CN116569028A - Irradiation System for AR Metrology Tools - Google Patents

Abstract

Embodiments described herein provide light engines for measurement systems and methods of using these light engines. The measurement system includes a light engine operable to illuminate a first grating of an optical device. The light engine projects a pattern with light from the light engine. The light engine projects a pattern onto the first grating so that a metrology measure can be extracted from one or more images captured by the detector of the measurement system. These metrology measures are extracted by processing the imagery. These metrology metrics determine whether the optical device meets image quality standards.

Description

Irradiation systems for AR metrology tools

background

technical field

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

Background technique

Virtual reality is generally considered to be a computer-generated simulated environment in which the user has an apparent physical presence. Virtual reality experiences can be generated in 3D and viewed through a head-mounted display (HMD), such as glasses or other wearable display devices with near-eye display panels as lenses, to display a virtual reality environment instead of the actual environment.

Augmented reality, however, enables an experience in which the user can still see through the display lenses of glasses or other HMD devices to see the surrounding environment and also see objects generated for display and appear as part of the environment. virtual object images. Augmented reality can include any type of input, such as audio and tactile input, as well as virtual images, graphics, and video that enhance or enhance the environment experienced by the user. As an emerging technology, augmented reality has many challenges and design constraints.

One such challenge is measuring optics against image quality standards. To ensure that image quality standards are met, metrics must be obtained for the fabricated optical device. However, existing measurement systems lack the desired field of view and suffer from ghost imaging. Accordingly, what is needed in the art is a measurement system and method of using the measurement system having an improved field of view and reduced occurrence of ghost imaging.

Contents of the invention

In one embodiment, a measurement system is provided. The measurement system includes a stage operable to hold an optical device or an optical device substrate on which at least one optical device is disposed. The measurement system further includes a light engine disposed above the stage. The light engine includes a plurality of light sources. The plurality of light sources is operable to project light to the optical device in a range of wavelengths. The light engine further includes a first lens operable to collimate light from each of the plurality of light sources. The light engine further includes a reticle tray disposed under the plurality of light sources. A plurality of reticles are arranged on the reticle bracket. Each reticle of the plurality of reticles has a pattern to be projected when the light is directed to each reticle of the plurality of reticles. The light engine further includes a second lens operable to receive the pattern projected from each reticle of the plurality of reticles. The second lens is operable to project the pattern onto an incoupling grating of the optical device.

In another embodiment, a measurement system is provided. The measurement system includes a stage operable to hold an optical device or an optical device substrate on which at least one optical device is disposed. The measurement system further includes a light engine disposed above the stage. The light engine includes a module operable to project one or more patterns toward the optical device. The light engine is operable to rotate and/or tilt to adjust the angle of incidence of the pattern projected onto the optical device or the optical device substrate. The measurement system further includes an alignment camera adjacent to the light engine. The alignment camera is positioned to capture one or more images of one or more alignment marks on the optical device or the optical device substrate. The measurement system further includes a reflection detector adjacent to the light engine. The reflection detector is positioned to detect outcoupled light beams projected from the optics.

In yet another embodiment, a method is provided. The method includes projecting a pattern. The pattern is projected by light from a light engine. The light engine is arranged in the measurement system. The measurement system includes an object stage arranged under the light engine. The measurement system further includes a bracket disposed on the stage. The carrier includes an optical device or an optical device substrate on which at least one optical device is disposed, and the optical device is operable to receive the pattern. The measurement system further includes a reflection detector oriented toward the stage. The method further includes detecting one or more images of the pattern. The image is detected when the pattern undergoing total internal reflection by the optics is outcoupled to the reflection detector. The method further includes processing the imagery to extract metrology metrics.

Description of drawings

So that the manner in which features of the disclosure recited above can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, for other equally effective embodiments may be admitted.

1A is a perspective front view of a substrate according to embodiments described herein.

Figure IB is a perspective front view of an optical device according to embodiments described herein.

Fig. 2 is a schematic cross-sectional view of a measurement system according to an embodiment described herein.

3A-3E are schematic illustrations of the configuration of a light engine of a measurement system according to embodiments described herein.

4 is a schematic illustration of an alignment camera configuration of a measurement system according to embodiments described herein.

5 is a flowchart of a method of metrology for an optical device according to embodiments described herein.

To facilitate understanding, the same reference signs have been used, where practicable, to refer to the same elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

Detailed ways

Embodiments of the present disclosure generally relate to optical devices for augmented reality, virtual reality, and mixed reality. More particularly, embodiments described herein provide a light engine for a measurement system and methods of using the light engine. The measurement system includes a stage operable to hold an optical device or an optical device substrate on which at least one optical device is disposed. The measurement system further includes a light engine disposed above the stage. The light engine includes a plurality of light sources. The plurality of light sources is operable to project light to the optical device in a range of wavelengths. The light engine further includes a first lens operable to collimate light from each of the plurality of light sources. The light engine further includes a reticle bracket disposed under the plurality of light sources. The reticle holder has a plurality of reticles disposed thereon. Each reticle of the plurality of reticles has a pattern to be projected when the light is directed to each reticle of the plurality of reticles. The light engine further includes a second lens operable to receive the pattern projected from each reticle of the plurality of reticles. The second lens is operable to project the pattern onto an incoupling grating of the optical device. The light engine may also include a module for projecting patterns.

A method of using the light engine includes projecting a pattern with light from the light engine. The method further includes detecting one or more images of the pattern. The image is detected when the pattern undergoing total internal reflection by the optics is outcoupled to the reflection detector. The method further includes processing the imagery to extract metrology metrics.

FIG. 1A is a perspective front view of a substrate 101 according to embodiments described herein. The substrate includes a plurality of optical devices 100 disposed on a surface 103 of the substrate 101 . In some embodiments (which can be combined with other embodiments described herein), the optical device 100 is a waveguide combiner for virtual reality, augmented reality, or mixed reality. In some embodiments (which can be combined with other embodiments described herein), optical device 100 is a flat optical device, such as a metasurface.

The substrate 101 can be any substrate used in the art, and can be opaque or transparent to a selected laser wavelength depending on the use of the substrate 101 . The substrate 101 includes, but is not limited to, silicon (Si), silicon dioxide (SiO ₂ ), fused silica, 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. Additionally, the substrate 101 may have various shapes, thicknesses, and diameters. For example, substrate 101 may have a diameter of 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 may be disposed on the surface 103 of the substrate 101 .

FIG. 1B is a perspective front view of optical device 100 . It will be appreciated that the optical device 100 described herein is an exemplary optical device and that other optical devices may be used or modified to achieve aspects of the present disclosure. The optical device 100 includes a plurality of optical device structures 102 disposed on a surface 103 of a substrate 101 . The optical device structure 102 may be a nanostructure having sub-micron dimensions (eg, nanometer-sized dimensions). A region of the optical device structure 102 corresponds 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 comprises at least a first grating 104a corresponding to the in-coupling grating and a third grating 104c corresponding to the out-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 the intermediate grating. The optical device structure 102 can be angled or binary. The optical device structure 102 may have other cross-sections including, but not limited to, circular, triangular, elliptical, regular polygonal, irregular polygonal, and/or irregularly shaped cross-sections.

In operation, the first grating 104a receives incident light beams from the light engine, the light beams having an intensity. In one embodiment (which can be combined with other embodiments described herein), the light engine is a microdisplay. The incident beam is split by the optics structure 102 into T1 beams having the full intensity of the incident beam to direct the virtual image to the intermediate grating (if used) or the third grating 104c. In one embodiment (which can be combined with other embodiments described herein), T1 beams undergo total internal reflection (TIR) through the optical device 100 until they contact the optical device structure 102 of the intermediate grating. The optical device structure 102 of the intermediate grating diffracts the T1 beams into T-1 beams which undergo TIR through the optical device 100 to the optical device structure 102 of the third grating 104c. The optics structure 102 of the third grating 104c outcouples these T-1 beams to the user's eye. The T-1 beam that is out-coupled to the user's eye displays the virtual image generated from the light engine from the user's perspective and further increases the viewing angle from which the user can view the virtual image. In another embodiment (which can be combined with other embodiments described herein), the T1 beams undergo total internal reflection (TIR) through the optical device 100 until the T1 beams contact the optical device structure 102 of the third grating 104c and are outcoupled to display virtual images generated from the light engine.

To ensure that the optical device 100 meets image quality standards, metrology of the optical device 100 as manufactured must be obtained. The metrology metrics of each optical device 100 are tested to ensure that predetermined values are achieved. Embodiments of the measurement system 200 described herein provide the ability to obtain multiple metrology measurements with increased throughput. Metrology metrics include one or more of the following: angular uniformity metrics, contrast metrics, efficiency metrics, color uniformity metrics, modulation transfer function (MTF) metrics, field of view (FOV) metrics, ghost image metrics, and eye box ( eye box) measure.

FIG. 2 is a schematic cross-sectional view of a measurement system 200 according to embodiments described herein. The measurement system 200 includes a body 201 having a first opening 203 and a second opening 205 to allow a stage 207 to move therethrough. The stage 207 is operable to move in the X direction, the Y direction, and the Z direction in the main body 201 of the measurement system 200 . Stage 207 includes a bracket 209 operable to hold optical device 100 (as shown herein) or one or more substrates 101 on which optical device 100 is disposed.

The measurement system 200 is operable to obtain one or more metrology metrics, including one or more of the following: angular uniformity metrics, contrast metrics, efficiency metrics, color uniformity metrics, MTF metrics, FOV metrics, ghost image metrics, or Eyebox metrics. Stage 207 and carrier 209 may be transparent such that metrology measurements taken by measurement system 200 are not affected by the translucency of stage 207 or carrier 209 . Measurement system 200 is in communication with controller 220 . Controller 220 is operable to facilitate operation of measurement system 200 .

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 . Upper portion 204 of measurement system 200 includes alignment camera 208 , light engine 210 , and reflection detector 212 . Alignment camera 208 is operable to determine the position of stage 207 . Alignment camera 208 is also operable to determine the position of optical device 100 disposed on stage 207 . Aligning the camera 208 includes aligning the camera body 211 . The light engine 210 is operable to project light. For example, the light engine 210 is operable to illuminate the first grating 104a of the optical device 100 . The light engine 210 includes a light engine body 213 . In one embodiment (which can be combined with other embodiments described herein), the light engine 210 projects a pattern onto the first grating 104a. The reflection detector 212 detects the outcoupled light beam projected from the third grating 104c of the optical device 100 . These outcoupled light beams can emerge from either the top side 222 or the bottom side 224 of the optical device 100 . These outcoupled beams may correspond to patterns from the light engine 210 . One or more images of the pattern are detected by reflection detector 212 . One or more images of the pattern may be processed by controller 220 to extract metrological metrics.

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 transmissive detector are positioned opposite the alignment camera 208 , light engine 210 , and reflective detector 212 on the other side of the stage 207 . The code reader 214 is operable to read a code of the optical device 100 , such as a quick response (QR) code or a barcode of the optical device 100 . The code read by the code reader 214 may include identifying information and/or instructions for obtaining one or more metrological measurements of the optical device 100 . The transmission detector 216 detects the outcoupled light 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), transmission detector 216 is coupled to transmission detector stage 226 . The transmission detector stage 226 is operable to move the transmission detector 216 in the X direction, the Y direction, and the Z direction. The transmission detector stage 226 is operable to adjust the position of the transmission detector 216 to enhance detection of the outcoupled beam projected from the third grating 104c.

In operation, metrology measurements are taken by illuminating the first grating 104a of the optical device 100 with the light engine 210 . The light engine 210 projects patterns to one or more optical devices 100 . Incoupled light undergoes TIR until the light is outcoupled (eg, reflected or transmitted) out of the optical device 100 . The pattern is captured by reflection detector 212 as one or more images. The one or more images may correspond to red, green, and blue channels. The one or more images may also correspond to one or more different metrology metrics. The one or more images are full-field images.

3A is a schematic diagram of a first configuration 300A of the light engine 210 of the measurement system 200 according to 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 holder 308, and a second lens 310 . First light source 302A, second light source 302B, third light source 302C, first mirror 304A, second mirror 304B, first lens 306, reticle holder 308, and second lens 310 are disposed in light engine body 213 .

The first light source 302A is operable 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 range of wavelengths is 620 nm to 750 nm corresponding to red light. The first light is directed to the first lens 306 .

The second light source 302B is operable 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 range of wavelengths is 495 nm to 570 nm corresponding to green light. The second light source 302B projects second light toward the first mirror 304A. The first mirror 304A is operable to direct the second light towards the first lens 306 .

The third light source 302C is operable to project third light corresponding to a third wavelength or third wavelength range. 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 range of wavelengths is 450 nm to 495 nm corresponding to blue light. The third light source 302C projects third light toward the second mirror 304B. The second mirror 304B is operable to direct the third light towards the first lens 306 .

The first light source 302A, the second light source 302B, and the third light source 302C are not limited to the orientations and positions shown in FIG. 3A. For example, the first light source 302A may be configured to project a first light to 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 are operable to reflect any wavelength range projected towards the first mirror 304A and the second mirror 304B. The first mirror 304A and the second mirror 304B may be dichroic mirrors.

The first light, the second light, and the third 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 collimating lens. The first lens 306 is operable to collimate light (such as first light, second light, or third light) as it passes through the first lens 306 . The first lens 306 collimates the light such that the light has an optical path of about 10 mm to about 50 mm. This optical path corresponds to the field of view of the measurement system 200 . In some embodiments (which can be combined with other embodiments described herein), light sources 302A, 302B, and 302C are extended light sources positioned to direct light to first lens 306 to reduce spatial coherence of illumination . In some implementations (which can be combined with other implementations described herein), the first lens 306 is removed from the light engine 210 to improve throughput.

The reticle holder 308 includes reticles 322 (ie, a first reticle 322A, a second reticle 322B, and a third reticle 322C). First lens 306 collimates light towards reticle 322 on reticle holder 308 . Each of the first reticle 322A, the second reticle 322B, and the third reticle 322C may include a pattern of the first grating 104 a to be projected to the optical device 100 . Each of the first reticle 322A, the second reticle 322B, and the third reticle 322C may include different patterns. The pattern is projected when one of the first light source 302A, the second light source 302B, and the third light source 302C projects light onto the reticle 322 such that the reticle 322 is illuminated. The pattern then illuminates the first grating 104a. The first grating 104 a corresponds to the incoupling grating of the optical device 100 . Reticle carriage 308 is operable to move in one or more of an X direction, a Y direction, and a Z direction. Accordingly, reticle carrier 308 may be adjusted such that light is transmitted through one projection of first reticle 322A, second reticle 322B, and third reticle 322C during operation of the methods described herein. The reticle carriage 308 is adjusted in the Z direction to improve the quality of the pattern to be projected. For example, adjusting reticle holder 308 in the Z direction can change the angle and intensity of light incident on reticle 322 .

Each of the patterns of first reticle 322A, second reticle 322B, and third reticle 322C may correspond to a different metrology measure to be determined by measurement system 200 . For example, each respective pattern of reticle 322 may allow a respective metrology measure to be determined. In some embodiments (which can be combined with other embodiments described herein), these metrological measures may correspond to the same pattern. In other embodiments (which can be combined with other embodiments described herein), these metrology measures may require more than one pattern to be extracted. Additionally, each of the patterns of the first reticle 322A, the second reticle 322B, and the third reticle 322C may correspond to a plurality of metrology measurements. Therefore, multiple reticles 322 are required to achieve different metrology metrics for the optical device 100 . Reticle holder 308 is not limited to three reticles 322 . Reticle holder 308 is operable to hold more or less than three reticles 322 . For example, an array of reticle 322 may be disposed on reticle carrier 308 .

The first light, the second light, and the third 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 lens. The second lens 310 is operable to direct the pattern from the reticle 322 to the first grating 104a. The second lens 310 transforms the pattern so that the first grating 104a receives the pattern. The pattern projected from the reticle 322 undergoes TIR until it is decoupled from the third grating 104c. The third grating 104c corresponds to an outcoupling grating.

3B is a schematic diagram of a second configuration 300B of the light engine 210 of the measurement system 200 according to embodiments described herein. The second configuration 300B includes a white light source 302D, a first lens 306 , a color filter holder 312 , a reticle holder 308 , and a second lens 310 . White light source 302D, first lens 306 , color filter holder 312 , reticle holder 308 , and second lens 310 are disposed in light engine body 213 .

The white light source 302D is operable to project white light corresponding to a wavelength range. In one embodiment (which can be combined with other embodiments described herein), 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 holder 312 includes a first color filter 314A, a second color filter 314B, and a third color filter 314C. The first color filter 314A is operable to allow white light to be filtered such that a first wavelength or range of wavelengths of first light to be projected to the optical device 100 is projected to the optical device 100 . The second color filter 314B is operable to allow white light to be filtered such that a second wavelength or range of wavelengths of the second light is projected to the optical device 100 . The third color filter 314C is operable to allow white light to be filtered such that a third wavelength or range of wavelengths of third light is projected to the optical device 100 . The color filter carriage 312 is operable to move in one or more of the X direction, the Y direction, and the Z direction such that light passes through the first color filter 314A, the second filter 314A, and the second filter during operation of the methods described herein. One of the color filter 314B, and the third color filter 314C is projected.

White light source 302D directs white light through first lens 306 and to color filter holder 312 . The color filter holder transforms white light into filtered light, such as the first light, second light, or third light described above. The light is directed to reticle carrier 308 to project a pattern corresponding to reticle 322, as described above with reference to first configuration 300A. The pattern is guided to the second lens 310 . The second lens 310 transforms the pattern so that the first grating 104a receives the pattern. The pattern projected from the reticle 322 undergoes TIR until it is decoupled from the third grating 104c. The third grating 104c corresponds to an outcoupling grating.

3C is a schematic diagram of a third configuration 300C of the light 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 disposed in the light engine body 213 . The display module 316 includes a micro LED module, a liquid crystal on silicon (LCOS) module, a digital light processing (DLP) module, or a laser projection module. The display module 316 is operable to project a pattern onto the first grating 104 a of the optical device 100 . The display module 316 is operable to project a plurality of different patterns onto the first grating 104a. Each pattern projected by display module 316 may correspond to a different metrology metric to be determined by measurement system 200 . Each pattern may correspond to red, green, and blue channels. The second lens 310 transforms the pattern so that the first grating 104a receives the pattern. Each pattern projected from the display module 316 undergoes TIR until it is decoupled from the third grating 104c. The third grating 104c corresponds to an outcoupling grating.

3D is a schematic diagram of a fourth configuration 300D of the light engine 210 of the measurement system 200 according to embodiments described herein. The fourth configuration 300D includes a laser module 318 disposed in the light engine body 213 . The laser module 318 can be one of a laser projection module or a laser scanning module. The laser module 318 is operable to project a pattern onto the first grating 104a of the optical device 100 . The laser module 318 is operable to project a plurality of different patterns onto the first grating 104a. Each pattern projected by laser module 318 may correspond to a different metrology metric to be determined by measurement system 200 . Each pattern may correspond to red, green, and blue channels. The pattern may be projected to individual pixels of the first grating 104a. The laser module 318 is scanned over the first grating 104a such that the pattern is projected onto a plurality of pixels of the first grating 104a. Each pattern projected from the laser module 318 undergoes TIR until it is decoupled from the third grating 104c. The third grating 104c corresponds to an outcoupling grating.

3E is a schematic diagram of a fifth configuration 300E of the light engine 210 of the measurement system 200 according to embodiments described herein. The fifth configuration 300E includes a module 320 and a second lens 310 . The module 320 and the second lens 310 are disposed in the light engine body 213 . In one embodiment (which can be combined with other embodiments described herein), module 320 may be 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 along with a color filter bracket 312) and the reticle 322 on the reticle bracket 308. Module 320 is operable to be rotated and/or tilted. Rotation of the module 320 allows the incident angle of light projected from the module 320 to be adjusted. For example, module 320 is rotated and/or tilted by a turn table. Module 320 is operable to project a plurality of different patterns onto first grating 104a. Each pattern projected by module 320 may correspond to a different metrology metric to be determined by measurement system 200 . Each pattern may correspond to red, green, and blue channels. The second lens 310 transforms the pattern so that the first grating 104a receives the pattern. By rotating and/or tilting the module 320, ghost imaging can be reduced. Ghost imaging is reduced because reflections of the pattern projected onto the first grating 104a are not directly reflected back to the module 320 and the second lens 310 . Additionally, rotation and/or tilting of module 320 will provide measurement system 200 with a field of view expansion. For example, rotation and/or tilting of module 320 provides a field of view of between about 10 degrees and about 120 degrees.

Configurations 300A- 300E of light engine 210 are all operable to be employed in measurement system 200 . The configurations 300A to 300E of the light engine 210 to be used in the measurement system 200 are determined by the design of the optical device 100 . Further, 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 configurations 300A-300E should match the field of view to be used by optical device 100 . Configurations 300A-300E are designed for measurement system 200 having a field of view between about 10 degrees and about 120 degrees.

FIG. 4 is a schematic diagram of an arrangement 400 of alignment cameras 208 of measurement system 200 according to embodiments described herein. 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 marks 407 on the optical device 100 . The one or more images are processed in the controller 220 to determine the position and orientation of the optical device 100 . A scan path for the measurement system 200 can be generated along the optical device 100 based on the one or more images of the alignment marks 407 . The scan path is operable to correct misalignment of the optical device 100 . Alignment camera 208 is operable to correct any misalignment of optical device 100 relative to light engine 210 and reflection detector 212 . Misalignment correction via the one or more alignment marks 407 allows the light engine 210 to accurately project a pattern onto the first grating 104a. For example, alignment marks 407 allow alignment of the field of view with the first grating 104a. Thus, having the field of view aligned with the first grating 104a and substantially equal to the width of the first grating 104a improves the overall efficiency of the measurement system 200 by efficiently in-coupling light into the first grating 104a.

FIG. 5 is a flowchart of a method 500 of optical device metrology according to embodiments described herein. The method 500 may be used to project a pattern onto the first grating 104 a of the optical device 100 . Method 500 may be exercised by any of configurations 300A-300E of light engine 210 . In one embodiment (which can be combined with other embodiments described herein), light engine 210 is operable to be disposed on a rotating table such that light engine 210 can be rotated and/or tilted as desired during method 500 .

In operation 501, a pattern is projected. The pattern is projected via the light engine 210 . As shown in the first configuration 300A, light may be projected by a first light source 302A. The light may be directed from the first light source 302A to the first lens 306 to collimate the light. As shown in the second configuration 300B, this light may be projected from a white light source 302D through a first color filter 314A of a color filter bracket 312 . The light may be directed from the white light source 302D to the first lens 306 to collimate the light. This light may be projected by the display module 316 as shown in the third configuration 300C. As shown in the fourth configuration 300D, the light may be projected by a laser module 318 . This light may be projected by module 320 as shown in fifth configuration 300E. The light corresponds to a wavelength or a range of wavelengths.

In some embodiments (which can be combined with other embodiments described herein), as shown in the first configuration 300A and the second configuration 300B, the reticle holder 308 is positioned such that light is projected onto the reticle holder Rack 308. The reticle holder 308 is positioned so that one of the first reticle 322A, the second reticle 322B, or the third reticle 322C among the plurality of reticles 322 provided on the reticle holder 308 One can receive light from the first lens 306 . Reticle 322 is selected based on one or more metrology metrics 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 104 a of the optical device 100 . The designed pattern can be guided to the first grating 104a through the second lens 310 . The second lens 310 is an eyepiece lens. In other embodiments (which can be combined with other embodiments described herein), as shown in the third configuration 300C, the fourth configuration 300D, and the fifth configuration 300E, the pattern is represented by the display module 316, the laser module 318, respectively. , or one of module 320 produces.

At operation 502, one or more images of the pattern are detected. The one or more images of the pattern are captured by reflection detector 212 . The pattern undergoes TIR until it is outcoupled (eg, reflected or transmitted) and captured by reflection detector 212 as one or more images. The one or more images are processed to extract metrology metrics. These images are global images. The one or more images may be processed in controller 220 (shown in FIG. 2 ). The controller 220 may be a remote controller 220 operable to receive the one or more images. The controller 220 may include a central processing unit (CPU) configured to process computer-executable instructions stored in a memory. These computer-executable instructions may include algorithms configured to extract metrology metrics. For example, controller 220 is configured to perform implementations of method 500 described herein, such as processing one or more images to determine values of metrology metrics corresponding to individual patterns captured in the one or more images. Those skilled in the art will appreciate that one or more elements of controller 220 may be located remotely and accessed via a network.

In operation 503, operations 501 and 502 are repeated for subsequent patterns. Each of the subsequent patterns may be projected by light corresponding to a wavelength or a range of wavelengths. For example, each pattern can be a red, green, or blue color channel. As shown in FIGS. 3A and 3B , the first configuration 300A and the second configuration 300B each include a reticle holder 308 such that each pattern of subsequent patterns may correspond to a different reticle 322 . As shown in FIGS. 3C-3E , the third configuration 300C, the fourth configuration 300D, and the fifth configuration 300E include a display module 316, a laser module 318, or a module 320, respectively, so that each pattern of subsequent patterns can be displayed by the display module 316, laser module 318, or module 320. Laser module 318, or module 320 to generate. In one embodiment (which can be combined with other embodiments described herein), each subsequent pattern is different from the previous pattern. In another embodiment (which can be combined with other embodiments described herein), each subsequent pattern is the same as the previous pattern.

In summary, light engines of measurement systems and methods of using the light engines are described herein. The measurement system includes a light engine operable to illuminate a first grating of an optical device. The light engine projects a pattern onto the first grating so that metrology metrics can be extracted from one or more images captured by a detector of the measurement system. Metrology metrics determine whether the optical device meets image quality standards. The light engine is operable to rotate and tilt such that ghost imaging can be reduced. In addition, the alignment camera of the measurement system allows for misalignment correction in the measurement system.

While the foregoing is directed to embodiments of the disclosure, other embodiments of the disclosure can be devised without departing from the essential scope of the disclosure, which is determined by the appended claims.

Claims (20)

1. A measurement system comprising: a stage operable to hold an optical device or an optical device substrate having at least one optical device disposed thereon; and Light engine, described light engine is arranged above described stage, and described light engine comprises: a plurality of light sources operable to project light toward the optical device in a range of wavelengths; a first lens operable to collimate the light from each of the plurality of light sources; A reticle bracket, the reticle bracket is arranged under the plurality of light sources, the reticle bracket has a plurality of reticle arranged thereon, each of the plurality of reticle The reticle has a pattern, the pattern is to be projected when the light is directed to each reticle of the plurality of reticles; and a second lens operable to receive the pattern projected from each reticle of the plurality of reticles, the second lens operable to project the pattern to the optical device The input coupling grating. 2. The measurement system of claim 1, wherein the light engine is coupled to a turntable operable to rotate or tilt the light engine. 3. The measurement system of claim 1, wherein said plurality of light sources comprises a first light source, a second light source, and a third light source, said first light source being operable to project a first wavelength range of 620 nm to 750 nm, The second light source is operable to project a second wavelength range of 495nm to 570nm and the third light source is operable to project a third wavelength range of 450nm to 495nm. 4. The measurement system of claim 1 , further comprising an alignment camera adjacent to the light engine, the alignment camera operable to capture a light on the optical device or on the optical device substrate. One or more images of one or more alignment marks. 5. The measurement system of claim 1, wherein the light engine includes a plurality of mirrors operable to direct the light from the plurality of light sources toward the first lens. 6. The measurement system of claim 1 , further comprising a reflection detector adjacent to the light engine, the reflection detector positioned to detect light projected from each reticle of the plurality of reticles. the pattern. 7. The measurement system of claim 1 , further comprising a transmission detector positioned on a side of the stage opposite the light engine, the transmission detector operable to The pattern projected from each reticle of the plurality of reticles is detected. 8. A measurement system comprising: a stage operable to hold an optical device or an optical device substrate having at least one optical device disposed thereon; Light engine, described light engine is arranged above described stage, and described light engine comprises: a module operable to project one or more patterns to the optical device, wherein The light engine is operable to rotate and/or tilt to adjust toward the optical device or the optical device Setting the incident angle of the pattern projected by the substrate; an alignment camera adjacent to the light engine, the alignment camera positioned to capture one or more of the one or more alignment marks on the optical device or the optical device substrate images; and A reflective detector adjacent to the light engine is positioned to detect an outcoupled light beam projected from the optical device. 9. The measurement system of claim 8, wherein the light engine further comprises a second lens operable to receive the pattern, the second lens operable to project the pattern onto The input coupling grating of the optical device. 10. The measurement system of claim 8, wherein the patterns can each correspond to red, green, and blue channels. 11. The measurement system of claim 8, wherein a micro LED module, a liquid crystal on silicon (LCOS) module, a digital light processing (DLP) module, or a laser projection module operable to project the one or more patterns . 12. The measurement system of claim 8, wherein the module is a laser projection module or a laser scanning module operable to project the one or more patterns. 13. The measurement system of claim 8, wherein the light engine has a field of view of between about 10 degrees and about 100 degrees. 14. The measurement system of claim 8, wherein the stage is transparent. 15. A method comprising: projecting a pattern, the pattern being projected by light from a light engine disposed in a measurement system having: an object stage, the object stage is arranged under the light engine; a carrier disposed on the stage, the carrier having an optical device or an optical device substrate having at least one optical device disposed thereon, the optical device being operable to receive the pattern; and a reflection detector oriented towards the stage; detecting one or more images of said pattern, said images being detected when said pattern undergoing total internal reflection by said optical device is outcoupled to said reflection detector; and The imagery is processed to extract metrology metrics. 16. The method of claim 15, wherein the optical width of the light is substantially equal to the width of an incoupling grating of the optical device. 17. The method of claim 15, further comprising rotating or tilting the light engine while projecting the light. 18. The method of claim 15, further comprising: employing an alignment camera of the measurement system to correct for misalignment of the optical device relative to the light engine. 19. The method of claim 15, wherein the metrology metrics include one or more of the following: angular uniformity metrics, contrast metrics, efficiency metrics, color uniformity metrics, modulation transfer function (MTF) metrics, field of view (FOV) metric, ghost image metric, eye box metric. 20. The method of claim 15, further comprising repeating the method for subsequent patterns.