Lighting systems for augmented reality measurement tools

Abstract

This invention provides an optical engine for a measurement system and a method for using the optical engine. [Solution] The measurement system includes an optical engine 210 that can operate to illuminate a first grating of an optical device. The optical engine projects a pattern using light from the optical engine. The optical engine projects the pattern onto the first grating so that a metrological metric can be extracted from one or more images captured by the detector of the measurement system. The metrological metric is extracted by processing the images. The metrological metric determines whether the optical device conforms to an image quality standard.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to optical devices for augmented, virtual, and mixed reality. More particularly, the embodiments described herein provide an optical engine for a measurement system and a method of using the optical engine.

Background Art

[0002] Virtual reality is generally considered to be a computer-generated simulated environment in which a user has a clear physical presence. Virtual reality experiences can be generated in 3D and can be observed using a head-mounted display (HMD) such as glasses, or other wearable display devices having a near-eye display panel as a lens for displaying a virtual reality environment that replaces the actual environment.

[0003] However, augmented reality enables a user to still see through the display lens of glasses or other HMD devices to observe the surrounding environment, while at the same time viewing an image of a virtual object that is generated to be displayed and appear as part of the environment. Augmented reality can include acoustic input and tactile input, as well as any type of input such as virtual images, graphics, and videos that enhance or augment the environment that the user experiences. As state-of-the-art technology, there are many problems and design constraints associated with augmented reality.

[0004] One such problem is a measurement optical device for image quality standards. In order to ensure compliance with image quality standards, the metrology of the manufactured optical device must be obtained. However, existing measurement systems lack a desirable field of view and have problems with ghost imaging. Therefore, there is a need in the art for a measurement system with an improved field of view and a reduced occurrence of ghost imaging, and a method of using such a measurement system.

Summary of the Invention

[0005] In one embodiment, a measurement system is provided. The measurement system includes a stage on which an optical device can be held, or which can be operated to hold an optical device substrate on which at least one optical device is placed. The measurement system further includes an optical engine located above the stage. The optical engine includes a plurality of light sources. The plurality of light sources can be operated to project light of a certain range of wavelengths onto an optical device. The optical engine further includes a first lens which can be operated to make the light from each of the plurality of light sources into a parallel beam. The optical engine further includes a reticle tray located below the plurality of light sources. The reticle tray has a plurality of reticles located on it. Each individual reticle of the plurality of reticles has a pattern which is projected when light is directed to the individual reticle of the plurality of reticles. The optical engine further includes a second lens which can be operated to receive the patterns projected from each of the plurality of reticles. The second lens can be operated to project the pattern onto the input coupling grating of the optical device.

[0006] In another embodiment, a measurement system is provided. The measurement system includes a stage on which an optical device can be held, or which can be operated to hold an optical device substrate on which at least one optical device is placed. The measurement system further includes an optical engine positioned above the stage. The optical engine includes a module that can be operated to project one or more patterns onto an optical device. The optical engine can be operated to rotate and / or tilt to adjust the angle of incidence of the patterns projected onto the optical device or optical device substrate. The measurement system further includes an alignment camera adjacent to the optical engine. The alignment camera is positioned to capture one or more images of one or more alignment markers on the optical device or optical device substrate. The measurement system further includes a reflectance detector adjacent to the optical engine. The reflectance detector is positioned to detect an out-coupled beam projected from the optical device.

[0007] In yet another embodiment, a method is provided. The method comprises projecting a pattern. The pattern is projected using light from an optical engine. The optical engine is located in a measurement system. The measurement system includes a stage located below the optical engine. The measurement system further includes a tray located on the stage. The tray includes an optical device, or includes an optical device substrate on which at least one optical device is located, and the optical device can operate to receive the pattern. The measurement system further includes a reflectance detector oriented toward the stage. The method further comprises detecting one or more images of the pattern. The images are detected when the pattern, which is undergoing total internal reflection via the optical device, is externally coupled to the reflectance detector. The method further comprises processing the images to extract a metrological metric.

[0008] Therefore, in a manner that allows for a more detailed understanding of the features described herein, the more specific descriptions of this disclosure, briefly summarized above, refer to embodiments in some cases, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings are merely illustrative and should not be considered to limit the scope of this disclosure, and other equally valid embodiments are permitted. [Brief explanation of the drawing]

[0009] [Figure 1A] This is a front perspective view of a substrate according to an embodiment described herein. [Figure 1B] This is a front perspective view of an optical device according to an embodiment described herein. [Figure 2] This is a substantially cross-sectional view of a measurement system according to an embodiment described herein. [Figure 3A] This is a schematic diagram of the configuration of the optical engine of the measurement system according to the embodiments described herein. [Figure 3B] This is a schematic diagram of the configuration of the optical engine of the measurement system according to the embodiments described herein. [Figure 3C] This is a schematic diagram of the configuration of the optical engine of the measurement system according to the embodiments described herein. [Figure 3D] This is a schematic diagram of the configuration of the optical engine of the measurement system according to the embodiments described herein. [Figure 3E] This is a schematic diagram of the configuration of the optical engine of the measurement system according to the embodiments described herein. [Figure 4] This is a schematic diagram of the configuration of the alignment camera of the measurement system according to the embodiments described herein. [Figure 5] This is a flowchart of the optical instrumentation method according to the embodiments described herein. [Modes for carrying out the invention]

[0010] For ease of understanding, the exact same reference numerals are used to indicate identical elements common to the figures where possible. Elements and features of one embodiment are intended to be advantageously incorporated into other embodiments without further detail.

[0011] Embodiments of this disclosure generally relate to optical devices for augmented, virtual, and mixed reality. More specifically, embodiments described herein provide an optical engine for a measurement system and a method of using the optical engine. The measurement system includes a stage on which it can operate to hold an optical device or to hold an optical device substrate on which at least one optical device is placed. The measurement system further includes an optical engine located above the stage. The optical engine includes a plurality of light sources. The plurality of light sources can operate to project light of a certain range of wavelengths onto an optical device. The optical engine further includes a first lens which can operate to make the light from each of the plurality of light sources into a parallel beam. The optical engine further includes a reticle tray located below the plurality of light sources. The reticle tray has a plurality of reticles located on it. Each individual reticle of the plurality of reticles has a pattern which is projected when light is directed to the individual reticle of the plurality of reticles. The optical engine further includes a second lens which can operate to receive the patterns projected from each of the plurality of reticles. The second lens can operate to project the pattern onto an input coupling grating of an optical device. The light engine may also include modules for projecting patterns.

[0012] A method using an optical engine includes projecting a pattern using light from the optical engine. The method further includes detecting one or more images of the pattern. The images are detected when the pattern, which is internally totally reflected through the optical device, is externally coupled to a reflectance detector. The method further includes processing the images to extract a metrological metric.

[0013] Figure 1A is a front perspective view of a substrate 101 according to an embodiment described herein. The substrate includes a plurality of optical devices 100 arranged on the surface 103 of the substrate 101. In some embodiments that can be combined with other embodiments described herein, the optical devices 100 are waveguide combiners used for virtual, augmented, or mixed reality. In some embodiments that can be combined with other embodiments described herein, the optical devices 100 are flat optical devices such as metasurfaces.

[0014] The substrate 101 may be any substrate used in the art, and may be either opaque or transparent to a selected laser wavelength, depending on how the substrate 101 is used. The substrate 101 may include, but is not limited to, silicon (Si), silicon dioxide (SiO2), quartz glass, quartz, silicon carbide (SiC), germanium (Ge), silicon germanium (SiGe), indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), silicon nitride (SiN), or sapphire-containing materials. Furthermore, the substrate 101 may have a variable shape, thickness, and diameter. For example, the substrate 101 may have a diameter from about 150 mm to about 300 mm. The substrate 101 may have a circular, rectangular, or square shape. The substrate 101 may have a thickness between about 300 μm and about 1 mm. Although only nine optical devices 100 are shown on the substrate 101, any number of optical devices 100 can be placed on the surface 103 of the substrate 101.

[0015] Figure 1B is a front perspective view of the optical device 100. It should be understood that the optical device 100 described herein is an exemplary optical device, and that embodiments of the disclosure can be achieved by using or modifying other optical devices. The optical device 100 includes a plurality of optical device structures 102 arranged on the surface 103 of a substrate 101. The optical device structures 102 may be nanostructures having sub-micron dimensions, for example, nano-size dimensions. Regions of the optical device structures 102 correspond to one or more gratings 104, such as a first grating 104a, a second grating 104b, and a third grating 104c. In one embodiment, which can be combined with other embodiments described herein, the optical device 100 includes at least a first grating 104a corresponding to an input coupling grating, and a third grating 104c corresponding to an output coupling grating. In another embodiment, which can be combined with other embodiments described herein, the optical device 100 also includes a second grating 104b corresponding to an intermediate grating. The optical device structure 102 may be angled or binary. The optical device structure 102 may have other cross-sections, including, but is not limited to, circular, triangular, elliptical, regular polygon, polygon and / or irregular cross-sections.

[0016] During operation, the first grating 104a receives an incident beam of light having a certain intensity from the optical engine. In one embodiment, which can be combined with other embodiments described herein, the optical engine is a microdisplay. The incident beam is split by the optical device structure 102 into a T1 beam having the full intensity of the incident beam in order to guide a virtual image to an intermediate grating (if used) or a third grating 104c. In one embodiment, which can be combined with other embodiments described herein, the T1 beam undergoes internal total internal reflection (TIR) ​​through the optical device 100 until the T1 beam contacts the optical device structure 102 of the intermediate grating. The optical device structure 102 of the intermediate grating diffracts the T1 beam into a T-1 beam, which TIRs through the optical device 100 to the optical device structure 102 of the third grating 104c. The optical device structure 102 of the third grating 104c externally couples the T-1 beam to the user's eye. The T-1 beam, externally coupled to the user's eye, displays a virtual image generated from the optical engine from the user's viewpoint, further increasing the viewing angle from which the user can observe the virtual image. In another embodiment, which can be combined with other embodiments described herein, the T1 beam undergoes internal total internal reflection (TIR) ​​through the optical device 100 until the T1 beam contacts the optical device structure 102 of the third grating 104c, is externally coupled, and displays a virtual image generated from the optical engine.

[0017] To ensure that the optical device 100 conforms to image quality standards, the metrological metrics of the manufactured optical device 100 must be obtained. The metrological metrics of individual optical devices 100 are tested to ensure that predetermined values ​​are achieved. Embodiments of the measurement system 200 described herein provide the ability to obtain multiple metrological metrics with high throughput. These metrological metrics include one or more of the following: angular uniformity metric, contrast metric, efficiency metric, color uniformity metric, modulation transfer function (MTF) metric, field of view (FOV) metric, ghost image metric, and eyebox metric.

[0018] Figure 2 is a substantially cross-sectional view of a measuring system 200 according to an embodiment described herein. The measuring system 200 includes a body 201 having a first opening 203 and a second opening 205, through which a stage 207 can be moved. The stage 207 can be operated to move in the X, Y, and Z directions within the body 201 of the measuring system 200. The stage 207 includes a tray 209 that can be operated to hold an optical device 100 (as shown herein) or to hold one or more substrates 101 on which the optical device 100 is placed.

[0019] The measurement system 200 can operate to acquire one or more metrological measures, including one or more of the following: angular uniformity metering, contrast metering, efficiency metering, color uniformity metering, MTF metering, FOV metering, ghost image metering, or eyebox metering. The stage 207 and tray 209 may be transparent so that the metrological measures acquired by the measurement system 200 are not affected by the translucency of the stage 207 or tray 209. The measurement system 200 communicates with the controller 220, which can operate to facilitate the operation of the measurement system 200.

[0020] The measurement system 200 includes an upper portion 204 oriented toward the top side 222 of the optical device 100 and a lower portion 206 oriented toward the bottom side 224 of the optical device 100. The upper portion 204 of the measurement system 200 includes an alignment camera 208, an optical engine 210, and a reflection detector 212. The alignment camera 208 can operate to determine the position of the stage 207. Also, the alignment camera 208 can similarly operate to determine the position of the optical device 100 disposed on the stage 207. The alignment camera 208 includes an alignment camera body 211. The optical engine 210 can operate to project light. For example, the optical engine 210 can operate to illuminate the first grating 104a of the optical device 100. The optical engine 210 includes an optical engine body 213. In one embodiment that can be combined with other embodiments described herein, the optical engine 210 projects a pattern onto the first grating 104a. The reflection detector 212 detects an external coupling beam projected from the third grating 104c of the optical device 100. The external coupling beam can be emitted from the top side 222 or the bottom side 224 of the optical device 100. The external coupling beam can correspond to the pattern from the optical engine 210. One or more images of the pattern are detected by the reflection detector 212. A controller 220 can be used to process one or more images of the pattern and extract individual metrology metrics.

[0021] The lower portion 206 of the measurement system 200 includes a code reader 214 and a transmission detector 216. The code reader 214 and the transmission detector are disposed on the other side of the stage 207, opposite to the alignment camera 208, the light engine 210, and the reflection detector 212. The code reader 214 can be operative to read a code of the optical device 100, such as a quick response (QR) code or a bar code of the optical device 100. The code read by the code reader 214 can include identification information and / or instructions for obtaining one or more metrological metrics of the optical device 100. The transmission detector 216 detects an externally coupled beam projected from the third grating 104c through the bottom side 224 of the optical device 100. In one embodiment, which can be combined with other embodiments described herein, the transmission detector 216 is coupled to a transmission detector stage 226. The transmission detector stage 226 can be operative to move the transmission detector 216 in the X, Y, and Z directions. The transmission detector stage 226 can be operative to adjust the position of the transmission detector 216 to enhance the detection of the externally coupled beam projected from the third grating 104c. <(

[0022] During operation, metrological metrics are obtained by illuminating the first grating 104a of the optical device 100 using the light engine 210. The light engine 210 projects a pattern onto one or more optical devices 100. The internally coupled light undergoes TIR until the light is externally coupled (e.g., reflected or transmitted) from the optical device 100. The pattern is imaged as one or more images by the reflection detector 212. The one or more images can correspond to a red channel, a green channel, and a blue channel. The one or more images can also correspond to one or more different metrological metrics. The one or more images are full field images.

[0023] Figure 3A is a schematic diagram of the first configuration 300A of the optical engine 210 of the measurement system 200 according to the embodiments described herein. The first configuration 300A includes a first light source 302A, a second light source 302B, a third light source 302C, a first mirror 304A, a second mirror 304B, a first lens 306, a reticle tray 308, and a second lens 310. The first light source 302A, the second light source 302B, the third light source 302C, the first mirror 304A, the second mirror 304B, the first lens 306, the reticle tray 308, and the second lens 310 are located within the optical engine body 213.

[0024] The first light source 302A can operate to project first light corresponding to a first wavelength or a first range of wavelengths. In one embodiment, which can be combined with other embodiments described herein, the first light source 302A is a light-emitting diode (LED). In another embodiment, which can be combined with other embodiments described herein, the first wavelength or first range of wavelengths is 620 nm to 750 nm, corresponding to red light. The first light is directed to the first lens 306.

[0025] The second light source 302B can operate to project a second light corresponding to a second wavelength or a second range of wavelengths. In one embodiment, which can be combined with other embodiments described herein, the second light source 302B is an LED. In another embodiment, which can be combined with other embodiments described herein, the second wavelength or second range of wavelengths is 495 nm to 570 nm, corresponding to green light. The second light source 302B projects the second light onto the first mirror 304A. The first mirror 304A can operate to guide the second light toward the first lens 306.

[0026] The third light source 302C can operate to project a third light corresponding to a third wavelength or a third range of wavelengths. In one embodiment, which can be combined with other embodiments described herein, the third light source 302C is an LED. In another embodiment, which can be combined with other embodiments described herein, the third wavelength or third range of wavelengths is 450 nm to 495 nm, corresponding to blue light. The third light source 302C projects the third light onto the second mirror 304B. The second mirror 304B can operate to guide the third light toward the first lens 306.

[0027] The first light source 302A, the second light source 302B, and the third light source 302C are not limited to the orientation and position shown in Figure 3A. For example, the first light source 302A may be configured to project the first light onto the first mirror 304A or the second mirror 304B. In one embodiment, which can be combined with other embodiments described herein, the first light source 302A, the second light source 302B, and the third light source 302C are point sources or extended sources. The first mirror 304A and the second mirror 304B can operate to reflect any range of wavelengths projected toward the first mirror 304A and the second mirror 304B. The first mirror 304A and the second mirror 304B may be dichroic mirrors.

[0028] The first, second, and third beams of light are guided to the first lens 306. In one embodiment, which can be combined with other embodiments described herein, the first lens 306 is a collimation lens. The first lens 306 can operate to make the light, such as the first, second, or third beams, parallel as they pass through the first lens 306. The first lens 306 parallelizes the light so that it has a beam diameter of about 10 mm to about 50 mm. This beam diameter corresponds to the field of view of the measuring system 200. In some embodiments, which can be combined with other embodiments described herein, light sources 302A, 302B, and 302C are extended light sources arranged to guide the light to the first lens 306 in order to reduce the spatial coherence of the illumination. In some embodiments, which can be combined with other embodiments described herein, the first lens 306 is removed from the optical engine 210 to improve throughput.

[0029] The reticle tray 308 includes reticles 322 (i.e., a first reticle 322A, a second reticle 322B, and a third reticle 322C). The first lens 306 directs light into a parallel beam toward the reticles 322 on the reticle tray 308. Each of the first reticles 322A, the second reticle 322B, and the third reticle 322C may include a pattern that is projected onto the first grating 104a of the optical device 100. Each of the first reticles 322A, the second reticle 322B, and the third reticle 322C may include a different pattern. The pattern is projected when one of the first light sources 302A, the second light source 302B, and the third light source 302C projects light onto the reticle 322 so that the reticle 322 is illuminated. The pattern then illuminates the first grating 104a, which corresponds to the input coupling grating of the optical device 100. The reticle tray 308 can be operated to move in one or more directions of the X, Y, and Z directions. Thus, the reticle tray 308 can be adjusted during operation of the method described herein so that light is projected through one of the first reticle 322A, the second reticle 322B, and the third reticle 322C. The reticle tray 308 is adjusted in the Z direction to improve the quality of the projected pattern. For example, by adjusting the reticle tray 308 in the Z direction, the angle and intensity of the light incident on the reticle 322 can be changed.

[0030] Each of the patterns of the first reticle 322A, the second reticle 322B, and the third reticle 322C may correspond to a different metrological metric determined by the measurement system 200. For example, each individual pattern of the reticle 322 can determine a different metrological metric. In some embodiments that can be combined with other embodiments described herein, the metrological metric may correspond to the same pattern. In other embodiments that can be combined with other embodiments described herein, the metrological metric may require the extraction of multiple patterns, depending on the case. Furthermore, each of the patterns of the first reticle 322A, the second reticle 322B, and the third reticle 322C may correspond to multiple metrological metrics. Therefore, multiple reticles 322 are required to obtain different metrological metrics for the optical device 100. The reticle tray 308 is not limited to three reticles 322. The reticle tray 308 can operate to hold more than three reticles 322 or fewer than three reticles 322. For example, there may be an array of reticles 322 placed on the reticle tray 308.

[0031] The first, second, and third beams of light are guided from the reticle 322 to the second lens 310. In one embodiment, which can be combined with other embodiments described herein, the second lens 310 is an eyepiece. The second lens 310 can operate to guide the pattern from the reticle 322 to the first grating 104a. The second lens 310 transforms the pattern so that the first grating 104a can receive it. The pattern projected from the reticle 322 undergoes TIR until the pattern is externally coupled from the third grating 104c. The third grating 104c corresponds to the output coupling grating.

[0032] Figure 3B is a schematic diagram of a second configuration 300B of the optical engine 210 of the measurement system 200 according to the embodiments described herein. The second configuration 300B includes a white light source 302D, a first lens 306, a color filter tray 312, a reticle tray 308, and a second lens 310. The white light source 302D, the first lens 306, the color filter tray 312, the reticle tray 308, and the second lens 310 are located within the optical engine body 213.

[0033] The white light source 302D can operate to project white light corresponding to a certain range of wavelengths. In one embodiment, which can be combined with other embodiments described herein, the white light source 302D is an LED. In another embodiment, which can be combined with other embodiments described herein, the wavelength range is 390 nm to 750 nm, corresponding to white light. The color filter tray 312 includes a first color filter 314A, a second color filter 314B, and a third color filter 314C. The first color filter 314A can operate to filter white light so that a first wavelength or a first range of wavelengths of a first light projected onto the optical device 100 is projected onto the optical device 100. The second color filter 314B can operate to filter white light so that a second wavelength or a second range of wavelengths of a second light is projected onto the optical device 100. The third color filter 314C can be operated to filter white light so that a third wavelength or wavelength within a third range of the third light is projected onto the optical device 100. The color filter tray 312 can be operated to move in one or more directions of the X, Y, and Z directions so that light is projected through one of the first color filter 314A, the second color filter 314B, and the third color filter 314C during operation of the method described herein.

[0034] The white light source 302D directs the white light to the color filter tray 312 via the first lens 306. The color filter tray converts the white light into filtered light, such as the first, second, or third light described above. This light is directed to the reticle tray 308 to project a pattern corresponding to the reticle 322, as described above with reference to the first configuration 300A. The pattern is directed to the second lens 310. The second lens 310 transforms the pattern so that the first grating 104a can receive it. The pattern projected from the reticle 322 undergoes TIR until the pattern is externally coupled from the third grating 104c. The third grating 104c corresponds to the output coupling grating.

[0035] Figure 3C is a schematic diagram of a third configuration 300C of the optical engine 210 of the measurement system 200 according to embodiments described herein. The third configuration 300C includes a display module 316 and a second lens 310. The display module 316 and the second lens 310 are located within the optical engine body 213. The display module 316 includes a micro-LED module, a liquid crystal on silicon (LCOS) module, a digital photon-processing (DLP) module, or a laser projection module. The display module 316 can operate to project a pattern onto the first grating 104a of the optical device 100. The display module 316 can operate to project multiple different patterns onto the first grating 104a. Each pattern projected by the display module 316 may correspond to different metrological measures determined by the measurement system 200. Each pattern may correspond to a red channel, a green channel, and a blue channel. The second lens 310 converts the pattern so that the first grating 104a can receive it. Individual patterns projected from the display module 316 undergo TIR until the patterns are externally coupled to a third grid 104c. The third grid 104c corresponds to the output coupling grid.

[0036] Figure 3D is a schematic diagram of a fourth configuration 300D of the optical engine 210 of the measurement system 200 according to embodiments described herein. The fourth configuration 300D includes a laser module 318 located within the optical engine body 213. The laser module 318 may be either a laser projection module or a laser scanning module. The laser module 318 can operate to project a pattern onto the first grating 104a of the optical device 100. The laser module 318 can operate to project multiple different patterns onto the first grating 104a. Each pattern projected by the laser module 318 may correspond to a different metrological metric determined by the measurement system 200. Each pattern may correspond to a red channel, a green channel, and a blue channel. A pattern may be projected onto a single pixel of the first grating 104a. The laser module 318 is scanned across the entire first grating 104a so that patterns are projected onto multiple pixels of the first grating 104a. Individual patterns projected from the laser module 318 undergo TIR until the patterns are externally coupled to the third grating 104c. The third grating 104c corresponds to the output coupling grating.

[0037] Figure 3E is a schematic diagram of a fifth configuration 300E of the optical engine 210 of the measurement system 200 according to an embodiment described herein. The fifth configuration 300E includes a module 320 and a second lens 310. The module 320 and the second lens 310 are located within the optical engine body 213. In one embodiment, which can be combined with other embodiments described herein, the module 320 may be a display module 316. In another embodiment, which can be combined with other embodiments described herein, the module 320 may include a light source (i.e., a first light source 302A, a second light source 302B, a third light source 302C, or a white light source 302D with a color filter tray 312) and a reticle 322 on a reticle tray 308. The module 320 can be operated to rotate and / or tilt. By rotating the module 320, the angle of incidence of light projected from the module 320 can be adjusted. For example, the module 320 is rotated and / or tilted using a rotating stage. Module 320 can operate to project multiple different patterns onto the first grid 104a. Each pattern projected by Module 320 may correspond to different metrological quantities determined by the measurement system 200. Each pattern may correspond to a red channel, a green channel, and a blue channel. The second lens 310 transforms the patterns so that the first grid 104a can receive them. Ghost imaging can be reduced by rotating and / or tilting Module 320. Ghost imaging can be reduced by reflections of the patterns projected onto the first grid 104a that are not reflected back directly to Module 320 and the second lens 310. Furthermore, rotation and / or tilting Module 320 will provide an expanded field of view for the measurement system 200. For example, rotation and / or tilting Module 320 provides a field of view between approximately 10 degrees and approximately 120 degrees.

[0038] The configurations 300A to 300E of the optical engine 210 can all be operated for use in the measurement system 200. The configuration 300A to 300E of the optical engine 210 used in the measurement system 200 is determined by the design of the optical device 100. Furthermore, the configurations 300A to 300E can be selected based on the intended use of the optical device 100 to be measured by the measurement system 200. For example, the field of view of the configurations 300A to 300E must match the field of view to be used with the optical device 100. The configurations 300A to 300E are designed for the measurement system 200 having a field of view between approximately 10 degrees and approximately 120 degrees.

[0039] Figure 4 is a schematic diagram of the configuration 400 of the alignment camera 208 of the measurement system 200 according to the embodiments described herein. The alignment camera 208 includes one or more cameras 401 disposed therein. One or more cameras 401 capture one or more images of one or more alignment markers 407 on the optical device 100. One or more images are processed in the controller 220 to determine the location and orientation of the optical device 100. A scanning path for the measurement system 200 can be generated along the optical device 100 based on one or more images of the alignment markers 407. The scanning path can be operated to correct misalignment of the optical device 100. The alignment camera 208 can be operated to correct any misalignment of the optical device 100 with respect to the optical engine 210 and the reflection detector 212. Misalignment correction via one or more alignment markers 407 allows the optical engine 210 to accurately project a pattern onto the first grating 104a. For example, the alignment marker 407 provides a field of view for alignment with the first grating 104a. Thus, by aligning the field of view with the first grating 104a and making it substantially equal to the width of the first grating 104a, the overall efficiency of the measurement system 200 is improved by effectively in-coupling the light to the first grating 104a.

[0040] Figure 5 is a flowchart of Method 500 of optical apparatus metrology according to an embodiment described herein. Method 500 can be used to project a pattern onto the first grating 104a of the optical apparatus 100. Method 500 can be used with any configuration of the optical engine 210 from configurations 300A to 300E. In one embodiment, which can be combined with other embodiments described herein, the optical engine 210 can be operated to be positioned on a rotating stage so that the optical engine 210 can be rotated and / or tilted as needed during Method 500.

[0041] In operation 501, a pattern is projected. The pattern is projected via the optical engine 210. As shown in the first configuration 300A, light can be projected by the first light source 302A. The light can be directed from the first light source 302A to the first lens 306 to make the light a parallel beam. As shown in the second configuration 300B, light can be projected from the white light source 302D, passing through the first color filter 314A of the color filter tray 312. The light can be directed from the white light source 302D to the first lens 306 to make the light a parallel beam. As shown in the third configuration 300C, light can be projected by the display module 316. As shown in the fourth configuration 300D, light can be projected by the laser module 318. As shown in the fifth configuration 300E, light can be projected by the module 320. The light corresponds to a certain wavelength or a certain range of wavelengths.

[0042] In some embodiments that can be combined with other embodiments described herein, the reticle tray 308 is positioned such that light is projected onto the reticle tray 308, as shown in the first configuration 300A and the second configuration 300B. The reticle tray 308 is positioned such that one of a plurality of reticles 322, specifically the first reticle 322A, the second reticle 322B, or the third reticle 322C, can receive light from the first lens 306. The reticle 322 is selected based on one or more metrological measures to be determined. A pattern corresponding to one of the first reticle 322A, the second reticle 322B, or the third reticle 322C is projected onto the first grating 104a of the optical device 100. The designed pattern can be guided to the first grating 104a via the second lens 310, which is an eyepiece. In other embodiments that can be combined with other embodiments described herein, the pattern is generated by one of the display module 316, laser module 318, or module 320, as shown in the third configuration 300C, the fourth configuration 300D, and the fifth configuration 300E.

[0043] In operation 502, one or more images of the pattern are detected. One or more images of the pattern are captured by the reflectance detector 212. The pattern is TIR until the pattern is externally coupled (e.g., reflected or transmitted) by the reflectance detector 212 as one or more images and captured by the reflectance detector 212. One or more images are processed and a metrological metric is extracted. The images are full-field images. One or more images can be processed in a controller 220 (shown in Figure 2). The controller 220 may be a remote controller 220 that can operate to receive one or more images. The controller 220 may include a central processing unit (CPU) configured to process computer-executable instructions stored in memory. The computer-executable instructions may include algorithms configured to extract a metrological metric. For example, the controller 220 may be configured to implement an embodiment of method 500 as described herein, such as processing one or more images to determine a value for a metrological metric corresponding to each pattern captured in one or more images. Those skilled in the art will recognize that one or more elements of the controller 220 can be remotely located and accessed via a network.

[0044] In operation 503, operations 501 and 502 are repeated for subsequent patterns. Each of the subsequent patterns can be projected by light corresponding to a certain wavelength or a certain range of wavelengths. For example, individual patterns may be in the red channel, green channel or blue channel. As shown in Figures 3A and 3B, the first configuration 300A and the second configuration 300B each include a reticle tray 308 so that individual patterns of the subsequent patterns can correspond to different reticles 322. As shown in Figures 3C to 3E, the third configuration 300C, the fourth configuration 300D, and the fifth configuration 300E each include a display module 316, a laser module 318, or a module 320 so that individual patterns of the subsequent patterns can be generated by the display module 316, a laser module 318, or a module 320. In one embodiment, which can be combined with other embodiments described herein, individual subsequent patterns are different from the preceding patterns. In another embodiment, which can be combined with other embodiments described herein, the individual subsequent patterns are the same as the preceding patterns.

[0045] In summary, this specification describes an optical engine for a measurement system and a method for using the optical engine. The measurement system includes an optical engine that can operate to illuminate a first grating of an optical device. The optical engine projects a pattern onto the first grating so that a metrological metric can be extracted from one or more images captured by the detector of the measurement system. The metrological metric determines whether the optical device conforms to an image quality standard. The optical engine can operate to rotate and tilt in order to reduce ghost imaging. Furthermore, an alignment camera of the measurement system can correct misalignments within the measurement system.

[0046] While the above description applies to embodiments of the present disclosure, other embodiments of the present disclosure can be constructed without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the following claims.

Claims

1. A measurement system, A stage capable of holding an optical device, or operating to hold an optical device substrate on which at least one optical device is placed, An optical engine positioned above the aforementioned stage, Multiple light sources, which are capable of operating to project light of a certain range of wavelengths onto the optical device, A first lens capable of operating to make the light from each of the plurality of light sources into parallel beams, A reticle tray positioned below the plurality of light sources, having a plurality of reticles positioned thereon, wherein each of the plurality of reticles has a pattern that is projected when the light is guided to each of the plurality of reticles; A second lens capable of receiving the pattern projected from each of the plurality of reticles, and capable of projecting the pattern onto the input coupling grating of the optical device, and Including an optical engine and A measurement system equipped with the following features.

2. The measurement system according to claim 1, wherein the optical engine is coupled to a rotating stage, and the rotating stage is capable of operating to rotate or tilt the optical engine.

3. The measurement system according to claim 1, wherein the plurality of light sources include a first light source capable of projecting wavelengths in a first range from 620 nm to 750 nm, a second light source capable of projecting wavelengths in a second range from 495 nm to 570 nm, and a third light source capable of projecting wavelengths in a third range from 450 nm to 495 nm.

4. The measurement system according to claim 1, further comprising an alignment camera adjacent to the optical engine, wherein the alignment camera is capable of capturing images of one or more alignment markers on the optical device or on the substrate of the optical device.

5. The measurement system according to claim 1, wherein the optical engine includes a plurality of mirrors, and the plurality of mirrors are capable of guiding the light from the plurality of light sources to the first lens.

6. The measurement system according to claim 1, further comprising a reflectance detector adjacent to the optical engine, wherein the reflectance detector is arranged to detect the pattern projected from each of the plurality of reticles.

7. The measurement system according to claim 1, further comprising a transmission detector positioned on the opposite side of the stage from the optical engine, wherein the transmission detector is capable of detecting the pattern projected from each of the plurality of reticles.

8. A measurement system, A stage capable of holding an optical device, or operating to hold an optical device substrate on which at least one optical device is placed, An optical engine positioned above the aforementioned stage, A module capable of operating to project one or more patterns onto an optical device, wherein the optical engine is capable of operating to rotate and / or tilt in order to adjust the angle of incidence of the patterns projected onto the optical device or the optical device substrate. An optical engine including, An alignment camera adjacent to the optical engine, which is positioned to capture images of one or more alignment markers on the optical device or the substrate of the optical device, A reflectance detector adjacent to the optical engine, the reflectance detector being arranged to detect an externally coupled beam projected from the optical device, A measurement system equipped with the following features.

9. The measurement system according to claim 8, further comprising a second lens on which the optical engine can operate to receive the pattern, the second lens can operate to project the pattern onto an input coupling grating of the optical device.

10. The measurement system according to claim 8, wherein the patterns can correspond to the red channel, green channel, and blue channel, respectively.

11. The measurement system according to claim 8, wherein the module is a micro-LED module, a liquid crystal on silicon (LCOS) module, a digital photoprocessing (DLP) module, or a laser projection module capable of operating to project the one or more patterns.

12. The measurement system according to claim 8, wherein the module is a laser projection module or a laser scanning module capable of operating to project the one or more patterns.

13. The measurement system according to claim 8, wherein the field of view of the optical engine is between approximately 10 degrees and approximately 100 degrees.

14. The measurement system according to claim 8, wherein the stage is transparent.

15. It is a method, Projecting a pattern, wherein the pattern is projected using light from an optical engine, the optical engine is located within a measurement system, and the measurement system is A stage located below the aforementioned optical engine, A tray placed on the stage, having an optical device, or having an optical device substrate on which at least one optical device is placed, and the tray is capable of operating so as to receive the pattern, A reflectance detector oriented toward the aforementioned stage and Projecting a pattern that has, The means of detecting one or more images of the pattern, wherein the image is detected when the pattern, which is undergoing total internal reflection through the optical device, is externally coupled to the reflection detector. The aforementioned image is processed to extract metrological metrics. A method that includes this.

16. The method according to claim 15, wherein the optical width of the light is substantially equal to the width of the input coupling grating of the optical device.

17. The method according to claim 15, further comprising rotating or tilting the light engine when projecting the light.

18. The method according to claim 15, further comprising using an alignment camera of the measurement system to correct misalignment of the optical device with respect to the optical engine.

19. The method according to claim 15, wherein the metrological metric includes one or more of angular uniformity metric, contrast metric, efficiency metric, color uniformity metric, modulation transfer function (MTF) metric, field of view (FOV) metric, ghost image metric, and eyebox metric.

20. The method according to claim 15, further comprising repeating the method for a subsequent pattern.

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