Abstract:
A subsystem is disclosed providing a steerable-beam light source. An array of micromechanical reflectors may be disposed to selectively direct portions of light from a light source to selected targets in a scene, such as for providing composed illumination for still or video photography. The array of reflectors may be continuously steerable, thereby achieving more than the mere inefficient patterning of illumination light available from prior art projection approaches, but instead efficiently redirecting light to the desired regions of the scene. The subsystem may be sufficiently compact so as to permit integration with a compact camera into a cellular telephone, a tablet computer, a laptop computer, a digital still-image camera, a digital video-image camera, and so on. The array may be operated in conjunction with a camera controller to selectively illuminate one or more targets of focus or zoom, omit illumination of undesirable image regions, etc.

Description:
BACKGROUND 
       [0001]    The present disclosure is related to illumination sources for portable devices, and more particularly to sources with directable illumination fields. 
         [0002]    Modern electronics design and manufacturing has made it possible to provide compact cameras that autonomously handle all aspects of settings and adjustments required to capture properly exposed, properly framed, and properly focused images. Compact digital cameras, point-and-shoot digital cameras, and cell phone and tablet computer cameras (collectively referred to herein as compact cameras) are examples of devices that provide such autonomous settings control. More specifically, such cameras are able to autonomously set aperture opening size (e.g., f-number), aperture opening duration, account for sensor gain (roughly equivalent to ISO film sensitivity), and so on. Such cameras may also identify an image target object in a field of view, and set focus for that target. In general, compact cameras are often intended to provide simple operation for rapid, spontaneous picture taking, and are expected to perform in a wide range of photographic situations, while increases in processing power and software enable the cameras to “understand” more of a scene. 
         [0003]    Among the set of situations compact cameras are often designed to perform in are low-light settings, for example indoors, in evening settings, and so on. Usage patterns are predominantly handheld (no tripod) and show an emphasis on snapshots of people. Even with highly sensitive electronic sensors taking the place of film, such settings necessitate using a supplemental light source (referred to as a flash herein) for example to freeze a target and avoid motion blur, to provide desired contrast, and so on. Most compact cameras therefore contain or are provided with a flash unit. 
         [0004]    However, to be of use in the widest set of situations (including indoor settings), compact cameras are often designed to provide a relatively wide field of view (with consequent short effective focal length). To accommodate the relatively wide field of view in low-light settings, flash units (often an LED source and today some plastic optics to define its light distribution) for compact cameras are typically designed to illuminate a corresponding wide field of view (wide view angle). Consequently, compact camera flash units illuminates the entire wide angle scene, regardless of the target of the exposure, and even if the camera is zoomed in for a telephoto image. This not only wastes precious energy on generating sufficient light to illuminate the widest possible field of view, but also often results in lower light levels at specific portions of the image frame as well as over-lighting of non-target elements of the image frame. As an example, if a shot is taken at 3× zoom, more than 85% of the flash output will typically go unused. A more efficient use of a light source in compact cameras would provide many benefits, including improved illumination of image target, reduced power consumption, faster image repetition rates, and so on. 
         [0005]    While typical compact camera flash sources are fixed in position, with fixed associated optics, some examples exist of flash source with lenses that move in tandem with motion of mechanically controlled zoom and focus imaging optics. In certain applications, these lenses “focus” the output of the flash within the field of the flash exposure. In other examples, an evaluator evaluates a scene to determine an intended image target of the photograph. A lens is then mechanically moved to direct the output of a flash element to the intended image target. Alternatively, the flash element may be tilted relative to the lens to achieve a similar objective. In each of these cases, the “compactness” of the flash system is compromised by the introduction of one or more moveable lenses and lens movement control mechanisms. And only gross position control of the light source (i.e., only control over the entire output of the source) is provided. 
       SUMMARY 
       [0006]    Accordingly, the present disclosure is directed to systems and processes for providing controllable, steerable flash lighting for compact cameras and other devices requiring object illumination. In certain embodiments of the present disclosure, a light source is directed to compact steerable reflective or transmissive array, which can aim individual light beams, originating from a single light source, to or away from desired elements in a scene to be photographed. The steerable reflective or transmissive array may comprise, in certain implementations, a micro-electro-mechanical (MEMS) mirror or lens array structure of a type providing individual control over the orientations and/or positions of the array element, thereby providing individual control over the light beams reflected or transmitted by the respective array elements. 
         [0007]    According to one aspect of the disclosure a subsystem is disclosed providing a steerable-beam light source. The light source comprises an optically transparent substrate, a light source disposed for directing light generated thereby into the optically transparent substrate, and an array comprising a plurality of independently addressable optical elements disposed such that light from the light source received through the transparent substrate is incident upon the array, each of the independently addressable optical elements being capable of independently redirecting a portion of the light from the light source into a desired light path. 
         [0008]    According to another aspect of the present disclosure, the optical elements may be reflective, or with the addition of a reflective structure, each of the optical elements may be transmissive (e.g., lenses). 
         [0009]    According to yet another aspect of the present disclosure, the array may be operated in conjunction with a camera controller to selectively concentrate the illumination on one or more targets identified by the camera, or inside the field of view at the camera&#39;s current zoom setting. 
         [0010]    The array comprises a plurality of rows, and each row comprises a plurality of optical elements. A first of the rows has a first number of optical elements and a second of the rows has a second number of optical elements. While in certain embodiments a regular array can be used, according to another aspect of the present disclosure, the first number and the second number are different. According to another aspect of the present disclosure, the dimensions of optical elements in the first row are different than the dimensions of the optical elements in the second row. According to a further aspect of the present disclosure, the shapes of optical elements in the first row are different than the shapes of the optical elements in the second row. According to a still further aspect of the present disclosure, the array itself has other than a rectangular array shape. 
         [0011]    The above is a brief summary of a number of unique aspects, features, and advantages of the present disclosure. The above summary is provided to introduce the context and certain concepts relevant to the full description that follows. However, this summary is not exhaustive. The above summary is not intended to be nor should it be read as an exclusive identification of aspects, features, or advantages of the claimed subject matter. Therefore, the above summary should not be read as imparting limitations to the claims nor in any other way determining the scope of said claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In the drawings appended hereto like reference numerals denote like elements between the various drawings. While illustrative, the drawings are not drawn to scale. In the drawings: 
           [0013]      FIGS. 1A ,  1 B, and  1 C are sectional views of a reflective steerable illumination structure such as may be used in a compact camera flash device and the like according to an embodiment of the present disclosure. 
           [0014]      FIGS. 2A ,  2 B, and  2 C are sectional views of a reflective steerable illumination structure such as may be used in a compact camera flash device and the like according to an alternate embodiment of the present disclosure. 
           [0015]      FIGS. 3A and 3B  are side views of a compact camera including a compact flash apparatus in first and second operating states according to an embodiment of the present disclosure. 
           [0016]      FIG. 4  is a block diagram illustrating certain elements of a compact camera according to one implementation of the present disclosure. 
           [0017]      FIG. 5A  is a perspective-view microphotograph of a MEMS mirror of a type which may form an element of a MEMS mirror array according to one implementation of the present disclosure. 
           [0018]      FIG. 5B  is a side view illustration of a MEMS mirror of the type illustrated in  FIG. 5A . 
           [0019]      FIG. 6  is a perspective-view microphotograph of a MEMS mirror array of a type that may be utilized in one implementation of the present disclosure. 
           [0020]      FIG. 7  is an illustration of mirror rotation of a MEMS mirror of a type that may be utilized in one implementation of the present disclosure. 
           [0021]      FIGS. 8A and 8B  are sectional views of a transmissive steerable illumination structure such as may be used in a compact camera flash device and the like according to an embodiment of the present disclosure. 
           [0022]      FIG. 9  is an illustration of a MEMS mirror array having non-uniform mirror-to-mirror spacing, mirror sizes, and mirror shapes according to an embodiment of the present disclosure. 
           [0023]      FIG. 10  is a non-rectangular MEMS mirror array according to an embodiment of the present disclosure. 
           [0024]      FIGS. 11A and 11B  are perspective cut-away views of a mobile device having reflective steerable illumination structure disposed there according to an embodiment of the present disclosure, including ray tracings illustrating two states of light output. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    We initially point out that description of well-known starting materials, processing techniques, components, equipment and other well-known details may merely be summarized or are omitted so as not to unnecessarily obscure the details of the present disclosure. Thus, where details are otherwise well known, we leave it to the application of the present disclosure to suggest or dictate choices relating to those details. 
         [0026]    A first implementation of the present disclosure is illustrated in  FIGS. 1A through 1C . With reference to  FIG. 1A , a steerable illumination structure  10 , such as may be used in a compact camera flash device and the like is shown. Structure  10  comprises a light source  14  such as an LED element, array of LED elements, single element bulb (e.g., xenon flash lamp), or another of a variety of known forms of light source. In certain examples, multiple different light sources may be employed. However, the LED array implementation has characteristics such as size, power consumption, flash speed, and so on that lend itself well to flash units employed in mobile devices such as telephones, and so this implementation will be described here by way of example. 
         [0027]    Disposed opposite light source  14  is a micro-electro-mechanical (MEMS) mirror array  16  of a type discussed in further detail below. Disposed proximate MEMS mirror array  16  is an actuation array  18  capable of actuating the mirrors of MEMS mirror array  16 . Actuation array  18  may actuate individual mirrors of MEMS mirror array  16  or may actuate groups of mirrors of MEMS mirror array  16 , and may be controlled by a controller  20 . In various embodiments, actuator array  18  may operate to actuate elements of array  16  by magnetic, electrostatic, thermal, piezoelectric, shape memory effect, or other form of actuation. 
         [0028]    In operation, light source  14  produces light, in one embodiment as a discrete burst or flash of light, and in another embodiment as a steady beam. Light from source  14  is incident on mirrors  16   a ,  16   b , and  16   c . While a three by three array of mirrors is shown in the view of  FIGS. 1A ,  1 B, and  1 C, the mirrors being rectilinearly aligned, it will be appreciated that the number of mirrors and arrangement thereof is relatively arbitrary, and may therefore vary in different configurations depending on design choice, application, and so on. 
         [0029]    The disposition of mirrors  16   a ,  16   b ,  16   c , and the angle α between the mirror plane and the beam path permits light from source  14  to be reflected by mirrors  16   a ,  16   b ,  16   c  toward a target image O. A frame  19  may secure light source  14  to array  16  to maintain a as a constant. The rotation angle of mirrors  16   a ,  16   b , and  16   c  are, in the present embodiment, individually adjustable in two dimensions by actuation array  18  (although they may similarly be adjustable in only one dimension, adjustable as groups, and so on). Thus, the orientation of mirrors  16   a ,  16   b ,  16   c  will determine aspects of the reflected light, such as the amount of light and where the light is directed. For example, with mirrors  16   a ,  16   b ,  16   c  aligned in a first state, the beams of light from source  14  may be effectively collimated and/or directed toward a single image target, O, essentially as shown in  FIG. 1A . Likewise, with mirrors  16   a ,  16   b ,  16   c  aligned in a second state, the beams of light from source  14  may be reflected such that only certain beams are directed to image target, O, while certain other beams are directed away from the image target O, as illustrated in  FIG. 1B . With reference to  FIG. 1C , structure  10  is shown in a view looking toward MEMS mirror array  16 . 
         [0030]    The implementation illustrated in  FIGS. 1A ,  1 B, and  1 C provide a very compact steerable light source such as a steerable flash for photography. For example, given known light sources, MEMS array structures, actuator arrays, and so on, physical dimensions for a complete steerable illumination structure may be on the order of depth (x) up to 5 mm (nominally 3 mm), height (y) up to 10 mm, and width (z) up to 10 mm. Devices at this scale are particularly well suited for integration into compact cameras, mobile telephones, tablet computers, and the like. The final dimensions of such MEMS array structures are a matter of design choice, and therefore do not form a material limitation on the scope of the present disclosure. 
         [0031]    It will be further appreciated that while certain embodiments will utilize mirror array  16  to divert a portion of the light from light source  14  to or away from an image target, such as when taking a flash photograph of the target image, the positioning of each of the mirrors comprising array  16  is continuously steerable. That is, the mirrors of array  16  do not provide a binary state of illuminating or non-illuminating, but may direct varying amounts of light from light source  14  toward (or away from) the image target. Therefore, by “continuously steerable” we mean that structure  10  may direct all light from source  14  away from the target image, direct all light from source  14  toward the target image, or direct a selectable portion of the light from source  14  toward the target image. 
         [0032]    Another implementation of the present disclosure is illustrated in  FIGS. 2A ,  2 B, and  2 C. With reference to  FIG. 2A , a steerable illumination structure  11 , such as may be used in a compact camera flash device and the like is shown. Structure  11  comprises a optical element  12  having a first surface  13  proximate which is disposed light source  14  which, as previously discussed, may be an LED element, array of LED elements, flash lamp, or any other of a variety of known forms of light source. Optical element  12  may (but need not necessarily) provide for total internal reflection (TIR) of light from light source  14  therein. While the functions described in the remainder of this paragraph are realizable with individual components, it is practical to design optical element  12  as a monolithic freeform element (e.g. produced by high quality injection molding) to serve the following purposes simultaneously: A) Collimation and shaping of the light from the light source. B) Providing a TIR surface via which the MEMS mirror array is illuminated. C) Forming the “window” to the world outside the device. D) Serving as the mechanical carrier for the subassembly and providing optional attachment and alignment features to receive the light source  14  (with or without index matching), the micromirror array  16  (with or without index matching), the actuator array  18 , electronic modules, etc. 
         [0033]    Optical element  12  has a second surface  15  proximate which is disposed MEMS mirror array  16 . Disposed proximate MEMS mirror array  16  is actuation array  18  capable of actuating the mirrors of MEMS mirror array  16 . Actuation array  18  may actuate individual mirrors of MEMS mirror array  16  or may actuate groups of mirrors of MEMS mirror array  16 , and may be controlled by controller  20 . 
         [0034]    In operation, light source  14  produces light, either as a flash or as a steady beam. Optical element  12  is optically transparent, at least at the wavelengths to be emitted by structure  11 . Accordingly, light from source  14  enters optical element  12  at surface  13 , travels through optical element  12 , and exits at surface  15 . An optional substrate  22  may be disposed between surface  15  and MEMS mirror array  16  to provide desired optical wave guiding and attenuate optical loss. If present, light travels through substrate  22  and is incident on mirrors  16   a ,  16   b , and  16   c . While a three by three array of mirrors are shown in the view of  FIGS. 2A ,  2 B, and  2 C, with rectilinearly aligned mirrors, it will be appreciated that the number of mirrors and arrangement thereof is relatively arbitrary, and may therefore vary in different configurations depending on design choice, application, and so on. 
         [0035]    The disposition of mirrors  16   a ,  16   b ,  16   c , and the angle of surface  15  relative to the plane of surface  13 , permits light from source  14  to be reflected by mirrors  16   a ,  16   b ,  16   c  back into optical element  12  toward third surface  23 , where the light may exit optical element  12 . Surface  15  and surface  23  are oriented at an angle α′ relative to one another. Due to the use of optical element  12 —and more specifically due to using the same areas of surface  23  both for supplying illuminating light via TIR and for transmitting outgoing light—α′ can be much smaller than a (implementation of  FIGS. 1A-1C , without optical element  12 ), creating a thinner form factor, desirable when compact integration is a concern. The orientation of mirrors  16   a ,  16   b ,  16   c  will determine aspects of the light exiting at surface  23 , such as the amount of light and where the light is directed. For example, with mirrors  16   a ,  16   b ,  16   c  aligned in a first state, the beams of light from source  14  may be effectively collimated and/or directed toward a single image target, O, essentially as shown in  FIG. 2A . Likewise, with mirrors  16   a ,  16   b ,  16   c  aligned in a second state, the beams of light from source  14  may be reflected such that only certain beams are directed to image target, O, while certain other beams are directed away from the image target O, as illustrated in  FIG. 2B . With reference to  FIG. 2C , structure  11  is shown in a view looking through structure  12  toward MEMS mirror array  16 . 
         [0036]    While it is not possible to provide a comprehensive list, this capability to selectively direct beams from source  14 , or in other words steer portions of light emitted by source  14 , provides the ability to:
       direct all or some of the light from source  14  to a primary image target when taking a picture, even if the primary image target is not centered in the field of view of the camera   allocate or balance illumination of multiple image targets when taking a picture   selectively avoid illuminating undesired portions of a scene being photographed (such as regions not in the image frame, reflective surfaces to prevent glare, background objects, objects very close to the camera to prevent overexposure, etc.);   “focus” illumination on one or more desired image target(s) permitting use of less energy on illumination of the image target(s);   automatically track illumination of an image target in tandem with the zoom function of a compact camera;   etc.       
 
         [0043]    Many more capabilities are provided by the methods and apparatus disclosed herein, as will be appreciated when those methods and apparatus are embodied in various implementations. While the present disclosure focuses on compact cameras as an illustrative application for implementations of the present disclosure, many other applications such as vision assistance and direction of other radiation are contemplated hereby, as will be appreciated by one skilled in the relevant art. 
         [0044]    With reference next to  FIGS. 3A and 3B , we illustrate the above in the context of a mobile (cellular) telephone  30  in which is disposed structure  10  as previously described. It will be appreciated that the present disclosure is not limited to applications in a cellphone, and that many other applications are contemplated such as a stand-alone flash, a tablet computer, a laptop computer, a digital still-image camera, a digital video-image camera, and other lighting devices, particularly where a burst of light, such as a photographic flash or special effects flash, is desired. The orientation of mirrors comprising MEMS mirror array  16  determine the direction of light exiting at a flash window  32  of telephone  30 . For example, with the mirrors of MEMS array  16  aligned in a first state, the beams of light from source  14  may be redirected so as to all effectively be directed toward image target O, as shown in  FIG. 3A . Likewise, with the mirrors of MEMS mirror array  16  aligned in a second state, only a portion of the light from source  14  is redirected to image target O, with a portion of the light directed away from the image target O and toward an image target O′. 
         [0045]    Selectively directing of all or a portion of light from phone  30  toward an image target, or similarly away from an image target, may be automatically controlled by a software component operating within phone  30 , may be manually controlled by the user of phone  30  through an appropriate interface, be the result of a selected image effect or user preference, or controlled by a combination of these methods. Test flashes may be performed in various configurations permitting analysis software components associated with phone  30  to analyze the response from the target scene. In response to the analysis, the software components may cause controller  20  (e.g.,  FIGS. 1A-1C ) to actuate one or more of the mirrors of MEMS mirror array  16  to direct a first portion of the light from light source  14  to a first desired portion of the target scene (e.g., a greater amount of the light towards image target O) and a second portion of the light from light source  14  to a second desired portion of the target scene (e.g., a lesser amount of the light towards image target O′). It will be readily appreciated that direction of light may be exclusively towards one image target, away from one image target, diffused across the target scene, and so on. 
         [0046]    With reference to  FIG. 4 , which illustrates a block diagram of certain elements of a compact camera according to one implementation of the present disclosure, a compact camera  40  may include, inter alia: shutter release  42 , an objective lens  44 , a zoom controller  46  for controlling physical zoom of objective lens  44 , MEMS mirror array  48 , MEMS mirror array controller  50 , image sensor array  52 , image sensor array controller  54 , scene analysis component  56 , exposure analysis component  58 , light source controller  62 , memory  64 , and focus controller  66 . These elements may communicate with one another, as appropriate, to effectuate scene analysis and settings controls, including the control of illumination of the scene, to obtain a desired exposure. In particular, certain image capture components (including associated controllers) such as zoom controller  46  and focus controller  66  may be communicatively coupled to MEMS mirror controller  50  such that when an objective lens is zoomed (or a software equivalent is employed) to zoom in (or out) on an element of a scene the MEMS mirror controller correspondingly adjusts the positions of one or more mirrors of the MEMS mirror array  48 , such as providing a more focused flash on the element of the scene being zoomed in upon. Similarly, when an element of a scene is identified as the object to be focused upon by focus controller  66 , the focus setting may be communicated to the MEMS mirror controller  50  which may correspondingly adjust the positions of one or more mirrors of the MEMS mirror array  48 , such as providing a more focused flash on the element of the scene being focused upon. As can be appreciated from the above, the input of many camera subsystems and controllers may desirably influence the optimal setting of the MEMS mirror array flash unit. To facilitate interchangeability (e.g., in the common setting of a flash units and cameras obtained from different suppliers), it may be beneficial to provide a separate controller to aggregate all the inputs into a “illumination pattern request” (IPR). This IPR—which could be as simple as a coarse greyscale bitmap—is then a hardware-independent description that can be submitted to any MEMS micro mirror array controller, which may have communicated its capabilities back to the camera before. 
         [0047]    An example of a MEMS mirror  70  of a type which may form an element of a MEMS mirror array referred to above is shown in  FIGS. 5A and 5B . In one implementation, mirror  70  comprises a substrate  72 , such as glass or similar optically transparent material, over which is formed a release structure  74  interconnected to substrate  72  by way of flexible cantilever spring structures  76 . In certain implementations, below each cantilever spring structure  76  is an actuation electrode  78 , which may be individually addressed. Applying a voltage, for example, to an actuation electrode  78  may cause a field to be generated such that the cantilever spring structure  76  located thereover is attracted to electrode  78  thereby inducing tilt into the position of the mirror. In another implementation, such as illustrated in  FIG. 1A , each mirror (or group of mirrors) is formed from or to include a magnetic surface, such as nickel. Each mirror has associated with it a magnetic actuator, which, when activated, attracts or deflects a portion of the mirror to thereby induce mirror tilt. 
         [0048]    In certain implementations, release structure  74  is formed of an optically transparent material, and a reflective coating  79  (which may be the aforementioned nickel layer) is applied thereover such that the surface  77  of release structure  74  opposite and facing substrate  72  is optically reflective. In another embodiment, the entirety of release structure  74  is of an optically reflective material such that surface  77  may reflect light striking it from through substrate  72 . An array  16  of individual release structures  74  forming MEMS mirrors is shown in  FIG. 6 . While  FIG. 6  illustrates a 12×12 array, other array sizes are contemplated as may be determined by the specific application of the present disclosure. 
         [0049]    MEMS mirrors such as mirror  16   a  of array  16  may be disposed on cantilever spring structures  76  to permit 2-axis control. The mechanical angular range of motion of each mirror of array  16  may be as wide as 45 degrees total, and in certain implementations at least +/−11 degrees in each axis for an optical deflection range of at least +/−22 degrees, as illustrated in  FIG. 7 . In this configuration, each mirror of array  16  serves a distinct zone of the angular field of view in the “all flat” state” (i.e., with no mirror deflected from substantially parallel to substrate  72 . When a targeted illumination is desired, each mirror of array  16  may be independently commissioned to direct light it reflects toward a desired region appropriate for the image (as determined, for example, by an image target, or facial detection algorithm) associated with controller  20  ( FIG. 1A ). 
         [0050]    While the preceding discussion has focused on a reflective array for selectively directing light from a light source to or away from an image target, an alternative implementation  80  may comprise an array of transmissive lenses, as illustrated in  FIGS. 8A and 8B . With reference to  FIG. 8A , according to one implementation a two-part substrate comprises a first part  82   a  and a second part  82   b . First part  82   a  has a first surface  84  proximate which is disposed a light source  86  such as an LED element, array of LED elements, or any other of a variety of other known forms of light source. In certain examples, multiple different light sources may be employed. 
         [0051]    First part  82   a  also comprises a second surface  88  over which is disposed a MEMS lens array  90  that may be controlled by a controller  92 . MEMS lens array  90  may be of a similar design to the MEMS mirror array previously discussed, and comprise individually addressable lenses  90   a ,  90   b ,  90   c , and so on. Addressing of lenses  90   a ,  90   b ,  90   c , may be by way of actuation electrodes (not shown, but as previously described with reference to  FIG. 5B , for example), controlled by controller  92 . 
         [0052]    Second part  82   b  has a first surface  94  disposed proximate MEMS lens array  90 . Second part  82   b  also has a second surface  96  over which is formed a reflective surface  98 , such as a metal coating. 
         [0053]    An optical system is thereby formed permitting light from source  86  to enter first part  82   a , travel therethrough, exit first part  82   a  and travel through the lenses of MEMS lens array  90 , which directs portions of the light into second part  82   b . Light so directed is reflected by surface  98 , toward a third surface  100  of second part  82   b . Light may exit at third surface  100 , and be selectively directed to or away from a on image target such as an object O in a scene to be photographed. 
         [0054]    As previously described with reference to MEMS mirror array  16 , MEMS lens array  90  may comprises an m×n array of independently addressable lenses, where m and n may be any appropriate number depending for example on the application of specific implementation of the present disclosure. In one implementation, m=n=5. In certain implementations, the lenses comprising MEMS lens array  90  may be addressable in groups, and in certain other implementations the lenses may be individually addressable. In certain implementations, the geometry of the optical system and stop-to-stop rotation of the lenses comprising MEMS lens array  90  are such that beam and exiting surface  100  may be controlled to +/−22.5 degrees, or a total sweep angle of up to 45 degrees. Once again, when a targeted illumination is desired, each lens of MEMS lens array  90  may be independently commissioned to direct light toward a desired region appropriate for the image (as determined, for example, by an image target, or facial detection algorithm) associated with controller  92 . 
         [0055]    The disposition of lenses  90   a ,  90   b ,  90   c , and the angle α of surface  96  relative to the plane of surface  100 , permits light from source  86  to be directed by lenses  90   a ,  90   b ,  90   c  into second part  82   b  and toward surface  96 , where the light is reflected to surface  100  and may exit second part  82   b . The orientation of lenses  90   a ,  90   b ,  90   c  will determine aspects of the light exiting at surface  100 , such as the amount of light and where the light is directed. For example, with mirrors  90   a ,  90   b ,  90   c  aligned in a first state, the beams of light from source  86  may be effectively collimated and/or directed toward a single image target, O, essentially as shown in  FIG. 8A . Likewise, with mirrors  90   a ,  90   b ,  90   c  aligned in a second state, the beams of light from source  86  may be reflected such that only certain beams are directed to image target, O, while certain other beams are directed away from the image target O, as illustrated in  FIG. 8B . 
         [0056]    In certain implementations of the present disclosure, the array of MEMS mirrors (or lenses) may be tailored to provide desired illumination patterns as light exits the flash system disclosed herein. For example, in one implementation illustrated in  FIG. 9 , the mirror-to-mirror spacing, mirror sizes, and mirror shapes of a MEMS mirror array  110  are selected so as to provide a desired fill factor of the exiting light. By way of example only, certain mirrors  112  in a first row  114  are larger and spaced further apart than other mirrors  116  in a second row  118 . While the mirrors of array  110  are all shown as being substantially rectangular, the intra-array mirror shapes may also differ, such as some rectangular, others trapezoidal, still others hexagonal, and so on. In another implementation, illustrated in  FIG. 10 , the shape of the array  120  itself may be other than rectangular, such as trapezoidal as shown, again with the possibility of similar or different shapes, sizes, and spacing of the individual mirrors comprising the array. And, while the above has been in terms of mirror arrays, similar considerations and design choices may also apply to lens arrays. 
         [0057]    As previously mentioned, the steerable illumination structure disclosed herein may find particular application when forming the flash unit for cameras and the like disposed in mobile devices such as cellular telephones. This is further illustrated in  FIGS. 11A and 11B , which are cutaway perspective views of a cellular telephone having a steerable illumination structure disposed therein.  FIGS. 11A and 11B  show ray tracings illustrating two different illumination patters, dispersed and focused, respectively. 
         [0058]    It should be understood that when a first layer or structure is referred to as being “on” or “over” a second layer or structure, it can be directly on the second layer or structure, or on an intervening layer or layers, or structure or structures, between the first and second layers or structures, respectively. Further, when a first layer or structure is referred to as being “on” or “over” a second layer or structure, the first layer or structure may cover the entire second layer or structure or merely a portion thereof. 
         [0059]    The physics of modern electrical devices and the methods of their production are not absolutes, but rather statistical efforts to produce a desired device and/or result. Even with the utmost of attention being paid to repeatability of processes, the nature of starting and processing materials, and so forth, variations and imperfections result. Accordingly, no limitation in the description of the present disclosure or its claims can or should be read as absolute. The limitations of the claims are intended to define the boundaries of the present disclosure, up to and including those limitations. To further highlight this, the term “substantially” may occasionally be used herein in association with a claim limitation (although consideration for variations and imperfections is not restricted to only those limitations used with that term). While as difficult to precisely define as the limitations of the present disclosure themselves, we intend that this term be interpreted as “to a large extent”, “as nearly as practicable”, “within technical limitations”, and the like. 
         [0060]    While examples and variations have been presented in the foregoing description, it should be understood that a vast number of variations exist, and these examples are merely representative, and are not intended to limit the scope, applicability or configuration of the disclosure in any way. Various of the above-disclosed and other features and functions, or alternative thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications variations, or improvements therein or thereon may be subsequently made by those skilled in the art which are also intended to be encompassed by the claims, below. 
         [0061]    Therefore, the foregoing description provides those of ordinary skill in the art with a convenient guide for implementation of the disclosure, and contemplates that various changes in the functions and arrangements of the described examples may be made without departing from the spirit and scope of the disclosure defined by the claims thereto.