Patent Publication Number: US-2023161234-A1

Title: Projection system and method with adjustable angle illumination

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from U.S. Provisional Application No. 63/014,239, filed on 23 Apr. 2020, and European Patent Application No. 20171002.7, filed on 23 Apr. 2020, which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Disclosure 
     This application relates generally to projection systems and methods of driving a projection system. 
     2. Description of Related Art 
     Digital projection systems typically utilize a light source and an optical system to project an image onto a surface or screen. The optical system includes components such as mirrors, lenses, waveguides, optical fibers, beam splitters, diffusers, spatial light modulators (SLMs), and the like. The contrast of a projector indicates the brightest output of the projector relative to the darkest output of the projector. Contrast ratio is a quantifiable measure of contrast, defined as a ratio of the luminance of the projector&#39;s brightest output to the luminance of the projector&#39;s darkest output. This definition of contrast ratio is also referred to as “static” or “native” contrast ratio. 
     Some projection systems are based on SLMs that implement a spatial amplitude modulation. In such a system, the light source may provide a light field that embodies the brightest level that can be reproduced on the image, and light is attenuated or discarded in order to create the desired scene levels. Some high contrast examples of projection systems based on this architecture use a semi-collimated illumination system and Fourier stop in the projection optics to improve contrast. In such architectures, the illumination angle on the SLM has a substantial effect on the projected image, including but not limited to effects on the contrast ratio and the clarity of the projected image. 
     BRIEF SUMMARY OF THE INVENTION 
     Various aspects of the present disclosure relate to devices, systems, and methods for projection display a high-contrast projection architecture. 
     In one exemplary aspect of the present disclosure, there is provided a projection system comprising a light source configured to emit a light in response to an image data; an illumination optical system configured to steer the light, the illumination optical system including a first mirror and a second mirror; a digital micromirror device including a plurality of micromirrors, wherein a respective micromirror is configured to reflect the steered light to a filter as on-state light in a case where the respective micromirror is in an on position and to reflect the steered light to a light dump as off-state light in a case where the respective micromirror is in an off position; and a controller configured to: determine a deviation between an actual angle of orientation of the digital micromirror device and an expected angle of orientation of the digital micromirror device, calculate a first amount of angle adjustment corresponding to the first mirror and a second amount of angle adjustment corresponding to the second mirror, and actuate the first mirror according to the first amount and the second mirror according to the second amount, thereby to maintain a position and a focus of the steered light on the digital micromirror device and to cause the on-state light to be incident within a predetermined distance from a center of the filter. 
     In another exemplary aspect of the present disclosure, there is provided a method of calibrating a projection system including a light source configured to emit a light in response to an image data, an illumination optical system configured to steer the light, the illumination optical system including a first mirror and a second mirror, and a digital micromirror device including a plurality of micromirrors respectively configured to reflect the steered light to a filter as on-state light in a case where the respective micromirror is in an on position and to reflect the steered light to a light dump as off-state light in a case where the respective micromirror is in an off position, the method comprising: determining a deviation between an actual angle of orientation of the digital micromirror device and an expected angle of orientation of the digital micromirror device, calculating a first amount of angle adjustment corresponding to the first mirror and a second amount of angle adjustment corresponding to the second mirror, and actuating the first mirror according to the first amount and the second mirror according to the second amount, thereby to maintain a position and a focus of the steered light on the digital micromirror device and to cause the on-state light to be incident within a predetermined distance from a center of the filter. 
     In another exemplary aspect of the present disclosure, there is provided a non-transitory computer-readable medium storing instructions that, when executed by a processor of a projection device including a light source configured to emit a light in response to an image data, an illumination optical system configured to steer the light, the illumination optical system including a first mirror and a second mirror, and a digital micromirror device including a plurality of micromirrors respectively configured to reflect the steered light to a filter as on-state light in a case where the respective micromirror is in an on position and to reflect the steered light to a light dump as off-state light in a case where the respective micromirror is in an off position, cause the projection device to perform operations comprising determining a deviation between an actual angle of orientation of the digital micromirror device and an expected angle of orientation of the digital micromirror device, calculating a first amount of angle adjustment corresponding to the first mirror and a second amount of angle adjustment corresponding to the second mirror, and actuating the first mirror according to the first amount and the second mirror according to the second amount, thereby to maintain a position and a focus of the steered light on the digital micromirror device and to cause the on-state light to be incident within a predetermined distance from a center of the filter. 
     In this manner, various aspects of the present disclosure provide for the display of images having a high dynamic range and high resolution, and effect improvements in at least the technical fields of image projection, holography, signal processing, and the like. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       These and other more detailed and specific features of various embodiments are more fully disclosed in the following description, reference being had to the accompanying drawings, in which: 
         FIG.  1    illustrates a block diagram of an exemplary projection system according to various aspects of the present disclosure; 
         FIGS.  2 A- 2 B  illustrate views of an exemplary spatial light modulator for use with various aspects of the present disclosure; 
         FIGS.  3 A- 3 B  illustrate exemplary optical states in an exemplary projection system according to various aspects of the present disclosure; 
         FIG.  4    illustrates an exemplary alignment method in the exemplary optical system of  FIGS.  3 A- 3 B ; 
         FIGS.  5 A- 5 B  illustrate an exemplary relationship between mirror angles in the exemplary optical system of  FIGS.  3 A- 3 B ; 
         FIG.  6    illustrates an exemplary optical state in another exemplary projection system according to various aspects of the present disclosure; 
         FIG.  7    illustrates an exemplary linkage for use with the exemplary optical system of  FIG.  6   ; 
         FIG.  8    illustrates another exemplary linkage for use with the exemplary optical system of  FIG.  6   ; 
         FIGS.  9 A- 9 B  illustrate exemplary optical states for another exemplary linkage for use with the exemplary optical system of  FIG.  6   ; 
         FIG.  10    illustrates an exemplary implementation of the exemplary optical system of  FIG.  6   ; and 
         FIG.  11    illustrates an exemplary alignment method in the exemplary optical system of  FIG.  6   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This disclosure and aspects thereof can be embodied in various forms, including hardware, devices, or circuits controlled by computer-implemented methods, computer program products, computer systems and networks, user interfaces, and application programming interfaces; as well as hardware-implemented methods, signal processing circuits, memory arrays, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and the like. The foregoing summary is intended solely to give a general idea of various aspects of the present disclosure, and does not limit the scope of the disclosure in any way. 
     In the following description, numerous details are set forth, such as optical device configurations, timings, operations, and the like, in order to provide an understanding of one or more aspects of the present disclosure. It will be readily apparent to one skilled in the art that these specific details are merely exemplary and not intended to limit the scope of this application. 
     Moreover, while the present disclosure focuses mainly on examples in which the various circuits are used in digital projection systems, it will be understood that this is merely one example of an implementation. It will further be understood that the disclosed systems and methods can be used in any device in which there is a need to project light; for example, cinema, consumer and other commercial projection systems, heads-up displays, virtual reality displays, and the like. 
     Projector Systems 
     The optics of an SLM-based projection system may be broadly categorized into two parts: the optics located on the illumination side (i.e., optically upstream of the SLM) and the optics located on the projection side (i.e., optically downstream of the SLM). The SLM itself includes a plurality of modulating elements arranged in, for example, a two-dimensional array. Individual modulating elements receive light from the illumination optics and convey light to the projection optics. In some examples, the SLM may be implemented as a digital micromirror device (DMD); this will be discussed in more detail below. Generally, however, a DMD includes a two-dimensional array of reflective elements (micromirrors or simply “mirrors”) which selectively reflect light towards the projection optics or discard light based on the position of the individual reflective elements. 
     As noted above, a high contrast projection system which uses a semi-collimated illumination system and Fourier stop in the projection optics may be greatly affected by differences in the angle of incidence light on the DMD. To prevent degradation in the projected image, a projection system may maintain the position and focus of an output of the illumination optics (e.g., light output from an integrating rod or other uniformity correcting device and subsequently reflected by one or more reflective elements) on the DMD, while at the same time keeping the reflected beam centered in the input of the projection optics (e.g., a filter aperture). However, the exact position of the first and second angle of the DMD mirrors may be subject to manufacturing or other tolerances, such that the actual first and second angles may vary by some amount. In order to compensate for differences in DMD mirror angle between different physical DMDs and ensure that the beam is appropriately centered, one may control the angle of light exiting (e.g., reflecting from) the DMD. Such control should be robust to variations in the first and second angle of the DMD mirrors. The robustness against angle variations may be provided by implementing an adjustment of the angle of incidence of the beam onto the DMD so that, when reflected by the DMD mirrors, the exit beam is always at (or substantially at) the nominal designed exit angle to the aperture. Moreover, because each color channel in color projection systems may have a different angle requirement, it is desirable to provide an adjustment for each color. 
     The architecture of such high contrast projection systems may provide particular constraints in addition to the adjustment and maintenance of proper illumination angle. For example, the projection systems may utilize a prism where the three colors are recombined and/or a fold mirror before the prism to reduce the size footprint of the optics and the projector itself. Moreover, because the illumination optics focuses an aperture onto the DMD, the optics may be constrained to maintain a constant distance between the aperture and the DMD. Furthermore, as noted above, the image of the aperture must be centered on the DMD. Herein, examples of projection systems are described which are capable of adjusting the input angle to the DMD without changing the focus or position of the integrating rod (or other uniformity correcting device) at the DMD. 
       FIG.  1    illustrates an exemplary high contrast projection system  100  according to various aspects of the present disclosure. In particular,  FIG.  1    illustrates a projection system  100  which includes a light source  101  configured to emit a first light  102 ; illumination optics  103  (one example of an illumination optical system in accordance with the present disclosure) configured to receive the first light  102  and redirect or otherwise modify it, thereby to generate a second light  104 ; a DMD  105  configured to receive the second light  104  and selectively redirect and/or modulate it as a third light  106 ; a filter  107  configured to filter the third light  106 , thereby to generate a fourth light  108 ; and projection optics  109  configured to receive the fourth light  108  and project it as a fifth light  110  onto a screen  111 . 
     In practical implementations, the projection system  100  may include fewer optical components or may include additional optical components such as mirrors, lenses, waveguides, optical fibers, beam splitters, diffusers, and the like. With the exception of the screen  111 , the components illustrated in  FIG.  1    may be integrated into a housing to provide a projection device. Such a projection device may include additional components such as a memory, input/output ports, communication circuitry, a power supply, and the like. 
     The light source  101  may be, for example, a laser light source, an LED, and the like. Generally, the light source  101  is any light emitter which emits coherent light. In some aspects of the present disclosure, the light source  101  may comprise multiple individual light emitters, each corresponding to a different wavelength or wavelength band. The light source  101  emits light in response to an image signal provided by the controller  112 ; for example, one or more processors such as a central processing unit (CPU) of the projection system  100 . The image signal includes image data corresponding to a plurality of frames to be successively displayed. Individual elements in the projector system  100 , including the illumination optics  103  and/or the DMD  105 , may be controlled by the controller  112 . The image signal may originate from an external source in a streaming or cloud-based manner, may originate from an internal memory of the projection system  100  such as a hard disk, may originate from a removable medium that is operatively connected to the projection system  100 , or combinations thereof. 
     Although  FIG.  1    illustrates a generally linear optical path, in practice the optical path is generally more complex. For example, in the projection system  100 , the second light  104  from the illumination optics  103  is steered to the DMD chip  105  (or chips) at a fixed angle, determined by the steering angle of the DMD mirrors. 
     To illustrate the effects of the angle of incidence and the DMD mirrors,  FIGS.  2 A- 2 B  show an exemplary DMD  200  in accordance with various aspects of the present disclosure.  FIG.  2 A  illustrates a plan view of the DMD  200 , and  FIG.  2 B  illustrates partial cross-sectional view of the DMD  200 . The DMD  200  includes a plurality of square micromirrors  202  arranged in a two-dimensional rectangular array on a substrate  204 . In some examples, the DMD  200  may be a digital light processor (DLP) from Texas Instruments. Each micromirror  202  may correspond to one pixel of the eventual projection image, and may be configured to tilt about a rotation axis  208 , shown for one particular subset of the micromirrors  202 , by electrostatic or other actuation. The individual micromirrors  202  have a width  212  and are arranged with gaps of width  210  therebetween. The micromirrors  202  may be formed of or coated with any highly reflective material, such as aluminum or silver, to thereby specularly reflect light. The gaps between the micromirrors  202  may be absorptive, such that input light which enters a gap is absorbed by the substrate  204 . 
     While  FIG.  2 A  expressly shows only some representative micromirrors  202 , in practice the DMD  200  may include many more individual micromirrors in an number equal to a resolution of the projector system  100 . In some examples, the resolution may be 2K (2048×1080), 4K (4096×2160), 1080p (1920×1080), consumer 4K (3840×2160), and the like. Moreover, in some examples the micromirrors  202  may be rectangular and arranged in the rectangular array; hexagonal and arranged in a hexagonal array, and the like. Moreover, while  FIG.  2 A  illustrates the rotation axis  208  extending in an oblique direction, in some implementations the rotation axis  208  may extend vertically or horizontally. 
     As can be seen in  FIG.  2 B , each micromirror  202  may be connected to the substrate  204  by a yoke  214 , which is rotatably connected to the micromirror  202 . The substrate  204  includes a plurality of electrodes  216 . While only two electrodes  216  per micromirror  202  are visible in the cross-sectional view of  FIG.  2 B , each micromirror  202  may in practice include additional electrodes. While not particularly illustrated in  FIG.  2 B , the DMD  200  may further include spacer layers, support layers, hinge components to control the height or orientation of the micromirror  202 , and the like. The substrate  204  may include electronic circuitry associated with the DMD  200 , such as CMOS transistors, memory elements, and the like. 
     Depending on the particular operation and control of the electrodes  216 , the individual micromirrors  202  may be switched between an “on” position, an “off” position, and an unactuated or neutral position. If a micromirror  202  is in the on position, it is actuated to an angle of (for example) −12° (that is, rotated counterclockwise by 12° relative to the neutral position) to specularly reflect input light  206  into on-state light  218 . If a micromirror  202  is in the off position, it is actuated to an angle of (for example) +12° (that is, rotated clockwise by 12° relative to the neutral position) to specularly reflect the input light  206  into off-state light  220 . The off-state light  220  may be directed toward a light dump that absorbs the off-state light  220 . In some instances, a micromirror  202  may be unactuated and lie parallel to the substrate  204 . The particular angles illustrated in  FIGS.  2 A- 2 B  and described here are merely exemplary and not limiting. In some implementations, the on- and off-position angles may be between ±12 and ±13 degrees (inclusive), respectively. 
     In the context of  FIG.  1   , where the DMD mirrors use an angle tilt of 12° to reflect or discard light, the second light  104  is steered to the DMD chip  105  at a fixed angle of 24°. When an individual mirror is tilted at a first predetermined angle (e.g., −12°), the mirror is considered to be in the on state and redirects light toward the filter  107  and the projection optics  109 . When an individual mirror is tilted at a second predetermined angle (e.g., +12°), the mirror is considered to be in the off state and redirects light to a light dump located outside the active image area. 
     In order to ensure that the image on the screen  111  has an acceptable clarity and contrast ratio, the illumination optics may be designed and/or controlled to ensure that the angle of incidence on the DMD  105  is correct, that aperture focus is maintained, and that aperture location is maintained, regardless of the presence of the prism and fold mirror in the projection system  100 . 
     Dual Mirror Alignment Control System 
     In one exemplary implementation of the present disclosure, the above may be realized by using two mirrors located in series.  FIGS.  3 A- 3 B  illustrate exemplary optical states of a partial optical system  300  in accordance with the present disclosure. 
     In particular,  FIGS.  3 A- 3 B  illustrate an integrating rod  301 , a first light  302 , an illumination lens system  303  (which may comprise one or more individual lenses), a second light  304 , a first mirror  305 , a third light  306 , a second mirror  307 , a fourth light  308 , a DMD  309 , a fifth light  310 , an aperture  311 , and a sixth light  312 . Both the first mirror  305  and the second mirror  307  are configured for angle adjustment. Because the first mirror  305  is located optically upstream (and thus farther from the DMD) compared to the second mirror  307 , when the first mirror  305  changes its angle the location of the third light  306  on the second mirror  307  moves. In this manner, the first mirror  305  is configured to provide mostly translation (i.e., an effective translation function) and the second mirror  307  is configured to provide mostly angle adjustment. For explanation purposes, the partial optical system  300  in  FIGS.  3 A- 3 B  is illustrated in an orientation where the first light  302  travels generally horizontally. Various elements illustrated in  FIGS.  3 A- 3 B  may correspond to various elements (or parts of various elements) illustrated in  FIG.  1   . 
     In some examples, the integrating rod  301  may be a component of the light source  101  which receives light from a light emitting element of the light source  101  and outputs light, such that the first light  302  corresponds to the first light  102 . In other examples, the integrating rod  301  may be a component of the illumination optics  103 , such that the integrating rod  301  receives the first light  102  and integrates it to form the first light  302 . In some examples, the illumination lens system  303 , the first mirror  305 , and the second mirror  307  are components of the illumination optics  103 , such that the fourth light  308  corresponds to the second light  104 . The first mirror  305  and/or the second mirror  307  may be formed of or coated with any highly reflective material, such as aluminum or silver, to thereby specularly reflect light. 
     The DMD  309  may correspond to the DMD  105 . For ease of explanation, the DMD  309  is illustrated as a flat surface; however, in practice the DMD  309  includes a plurality of individual reflective elements that may or may not be oriented along the same plane. In this manner, the DMD  309  may have a structure as illustrated in  FIGS.  2 A- 2 B  so as to selectively reflect and direct the fourth light  308  (i.e., the second light  104 ) depending on whether individual reflective components of the DMD  309  are in the on position, the off position, or the neutral position. Thus, the fifth light  310  may correspond to the third light  106 . In some examples, the aperture  311  may be a component of the filter  107  thereby to provide filtered illumination to the projection optics, which are not illustrated in  FIGS.  3 A- 3 B . In order to provide an appropriate contrast ratio and image clarity, the fifth light  310  should be centered on the aperture  311 . 
     In the state illustrated in  FIG.  3 A , the surface of the DMD  309  is oriented at an angle of 12.5° (measured from the vertical). In order to ensure that the fifth light  310  is centered on the aperture  311 , then, the first mirror  305  and the second mirror  307  are each oriented at an angle of 45°. The first light  302  travels along a horizontal optical axis from the integrating rod  301  to the illumination lens system  303 . In practice, the first light  302  expands as it travels, such that it subtends a non-zero solid angle at a surface of the illumination lens system  303 . The illumination lens system  303  is configured to image the first light  302  onto the DMD  309 , such that the second light  304  is focused on a virtual point that is the same optical distance from an exit of the illumination lens system  303  as the DMD  309 . In other words, the focus of the illumination lens system  303  is located at a distance substantially equal to the sum of the optical path distances of the second light  304 , the third light  306 , and the fourth light  308 . 
     The second light  304  is specularly reflected by the first mirror  305 , such that the third light  306  travels vertically toward the second mirror  307 . The third light  306  is specularly reflected by the second mirror  307 , such that the fourth light  308  travels horizontally toward the DMD  309 , where it is reflected as the fifth light  310  toward the center of the aperture  311 . 
     In practice, however, any deviation in the angle of orientation of the DMD  309  will result in a shift in the point of incidence of the fifth light  310  on the aperture  311 . This shift may be counteracted by adjusting the first mirror  305  and the second mirror  307 .  FIG.  3 B  illustrates such a countermeasure. 
     In the state illustrated in  FIG.  3 B , the surface of the DMD  309  is oriented at an angle of 10.5° (measured from the vertical), which is a 2° difference from the state illustrated in  FIG.  3 A . This angle difference is provided for ease of explanation in the visualization; in practical implementations, manufacturing and other tolerances in the DMD  309  may result in angle differences on the order of 0.5° or less. In order to accommodate a change in the orientation of the DMD  309 , the input angle of the fourth light  308  to the DMD  309  may be changed. This may be effected by adjusting the first mirror  305  and the second mirror  307  appropriately. 
     The adjustments are such that the first mirror  305  is tilted to move the beam to the left. In the particular example illustrated in  FIG.  3 B , the first mirror  305  is provided with a 0.5° counterclockwise tilt adjustment relative to the position in  FIG.  3 A . The second mirror  307  is tilted to move the beam up, which corresponds to a 1.5° counterclockwise tilt adjustment relative to the position in  FIG.  3 A . Together, these tilt adjustments accommodate for the orientation deviation in the DMD  309 , such that the fifth light  310  remains centered on the aperture  310 . The first mirror  305  and the second mirror  307  may be actuated by, for example, servo motors. 
     The adjustments to the first mirror  305  and the second mirror  307  may be made during a calibration of the projection system  100 . The calibration may occur in real-time (e.g., after installation of the projection system  100  and before or during image projection) or during manufacture. 
     Dual Mirror Alignment Method 
       FIG.  4    illustrates an exemplary alignment method, which may be performed during the calibration of the partial optical system  300  illustrated in  FIGS.  3 A- 3 B . The alignment method of  FIG.  4    may be performed in an automated manner; for example, through a computer program as will be described in more detail below. 
     At operation  401 , the alignment method determines an angle of orientation, or a deviation in the angle of orientation from the expected angle, of the DMD  309 . The angle of orientation may be determined directly by, for example, physically measuring the angle of orientation of the DMD  309  in the projection system  100 . Additionally or alternatively, the angle of orientation may be determined indirectly by, for example, illuminating the DMD  309  at a known angle and measuring the output angle of reflected light. In some implementations, operation  401  may be performed in a test fixture before the DMD  309  is installed on its prism assembly. 
     At operation  402 , the alignment method calculates the appropriate amount of angle adjustments for the first mirror  305  and the second mirror  307 , based on the measured angle of orientation (or deviation) of the DMD  309 . The appropriate amount of angle adjustments may be the amount which causes the fifth light  310  to be centered on the aperture  310 . The calculations of operation  402  may be performed through the use of a computer program that receives a single input (the angle of orientation of the DMD  309 , or the angle of orientation of the DMD  309  relative to the expected angle) and outputs angles of orientation for the first mirror  305  and the second mirror  307 . An exemplary calculation process, which takes as an input the difference between the angle of orientation of the DMD  309  and the expected angle (“dmddeltheta”), as depicted in Table 1 in a MATLAB-like pseudocode format to perform ray tracing. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 dmddeltheta = −0.5:0.1:0.5; %degrees 
               
               
                 dmdmd = 100; %distance from mirror to DMD (dmd mirror distance) 
               
               
                 mirrortheta = 45; %degrees for nominal 0 degree DMD delta angle, near mirror 
               
               
                 m2theta = 45; %degrees for nominal 0 degree DMD delta angle, far mirror 
               
               
                 mrad = mirrortheta*pi/180; 
               
               
                 mmd = 200; %distance between two mirrors in mm 
               
               
                 %calculate interception and distances on mirror 
               
               
                 dfm = dmdmd*sin(dmddeltheta*pi/180); 
               
               
                 %use AAS and law of sines to determine location on mirror 
               
               
                 Ctheta = 90 + dmddeltheta; %mirror triangle angle C 
               
               
                 Atheta = 90 − mirrortheta; %mirror triangle angle A at near mirror loc 
               
               
                 Btheta = 180 − Ctheta − Atheta; %mirror triangle B at far mirror loc 
               
               
                 Crad = Ctheta*pi/180; 
               
               
                 Brad = Btheta*pi/180; 
               
               
                 Arad = Atheta*pi/180; 
               
               
                 B = dfm; 
               
               
                 C = B.*sin(Crad)./sin(Brad); 
               
               
                 A = B.*sin(Arad)./sin(Brad); %delta distance on ray path 
               
               
                 mpointx = −C.*cos(mrad); %x location from center of mirror 
               
               
                 mpointy = −C.*sin(mrad); %y location from center of mirror 
               
               
                 %Use xy location to calculate required angle tilt. 
               
               
                 mmd2 = sqrt(mpointx.{circumflex over ( )}2 + (mmd + mpointy).{circumflex over ( )}2); %ray distance between mirrors 
               
               
                 mrad2del = atan(mpointx./(mmd + mpointy)); %delta angle from mirror to mirror 
               
               
                 mtheta2del = 0.5*mrad2del*180/pi; %required mirror delta angle in degrees 
               
               
                 m2thetanew = m2theta − mtheta2del; 
               
               
                 mirrortheta2 = mirrortheta − mtheta2del + dmddeltheta/2; 
               
               
                 %print out to console 
               
               
                 farmirrortheta = m2thetanew 
               
               
                 nearmirrortheta = mirrortheta2 
               
               
                 %ray distance minus nominal ray distance = focus point change 
               
               
                 deltafocus = (A + mmd2 + dmdmd) − dmdmd − mmd 
               
               
                   
               
            
           
         
       
     
     The calculations of Table 1 output the adjusted angle of orientation of the first mirror  305  (“farmirrortheta”), the adjusted angle of orientation of the second mirror  307  (“nearmirrortheta), and the change in the focus point (“deltafocus”). The change in the focus point may result in some degree of defocus; however, depending on the f-number of the projection system  100 , the change in the focus point may not be detectable. The input and outputs of the calculations of Table 1 are depicted in  FIG.  5 A . Moreover,  FIG.  5 B  illustrates the quantities farmirrortheta ( 501 ) and nearmirrortheta ( 502 ) as a function of dmdeltheta. While  FIGS.  5 A- 5 B  illustrate an example in which the magnitude of farmirrortheta is between zero and 0.1267 degrees and the magnitude of nearmirrortheta is between zero and 0.3737 degrees, the present disclosure is not so limited. In some examples (and depending on the relative locations of the first mirror  305  and the second mirror  307 ), the magnitude of farmirrortheta may be between zero and 0.2 degrees and the magnitude of nearmirrortheta may be between zero and 0.6 degrees. 
     As can be seen from  FIG.  5 A , any changes to the focus point of the system are small (2 μm or less). Shifts in the focus point may not become apparent until the change exceeds ˜20 μm depending on the system parameters, and generally are more apparent for projection systems having a small f-number. In some implementations, the projection system  100  has an f-number of f15 or higher. In such implementations, the effects on the focal point of the system  100  are not detectable. If, however, the projection system  100  has a very small f-number, in one example at least one of the first mirror  305  or the second mirror  307  should translate in addition to its rotation. In another example, the position of the illumination lens system  303  along the optical axis of the first light  302  may be adjusted to maintain the focus. 
     The calculations of operation  402  may be carried out at a time of calibration, or may be performed beforehand and stored in a lookup table associated with the projection system  100 . In such an implementation, the calibration method may calculate the appropriate mirror angle adjustment by referencing the lookup table instead of by performing the operations illustrated in Table 1. 
     After the above calculations of operation  402 , the alignment method actuates the mirrors at operation  403  to impart the calculated orientation thereon. This actuation may be implemented using a stepper motor, servo motor, or other appropriate adjustment mechanism. In some examples, the actuation is performed under the control of the controller  112  of  FIG.  1   . In other examples, the actuation is performed under manual control. 
     Mechanical Pivot Alignment Control System 
     While  FIGS.  3 A- 5 B  illustrate a dual mirror implementation of the projection system  100 , the present disclosure is not so limited. In another exemplary implementation of the present disclosure, the above may be realized by using a single mirror and by adjusting both the angle of the mirror and its position. 
     In such any implementation, changes to the position of the mirror will result in changes to the focus of the aperture. As such, the illumination optics  103  should be refocused for each angle adjustment. However, the focus adjustment also results in small changes to the appropriate position of the mirror, such that multiple adjustments may be implemented to achieve the proper combination of focus, position, and angle. 
       FIG.  6    illustrates a partial optical system  600  in accordance with the present disclosure. In particular,  FIG.  6    illustrates an illumination lens system  601  (which may comprise one or more individual lenses), a first light  602 , a mirror  603 , a second light  604 , a DMD  605 , a third light  606 , a virtual light path  607 , and a virtual pivot point  608 . For explanation purposes, the partial optical system  600  in  FIG.  6    is illustrated in an orientation where the first light  602  travels generally vertically. Various elements illustrated in  FIG.  6    may correspond to various elements (or parts of various elements) illustrated in  FIG.  1   . 
     In some components, the illumination lens system  601  may be a component of the illumination optics  103  which receives either the first light  102  or intermediate light from upstream optical components within the illumination optics  103 . The illumination lens system  601  conveys the received light as the first light  602  to the mirror  603 , which may be formed of or coated with any highly reflective material, such as aluminum or silver, to thereby specularly reflect the first light  602  as the second light  604 . 
     The DMD  605  may correspond to the DMD  105 . For ease of explanation, the DMD  605  is illustrated as a flat surface; however, in practice the DMD  605  includes a plurality of individual reflective elements that may or may not be oriented along the same plane. In this manner, the DMD  605  may have a structure as illustrated in  FIGS.  2 A- 2 B  so as to selectively reflect and direct the second light  604  depending on whether individual reflective components of the DMD  605  are in the on position, the off position, or the neutral position. Thus, the third light  606  may correspond to the third light  106 , and may be directed to and centered on downstream components so as to provide an appropriate contrast ratio and image clarity. 
     In a comparative example, if no mirror were present and thus an optical path from the illumination optics goes directly from the illumination aperture to the DMD at the correct angle and with the correct focus, and the system had a configuration in which the components had a single axis pivot point located at the center of a surface of the DMD, then the angle of the illumination could be adjusted without affecting the position or focus of the aperture image. However, this comparative example is not practical in a configuration including mirrors (such as a fold mirror or total internal reflection in a prism). Therefore, to recreate the effects of such a pivot,  FIG.  6    further illustrates a virtual pivot simulation. 
     In  FIG.  6   , because the individual reflective elements of the DMD  605  pivot on a single axis and because a sufficient contrast ratio and projected image clarity relies on a correction of different mirror pivot angles, then the optical path of light incident on the DMD  605  similarly may only pivot about the same single axis. To illustrate this,  FIG.  6    further shows a virtual light path  607  and a virtual pivot point  608 . The virtual light path  607  traces the trajectory of the first light  602  if the mirror  603  were not present. The virtual pivot point  608  represents, but is not physically located on, the DMD  605  surface. While  FIG.  6    illustrates an example in which only one reflective element exists in the optical path, the virtual pivot point  608  may be found even in systems with multiple reflective elements (e.g., mirrors, total internal reflection prisms, and so on) by unfolding all of the reflections (e.g., by determining and utilizing multiple virtual light paths). In any case, if the source of the first light  602  (e.g., the illumination lens system  601 ) is rotated physically about the virtual pivot point, then the location and focus do not change when the angle of a reflective surface of the DMD  605  is adjusted. Mechanical linkages may be used to effect this rotation. 
       FIG.  7    illustrates one exemplary mechanical linkage configuration. In  FIG.  7    (and subsequent figures), filled circles represent connector hinges that have a fixed location, which may be referred to as hinges that are “tied to ground.” Empty circles represent connector hinges which are free to translate. Thus,  FIG.  7    illustrates a first fixed connector hinge  701 , a second fixed connector hinge  702 , a first connector  711  having a first end connected to the first fixed connector hinge  701 , a second connector  712  having a first end connected to the second fixed connector hinge  702 , a first free hinge  721  connected to a second end of the first connector  711 , a second free hinge  722  connected to a second end of the second connector  712 , a carrier body  731 , and a pivot point  741  which may be coincident with a third free hinge. The first connector  711 , the second connector  712 , and the carrier body  731  are rigid bodies. In the left portion of  FIG.  7   , the carrier body  731  is in an unadjusted configuration. In such a configuration, the first connector  711  and the second connector  722  are pointed at the pivot point location. In the right portion of  FIG.  7   , the carrier body  731  has been given a counterclockwise rotation to provide the desired rotation and accommodate the orientation angle of the DMD  605 . 
     The location of the pivot point  741  moves by only a small amount as a result of the counterclockwise rotation. The amount of change in the focus position depends on the respective lengths of the first connector  711  and the second connector  722 , and the amount of change in the location of the pivot point depends on the particular geometry of the linkage implementation. 
       FIG.  8    illustrates another exemplary linkage  800 .  FIG.  8    illustrates a first fixed connector hinge  801 , a second fixed connector hinge  802 , a first connector  811  having a first end connected to the first fixed connector hinge  801 , a second connector  812  having a first end connected to the second fixed connector hinge  802 , a first free hinge  821  connected to a second end of the first connector  811 , a second free hinge  822  connected to a second end of the second connector  712 , a carrier body  731 , and a pivot point  841 . The first connector  811 , the second connector  812 , and the carrier body  831  are rigid bodies. The carrier body  831  has a generally coffin-like shape; however, because the pivot point  841  should not be a part of the optical surface, in practice the uppermost portion of the carrier body  831  may be cut off (represented by the dotted line in  FIG.  8   ). In one particular example, the optical path of a system including the exemplary linkage configuration of  FIG.  8    has an optical path of about 500 mm, which is near the minimum practical length for D-Cinema DMD devices which are about 35 mm diagonal. 
     The linkage  800  of  FIG.  8    is driven by a combination of a drive mechanism  851 , a drive hinge  852 , and a drive connector  853  which extends between the drive hinge  852  and a lower vertex of the carrier body  831 . The action of the drive mechanism, conveyed to the carrier body  831  via the drive connector  853 , provides the translation of the carrier body  831 . Compared to the linkage illustrated in  FIG.  7   , the linkage  800  illustrated in  FIG.  8    may result in an even smaller amount of change in the location of the pivot point  841 . In one particular example, the rotation applied to accommodate for an angle shift of the optical path from 0 to 0.5° (e.g., as a result of a change in the angle of orientation of a reflective element of the DMD) may result in a translation of the pivot point of 0.06 μm. Such a translation would be undetectable. The position shift in the focus may be larger (e.g., ˜13 μm), which is likely to be undetectable with optical systems having a f-number of f20 or f15. In any event, the nature and architecture of the DMD may themselves mitigate the effects of a focus change or confine the effects to the edges. 
     In practical implementations, the effects of play in the bearings (e.g., the bearings in various ones of the hinges illustrated in  FIGS.  7 - 8   ) may themselves affect the position of the virtual pivot point. This, however, may be alleviated by modifying the geometry of the linkage such that the linkage is more tolerant of the bearing play.  FIGS.  9 A- 9 B  illustrate one such example of such a geometry for a linkage  900 . 
       FIGS.  9 A-B  illustrate a first fixed connector hinge  901 , a second fixed connector hinge  902 , a first connector  911  having a first end connected to the first fixed connector hinge  901 , a second connector  912  having a first end connected to the second fixed connector hinge  902 , a first free hinge  921  connected to a second end of the first connector  911 , a second free hinge  922  connected to a second end of the second connector  912 , a carrier body  931 , and a pivot point  941 . The first connector  911 , the second connector  912 , and the carrier body  931  are rigid bodies. The carrier body  931  has a generally coffin-like shape; however, because the pivot point  941  should not be a part of the optical surface, in practice the uppermost portion of the carrier body  931  may be cut off (represented by the dotted line in  FIGS.  9 A-B ).  FIG.  9 A  illustrates the linkage  900  in an unrotated position, and  FIG.  9 B  illustrates the linkage  900  in a rotated position. 
     The linkage  900  is driven by a combination of a drive mechanism  951 , a drive hinge  952 , and a drive connector  953  which extends between the drive hinge  952  and a lower vertex of the carrier body  931 . The action of the drive mechanism, conveyed to the carrier body  931  via the drive connector  953 , provides the translation of the carrier body  931 . 
     Compared to the linkage  800  of  FIG.  8   , the angle between the first and second connectors and (in  FIGS.  9 A- 9 B , the angle between the first connector  911  and the second connector  912 ) is larger. The increase in angle increases the tolerance to bearing play of the linkage  900  up to an angle of 45°, which is the particular angle between the first connector  911  and the second connector  912  illustrated in  FIGS.  9 A- 9 B . However, this change may result in slightly greater focal changes (e.g., 16 μm vs. 13 μm). In the event that this increase causes the change in focus to become noticeable, the lengths of the first connector  911  and the second connector  912  may be increased to compensate while the angle therebetween is maintained. The amount of increase in the lengths of the first connector  911  and the second connector  912  may be limited by the thermal expansion coefficient of the material of the first connector  911  and the second connector  912 . 
     To further reduce the amount of bearing play in the linkage  900 , it is possible to apply a preload to the bearings. In addition to an axial preload (e.g., with two bearings per pivot point), it is possible to add a spring that is attached to the bottom surface of the carrier body  931  at one end and attached to a fixed point (e.g., ground) at the other end. In some examples, the carrier body  931  is provided with a slot to allow a bolt (or other fastening mechanism) to lock the linkage  900  in place after adjustment. In some examples, the slot may be provided between the first connector  921  and the second connector  922  in a straight line. 
     In some implementations, the optical system  100  includes a linkage that has a coffin-like shape similar to the shape illustrated in  FIGS.  8  and  9 A- 9 B  with an angle between the first and second connectors of between 10° and 40° and a length sufficient to maintain the required focus. In one particular example, the angle is 30° and the length is greater than or equal to 500 mm. 
     Regardless of the particular linkage architecture used, various portions of the illumination optics  103 , including but not limited to those elements illustrated in  FIG.  6   , may be mounted to the carrier body.  FIG.  10    illustrates one such example of such a configuration using the linkage  900  of  FIGS.  9 A- 9 B . In  FIG.  10   , a partial optical system  1000  includes the linkage illustrated in  FIG.  9   , an integrating rod  1001 , and an illumination lens system  1002  are mounted on the carrier body  931 . In some examples, the integrating rod  1001  may be a component of the light source  101  which receives light from a light emitting element of the light source  101 ; however, in other examples, the integrating rod  1001  may be a component of the illumination optics  103 . Other methods to create a uniform illumination such as a fly&#39;s eye assembly may be used in place of the integrating rod. 
     The adjustments to the linkage to compensate for deviations in the angle of the DMD  605  may be made during a calibration of the projection system  100 . The calibration may occur in real-time (e.g., after installation of the projection system  100  and before or during image projection) or during manufacture. 
     Mechanical Pivot Alignment Method 
       FIG.  11    illustrates an exemplary alignment method, which may be performed during the calibration of the partial optical system  1000  illustrated in  FIG.  10   . The alignment method of  FIG.  11    may be performed in part or in whole as an automated procedure. 
     At operation  1101 , the alignment determines an angle of orientation of the DMD  605 . The angle of orientation may be determined directly by, for example, physically measuring the angle of orientation of the DMD  605  in the projection system  100 . Additionally or alternatively, the angle of orientation may be determined indirectly by, for example, illuminating the DMD  605  at a known angle and measuring the output angle of reflected light. In some implementations, operation  1101  may be performed in a test fixture before the DMD  605  is installed on its prism assembly. 
     At operation  1102 , the alignment method calculates the appropriate linkage adjustment for the linkage  900 , based on the measured angle of orientation of the DMD  605 . Operation  1102  may include first calculating an appropriate rotational and/or translational adjustment to be made to the carrier body  931 , and then determining the corresponding linkage adjustment of the linkage  900  that would cause such a rotational and/or translational adjustment. 
     The calculations of operation  1102  may be carried out at a time of calibration, or may be performed beforehand and stored in a lookup table associated with the projection system  100 . In such an implementation, the calibration method may calculate the appropriate rotational and/or translational adjustment by referencing the lookup table instead of by performing calculations at the time of calibration. In other examples, the calibration method may calculate the appropriate rotational and/or translational adjustment at the time of calibration, and may use a lookup table to determine the corresponding linkage adjustment. 
     After the calculations of operation  1102 , the alignment method drives the linkage at operation  1103  to impart the calculated orientation thereon. This actuation may be implemented by using a stepper motor, servo motor, or other appropriate adjustment mechanism as the drive mechanism  951 . The drive mechanism  951  may be controlled by the controller  112  illustrated in  FIG.  1   . Operation  1103  further includes securing the linkage after it has been driven to the appropriate orientation. In some examples, the securing and/or adjustment of the linkage may be performed manually. 
     Effects 
     The above projection systems and calibration methods may provide for a configuration having illumination optics which are able to adjust and maintain the proper illumination angle, maintain focus of the aperture, maintain the location of the aperture, and perform all this in an architecture which uses a prism and fold mirror. 
     Systems, methods, and devices in accordance with the present disclosure may take any one or more of the following configurations. 
     (1) A projection system, comprising: a light source configured to emit a light in response to an image data; an illumination optical system configured to steer the light, the illumination optical system including a first mirror and a second mirror; a digital micromirror device including a plurality of micromirrors, wherein a respective micromirror is configured to reflect the steered light to a filter as on-state light in a case where the respective micromirror is in an on position and to reflect the steered light to a light dump as off-state light in a case where the respective micromirror is in an off position; and a controller configured to: determine a deviation between an actual angle of orientation of the digital micromirror device and an expected angle of orientation of the digital micromirror device, calculate a first amount of angle adjustment corresponding to the first mirror and a second amount of angle adjustment corresponding to the second mirror, and actuate the first mirror according to the first amount and the second mirror according to the second amount, thereby to maintain a position and a focus of the steered light on the digital micromirror device and to cause the on-state light to be incident within a predetermined distance from a center of the filter. 
     (2) The projection system according to (1), wherein the first mirror is located optically upstream from the second mirror. 
     (3) The projection system according to (2), wherein the first amount is smaller than the second amount. 
     (4) The projection system according to any one of (1) to (3), wherein the first amount and the second amount are proportional to the deviation. 
     (5) The projection system according to any one of (1) to (4), further comprising the filter, wherein the filter includes an aperture. 
     (6) The projection system according to any one of (1) to (5), wherein the first amount is between zero and 0.2 degrees. 
     (7) The projection system according to any one of (1) to (6), wherein the second amount is between zero and 0.6 degrees. 
     (8) The projection system according to any one of (1) to (7), wherein an f-number of the projection system is f15 or higher. 
     (9) The projection system according to any one of (1) to (8), wherein the position of the steered light on the digital micromirror device is maintained within 20 μm. 
     (10) The projector system according to any one of (1) to (9), wherein the first amount or the second amount includes a rotational displacement and a translational displacement. 
     (11) A method of calibrating a projection system including a light source configured to emit a light in response to an image data, an illumination optical system configured to steer the light, the illumination optical system including a first mirror and a second mirror, and a digital micromirror device including a plurality of micromirrors respectively configured to reflect the steered light to a filter as on-state light in a case where the respective micromirror is in an on position and to reflect the steered light to a light dump as off-state light in a case where the respective micromirror is in an off position, the method comprising: determining a deviation between an actual angle of orientation of the digital micromirror device and an expected angle of orientation of the digital micromirror device, calculating a first amount of angle adjustment corresponding to the first mirror and a second amount of angle adjustment corresponding to the second mirror, and actuating the first mirror according to the first amount and the second mirror according to the second amount, thereby to maintain a position and a focus of the steered light on the digital micromirror device and to cause the on-state light to be incident within a predetermined distance from a center of the filter. 
     (12) The method according to (11), wherein determining the deviation includes directly measuring the angle of orientation of the digital micromirror device. 
     (13) The method according to (11) or (12), wherein determining the deviation includes illuminating the digital micromirror device with the light from the light source, and measuring the output angle of light reflected from the digital micromirror device. 
     (14) The method according to any one of (11) to (13), wherein calculating the first amount and the second amount includes calculating ray traces based on an amount of the deviation. 
     (15) The method according to any one of (11) to (14), wherein calculating the first amount and the second amount includes using a lookup table based on an amount of the deviation. 
     (16) The method according to any one of (11) to (15), wherein the first amount and the second amount are proportional to the deviation. 
     (17) The method according to any one of (11) to (16), wherein the expected angle of orientation of the digital micromirror device is a first predetermined angle in the on position, and is a second predetermined angle in the off position. 
     (18) The method according to any one of (11) to (17), wherein the position of the steered light on the digital micromirror device is maintained within 20 μm. 
     (19) The method according to any one of (11) to (18), wherein actuating the first mirror includes rotating the first mirror and translating the first mirror, or actuating the second mirror includes rotating the second mirror and translating the second mirror. 
     (20) A non-transitory computer-readable medium storing instructions that, when executed by a processor of a projection system, cause the projection system to perform operations comprising the method according to any one of (11) to (19). 
     (21) A projection system, comprising: a light source configured to emit a light in response to an image data; an illumination optical system configured to steer the light, the illumination optical system including a mirror and a linkage; a digital micromirror device including a plurality of micromirrors, wherein a respective micromirror is configured to reflect the steered light to a filter as on-state light in a case where the respective micromirror is in an on position and to reflect the steered light to a light dump as off-state in a case where the respective micromirror is in an off position; a filter including an aperture; and a controller configured to: determine a deviation between an actual angle of orientation of the digital micromirror device and an expected angle of orientation of the digital micromirror device, calculate an adjustment amount of the linkage, and actuate the linkage according to the adjustment amount, thereby to maintain a position and a focus of the steered light on the digital micromirror device and to cause the reflected light to be incident within a predetermined distance from a center of the aperture. 
     (22) The projection system according to (21), wherein the controller is configured to actuate the linkage so as to pivot about a pivot point. 
     (23) The projection system according to (22), wherein the pivot point corresponds to a virtual location of the digital micromirror device in the absence of reflection. 
     (24) The projection system according to any one of (21) to (23), wherein the linkage includes a carrier body, a first connector, and a second connector. 
     (25) The projection system according to (24), wherein the first connector includes a first end attached to a first fixed hinge and a second end attached to a first free hinge, wherein the first free hinge is located on the carrier body. 
     (26) The projection system according to (24) or (25), wherein the second connector includes a first end attached to a second fixed hinge and a second end attached to a second free hinge, wherein the second free hinge is located on the carrier body. 
     (27) The projection system according to any one of (24) to (26), wherein an angle formed by the first connector and the second connector is between 10° and 40°. 
     (28) The projection system according to any one of (24) to (27), wherein an angle formed by the first connector and the second connector is 30°. 
     (29) The projection system according to any one of (24) to (27), wherein respective lengths of the first connector and the second connector are greater than or equal to 500 mm. 
     (30) The projection system according to any one of (24) to (29), wherein the linkage further includes a drive mechanism configured to actuate the carrier body. 
     (31) The projection system according to any one of (24) to (30), wherein an integrating rod is mounted on the carrier body. 
     (32) The projection system according to any one of (24) to (31), wherein the carrier body has a coffin-like shape. 
     (33) The projection system according to any one of (21) to (32), wherein the expected angle of orientation of the digital micromirror device is a first predetermined angle in the on position, and is a second predetermined angle in the off position. 
     (34) A method of calibrating a projection system including a light source configured to emit a light in response to an image data, an illumination optical system configured to steer the light, the illumination optical system including a mirror and a linkage, a digital micromirror device including a plurality of micromirrors respectively configured to reflect the steered light to a filter as on-state light in a case where the respective micromirror is in an on position and to reflect the steered light to a light dump as off-state light in a case where the respective micromirror is in an off position, and a filter including an aperture, the method comprising: determining a deviation between an actual angle of orientation of the digital micromirror device and an expected angle of orientation of the digital micromirror device, calculating an adjustment amount of the linkage, and actuating the linkage according to the adjustment amount, thereby to maintain a position and a focus of the steered light on the digital micromirror device and to cause the reflected light to be incident within a predetermined distance from a center of the aperture. 
     (35) The method according to (34), further comprising securing the linkage in an orientation, after the actuating. 
     (36) The method according to (34) or (35), wherein actuating the linkage includes pivoting the linkage about a pivot point. 
     (37) The method according to (36), wherein the pivot point corresponds to a virtual location of the digital micromirror device in the absence of reflection. 
     (38) The method according to any one of (34) to (37), wherein actuating the linkage includes actuating the carrier body via a drive mechanism. 
     (39) The method according to any one of (34) to (38), wherein calculating the adjustment amount includes calculating a rotational, translational, or rotational and translational adjustment to be made to a carrier body of the linkage, and determining a value of the adjustment amount corresponding to the rotational, translational, or rotational and translational adjustment. 
     (40) A non-transitory computer-readable medium storing instructions that, when executed by a processor of a projection system, cause the projection system to perform operations comprising the method according to any one of (34) to (39). 
     With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claims. 
     Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technologies discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the application is capable of modification and variation. 
     All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary. 
     The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments incorporate more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.