacement generation module 4 to drive the image sensing module 3 to be located at the position corresponding to the peak value, that is, the focusing is completed. Also, regarding a modified example of the MTF numerical analysis focusing method, similarly, the controller 5 controls the displacement generation module 4 to drive the image sensing module 3 to move at different positions, so as to obtain a plurality of focused images Pa, and calculate the MTF numerical value to obtain a focusing curve. Please refer to the upper part of FIG. 4B. The specific method is to perform differential processing on the edge information of the high-contrast hypotenuse pattern to obtain a line spread function, and then through the FFT Fourier transform operation, a curve waveform diagram of the MTF numerical value and the spatial frequency can be obtained (the upper part of FIG. 4B), and then it is converted into the final focusing curve (the lower part of FIG. 4B), and the peak value of the focusing curve is the optimal focusing position. The above embodiments are only examples for convenience of description. The scope of the rights claimed by the present invention should be subject to what is described in the patent application scope, rather than being limited to the above embodiments. 2: Imaging module 3: Image sensing module 4: Displacement generation module 5: Controller 51: Memory D: Near-eye display device GS: Template image Pa: Focused image Ps: Specific pattern FIG. 1 is a schematic diagram of a system according to an embodiment of the present invention. FIG. 2A is a schematic diagram of an optical path according to an embodiment of the present invention. FIG. 2B is a system architecture diagram according to an embodiment of the present invention. FIG. 3 is a measurement flowchart according to an embodiment of the present invention. FIG. 4A is a focusing curve diagram using contrast analysis according to an embodiment of the present invention. FIG. 4B is a focusing curve diagram using MTF numerical analysis according to an embodiment of the present invention. 2: Imaging module 3: Image sensing module 4: Displacement generation module 5: Controller D: Near-eye display device Pa: Focused image Ps: Specific pattern
Claims
1. An automated optical measurement system for a near-eye display device, comprising: An imaging module for connecting to the near-eye display device; and an image sensing module connected to the imaging module. A displacement generation module adapted to displace an image sensing module in at least one dimension; and a controller electrically connected to the near-eye display device, the image sensing module, and the displacement generation module; wherein the controller is configured to: control the near-eye display device to display a specific pattern, the specific pattern including a high-contrast bevel pattern; control the displacement generation module to move the image sensing module relative to the imaging module to a plurality of positions; control the image sensing module to capture the specific pattern at each of the plurality of positions to obtain a plurality of focused images; and perform the following focusing steps: obtaining a plurality of line spread functions from the plurality of focused images through differential processing based on edge information of the high-contrast bevel pattern; calculating MTF values by performing a fast Fourier transform on the line spread functions, thereby generating a waveform graph representing the relationship between the MTF values and a spatial frequency; converting the waveform graph into a focusing curve; and determining the peak value of the focusing curve and controlling the displacement generation module to drive the image sensing module to move to the position corresponding to the peak value.
2. The optical automated measurement system as described in request item 1, wherein, The controller further controls the image sensing module to measure at least one of the following: image quality, color brightness, viewing distance (AID), virtual image distance (VID), and binocular refractive power of the near-eye display device.
3. An automated optical measurement method for a near-eye display device, comprising the following steps: (A) A controller controls the near-eye display device to display a specific pattern, the specific pattern including a high-contrast bevel pattern; (B) The controller controls a displacement generating module to drive an image sensing module to move relative to an imaging module to multiple positions; (C) The controller controls the image sensing module to capture the specific pattern at each of the multiple positions to obtain multiple focused images; (D) The controller obtains multiple line spread functions from the multiple focused images through differential processing based on edge information of the high-contrast bevel pattern; (E) The controller calculates MTF values by performing a fast Fourier transform on the line spread functions, thereby generating a waveform graph representing the relationship between the MTF values and a spatial frequency; (F) The controller converts the waveform graph into a focusing curve and determines the peak value of the focusing curve; (G) The controller controls the displacement generating module to drive the image sensing module to the position corresponding to the peak value; and (H) The controller controls the measurement of the optical characteristics of the near-eye display device.
4. The automated optical measurement method as described in request item 3, wherein, In step (C), the optical characteristics include at least one of the following: image quality, color brightness, viewing distance (AID), virtual image distance (VID), and binocular refractive power of the near-eye display device.