Panel delay measurement

Abstract

A method for determining the residual delay of an LCOS (liquid crystal on silicon) panel comprises: sending a light beam to the LCOS panel at an incident angle and measuring the intensity of the reflected light beam. The method comprises: biasing the LCOS panel in a dark state; and measuring the dark state intensity of the reflected light beam. The method also comprises: biasing the LCOS panel in a bright state; and measuring the bright state intensity of the reflected light beam. The residual delay of the LCOS panel is determined based on a contrast ratio of the bright state intensity to the dark state intensity. The method may also include selecting a compensator for the LCOS panel based on the residual delay.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 879,197, filed on July 26, 2019, entitled “PANEL RETARDANCE MEASUREMENT,” the entire contents of which are incorporated herein by reference for all purposes. Background Art

[0003] LCOS (liquid crystal on silicon) panels are attractive for use as light modulators in projection display systems (such as near-eye display systems), in part due to the ability to integrate pixel switches and interconnecting circuits and components on a silicon substrate, enabling the high pixel density required for high-resolution displays. However, LCOS panels may introduce residual delays that limit the contrast of displayed images. Further, the residual delays may vary for different LCOS panels. Therefore, it is often necessary to determine the residual delay of each LCOS panel in a production environment.

[0004] However, conventional techniques for determining residual delay of LCOS panels have many disadvantages. Disadvantages include requiring expensive equipment and highly skilled personnel, as well as time-consuming operations. The impact of these disadvantages is magnified in a mass production environment. Therefore, there is a need in the art for improved residual delay techniques for LCOS panels. Summary of the invention

[0005] The present disclosure relates generally to display devices using LCOS (Liquid Crystal On Silicon) panels.Some embodiments of the present invention provide systems and methods for determining the residual retardation of an LCOS panel in an efficient and cost-effective manner.

[0006] Conventional methods for measuring the residual delay of LCOS panels often involve expensive equipment and highly skilled operators, and can be time consuming. In a mass production environment, these disadvantages become more serious. In some embodiments, a system and method are provided to estimate the residual delay of an LCOS panel by using a contrast ratio such as calculated by the reflected light intensity in a bright state and a dark state. Further, the system and method may also provide an alignment angle of the compensator relative to the LCOS panel. Based on the residual delay value and the alignment angle, a compensator can be selected to maximize the intensity contrast of the product. The system and method provided in the embodiments of the present invention are effective and cost-effective, and are very suitable for a mass production environment.

[0007] According to some embodiments, a method for determining the residual delay of a liquid crystal on silicon (LCOS) panel includes providing a light beam from a light source and sending the light beam to the LCOS panel at a non-normal angle of incidence. The light beam passes through a transmitter optical group, a circular polarizer, and a bias retarder to reach the LCOS panel. The method also includes reflecting the light beam from the LCOS panel through the bias retarder, the circular polarizer, and the receiver optical group and reaching a detector for measuring the intensity of the received light beam. The method also includes determining the retarder alignment angle by the following steps: rotating the bias retarder and measuring the intensity of the received light beam using the LCOS panel in a dark state; and identifying the rotation angle of the bias retarder associated with the minimum value of the intensity of the received light beam as the retarder alignment angle. Using the bias retarder set at the retarder alignment angle and the LCOS panel in the dark state, the dark state intensity of the received light beam is measured. Using the bias retarder set at the retarder alignment angle and the LCOS panel in the bright state, the bright state intensity of the received light beam is measured. The method also includes determining a contrast ratio of the bright state intensity and the dark state intensity. Determine the total delay based on the contrast ratio of the bright state intensity and the dark state intensity. A residual delay of the LCOS panel is determined based on the total delay. The method also includes selecting a compensator for the LCOS panel based on the residual delay, and specifying a retarder alignment angle of the bias retarder as the compensator alignment angle of the selected compensator relative to the LCOS panel.

[0008] In some embodiments of the above method, determining the residual retardation of the LCOS panel includes removing the retardation of the bias retarder and the retardation of the circular polarizer from the total retardation.

[0009] In some embodiments, determining the total delay (γ) based on the contrast ratio (CR) includes determining the total delay (γ) using the following equation:

[0010] 1 / CR=sin^2(2πγ / λ).

[0011] In some embodiments, the transmitter optical train includes a collimating lens and a focusing lens.

[0012] In some embodiments, the receiver optics group includes a collimating lens and a focusing lens.

[0013] According to some embodiments, a method for determining the residual delay of a liquid crystal on silicon (LCOS) panel includes: sending a light beam to the LCOS panel at an incident angle and measuring the intensity of the reflected light beam; biasing the LCOS panel in a dark state; measuring the dark state intensity of the reflected light beam; biasing the LCOS panel in a bright state; measuring the bright state intensity of the reflected light beam; determining the residual delay of the LCOS panel based on a contrast ratio of the bright state intensity and the dark state intensity; and selecting a compensator for the LCOS panel based on the residual delay.

[0014] In some embodiments of the above method, the angle of incidence is a non-normal angle of incidence.

[0015] In some embodiments, the angle of incidence is a normal angle of incidence.

[0016] In some embodiments, the method further comprises: determining a contrast ratio of bright state intensity and dark state intensity; determining a total delay based on the contrast ratio of bright state intensity and dark state intensity; and determining a residual delay of the LCOS panel based on the total delay.

[0017] In some embodiments, determining the total delay (γ) based on the contrast ratio (CR) includes determining the total delay (γ) using the following equation:

[0018] 1 / CR=sin^2(2πγ / λ).

[0019] In some embodiments, determining the residual retardation of the LCOS panel includes removing the retardation of the bias retarder and the retardation of the circular polarizer from the total retardation.

[0020] In some embodiments, sending the light beam to the LCOS panel includes sending the light beam to the LCOS panel through a polarizer.

[0021] In some embodiments, measuring the intensity of the reflected light beam includes passing the reflected light beam through a polarizer to a detector.

[0022] In some embodiments, the polarizer comprises a circular polarizer.

[0023] In some embodiments, the polarizer comprises a linear polarizer.

[0024] In some embodiments, sending the light beam to the LCOS panel includes sending the light beam through a transmitter optical group including a collimating lens and a focusing lens.

[0025] In some embodiments, sending the light beam to the LCOS panel includes sending the light beam to the LCOS panel through a biased retarder.

[0026] In some embodiments, measuring the intensity of the reflected light beam includes passing the reflected light beam through a biased retarder to a detector.

[0027] In some embodiments, the method further comprises determining a retarder alignment angle for the bias retarder by rotating the bias retarder and measuring the intensity of the reflected light beam using the LCOS in a dark state, and identifying the rotation angle of the bias retarder associated with the minimum value of the intensity as the retarder alignment angle for the bias retarder.

[0028] In some embodiments, the method further comprises identifying a retarder alignment angle of the biased retarder as a compensator alignment angle of the selected compensator relative to the LCOS panel.

[0029] According to some embodiments, a system for determining the residual delay of a liquid crystal on silicon (LCOS) panel includes: a holder for the LCOS panel; a bias retarder disposed on the LCOS panel; a polarizer disposed on the bias retarder; an emitter optical group disposed on the polarizer; a light source disposed on the emitter optical group, wherein the emitter optical group is configured to focus a light beam from the light source through the polarizer and the bias retarder to the LCOS panel at a non-normal incident angle. The system also includes: a receiver optical group disposed on the polarizer; and a detector disposed on the receiver optical group for measuring the intensity of light reflected from the LCOS panel. The receiver optical group is configured to focus the light beam reflected from the LCOS panel through the bias retarder and the polarizer to the detector. The system also includes a controller for alternately biasing the LCOS panel to a dark state and a bright state.

[0030] In some embodiments, the system is configured to determine the bright-state intensity and the dark-state intensity of light reflected from the LCOS panel.

[0031] In some embodiments, the system is configured to determine the residual retardation of the LCOS panel based on a contrast ratio of a bright state intensity and a dark state intensity of light reflected from the LCOS panel.

[0032] In some embodiments, determining the total delay (γ) based on the contrast ratio (CR) includes determining the total delay (γ) using the following equation:

[0033] 1 / CR=sin^2(2πγ / λ).

[0034] In some embodiments, the polarizer comprises a circular polarizer.

[0035] In some embodiments, the polarizer comprises a linear polarizer.

[0036] A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 shows a cross-sectional view of an LCOS (liquid crystal on silicon) device;

[0038] Figure 2 A simplified schematic diagram of a system for determining residual retardation of an LCOS (Liquid Crystal On Silicon) panel according to various embodiments of the present invention is shown;

[0039] Figure 3 shows the optical path and optical elements in a system for determining residual retardation of an LCOS (liquid crystal on silicon) panel according to various embodiments of the present invention;

[0040] Figure 4is a flow chart illustrating an embodiment of a process for gradient-based exposure and gain control in a content capture device according to various embodiments of the present invention;

[0041] Figure 5A and Figure 5B Various axes of compensators and circular polarizers are shown according to various embodiments of the present invention;

[0042] FIG. 6A to FIG. 6D shows a diagram based on an alternative method for determining residual delay according to various embodiments of the present invention;

[0043] FIG. 7A to FIG. 7D A diagram showing an alternative method for determining residual delay according to various embodiments of the present invention; and

[0044] Figure 8 An example of a block diagram of a computer system that can be used to implement various aspects according to various embodiments of the invention is shown. DETAILED DESCRIPTION

[0045] In the following description, for the purpose of explanation, specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it is apparent that various embodiments can be implemented without these specific details. The drawings and descriptions are not intended to be limiting.

[0046] The subsequent description provides only exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the present disclosure. Instead, the subsequent description of the exemplary embodiments will provide an enabling description for implementing the exemplary embodiments to those skilled in the art. For example, although the description may describe pixel information, images, and / or displays, it should be appreciated that audio may be generated by an augmented reality device and presented to a user instead of, or in addition to, visual content. It should also be understood that various changes may be made to the functionality and arrangement of elements without departing from the spirit and scope of the present disclosure as set forth in the appended claims.

[0047] In a liquid crystal on silicon (LCOS) display, a CMOS chip controls the voltage on square reflective aluminum electrodes buried just below the chip surface, with each electrode controlling one pixel. Each electrode can control a pixel in the display, with each pixel having an independently addressable voltage. The common voltage for all pixels is provided by a transparent conductive layer made of indium tin oxide (ITO) on the cover glass.

[0048] Figure 1 is a simplified cross-sectional view showing an LCOS device. Figure 1As shown, the LCOS device 100 includes a silicon substrate 110, which may include a CMOS layer. On the silicon substrate 110, there may be an insulating layer 120, a plurality of reflective pixel electrodes 130, a liquid crystal layer 140, a transparent electrode 150 such as indium tin oxide (ITO), a transparent cover glass layer 160, and a compensator 170.

[0049] LCOS device 100 is a reflective LCOS device. In operation, a polarized light beam is directed onto at least a portion of LCOS device 100. The polarized light beam passes through transparent cover glass layer 160, transparent electrode 150 and liquid crystal layer 140. The polarized light beam is reflected by reflective pixel electrode 130 and passes back through liquid crystal layer 140 and transparent cover glass layer 160. When a voltage is applied across the liquid crystal material, the polarization of the light beam changes, for example, from one linear polarization to an orthogonal linear polarization. In this sense, liquid crystal layer 140 acts as a polarization modulator depending on the voltage difference applied between pixel electrode 130 and transparent electrode 150. Therefore, in addition to acting as a polarizing element of a polarization analyzer, liquid crystal layer 140 can be in a bright state to allow light to pass, or in a dark state to block light. A polarization modulated light beam is emitted from reflective LCOS device 100. The polarization modulated light beam can then pass through an imaging lens to a screen to display an image.

[0050] When the LOCS device 100 is driven to a dark state, it can introduce residual retardation to light incident thereon, thereby limiting the contrast of the displayed image. Figure 1 As shown, in order to compensate for the residual retardation and thus achieve a desired contrast ratio, the LCOS device 100 can be equipped with a compensator 170 placed on the cover glass layer 160. The compensator 170 (also referred to as a compensator foil) is designed to induce birefringence so that light passing through it experiences a retardation opposite to the residual retardation produced by the reflective LCOS. Thus, the contrast of the displayed image is improved.

[0051] Further discussion of issues regarding residual delay and the use of compensation in LCOS devices may be found in Shimizu US Patent Application Publication No. 2006 / 0256263, the entire contents of which are incorporated herein by reference for all purposes.

[0052] In order to match the appropriate compensator to the LCOS device, it may be necessary to determine the residual delay of each individual LCOS panel. Unfortunately, there are disadvantages associated with conventional methods for measuring residual delay. For example, some conventional systems may use parameter-based methods, using a series of known input polarization states, measuring the output polarization state, and directly calculating the delay. Such conventional methods for measuring the residual delay of LCOS panels often involve expensive equipment and highly skilled operators, and may be time consuming. In a mass production environment, these disadvantages become more serious.

[0053] Embodiments of the present invention provide systems and methods for determining the residual resistance of an LCOS panel in a cost-effective and time-saving manner. The use of expensive equipment is reduced or eliminated, and the methods and systems described herein are particularly suitable for high-volume production environments.

[0054] In some embodiments, an LCOS compensator binning tool and method are provided for determining a specific compensator (or class of compensators) to use with each LCOS panel to compensate for the residual retardation of the panel. One such system uses the sequential contrast of a bare (non-compensated) LCOS (liquid crystal on silicon) panel to estimate the residual retardation of the panel. Based on this value, an ideal compensator can be selected to maximize the sequential contrast of the product.

[0055] In the example, the system uses circular polarization as the base state, therefore, the delay measurement system for LCOS panels uses circularly polarized input and output light. This is produced by a circular polarizer placed in the beam path. Assuming a perfect circular polarization state, any delay in the light path will change the polarization state ellipticity and reduce the extinction when passing through the second orthogonal polarizer. The reduction in extinction is described by Malus's law. Therefore, the delay of the system can be indirectly measured by measuring the change in extinction of a pair of crossed polarizers.

[0056] In the example, the tester described here uses a single polarizer that acts as both the initial polarization element and the orthogonal analyzer. This is because upon reflection within the LCOS cell, the polarization state changes handedness. Therefore, the polarizer is orthogonal to the polarization state of the reflected light. In an ideal case, all reflected light would be absorbed by the circular polarizer.

[0057] The retardation axis of the LCOS cell can also be determined. To measure the slow axis, a retarder with a known polarization axis is placed between the circular polarizer and the LCOS panel. Optimal extinction occurs when the polarization axis of the retarder is perpendicular (crossed) to the polarization axis of the LCOS cell. By rotating the retarder and measuring the extinction, the intrinsic slow axis of the cell can be indirectly measured.

[0058] In some embodiments, the system interrogates the LCOS primitive using a specific light cone angle and makes measurements based on the integration of the contrast over that cone angle. The cone angle is input to the LCOS through a lens (or series of lenses) and captured again after being reflected from the LCOS through a lens (or series of lenses) and a single pixel detector.

[0059] In some embodiments, the residual retardation is derived from a measured contrast ratio.The intensity of the reflected light is measured in the dark state and the light state, and the contrast ratio can be calculated.

[0060] Prior to contrast measurement, the optimal retarder angle, also referred to as the retarder alignment angle, is determined. The bias retarder is rotated to different angles (e.g., 5 angles at 20 degree intervals are used). At each angle, the flux of the panel in the dark state (e.g., high voltage) is measured. The dark state flux and compensator angle are fit to a cosine function. The angle associated with the minimum of the cosine function corresponds to the optimal compensator angle or compensator alignment angle for the panel under test.

[0061] The sequential contrast ratio of a panel is measured by taking the ratio of the flux in the bright state (low voltage) and the flux in the dark state (high voltage) with the retarder oriented at the optimal retarder angle. The contrast ratio (CR) is related to the retardation (γ) of the system in the following expression:

[0062]

[0063] Where CR = contrast ratio, γ = system delay, and λ = wavelength.

[0064] Next, the residual delay (RR) of the LCOS panel can be determined from the system delay (γ) according to the following relationship.

[0065] RR=γ+Comp-ToolResidual

[0066] The γ calculated in this equation is the system delay, which takes into account the delay from the circular polarizer and the bias compensator. The residual delay RR of the panel is calculated using the above equation. In this example, Comp is the delay of the bias retarder, and ToolResidual is the additional delay introduced by the circular polarizer. As used herein, the bias retarder is also called the bias compensator.

[0067] Figure 2 A simplified schematic diagram of a system for determining residual retardation of an LCOS (liquid crystal on silicon) panel according to various embodiments of the present invention is shown. Figure 2 As shown, a system 200 for determining a residual delay of an LCOS panel 210 may include a support 201 for the LCOS panel 210, a bias retarder 220 disposed on the LCOS panel 210, a polarizer 230 disposed on the bias retarder 220, and an emitter optical group 240 disposed on the polarizer 230. A light source 250 is disposed on the emitter optical group 240. Figure 2 As shown, the emitter optical group 240 includes a plurality of optical elements (e.g., lenses), and the specific design of the emitter optical group 240 will depend on the specific application. The emitter optical group is configured to focus an input light beam 251 from a light source 250 through a polarizer 230 and a bias retarder 220 to the LCOS panel 210 at a non-normal incident angle. Figure 2As shown, the optical path 253 of the input light beam 251 forms an incident angle θ relative to the normal 211 of the LCOS panel 210.

[0068] The system 200 also has a receiver optical group 260 disposed on the polarizer 230 and a detector 270 disposed on the receiver optical group 260 for measuring the intensity of light 271 reflected from the LCOS panel. Figure 2 As shown, the receiver optical group 260 includes a plurality of optical elements (e.g., lenses), and the specific design of the receiver optical group 260 will depend on the specific application. The receiver optical group 260 is configured to focus the light beam reflected from the LCOS panel 210 through the bias retarder 220 and the polarizer 230 to the detector 270. The system 200 may also have a controller 280.

[0069] In some embodiments, the bias retarder 200 can be a low retardation plate, for example, having a retardation of about 4 nm, used to determine the rotation angle of the compensator. The rotation angle can help determine the angle at which the compensator is placed on the LCOS panel. The retardation value of the bias retarder 200 is selected to be lower than the possible retardation value, lower than the compensator that will be used with the LCOS panel. The low retardation bias retarder with a known slow axis is used to determine the slow axis of the retardation of the LCOS panel.

[0070] In system 200, polarizer 230, bias retarder 220, and LCOS panel 210 can be rotated to allow testing with an input beam to strike LCOS 210 at different angles of incidence. For example, red, green, and blue light sources can be used at different angles of incidence.

[0071] exist Figure 2 In the example of FIG. 1 , polarizer 230 is shown as a circular polarizer. In this case, the effect of the s and p components of the light on the residual delay can be determined. In other embodiments, other types of polarizers, such as linear polarizers, can also be used. In some embodiments, the incident light beam is sent to the LCOS panel at a non-normal angle of incidence. Figure 2 , the input beam 251 forms an incident angle θ relative to the normal 211 of the LCOS panel 210. In other embodiments, normal angle incidence may also be used. In this case, the incident angle θ is 0°. Those of ordinary skill in the art will recognize many variations, modifications and alternatives.

[0072] The controller 280 in the system 200 can perform various control functions. For example, the controller 280 can bias the LCOS panel 210 in a dark state or a bright state for various measurements. In some embodiments, the system 200 is configured to determine the residual delay of the LCOS panel 210 based on the contrast ratio of the bright state intensity and the dark state intensity of the light reflected from the LCOS panel 210. Figure 4 A method for determining residual delay is described.

[0073] Figure 3 The optical paths and optical elements in a system for determining the residual retardation of an LCOS (liquid crystal on silicon) panel according to various embodiments of the present invention are shown. Figure 3 The transmitter optical group 340 is shown to include three lenses 341, 342, and 343. These lenses include a collimating lens and a focusing lens. The transmitter optical group 340 is configured to focus an input light beam 351 from a light source 350 onto the LCOS panel 310 at a non-normal incident angle. Figure 3 As shown, the optical path 353 of the input light beam 351 forms an incident angle θ with the normal 311 of the LCOS panel 310. In some embodiments, the angle θ may be between 10 degrees and 15 degrees. Figure 3 Further shown are distance L1 between light source 350 and lens 341, distance L2 between lenses 341 and 342, distance L3 between lenses 342 and 343, and distance L4 between lens 343 and LCOS panel 310. In some embodiments, distances L1-L4 may be between 10 mm and 100 mm.

[0074] Figure 3 Also shown is a receiver optical group 360 for directing a light beam 371 reflected from the LCOS panel 30 to a detector (not shown). The receiver optical group 360 is configured to focus the light beam reflected from the LCOS panel 310 to the detector. Figure 3 A receiver optical group 360 is shown comprising three lenses 361, 362 and 363. These lenses include a collimating lens and a focusing lens. Figure 3 The optical path 373 of the reflected light beam 371 is also shown.

[0075] Figure 4 4 is a flowchart of a method for determining residual delay of an LCOS (liquid crystal on silicon) panel according to various embodiments of the present invention. Method 400 is a method for determining residual delay of an LCOS panel, which can be used in combination with the above Figure 2 The system 200 described is implemented in the system. Figure 4 As shown, method 400 includes providing a light beam from a light source at 410. The light source may be a laser light source delivered by, for example, an optical fiber.

[0076] At 420, the light beam is sent to the LCOS panel at a non-normal incidence angle, passes through the transmitter optical group, the circular polarizer, and the bias retarder to reach the LCOS panel. Figure 2As shown, an input light beam 251 from a light source 250 is sent to the LCOS panel 210 through the transmitter optical group 240, the polarizer 230 and the bias retarder 220 at a non-normal incidence angle. Figure 2 As shown, the optical path 253 of the input light beam 252 forms an incident angle θ relative to the normal 211 of the LCOS panel 210. Figure 3 The transmitter optical group 340 is shown including three lenses 341, 342 and 343. These lenses include a collimating lens and a focusing lens. Figure 2 and Figure 3 In the example in FIG. 1 , the incident light has a non-normal incident angle. In other embodiments, a normal incident angle with an incident angle θ of 0° may also be used.

[0077] At 430, the light beam is reflected from the LCOS panel through the bias retarder, circular polarizer, and receiver optical set to a detector for measuring the intensity of the received light beam. Figure 2 As shown, the light beam reflected from the LCOS panel 210 is transmitted through the bias retarder 220 , the polarizer 230 , and the receiver optical group 260 to reach the detector 270 . Figure 3 A receiver optical group 360 is shown comprising three lenses 361, 362 and 363. These lenses include a collimating lens and a focusing lens.

[0078] At 440, the method includes determining a retarder alignment angle, also referred to as a contrast measurement angle associated with the bias retarder, by rotating the bias retarder and measuring the intensity of the reflected light beam using the LCOS in the dark state. The rotation angle of the bias retarder associated with the minimum value of the intensity of the reflected light beam is then determined as the retarder alignment angle, or contrast measurement angle. In some embodiments, the retarder alignment angle or contrast measurement angle is also referred to as the optimal angle of the bias retarder because the angle is used as the compensator alignment angle for orienting the selected compensator relative to the LCOS panel.

[0079] At 450, with the biased retarder set at the retarder alignment angle or contrast measurement angle, and the LCOS in the dark state, the method measures the dark state intensity of the reflected beam. Then, with the biased retarder still set at the contrast measurement angle and the LCOS in the bright state, the method measures the bright state intensity of the reflected beam. Here, by, for example Figure 2 The processor 280 in varies the voltage applied to the LCOS panel, which can be biased in a dark state or a bright state.

[0080] At 460, the method includes determining a contrast ratio of the bright state intensity and the dark state intensity. The contrast ratio (CR) is the ratio of the intensity of light reflected from the LCO biased in the dark state and the bright state.

[0081] At 470, a total delay is determined based on a contrast ratio of the bright state intensity and the dark state intensity. In some embodiments, the total delay (γ) may be determined based on the contrast ratio (CR), including determining the total delay (γ) using the following equation:

[0082]

[0083] Where CR = contrast ratio, γ = system delay, and λ = wavelength.

[0084] At 480, the residual delay (RR) of the LCOS panel is determined based on the total delay. The residual delay (RR) can be calculated using the above equation and then adjusted for the compensator already in place.

[0085] RR=γ+Comp-ToolResidual

[0086] Here, in this example, Comp is the retardation of the bias retarder, and ToolResidual is the additional retardation introduced by the circular polarizer.

[0087] At 490, a compensator is selected for the LCOS based on the residual retardation, and a retarder alignment angle is specified as the compensator alignment angle of the selected compensator relative to the LCOS panel.

[0088] The method may also include selecting a compensator for the LCOS panel based on the residual delay. In some embodiments, the test results of the residual delay (RR) are grouped into different bins. A bin is a range of residual delay (RR) values ​​measured by a device. According to an embodiment of the present invention, once the LCOS panel is analyzed and a bin corresponding to the measured RR value of the LCOS panel is determined, a compensator having a delay value associated with that particular bin may be used for that particular LCOS panel.

[0089] It should be understood that Figure 4 The specific steps shown provide specific methods for determining residual delay of an LCOS (liquid crystal on silicon) panel according to various embodiments of the present invention. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the above steps in a different order. Furthermore, Figure 4 The individual steps shown may include multiple sub-steps, which may be performed in various orders suitable for the individual steps. In addition, additional steps may be added or removed depending on the specific application. Those of ordinary skill in the art will recognize many variations, modifications and substitutions.

[0090] In the embodiments described above, the residual delay is measured at a single location of the LCOS panel (e.g., at the center of the LCOS panel). The compensator plate is then selected based on the measured residual delay and is placed over the entire active area of ​​the LCOS panel when the LCOS device is assembled. In alternative embodiments, the residual delay at multiple pixel locations across the LCOS panel can be measured using the methods described above. In these alternative embodiments, a representative value of the residual delay can be determined based on residual delay data for multiple pixel locations measured in various ways (including an average of multiple data, a root mean square value of multiple data, a weighted average, a best fit, etc.). The representative value of the residual delay can then be used to select a compensator plate for the LCOS panel.

[0091] Figure 5A and Figure 5B Various axes of compensators and circular polarizers are shown according to various embodiments of the present invention. Figure 5A A top view of a compensator showing the slow axis of the compensator is shown with a slow axis indicator in the form of a notch at the periphery of the compensator. Alternatively, the slow axis may be marked at the periphery of the compensator by a flat edge. Figure 5B Shown is a top view of a circular polarizer having the polarization transmission axis marked by notches at the perimeter of the circular polarizer. Figure 5B Also shown is the slow axis rotated 45° from the polarization transmission axis.The method described above provides information for orienting the compensator relative to the circular polarizer.

[0092] FIG. 6A to FIG. 6D A diagram based on an alternative method for determining residual delay according to various embodiments of the present invention is shown. FIG. 6A to FIG. 6D In Figure 1, the horizontal axis is the ideal compensator retardation, and the vertical axis is the residual retardation calculated from the measurement. For the horizontal axis, the ideal compensator is determined by the following methods: zero polarization method or measuring the contrast ratio using a set of discrete compensators and fitting the result to obtain the ideal compensator value. The residual retardation can be estimated from the contrast ratio (CR) measurement without the compensator, that is, compensator retardation = 0nm,

[0093]

[0094] Where CR = contrast ratio, γ = system delay, and λ = wavelength offset.

[0095] The inventors performed an analysis using different compensators with different delay values. Fig. 6A Using a bias compensator with 5 nm delay, Figure 6B Using a bias compensator with 8nm delay, Figure 6C A compensator with 10 nm retardation is used in Fig.6DA bias compensator with 12 nm retardation is used in . The residual retardation is calculated using the above equation and then adjusted for the compensator already in place as follows.

[0096] RR=γ+Comp-ToolResidual

[0097] where RR is the residual retardation of the panel, Comp is the retardation of the bias retarder, and ToolResidual is the additional retardation introduced by the circular polarizer.

[0098] Here, the contrast reaches a peak when the compensator delay matches the residual delay of the LCOS panel. Any deviation (+ or -) may reduce the contrast. As an example, if the residual delay of the panel is 8nm (initially unknown) and a compensator with a delay of 5nm is used, the measured contrast will be the first value. When the compensator with 5nm delay is replaced with a compensator with 8nm delay, a higher contrast value will be measured; when the compensator with 8nm delay is replaced with a compensator with 10nm delay, a lower contrast value will be measured. Therefore, the residual delay of the panel will be determined to be 8nm, because the deviation of the contrast from 8nm reduces the measured contrast.

[0099] exist Fig. 6A In , using a compensator with 5 nm retardation, a linear curve is produced, indicating a one-to-one correspondence between the values ​​on the horizontal axis and the values ​​on the vertical axis. This result is consistent with the method described above using a low-retardation bias retarder in the optical path. If a low-retardation bias retarder is not used, then using the method described above would use only two contrast measurements because given the contrast changes for different compensators, it is unclear whether a lower retardation compensator or a higher retardation compensator is needed to determine the residual retardation. FIG. 6B to FIG. 6D and with Fig. 6A In contrast, there is no one-to-one correspondence between the values ​​on the horizontal axis and the values ​​on the vertical axis. Instead, based on the contrast calculation, there are two possible residual delay values. Therefore, when using contrast measurement to determine residual delay, a bias compensator with a low delay value is used. Moreover, these figures indicate that contrast measurement is an effective technique for determining residual delay of LCOS panels.

[0100] Contrast change as a function of voltage change (see below FIG. 7A to FIG. 7D ) can be used to determine if the panel is over-compensated or under-compensated by the compensators in the path.

[0101] FIG. 7A to FIG. 7D A diagram based on an alternative method for determining residual delay according to various embodiments of the present invention is shown. FIG. 6A to FIG. 6D ,exist FIG. 7A to FIG. 7DIn Figure 1, the horizontal axis is the ideal compensator delay, and the vertical axis is the residual delay calculated from the measurement. For the horizontal axis, no compensator is used. The residual delay can be estimated from the contrast ratio (CR) measurement without the compensator. For the vertical axis, a compensator with a different delay value is used. In this example, Fig. 6A A compensator with 5 nm retardation is used in Figure 6B A compensator with 8 nm delay is used in Figure 6C A compensator with 10 nm retardation is used in Fig.6D A compensator with 12 nm retardation is used in . The residual retardation is calculated using the above equation and then adjusted for the compensator already in place.

[0102] FIG. 7A to FIG. 7D The effect of varying the voltage applied to the LCOS panel is shown. Varying the voltage of the panel and the measurement of contrast can be used to determine if the particular bias compensator used causes the panel to over-compensate or under-compensate. In the first case, if the bias compensator has too low a retardation, causing the LCOS panel to under-compensate, then an increase in voltage will increase the contrast ratio (CR). For example, CR@3.2V-CR@2.8V will be greater than 0. Therefore, it is possible to insert a bias compensator, measure the contrast associated with the two LCOS panel voltages, and determine that when the contrast increases due to an increase in voltage, the panel is under-compensated.

[0103] In the second case, if the bias compensator has too high a retardation, causing the LCOS panel to overcompensate, an increase in voltage will reduce the contrast ratio (CR). For example, CR@3.2V-CR@4.8V will be less than 0. Therefore, it is possible to insert the bias compensator, measure the contrast ratio associated with the two LCOS panel voltages, and determine that the panel is overcompensated when the contrast ratio decreases due to an increase in voltage.

[0104] RR=|γ+sign(CR@3.2V-CR@2.8V)·Comp|

[0105] In this case, the calculated residual delay takes into account the sign of the contrast change.

[0106] exist FIG. 7A to FIG. 7D In FIG. 1 , when the bias compensator is characterized by a retardation that is less than the residual retardation of the panel, the residual retardation calculated based on the contrast measurement will be less than the ideal residual retardation, which is represented by the data point to the left of the bias compensator retardation value for each graph (i.e., for Fig. 7A 5nm, targeting Figure 7B 8nm, targeting Figure 7C 10nm, and Fig.7DSimilarly, when the bias compensator features a retardation greater than the residual retardation of the panel, the residual retardation calculated based on the contrast measurement will be greater than the ideal residual retardation, which is represented by the data points to the right of the bias compensator retardation value for each graph. FIG. 6A to FIG. 6D Like the techniques discussed above, these figures indicate that contrast measurement is an effective technique for determining the residual retardation of LCOS panels.

[0107] Figure 8 is a block diagram of a computer system or information processing device that may incorporate an embodiment, be incorporated into an embodiment, or be used to practice any innovation, embodiment, and / or example found within the present disclosure.

[0108] Figure 8 is a block diagram of a computer system 800 . Figure 8 This is exemplary only. In some embodiments, the computer system includes a single computer device, wherein the subsystem may be a component of the computer device. In other embodiments, the computer system may include multiple computer devices, each of which is a subsystem with internal components. The computer system 800 and any of its components or subsystems may include hardware and / or software elements configured to perform the methods described herein.

[0109] The computer system 800 may include familiar computer components, such as one or more data processors or central processing units (CPUs) 805, one or more graphics processors or graphics processing units (GPUs) 810, a memory subsystem 815, a storage subsystem 820, one or more input / output (I / O) interfaces 825, a communication interface 830, etc. The computer system 800 may include a system bus 835 that interconnects the above components and provides functions such as connectivity for inter-device communications.

[0110] One or more data processors or central processing units (CPUs) 805 can execute logic or program code, or be used to provide specialized functions. Some examples of (one or more) CPUs 805 may include one or more microprocessors (e.g., single-core and multi-core) or microcontrollers, one or more field programmable gate arrays (FPGAs), and application-specific integrated circuits (ASICs). As used herein, processors include multi-core processors on the same integrated chip, or multiple processing units on a single circuit board or network.

[0111] One or more graphics processors or graphics processing units (GPUs) 810 may execute logic or program code associated with graphics or for providing graphics-specific functions. GPU 810 may include any conventional graphics processing unit, such as a graphics processing unit provided by a conventional video card. In various embodiments, GPU 810 may include one or more vector or parallel processing units. These GPUs may be user programmable and include hardware elements for encoding / decoding specific types of data (e.g., video data) or for accelerating 2D or 3D drawing operations, texture operations, shading operations, etc. One or more graphics processors or graphics processing units (GPUs) 810 may include any number of registers, logic units, arithmetic units, caches, memory interfaces, etc.

[0112] The memory subsystem 815 may store information, for example, using a machine-readable article, an information storage device, or a computer-readable storage medium. Some examples may include random access memory (RAM), read-only memory (ROM), volatile memory, non-volatile memory, and other semiconductor memory. The memory subsystem 815 may include data and program code 840.

[0113] The storage subsystem 820 may also use a machine-readable article, an information storage device, or a computer-readable storage medium to store information. The storage subsystem 820 may use a storage medium 845 to store information. Some examples of storage media 845 used by the storage subsystem 820 may include a floppy disk, a hard disk, an optical storage medium such as a CD-ROM, a DVD, and a bar code, a removable storage device, a network storage device, etc. In some embodiments, the storage subsystem 820 may be used to store all or part of the data and program code 840.

[0114] One or more input / output (I / O) interfaces 825 may perform I / O operations. One or more input devices 850 and / or one or more output devices 855 may be communicatively coupled to the one or more I / O interfaces 825. One or more input devices 850 may receive information from one or more sources for the computer system 800. Some examples of one or more input devices 850 may include a computer mouse, a trackball, a trackpad, a joystick, a wireless remote control, a drawing tablet, a voice command system, an eye tracking system, an external storage system, a monitor appropriately configured as a touch screen, a communication interface appropriately configured as a transceiver, and the like. In various embodiments, one or more input devices 850 may allow a user of the computer system 800 to interact with one or more non-graphical or graphical user interfaces to enter annotations, select objects, icons, text, user interface widgets, or other user interface elements that appear on a monitor / display device via commands, clicks of buttons, and the like.

[0115] The one or more output devices 855 may output information to one or more destinations for the computer system 800. Some examples of the one or more output devices 855 may include a printer, a fax machine, a feedback device for a mouse or joystick, an external storage system, a monitor or other display device, a communication interface appropriately configured as a transceiver, etc. The one or more output devices 855 may allow a user of the computer system 800 to view objects, icons, text, user interface widgets, or other user interface elements. A display device or monitor may be used with the computer system 800 and may include hardware and / or software elements configured to display information.

[0116] The communication interface 830 can perform communication operations, including sending and receiving data. Some examples of the communication interface 830 may include a network communication interface (e.g., Ethernet, Wi-Fi). For example, the communication interface 830 can be coupled to a communication network / external bus 860, such as a computer network, a USB hub, etc. The computer system may include multiple identical components or subsystems, for example, connected together through the communication interface 830 or an internal interface. In some embodiments, the computer system, subsystem, or device can communicate through a network. In such an example, a computer can be considered as a client, and another computer can be considered as a server, wherein each computer can be part of the same computer system. The client and the server can each include multiple systems, subsystems, or components.

[0117] The computer system 800 may also include one or more applications (e.g., software components or functions) to be executed by the processor to perform, perform, or otherwise implement the techniques disclosed herein. These applications may be implemented as data and program code 840. In addition, computer programs, executable computer code, human-readable source code, shader code, rendering engines, etc., as well as data such as image files, models including geometric descriptions of objects, ordered geometric descriptions of objects, process descriptions of models, scene descriptor files, etc., may be stored in the memory subsystem 815 and / or the storage subsystem 820.

[0118] Such a program can also be encoded and sent using a carrier signal suitable for transmission via wired, optical and / or wireless networks that meet various protocols (including the Internet). Therefore, the computer-readable medium according to an embodiment of the present invention can be created using a data signal encoded by such a program. The computer-readable medium encoded with program code can be packaged with a compatible device, or provided separately from other devices (for example, downloaded via the Internet). Any such computer-readable medium can reside on or inside a single computer product (for example, a hard disk drive, a CD or a whole computer system), and can be present on or inside different computer products in a system or network. A computer system may include a monitor, a printer or other suitable displays for providing any result mentioned herein to the user.

[0119] Any method described herein can be performed in whole or in part using a computer system including one or more processors, which can be configured to perform steps. Therefore, an embodiment can relate to a computer system configured to perform the steps of any method described herein, potentially utilizing different components that perform corresponding steps or corresponding step groups. Although presented as numbered steps, the steps of the method herein can be performed simultaneously or in different orders. In addition, parts of these steps can be used together with parts of other steps from other methods. Moreover, all or part of the steps can be optional. In addition, any step of any method can be performed using modules, circuits or other devices for performing these steps.

[0120] Although various embodiments of the present invention have been described above, it should be understood that they are presented only by way of example and not by way of limitation. Similarly, various figures may depict example architectures or other configurations for the present disclosure, which may be included in the present disclosure in order to help understand the features and functions. The present disclosure is not limited to the example architectures or configurations shown, but may be implemented using various alternative architectures and configurations. In addition, although the present disclosure is described above according to various exemplary embodiments and implementations, it should be understood that the various features and functions described in one or more separate embodiments are not limited to the applicability of the specific embodiments used to describe them. On the contrary, they may be applied to one or more of the other embodiments of the present disclosure, either alone or in some combination, whether or not such embodiments are described, and whether such features are presented as part of the described embodiments. Therefore, the breadth and scope of the present disclosure should not be limited by any of the exemplary embodiments described above.

[0121] In this document, the term "module" as used herein refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. In addition, for the purpose of discussion, various modules are described as discrete modules; however, as will be apparent to one of ordinary skill in the art, two or more modules may be combined to form a single module that performs the associated functions according to embodiments of the present invention.

[0122] It should be understood that, for clarity purposes, the above description has described embodiments of the present invention with reference to different functional units and processors. However, it is apparent that any suitable distribution of functionality may be used between different functional units, processors, or domains without departing from the present invention. For example, functions shown to be performed by separate processors or controllers may be performed by the same processor or controller. Therefore, references to specific functional units are only viewed as references to suitable means for providing the described functionality, rather than indicating a strict logical or physical structure or organization.

[0123] Unless otherwise expressly stated, the terms and phrases used in this document and their variations should be interpreted as open-ended, as opposed to restrictive. As an example of the above: the term "including" should be understood to mean "including but not limited to" and the like; the term "example" is used to provide an exemplary example of the item under discussion, rather than an exhaustive or restrictive list thereof; and adjectives such as "conventional", "traditional", "normal", "standard", "known", and terms of similar meaning should not be interpreted as limiting the items described to a given time period, or to items available as of a given time. But on the contrary, these terms should be understood to cover conventional, traditional, normal or standard technologies that may be available, known, now or at any time in the future. Similarly, a group of items connected with the conjunction "and" should not be understood to require that each of these items be present in the grouping, but should be understood as "and / or", unless otherwise expressly stated. Similarly, a group of items connected with the conjunction "or" should not be understood to require mutual exclusion between the group of items, but should also be understood as "and / or", unless otherwise expressly stated. In addition, although the items, elements or components of the present disclosure may be described or claimed in the singular, the plural is contemplated within its scope unless limitation to the singular is explicitly stated. In some instances, the presence of extended words and phrases such as "one or more", "at least", "but not limited to" or other similar phrases should not be understood to mean that a narrower case is expected or required in instances where such extended phrases may be absent.

[0124] It should also be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes therefrom will be suggested to those skilled in the art and will be included within the spirit and purview of the present application and the scope of the claims.

Claims

1. A method for determining residual retardation of a liquid crystal on silicon (LCOS) panel, the method comprising: providing a light beam from a light source; sending the light beam to the LCOS panel at a non-normal incident angle, the light beam passing through a transmitter optical group, a circular polarizer, and a bias retarder to reach the LCOS panel; reflecting the beam from the LCOS panel through the bias retarder, the circular polarizer and a receiver optical stack and to a detector for measuring the intensity of the received beam; Determine the retarder alignment angle by following these steps: rotating the bias retarder and measuring the intensity of the received beam using the LCOS panel in a dark state; as well as identifying a rotation angle of the biased retarder associated with a minimum value of the intensity of the received light beam as the retarder alignment angle; measuring a dark state intensity of the received light beam using the biased retarder disposed at the retarder alignment angle and the LCOS panel in the dark state; measuring a bright state intensity of the received light beam using the biased retarder disposed at the retarder alignment angle and the LCOS panel in a bright state; determining a contrast ratio of the bright state intensity to the dark state intensity; determining a total delay based on a contrast ratio of the bright state intensity and the dark state intensity; determining a residual delay of the LCOS panel based on the total delay; selecting a compensator for the LCOS panel based on the residual delay; as well as The retarder alignment angle of the bias retarder is designated as the compensator alignment angle of the selected compensator relative to the LCOS panel.

2. The method according to claim 1, wherein: Determining the residual retardation of the LCOS panel includes removing the retardation of the bias retarder and the retardation of the circular polarizer from the total retardation.

3. The method according to claim 1, wherein: Determining the total delay (γ) based on the contrast ratio (CR) includes determining the total delay (γ) using the following equation: Wherein, λ is the wavelength of the light beam.

4. The method according to claim 1, wherein: The transmitter optical group includes a collimating lens and a focusing lens.

5. The method according to claim 1, wherein: The receiver optical group includes a collimating lens and a focusing lens.

6. A method for determining residual retardation of a liquid crystal on silicon (LCOS) panel, the method comprising: sending a light beam to the LCOS panel at an incident angle and measuring the intensity of the reflected light beam; biasing the LCOS panel in a dark state; measuring the dark state intensity of the reflected light beam; The LCOS panel is biased in a bright state; measuring the bright-state intensity of the reflected light beam; determining a residual retardation of the LCOS panel based on a contrast ratio of the bright state intensity to the dark state intensity; and A compensator is selected for the LCOS panel based on the residual delay.

7. The method according to claim 6, wherein: The incident angle is a non-normal incident angle.

8. The method according to claim 6, wherein: The incident angle is a normal incident angle.

9. The method according to claim 6, further comprising: determining the contrast ratio of the bright state intensity and the dark state intensity; determining a total delay based on the contrast ratio of the bright state intensity and the dark state intensity; as well as The residual delay of the LCOS panel is determined based on the total delay.

10. The method according to claim 9, wherein: Determining the total delay (γ) based on the contrast ratio (CR) includes determining the total delay (γ) using the following equation: Wherein, λ is the wavelength of the light beam.

11. The method according to claim 9, wherein: Sending the light beam to the LCOS panel includes sending the light beam to the LCOS panel sequentially through a circular polarizer and a bias retarder; Measuring the intensity of the reflected light beam comprises passing the reflected light beam sequentially through the bias retarder and the circular polarizer to a detector; and Determining the residual retardation of the LCOS panel includes removing the retardation of the bias retarder and the retardation of the circular polarizer from the total retardation.

12. The method according to claim 6, wherein: Sending a light beam to the LCOS panel includes sending the light beam to the LCOS panel through a polarizer.

13. The method according to claim 12, wherein: Measuring the intensity of the reflected light beam includes passing the reflected light beam through the polarizer to a detector.

14. The method according to claim 12, wherein: The polarizer comprises a circular polarizer.

15. The method according to claim 12, wherein: The polarizer includes a linear polarizer.

16. The method according to claim 6, wherein: Sending a light beam to the LCOS panel includes sending the light beam through a transmitter optical group including a collimating lens and a focusing lens.

17. The method according to claim 6, wherein: Sending a light beam to the LCOS panel includes sending the light beam to the LCOS panel through a biased retarder.

18. The method according to claim 17, wherein: Measuring the intensity of the reflected light beam includes passing the reflected light beam through the bias retarder to a detector.

19. The method according to claim 17, further comprising: The retarder alignment angle for the bias retarder is determined by rotating the bias retarder and measuring the intensity of the reflected light beam using the LCOS in a dark state, and identifying the rotation angle of the bias retarder associated with a minimum value of the intensity as the retarder alignment angle for the bias retarder.

20. The method according to claim 19, further comprising: The retarder alignment angle of the bias retarder is identified as the compensator alignment angle of the selected compensator relative to the LCOS panel.

21. A system for determining residual retardation of a liquid crystal on silicon (LCOS) panel, the system comprising: a holder for the LCOS panel; A bias retarder disposed on the LCOS panel; a polarizer disposed on the bias retarder; a transmitter optical group disposed on the polarizer; a light source disposed on the emitter optical group; wherein the emitter optical group is configured to focus a light beam from the light source through the polarizer and the bias retarder to the LCOS panel at a non-normal incidence angle; a receiver optical group disposed on the polarizer; a detector disposed on the receiver optical group for measuring the intensity of light reflected from the LCOS panel, wherein the receiver optical group is configured to focus a light beam reflected from the LCOS panel through the bias retarder and the polarizer to the detector; and a controller for alternately biasing the LCOS panel into a dark state and a bright state, The system is configured to: determining a bright state intensity and a dark state intensity of light reflected from the LCOS panel; determining a total delay based on a contrast ratio of the bright state intensity and the dark state intensity of the light reflected from the LCOS panel; and A residual delay of the LCOS panel is determined based on the total delay.

22. The system of claim 21, wherein: Determining the total delay (γ) based on the contrast ratio (CR) includes determining the total delay (γ) using the following equation: Wherein, λ is the wavelength of the light beam.

23. The system of claim 21, wherein: The polarizer comprises a circular polarizer.

24. The system of claim 21, wherein: The polarizer includes a linear polarizer.

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