Method and apparatus for guided wave measurements

Abstract

Embodiments described herein relate to an apparatus for measuring and evaluating the performance of augmented and virtual reality waveguide structures that utilize glass substrates. The waveguide performance measurement system generally includes a light source configured to direct light onto a coupling grating area on a waveguide and one or more photodetectors configured to collect light from a decoupling grating area on a second side of the waveguide. The light source and one or more photodetectors are disposed on one or more adjustable stages disposed about the waveguide. In certain embodiments, the one or more adjustable stages are configured to move in a linear manner or to revolve and / or rotate in an orbital motion about the waveguide.

Description

[Technical Field]

[0001]

[0001] Embodiments of the present disclosure generally relate to waveguides for augmented, virtual, and mixed reality, and apparatus for characterizing such waveguides. In particular, embodiments described herein relate to a measurement apparatus for determining the performance efficiency of waveguide couplers. [Background technology]

[0002]

[0002] Virtual reality is generally considered to be a computer-generated simulated environment in which a user has an apparent physical presence. Virtual reality experiences may be generated in three dimensions (3D) and viewed using a head-mounted display (HMD), such as glasses or other wearable display devices with display panels near the eyes as lenses to display the virtual reality environment that replaces the real environment.

[0003]

[0003] Augmented reality, however, enables an experience in which a user can still see the surrounding environment through the display lenses of glasses or other HMD devices, but can also see images of virtual objects that are generated for display and that appear as part of or superimposed on the environment. Augmented reality can include any type of input, such as voice input or tactile input, as well as virtual images, graphics, and video that enhance or extend the environment the user experiences. As an emerging technology, augmented reality presents many challenges and design constraints.

[0004] One such challenge is managing the quality of augmented reality display devices. Many current augmented reality display devices utilize waveguide couplers to assist in overlaying a virtual image on the surrounding environment. Manufacturing waveguide couplers can be challenging because waveguides tend to have non-uniform properties, causing light to propagate differently from one device to another. Therefore, post-manufacturing quality control of waveguide couplers is critical to maintaining consistent performance across augmented reality display devices. Conventional waveguide metrology systems are used in the characterization and post-manufacturing quality control of waveguides. Conventional metrology systems are configured to illuminate a single spot on the waveguide and collect light propagation data therefrom. Advanced waveguides often employ complex grating designs, resulting in multiple distinct regions with different light modulation characteristics, making collecting light from a single point or region an incomplete and inaccurate assessment of the waveguide's overall performance.

[0005]

[0005] Therefore, there is a need for improved methods and apparatus for evaluating the performance of waveguide couplers. Summary of the Invention

[0006] In one embodiment, a waveguide metrology system is provided. The waveguide metrology system includes a light source coupled to a first stage, a sample holder coupled to a second stage, and one or more scanning detectors disposed on a third stage. The light source is configured to direct light toward the sample holder. The scanning detector is positioned on a trajectory adjacent to the sample holder and opposite the light source, and is configured to collect transmitted light. A spectrometer is in communication with the scanning detector.

[0007] In one embodiment, a waveguide metrology system is provided. The waveguide metrology system includes a light source coupled to a first stage, a sample holder coupled to a second stage, one or more scatterometers coupled to a third stage, and one or more reflectance detectors coupled to a fourth stage. The light source is configured to transmit light toward the sample holder. The scatterometer is positioned adjacent to the sample holder and opposite the light source and is configured to collect the light transmitted by the light source. The reflectance detector is configured to collect the reflected light. A spectrophotometer is in communication with the scatterometers and the reflectance detectors.

[0008] In one embodiment, a guided-wave measurement system is provided. The guided-wave measurement system includes a white light source coupled to a first stage, a sample holder coupled to a second stage, two or more reflection detectors coupled to a third stage, and two or more transmission detectors coupled to a fourth stage. The white light source is configured to generate a collimated incident light beam. The reflection detectors are configured to collect light reflected from the direction of the sample holder. The transmission detectors are configured to collect light transmitted from the white light source. A spectrophotometer is in communication with the reflection detectors and the transmission detectors.

[0009]

[0009] In order that the above-mentioned features of the present disclosure may be understood in detail, the disclosure briefly summarized above will now be more particularly described with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings show only exemplary embodiments and therefore should not be considered to limit the scope of the present disclosure, as other equally effective embodiments may also be acceptable. [Brief explanation of the drawings]

[0010] [Figure 1A]

[0010] A schematic side view of a waveguide coupler according to one embodiment of the present disclosure is shown. [Figure 1B]

[0011] 1B shows a schematic perspective view of the waveguide coupler of FIG. 1A according to one embodiment described herein. [Figure 2A]

[0012] FIG. 1 shows a schematic perspective view of a guided wave measurement system according to an embodiment of the present disclosure. [Figure 2B]

[0013] 2B shows a schematic plan view of the measurement system of FIG. 2A, according to one embodiment of the present disclosure. [Figure 3A]

[0014] FIG. 1 shows a schematic perspective view of a guided wave measurement system according to an embodiment of the present disclosure. [Figure 3B]

[0015] 3B shows a schematic plan view of the measurement system of FIG. 3A, according to one embodiment of the present disclosure. [Figure 4A]

[0016] FIG. 1 shows a schematic perspective view of a guided wave measurement system according to an embodiment of the present disclosure. [Figure 4B]

[0017] 5 shows a schematic plan view of the measurement system of FIG. 4, according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0018] For ease of understanding, where possible, the same reference numerals have been used to designate identical elements that are common to multiple figures. It is believed that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0012]

[0019] Embodiments described herein relate to an apparatus for measuring and evaluating the performance of augmented and virtual reality waveguide structures that utilize glass substrates. The waveguide performance measurement system includes a light source configured to direct light onto an incoupling grating area on a first side of the waveguide and one or more photodetectors configured to collect light from an outcoupling grating area on a second side of the waveguide. The light source and one or more photodetectors are disposed on one or more adjustable stages disposed about the waveguide. In certain embodiments, the one or more adjustable stages are configured to move in a linear manner or to rotate and / or revolve in an orbital motion about the waveguide.

[0013]

[0020] 1A-1B show schematic diagrams of a waveguide coupler 100 (e.g., for VR or AR applications) having three gratings 103, 105, and 107. It should be understood that the waveguide coupler 100 described below is an exemplary waveguide coupler, and other waveguide couplers may be used or modified to implement aspects of the present disclosure. For example, a waveguide coupler having four or more gratings, such as five or more gratings, may also be used. Alternatively, a waveguide coupler having two or fewer gratings, such as two gratings, may also be used. In another embodiment, a waveguide coupler having gratings on both major sides may also be used. In yet another embodiment, a waveguide coupler having two or more input coupling regions and two or more output coupling regions may also be used.

[0014]

[0021] 1A shows a side view of a first side 101 of a waveguide coupler 100. The waveguide coupler 100 includes an input coupling region 102 defined by a first plurality of gratings 103, an intermediate region 104 defined by a second plurality of gratings 105, and an output coupling region 106 defined by a third plurality of gratings 107. In some embodiments, the input coupling region 102, the intermediate region 104, and the output coupling region 106 are arranged to achieve substantially total internal reflection of light between the input coupling region 102 and the output coupling region 106.

[0015]

[0022] During operation within a display device, the input coupling region 102 receives an incident light beam (shown in FIG. 1B ) having an intensity from a microdisplay (not shown). Each grating of the plurality of gratings 103 is angled with respect to a plane of the waveguide coupler 100, such as the first side 101. In one embodiment, the plurality of gratings 103 splits the incident light beam into multiple reflected and transmitted diffraction orders, e.g., a zeroth-order mode, a positive first-order mode, or a negative first-order mode. In one embodiment, the zeroth-order transmitted mode light beam refracts into and out of the waveguide coupler 100 and is eventually lost to the background. The positive first-order mode light beam is coupled through the waveguide coupler 100 to the intermediate region 104 by total internal reflection, and the negative first-order mode light beam propagates within the waveguide coupler 100 in the opposite direction to the positive first-order light beam.

[0016]

[0023] 1B shows a perspective view of waveguide coupler 100 depicting the travel path of incident light ray 109 within waveguide coupler 100. Waveguide coupler 100 has a first side 101 and a second side 111 arranged in parallel to allow propagation of light within the interior dimensions of waveguide coupler 100. Waveguide coupler 100 is fabricated from an optically transparent material configured to allow a user to see through the major sides 101, 111 of waveguide coupler 100.

[0017]

[0024] In one embodiment, an incident light beam 109 generated by a light source 110 is directed onto a first plurality of gratings 103 that define an input coupling region 102. Each grating in the first plurality of gratings 103 is angled with respect to the plane (i.e., side) of the waveguide coupler 100 to enhance a desired diffraction order within the waveguide coupler 100. In one embodiment, each grating in the first plurality of gratings 103 is angled such that positive first mode rays are reflected within the waveguide coupler 100. For example, each grating in the first plurality of gratings 103 is angled to suppress zeroth mode rays and negative first mode rays.

[0018]

[0025] After contacting the first plurality of gratings 103, the desired optical mode is split from the incident light beam 109 and is internally reflected within the guide-wave coupler 100 toward the intermediate region 104. Optical paths 119A, 119B are the propagation paths (e.g., projections) of the light beam 109 inside the guide-wave combiner 100. As the light beam 109 propagates through the intermediate region 104, it undergoes total internal reflection (TIR) ​​and contacts the second plurality of gratings 105. Like the first plurality of gratings 103, each grating in the second plurality of gratings 105 is angled with respect to the plane of the guide-wave coupler 100 to reflect the desired light beam within the guide-wave coupler 100. In one embodiment, each grating in the second plurality of gratings 105 is angled such that positive first-order mode light beams are reflected within the guide-wave coupler 100. For example, each grating in the second plurality of gratings 105 is angled to suppress zero-order mode light beams. In one embodiment, each grating in the second plurality of gratings 105 is angled to reflect positive first mode rays towards the out-coupling region 106 while suppressing zero mode rays.

[0019]

[0026] The desired light rays reflected by the second plurality of gratings 105 are then directed to a third plurality of gratings 107 in the output coupling region 106. Similar to the first plurality of gratings 103 and the second plurality of gratings 105, the third plurality of gratings 107 splits and propagates the desired light mode 113 out of the waveguide coupler 100 from the first side 101 for coupling the light rays with ambient light from the surrounding environment on an image plane. Typically, the image plane is at a focal point a distance from the waveguide coupler 100.

[0020]

[0027] 2A-2B show schematic diagrams of a guided-wave measurement system 200 according to one embodiment of the present disclosure. FIG. 2A shows a perspective view of the guided-wave measurement system 200. FIG. 2B shows a top view of the guided-wave measurement system 200. Therefore, FIGS. 2A and 2B will be described simultaneously to facilitate understanding of the present disclosure. For reference, x-, y-, and z-axis frames are shown in FIG. 2A. The y-axis is perpendicular to the sides 101, 111 of the guided-wave coupler 100. The z-axis is vertically parallel to the sides 101, 111 of the guided-wave coupler 100. The x-axis is horizontally parallel to the sides 101, 111 of the guided-wave coupler.

[0021]

[0028] The measurement system 200 includes a light source 210, a sample holder 230, and one or more photodetectors 212. Examples of suitable photodetectors include a photosensor, an active pixel sensor (APS), a charge-coupled device (CCD), a photoresistor, a photodiode, a semiconductor detector, etc. The light source 210 is disposed on the first stage 240 adjacent to the side 111 and is configured to generate and direct an incident light beam 209 toward the in-coupling region 102 of the waveguide coupler 100. Any suitable type of light source that may be used for the measurement system 200 includes, but is not limited to, a white light source, a light engine, an image generator, a laser, or a light-emitting diode (LED). In one embodiment, the light source 210 includes a collimating device (not shown). In some embodiments, the light source 210 directs collimated light toward the in-coupling region 102 of the waveguide coupler 100. In another embodiment, the light source 210 directs uncollimated or diffused light into the input coupling region 102 of the waveguide coupler 100 .

[0022]

[0029] In one embodiment, the first stage 240 further includes one or more reflective detectors 218 disposed thereon. Examples of suitable reflective detectors include photosensors, active pixel sensors (APS), charge-coupled devices (CCD), photoresistors, photodiodes, semiconductor detectors, etc. The reflective detectors 218 are configured to detect and collect any light that is reflected or refracted from the side surface 111 and is not internally transmitted through the waveguide coupler 100. The one or more reflective detectors 218 and light source 210 may be disposed on the first stage 240 in any suitable quantity and configuration. For example, two reflective detectors 218 and a single light source 210 may be disposed in a linear or crescent configuration, with one reflective detector 218 on each side of the light source 210. Furthermore, the reflective detectors 218 may be oriented at an angle relative to the central light source 210 around the focal points of the reflective detectors 218 and light source 210, respectively. Alternatively, a single reflective detector 218 may be disposed on the first stage 240. In some embodiments, the first stage 240 includes one or more scanning arms configured to actuate the first stage 240, thus enabling collection of light reflected at various angles using a single reflectance detector 218, eliminating the use of multiple detectors positioned at various positions and / or angles.

[0023]

[0030] The first stage 240 may be linearly adjustable about the x-, y-, and z-axes, thereby allowing the light source 210 and / or the reflectance detector 218 to move both vertically and horizontally relative to the waveguide coupler 100. For example, the first stage 240 may include several guide members extending in the x-, y-, and z-directions on which the first stage 240 may move. In another embodiment, the first stage 240 may be coupled to a scanning arm configured to move linearly along the x-, y-, and z-axes. In yet another embodiment, the first stage 240 may be disposed on a rolling platform configured to move linearly along the x-, y-, and z-axes.

[0024]

[0031] The first stage 240 is further configured to rotate about a z-axis that passes through a point on the first stage 240. For example, the first stage 240 rotates from about 1 degree to about 360 degrees about the z-axis that passes through the first stage 240. In some embodiments, the first stage 240 is also configured to revolve (e.g., orbit, pivot) about the waveguide coupler 100 between about 1 degree and about 180 degrees relative to its side surface 111. For example, the first stage 240 is configured to revolve about 180 degrees clockwise or counterclockwise about the waveguide coupler 100, i.e., about the z-axis. The combination of linear, rotational, and orbital adjustability of the first stage 240 allows the light source 210 to direct the incident light beam 209 toward the in-coupling region 102 at various angles and over various distances from the waveguide coupler 100. Additionally, the combination of linear, rotational, and revolutionary adjustability of first stage 240 allows reflectance detector 218 to measure reflected light at a variety of angles and distances.

[0025]

[0032] It should be noted that first stage 240, like any other stage described herein, may include one or more movable (e.g., maneuverable) support structures for supporting one or more light sources and / or detectors thereon. For example, in some embodiments, the stages described herein may include one or more movable platforms, stands, articulated arms, scanning arms, guides, rails, tracks, etc.

[0026]

[0033] The sample holder 230 is disposed on a second stage 250 and configured to secure a sample (e.g., the waveguide coupler 100) for analysis. Similar to the first stage 240, the second stage 250 is linearly adjustable about the x-, y-, and z-axes so that the waveguide coupler 100 can be moved both vertically and horizontally. For example, the second stage 250 may include several guide members extending in the x-, y-, and z-axes directions on which the second stage 250 can be moved. In another embodiment, the second stage may be coupled to an adjustable scanning arm configured to linearly move the second stage 250 in the x-, y-, and z-axes directions. In yet another embodiment, the second stage 250 may be disposed on a rolling platform configured to linearly move along the x-, y-, and z-axes.

[0027]

[0034] The second stage 250 is further configured to rotate 360 ​​degrees around a z-axis that passes through the center point of the stage. For example, the second stage 250 may be rotated clockwise or counterclockwise around the z-axis. The combination of linear and rotational adjustability of the second stage 250 allows the waveguide coupler 100 to couple and decouple light at a range of horizontal and vertical angles relative to the light source 210, the reflectance detector 218, and the photodetector 212. The ability to measure the coupled and decoupled light at various angles allows for more precise measurement of the grating characteristics of the waveguide coupler 100, which may allow for improved patterning or etching of those gratings. In certain embodiments, a prism (not shown) is mounted on the waveguide coupler 100 while fixed on the second stage 250 to couple light into the input-coupling region 102 or out of the output-coupling region 106. In such an embodiment, a refractive index matching fluid is used as an intermediate between the waveguide coupler 100 and the prism to prevent unwanted reflection and refraction of the coupled and decoupled light. Examples of refractive index matching fluids that may be utilized include silica-based matching fluids, oils, and gels.

[0028]

[0035] One or more photodetectors 212 are disposed on the third stage 260 adjacent to the side 101 and facing the first stage 240 and the light source 210. The photodetectors 212 may be disposed in any suitable quantity and configuration on the third stage 260. For example, three photodetectors 212 may be disposed in a crescent configuration, with the distal photodetectors each positioned at an approximately 45-degree angle relative to the central detector around the focal point of the three photodetectors 212. In another embodiment, three photodetectors 212 are disposed in a linear configuration and equidistant from one another on the third stage 260. Alternatively, a single photodetector 212 may be disposed on the third stage 260. The third stage 260 may be coupled to a scanning arm, thus enabling collection of light diffracted at various angles by a single photodetector 212, eliminating the use of multiple detectors.

[0029]

[0036] The third stage 260 is configured to revolve around the waveguide coupler 100 between about 1 degree and about 180 degrees relative to its side 101. For example, the third stage 260 is configured to revolve about 180 degrees around the waveguide coupler 100, i.e., clockwise or counterclockwise about the z-axis. The adjustable revolution of the third stage 260 allows the photodetector 212 to measure the transmitted light ray 213 exiting the out-coupling region 106 at various angles relative to the waveguide coupler 100.

[0030]

[0037] 2A, the optical detector 212 is further coupled to a spectrophotometer 220, although any suitable optical metrology system may be used when evaluating the performance of a guided-wave coupler. The optical detector 212 may further include any suitable type of optical sensor, including, but not limited to, a scanning scatterometer or a conoscopic scatterometer. The optical detector 212 is configured to detect and collect transmitted light 213 propagating from the out-coupling region 106 of the guided-wave coupler 100.

[0031]

[0038] In measuring the performance characteristics of the waveguide coupler 100, light scattering data is collected by the reflectance detector 218 and the photodetector 212 and relayed to the spectrophotometer 220 for data analysis. Once analyzed by the spectrophotometer 220, the results are relayed to and displayed on a graphical user interface (GUI) (not shown). In one embodiment, the performance characteristics of the sample waveguide coupler 100 are displayed as a two-dimensional grid corresponding to one of the sides 101, 111 of the waveguide coupler 100.

[0032]

[0039] The tunability of the stages 240, 250, 260 and the number of detectors 212, 218 utilized in the metrology system 200 allows a user to more accurately measure a wide range of performance characteristics of the waveguide coupler 100. In one embodiment, the metrology system 200 is configured to measure and analyze the reflective diffraction efficiency of the waveguide coupler 100. In another embodiment, the metrology system 200 is configured to measure and analyze the transmissive diffraction efficiency of the waveguide coupler 100.

[0033]

[0040] 3A-3B show schematic diagrams of a metrology system 300 according to one embodiment of the present disclosure. FIG. 3A shows a perspective view of the guided-wave metrology system 300. FIG. 3B shows a top view of the guided-wave metrology system 300, with the stages 240 and 250 offset from the stages 260 and 370 for clarity. Thus, FIGS. 3A and 3B will be discussed simultaneously to facilitate understanding of the present disclosure. For reference, the x-, y-, and z-axis frames are shown in FIG. 3A and have substantially the same orientation as in FIG. 2A.

[0034]

[0041] Measurement system 300 is similar in configuration to measurement system 200. However, unlike measurement system 200, one or more reflection detectors 218 of measurement system 300 are disposed on a fourth stage 370 adjacent to side 111 of waveguide coupler 100. Similar to third stage 260, fourth stage 370 is configured to revolve around waveguide coupler 100 between about 1 degree and about 180 degrees relative to side 111. For example, fourth stage 370 is configured to revolve 180 degrees around waveguide coupler 100, i.e., clockwise or counterclockwise around the z-axis. The adjustable revolution of fourth stage 370 allows reflection detector 218 to measure reflected light at various angles relative to waveguide coupler 100.

[0035]

[0042] One or more reflectance detectors 218 may be arranged on the fourth stage 370 in any suitable quantity and configuration. For example, three reflectance detectors 218 may be arranged in a linear or crescent configuration. The distal reflectance detectors may each be oriented at a 45-degree angle relative to the central reflectance detector around the focal point of the three reflectance detectors 218. Alternatively, in another embodiment, a single reflectance detector 218 may be arranged on the fourth stage 370. The fourth stage 370 may be coupled to a scanning arm, thus allowing collection of light reflected at various angles by a single reflectance detector 218 and eliminating the use of multiple detectors.

[0036]

[0043] The addition of the fourth stage 370 coupled to one or more reflectance detectors 218 enables the metrology system 300 to perform additional types of performance characterization of the guided-wave coupler 100 compared to the metrology system 200. For example, the addition of the fourth stage 370 enables the metrology system 300 to measure the field of view characteristics and the overall coupling efficiency of the guided-wave coupler 100. In one embodiment, the first stage 240 and the second stage 250 are synchronized to be spatially adjusted simultaneously. By simultaneously adjusting the spatial position and orientation of the first and second stages 240, 250, the metrology system 300 can also measure the angular uniformity and spatial uniformity of the guided-wave coupler 100. In another embodiment, the metrology system is further configured to measure the color uniformity of the guided-wave coupler 100. In yet another embodiment, the metrology system 300 is configured to utilize a light engine as the light source 210 and measure the image resolution and contrast characteristics of the guided-wave coupler 100.

[0037]

[0044] 4A-4B show schematic perspective views of a metrology system 400 according to one embodiment of the present disclosure. FIG. 4A shows a perspective view of the guided-wave metrology system 400, and FIG. 4B shows a top view of the guided-wave metrology system 400, with stages 240 and 250 offset from stages 480 and 490 for clarity. Thus, FIGS. 4A and 4B will be discussed simultaneously to facilitate understanding of the present disclosure. For reference, the x-, y-, and z-axis frames are shown in FIG. 4A and have substantially the same orientation as in FIG. 2A.

[0038]

[0045] Measurement system 400 is similar in configuration to measurement system 300. However, unlike measurement system 300, third stage 260 and fourth stage 370 are replaced with fifth stage 480 and sixth stage 490. Fifth stage 480 and sixth stage 490 are positioned opposite each other, each facing a different side of waveguide coupler 100. In one embodiment, fifth stage 480 is positioned adjacent to side 111, and sixth stage 490 is positioned adjacent to side 101.

[0039]

[0046] Additionally, the fifth stage 480 and the sixth stage 490 are linearly adjustable about the x, y, and z axes. For example, the fifth stage 480 and the sixth stage 490 may include several guide members extending in the x, y, and z directions on which the stages may move. In another embodiment, the fifth stage 480 and the sixth stage 490 may be coupled to an adjustable scanning arm configured to linearly move the stages along the x, y, and z axes. In yet another embodiment, the fifth stage 480 and the sixth stage 490 may be disposed on a rolling platform configured to linearly move along the x, y, and z axes. The linear adjustability of the fifth stage 480 and the sixth stage 490 allows the reflection detector 218 and the photodetector 212 to measure reflected and transmitted light beams at various vertical and horizontal angles and distances.

[0040]

[0047] One or more photodetectors 212 are disposed on the fifth stage 480. The photodetectors 212 may be disposed on the fifth stage 480 in any suitable quantity and configuration. For example, three photodetectors 212 may be disposed in a linear or crescent configuration. Furthermore, distal photodetectors may each be disposed at an angle relative to the central photodetector around the focal point of the three photodetectors 218. Alternatively, in another embodiment, a single photodetector 212 may be disposed on the fifth stage 480. The fifth stage 480 may be coupled to a scanning arm, thus enabling collection of light diffracted at various angles by a single photodetector 212, eliminating the use of multiple detectors.

[0041]

[0048] Similarly, one or more reflectance detectors 218 are disposed on the sixth stage 490, and may be disposed on the sixth stage 490 in any suitable quantity and configuration. For example, three reflectance detectors 218 may be disposed in a linear or crescent configuration, with the distal reflectance detectors each positioned at an angle relative to the central reflectance detector around the focal point of the three reflectance detectors 218. Alternatively, in another embodiment, a single reflectance detector 218 may be disposed on the sixth stage 490. The sixth stage 490 may be coupled to a scanning arm, thus allowing collection of light reflected at various angles by a single reflectance detector 218, eliminating the use of multiple detectors.

[0042]

[0049] By utilizing fifth stage 480 and sixth stage 490 instead of third stage 260 and fourth stage 370, metrology system 400 can perform additional characterization of waveguide coupler 100 beyond that of metrology systems 200 and 300. For example, by detecting the focus of transmitted beam 213 or reflected beam 414 with photodetector 212 or reflection detector 218, metrology system 400 can measure the overall optical intensity of waveguide coupler 100. In another embodiment, by moving fifth stage 480 along the x, y, and z axes and measuring beam 213 at multiple positions with photodetector 212, metrology system 400 can measure the spatial uniformity of waveguide coupler 100 at various angles. In yet another embodiment, by utilizing a collimated light source 210 that generates a collimated incident light beam 209, the measurement system 400 can measure the entrance and exit pupil size and therefore determine the pupil replication characteristics of the waveguide coupler 100.

[0043]

[0050] In summary, a tunable and flexible metrology system for measuring the performance of waveguide couplers is described herein. The waveguide couplers have non-uniform properties throughout and utilize multiple diffraction gratings to refract and reflect light rays. By utilizing multiple translation, revolution, and / or rotation stages as well as multiple photodetectors, the metrology system can collect data at a wider range of positions and angles. Thus, a metrology system utilizing multiple translation and rotation stages as well as multiple photodetectors provides improved waveguide coupler characterization, enabling improved quality control in the manufacture of waveguide couplers.

[0044]

[0051] While the forgoing description is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the claims that follow.

Claims

1. 1. A guided wave measurement system, comprising: a light source coupled to the first stage, the light source configured to direct light to an input coupling region of a sample waveguide in a sample waveguide holder disposed on a second stage, the light source disposed on a first side of the second stage; one or more scanning detectors coupled to a third stage on a second side of the second stage opposite the first side, the one or more scanning detectors configured to collect light transmitted in a first direction from the sample waveguide holder toward the second side, the light including transmitted light propagating from an output coupling region of the sample waveguide that is different from the input coupling region; a first reflection detector coupled to a fourth stage on the first side of the second stage, the first reflection detector configured to collect light reflected from the sample waveguide holder in a second direction toward the first stage; and a spectrophotometer in communication with the one or more scanning detectors; the waveguide measurement system is configured to measure reflected light diffraction efficiency characteristics and transmitted light diffraction efficiency characteristics of the sample waveguide within the sample waveguide holder; 10. A guided wave metrology system, wherein the first stage is configured to move linearly along an x, y, or z axis.

2. 10. The guided wave metrology system of claim 1, wherein the first stage is further configured to revolve up to 180 degrees around the second stage independent of any rotation by the second stage.

3. The guided-wave metrology system of claim 1 , wherein the second stage is configured to move linearly along x, y, and z axes and to rotate about the z axis.

4. The waveguide metrology system of claim 1 , further comprising a second reflection detector disposed on the first stage adjacent the light source.

5. 1. A guided wave measurement system, comprising: a light source coupled to the movable first stage, the light source configured to transmit light toward an input coupling region of a sample waveguide in a sample waveguide holder disposed on a second stage, the light source being disposed on a first side of the second stage; one or more scatterometers coupled to a movable third stage on a second side of the second stage opposite the first side, the third stage being movable independently of the first stage, the one or more scatterometers configured to collect light transmitted in a first direction from the sample waveguide holder toward the second side, the light including transmitted light propagating from an output coupling region of the sample waveguide that is different from the input coupling region; one or more reflectance detectors coupled to a movable fourth stage on the first side of the second stage, the fourth stage being movable independently of the first stage and the third stage, the reflectance detectors configured to collect light reflected from the sample waveguide holder in a second direction toward the first side; and a spectrophotometer in communication with the one or more scatterometers and the one or more reflectance detectors; the waveguide measurement system is configured to measure reflected light diffraction efficiency characteristics and transmitted light diffraction efficiency characteristics of the sample waveguide within the sample waveguide holder; The first stage is configured to move linearly along x, y, and z axes.

6. 6. The waveguide metrology system of claim 5, wherein the first stage is further configured to revolve up to 180 degrees around the sample waveguide holder independent of any rotation by the second stage.

7. The guided wave metrology system of claim 5 , wherein the second stage is configured to move linearly along x, y, and z axes.

8. The guided-wave metrology system of claim 7 , wherein the second stage is further configured to rotate about the z-axis.

9. 6. The waveguide metrology system of claim 5, wherein the third stage and the fourth stage are configured to revolve up to 180 degrees around the sample waveguide holder independent of any rotation by the second stage.

10. 6. The waveguide metrology system of claim 5, wherein the first stage and the second stage are synchronized to measure angular and spatial uniformity characteristics of the sample waveguide.

11. 1. A guided wave measurement system, comprising: a light source coupled to the movable first stage and outputting collimated light; a sample waveguide holder disposed on a movable second stage, the sample waveguide holder configured such that a light source outputting the collimated light directs light toward an input coupling region of a sample waveguide within the sample waveguide holder; a reflectance detector coupled to a movable third stage on a first side of the sample waveguide holder and configured to collect light reflected from the sample waveguide holder in a first direction; a transmission detector coupled to a movable fourth stage on a second side of the sample waveguide holder, the transmission detector configured to collect light transmitted in a second direction from the sample waveguide holder, the light including transmitted light propagating from an output coupling region of the sample waveguide that is different from the input coupling region; and a spectrophotometer in communication with the reflectance detector and the transmission detector; the first stage, the third stage, and the fourth stage are configured to revolve up to 180 degrees around the sample waveguide holder independent of any rotation by the second stage; the waveguide measurement system is configured to measure reflected light diffraction efficiency characteristics and transmitted light diffraction efficiency characteristics of the sample waveguide within the sample waveguide holder; 1. A guided-wave metrology system, wherein the first stage and the second stage are configured to move linearly along x, y, and z axes and rotate about the z axis.

12. The guided wave metrology system of claim 11 , wherein the third stage and the fourth stage are configured to move linearly along x, y, and z axes.

13. The waveguide metrology system of claim 5 , wherein the waveguide metrology system is configured to measure field of view and optical coupling efficiency characteristics of the sample waveguide.

14. The waveguide metrology system of claim 5 , wherein the waveguide metrology system is configured to measure chromatic uniformity characteristics of the sample waveguide.

15. The waveguide metrology system of claim 5 , wherein the light source is a light engine, and the waveguide metrology system is configured to measure image resolution and contrast characteristics of the sample waveguide.

16. The waveguide measurement system of claim 11, wherein the light source that outputs the parallel light includes a white light source, a laser, or a light-emitting diode.

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