Abstract:
A system and method for auto-focusing light. The system includes at least one focusing lens operable to direct light toward a focal point. The system further includes a sensor array disposed adjacent to the lens assembly such that the light through the lens assembly is directed to the sensor array near the focal point and a bubble array having a plurality of bubble generators. The bubble array supports the sensor array and the bubble generators are operable to maneuver the supported sensor array with respect to the focal point. Such a light focusing system is able to provide an auto-focus capability to a camera system that does not have a large amount of space available for a motor-driven auto-focus system. Furthermore, the bubble array is power efficient and does not require the amount of energy to operate as is required for a motor-driven auto-focus system.

Description:
BACKGROUND OF THE INVENTION 
     Auto-focus systems are used in many different kinds of camera systems including digital still cameras, digital video cameras, and any number of non-digital cameras. An auto-focus system provides the camera with a capability of automatically adjusting a focus lens so as to achieve an optimal level of sharpness in an image during an image capture procedure. For example, some cameras detect the activation of the shutter button and, before capturing an image, performs an iterative focusing procedure whereby a focus lens is moved back and forth until an optimal focus is determined by the circuitry of the auto-focus system. Then, after the focus lens is set to an optimal setting, the camera captures the image. 
     Typically, one of two types of auto-focus systems are used in conventional camera systems; active and passive, both of which are described in more detail below. Some cameras may have a combination of both types, depending on the complexity and price of the camera. In general, less expensive point-and-shoot cameras use an active system, while more expensive SLR (single-lens reflex) cameras with interchangeable lenses use a passive system. 
     An active auto-focus system typically utilizes an emitted signal from the camera in order to induce a signal echo. Based on the echo that bounces off the target object, the active system is able to determine a distance to the target object and, thereby, set the auto-focus system to a focus level corresponding to the determined distance. Such active systems typically use an infrared signal or a sound wave to determine the distance to the target object. For example, a camera having an active auto-focus system may emit an infrared signal when the shutter button is depressed and after a signal is received back from bouncing off the target, the auto-focus system of the camera sets a focus lens to a setting that is based on the returned signals. The camera may then capture the image in a conventional manner. 
     A passive auto-focus system, however, does not emit any signal and typically uses an analysis of image being captured to set the auto-focus system. The camera will analyze, in real-time, an image being registered at a capture point in the camera system. The capture point may be a pixel strip or pixel array that is able to convert incident light into electrical signals in order to determine the sharpness of the captured image by comparing pixels that are adjacent to each other. For example, when a camera having a passive auto-focus system is aimed at a target, an image of the target, or portion thereof, is captured at a pixel strip. The data from the pixel strip is then analyzed by a processor to determine the sharpness of adjacent portions of the captured image. The auto-focus system then maneuvers a focus lens while at the same time performing subsequent analyses of recaptured data until the captured image attains the sharpness desired. 
     Cameras having an auto-focus system, whether active or passive, require a lens assembly to be maneuvered in order to attain the sharpness desired. That is, the lens assembly, which focuses light through at least one focus lens onto a capture medium, such as film or a pixel array, is maneuvered toward or away from the medium such that the focal point of the focus lens changes with respect to the distance from the medium. Thus, in order to maneuver the lens assembly, a motor or group of motors is typically required. As is described below in a conventional auto-focus system, motors are bulky and power hungry. 
       FIG. 1  is a diagram of a conventional auto-focus system that uses a motor  122  to maneuver a lens assembly  105 . The auto-focus system  100  includes a lens assembly  105  that is able to be moved by a drive mechanism  115  that is powered by a motor  122 . The motor  122  is powered by a power supply  123  and controlled by a processor  132  that receives data from an auto-focus circuit  131 . The nature and operation of this conventional auto-focus system  100  is described in more detail in the following paragraphs. 
     The lens assembly  105  typically includes a number of different lenses such as a focus lens  110 , a zoom lens  111  and/or a filter lens  112 . Each of these lenses are typically used to modify light, i.e., an image, that is directed through the lens assembly  105  toward a sensor array  130 . The lenses of the lens assembly  105  along with a redirecting mirror  113  form the optical train in which light is directed toward the sensor array  130 . As such, the lens assembly  105  may be moved with respect to the sensor array  130  and/or the redirecting mirror  113  in order to alter the manner in which the light is redirected. That is, the focal point (not shown) of the focusing lens  110  changes as the lens assembly  105  is moved such that any image that is incident upon the sensor array  130  can be maneuvered until the image is in focus. 
     In order to maneuver the lens assembly  105  to correctly focus an incident image on the sensor array  130 , one or more relatively large motors  122  (only one shown) are required to provide the energy to move the lens assembly  105 . In  FIG. 1 , the motor  122  is coupled to a drive mechanism  121  that translates rotational torque into lateral motion along a shaft  125 . The shaft  125  is coupled to another translation point  120  that is able to maneuver the focusing lens separate from the rest of the lens assembly  105  through a screw drive mechanism  126 . In other conventional systems not shown, the motor  122  and drive mechanism  121  may be coupled to the lens assembly such that the entire lens assembly is moved with respect to the sensor array  130 . 
     The motor  122  is controlled by a processor  132  in conjunction with an auto-focus circuit  131 . Typically, the sensor array  130  includes a certain number of sensors (not shown individually) that are dedicated to the auto-focus system, i.e., a focus strip  135 . That is, instead of using the sensors of the focus strip  135  to collect data about an image for capture, the sensors of the focus strip  135  are used to determine whether or not the image about to be captured is in focus or not. A typical sensor array  130  is a charge-coupled device (CCD) that provides input to the auto-focus circuit  131  that is able to compute the contrast between actual picture elements. The focus strip  135  is typically a single strip of 100 or 200 pixels. 
     As such, the data collected from the focus strip  135  is analyzed with respect to one another to determine whether the image is focused correctly on the focus strip  135  and, subsequently, the sensors of the sensor array  130  that will be used for image capture. Various auto-focus algorithms and mathematical analyses for determining whether an image is focused are well known in the art and are not discussed in greater detail herein. Suffice it to say, data collected from the focus strip  135  through the auto-focus circuit  131 , when analyzed by the processor  132  allow the processor  132  to control the motor  122  such that the lens assembly  105  is moved in one direction or the other in a repeating and iterative process until data collected from the focus-strip  135  indicates that the image is optimally focused. 
     Several problems exist in conventional auto-focus systems, such as the auto-focus system  100  of  FIG. 1 . For one, larger motors, such as motor  122 , require a larger amount of space inside a camera assembly. With traditional camera systems, space is typically available for larger motors. However, as cameras are being realized in much smaller packages and assemblies, such as cell phones and the like, larger motors become more difficult to fit into the tighter space available for the camera assembly. As a result, motors to manipulate a focusing lens may not be feasible in such small places. 
     Additionally, these larger motors, even if used in a camera with enough space, still require a large amount of power that is undesirable in devices that are typically always powered on. That is, if power is required for a motor-driven auto-focus system in a camera that is part of a cell phone, the battery supplying the entire cell phone is drained all the faster when the motor is required to manipulate the lens assembly for focusing. 
     Other solutions, such the use of piezoelectric motors which may be smaller than the above-described motor  122  are also impractical because the power required to utilize the piezoelectric motors when manipulating the lens assembly is still at an undesirable high level. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention is directed to a light-focusing system having a lens assembly a sensor array and a bubble array for focusing light for a camera system. The system includes at least one focusing lens operable to direct light toward a focal point. The system further includes a sensor array disposed adjacent to the lens assembly such that the light through the lens assembly is directed to the sensor array near the focal point and a bubble array having a plurality of bubble generators. The bubble array supports the sensor array and the bubble generators are operable to maneuver the supported sensor array with respect to the focal point. 
     In this manner, based on feedback from a strip of sensors dedicated to an auto-focus system, the bubble array is maneuvered until the image incident on the sensor array is in optimal focus. The process may be iterative such that the bubbles are slightly adjusted each time additional feedback is received until the feedback received from iteration to iteration does not change substantially. 
     On one embodiment, the entire array moves up and down together as several bubbles that support the sensor array are each controlled by a central control signal. In other embodiments, each bubble is controlled by a dedicated control signal. 
     Such a light focusing system is able to provide an auto-focus capability to a camera system that does not have a large amount of space available for a motor-driven auto-focus system. Furthermore, the bubble array is power efficient and does not require the amount of energy to operate as is required for a motor-driven auto-focus system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a diagram of a conventional auto-focus system that uses a motor to maneuver a lens assembly; 
         FIG. 2  is a diagram of a an auto-focus system having a sensor array that is able to be positioned by a plurality of inflatable bubbles disposed on a bubble array according to an embodiment of the invention; 
         FIG. 3  is an isometric view of a bubble array having a plurality of bubbles disposed thereon according to an embodiment of the invention; 
         FIG. 4  is a diagram of the sensor array and bubble array of  FIG. 2  in zero-inflation state according to an embodiment of the invention; 
         FIG. 5  is a diagram of the sensor array and bubble array of  FIG. 2  in a mid-level inflation state according to an embodiment of the invention; and 
         FIG. 6  is a diagram of the sensor array and bubble array of  FIG. 2  that illustrates an alternative method for reaching an optimal focus state according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following discussion is presented to enable a person skilled in the art to make and use the invention. The general principles described herein may be applied to embodiments and applications other than those detailed above without departing from the spirit and scope of the present invention. The present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed or suggested herein. 
       FIG. 2  is a diagram of a an auto-focus system  200  having a sensor array  230  that is able to be positioned by a plurality of inflatable bubbles  245  disposed on a bubble array  242  according to an embodiment of the invention. The sensor array  230  includes a focus strip  235  of sensors that are dedicated to capturing image data to be used for an analysis of the sharpness of the image. The focus strip  235  is electrically coupled to an auto-focus circuit  231  and collectively, these two components are able to generate an indication of the sharpness of the incident image that may be detected by the focus-strip  235 . In this manner, a processor  232  is able to use the sharpness indication generated by the auto-focus circuit  231  to adjust the inflation level of the bubbles  245  in the bubble array  242  such that the entire sensor array  230  is raised or lowered accordingly. As a result, the raising and lowering allows the incident light to attain better sharpness, i.e., focus, when captured by the sensors of the sensor array  230  that are dedicated for image capture. Both the bubble array  242  and the auto-focus circuit  231  are described in further detail below. 
     The bubble array  242  is electrically coupled to the processor  232  and is able to be controlled by the processor  232 . When the auto-focus circuit  231  determines that an adjustment is required, the auto-focus circuit  231  communicates a signal to the processor  232 . The processor  232 , in turn, generates a signal in response to the auto-focus circuit  231  determination that causes the one or more bubbles  245  in the bubble array  242  to inflate to an appropriate level such that an image incident on the sensor array  230  comes into focus. 
     For example, when light (i.e., light from an image that is to be captured) is incident on the sensor array  230  through the lens assembly  205 , the auto-focus system  200  of the present invention analyzes the incident light for sharpness to determine the best position for the sensor array  230  to accurately capture the incident light. As such, light that is incident on the focus strip  235  is captured by sensors thereon and signals representing the captured light are transmitted to the auto-focus circuit  231 . 
     The auto-focus circuit  231  then analyzes the captured data to determine a sharpness factor or focus factor. The focus factor is an indication of the intensity differences between adjacent pixels. When an image is out of focus, the intensity levels between adjacent pixels does not change much from pixel to pixel. Hence, the reason that an image will appear blurred. However, in a focused image, the intensities between pixels changes more rapidly as the image appears sharp to the human eye. Thus, the focus factor is a numerical quantization of the differential intensities from pixel to pixel. 
     Once the focus factor is determined, it is transmitted to the processor  232 . The processor  232  receives the focus factor and determines how much the sensor array  230  should be moved in order to adjust the focus of the image being captured. Thus, an adjustment signal is generated by the processor  232 , which is then transmitted to the bubble array  242 . The adjustment signal may be digital or analog and may be a multiplexed signal having several adjustment signals that may correspond to several bubbles  245  of the bubble array  242 . The bubbles  245  of the bubble array  242  are then inflated to a level corresponding to the adjustment signal received. 
     Typically, when a method for auto-focusing begins, the bubbles  245  of the bubble array  242  are at a zero-inflation state. Inflating the bubbles  245  from a zero-inflation state to a fully-inflated state provides a movable distance to the sensor array  230  of about 100 um. Thus, when completely deflated, the sensor array  230  is at the beginning of the 100 um range and typically focused at infinity, which for the purposes of image capture in a camera, corresponds to objects beyond about 100 meters from the camera. If target objects are within 100 meters of the camera at image capture, the auto-focus system  200  adjusts the sensor array  230  by inflating the bubbles  245  of the bubble array  242  in an attempt to attain optimal focus. The bubbles  245  may be inflated to a corresponding discrete level, i.e., a level that corresponds to one of ten, for example, discrete distance determinations between 0 meters and 100 meters. Alternatively may be inflated to a level that linearly corresponds to the determined distance, i.e., a distance of 50 meters (half of the 0-100 meter range) would result in the bubbles  245  being half inflated (50 um vertical movement). 
     The bubble array  242  of  FIG. 2  comprises a plurality of bubbles  245  arranged on the bubble array  242  substrate and each individual bubble  245  is operable to be controlled by the processor  232 . The bubble array  242  is described in greater detail with respect to  FIG. 3 . 
     The bubbles  245  of the bubble array  242  are typically covered by an elastic membrane  240  that prevents the sensor array  230  or anything else from coming into direct contact with the sensitive bubbles  245 . The elastic membrane  240  is form fit to the contour of the upper plane of the bubble array  242 . That is, the membrane  240  does not form fit to the spherical contours of each individual bubble  245 , but rather, the membrane engages each top-most portion of the bubbles  245  as they inflate such that the membrane as a whole provides a semi-flat surface for the sensor array  230  to be affixed to. Thus, as the bubbles  245  inflate, the sensor array  230  supported by the bubbles  245  maintains a relatively flat position as well because the membrane does not completely fall to the contours of the spherical bubbles  245 . Likewise, as the bubbles  245  deflate, the sensor array  230  may be lowered to an original position, i.e., focused at infinity. 
     Using bubble technology to raise and lower the sensor array  230  during a focusing process is a faster method of focusing an incident image when compared to the slower nature of motor movement. Furthermore, the electrical power required to heat the individual bubbles for inflation is far less than the power required for actuating one or more motors. Thus, the auto-focusing system  200  is more power efficient and faster than conventional auto-focus systems. 
     Because the sensor array  230  is able to move up and down as the bubbles  245  of the bubble array  242  are inflated and deflated, any I/O points for the sensors of the sensor array  230  are typically connected to a flexible I/O link, such as I/O link  241 . As shown in.  FIG. 2 , the I/O link is coupled between the focus strip  235  and the auto-focus circuit  231  although this I/O link represents a connection to all sensors of the sensor array  230  including those dedicated as the focus strip  235 . The I/O link is also connected to the sensor array  230  (although not shown in detail) such that signals generated at the sensors of the sensor array  230  may be transmitted to the processor  232 . Typically, the I/O link  241  will be a single flexible serial cable such that all signals from the sensor array  230  are transmitted therein. Alternatively, the I/O link  241  may be a pair of serial links such that signals from the focus strip  235  are transmitted to the auto-focus circuit  231  and signals from the sensors of the sensor array  230  dedicated for image capture are transmitted to the processor  232 . However, any I/O distribution is possible and the auto-focus circuit  231  may even be part of the processor  232  as a software implementation within the processor  232 . 
     Additionally, all data collected by the processor  232  from the focus strip  235  and the sensor array  230  may be stored in a memory  233  that is coupled to the processor  232 . The memory  233  may archive this data for later analysis, such as a focus algorithm that surveys focus data over a period of time before the processor generates an adjustment signal. Further, the particular discrete focus settings may be stored such that when the focus data is analyzed to meet a specific criteria, i.e., a great deal of light in one section of the focus strip  235  indicating the possible position of the sun behind the target objects, then the processor  232  positions the sensor array  230  to a predetermined position. In another example, the algorithm may be biased for foreground or background image focus. As such, the presence of a small object in the foreground may take precedence over many objects in the background when determining where to position the sensor array  230 . Other scenarios for automatic discrete focus settings are contemplated but not discussed in greater detail herein. 
     The lens assembly is  FIG. 2  is shown as affixed to a housing  250  of the sensor array  230  and bubble array  242 . The lens assembly  205  is also shown having a focus lens  210 , a filtering lens  211  and a zoom lens  212 . Other combinations of lenses in the lens assembly  205  are possible, but not discussed herein. Furthermore, the lens assembly  205  need not be affixed to the housing  250 , but rather may be designed to include additional movable parts such as a zoom feature that allows the zoom lens  211  to be adjusted. These additional lens assembly  205  features are contemplated but not discussed in greater detail herein. 
     A typical focus strip  235  is a charge-coupled device (CCD) that provides input to auto-focus circuit  231  that may compute the contrast of the actual picture elements of focus strip  235 . The CCD is typically a single strip of 100 or 200 pixels. Light from the scene hits this strip and the auto-focus circuit  231  analyzes the values from each pixel. Typically, the focus strip  235  is vertical or horizontal with respect to the image being captured. In one embodiment, the auto-focus system  200  may incorporate two focus strips  235 , one vertical and one horizontal, to better analyze the incident light for focusing. 
       FIG. 3  is an isometric view of a bubble array  242  having a plurality of bubbles  245   a - e  disposed thereon according to an embodiment of the invention. The bubble array  242  typically embodies a surface area equivalent to the sensor array  230  (not shown in  FIG. 3 ) that is supported by the bubble array  242 . However, the entire surface area (shown as the top side of the bubble array  242 ) need not necessarily consists entirely of bubbles  245 . For example, as shown in  FIG. 3 , only the outside edges of the bubble array  242  may have bubbles  245  (although only one side is shown having bubbles  245  in  FIG. 3 ). Other bubble  245  patterns may include a checkerboard of bubbles  245 , only bubbles  245  on the corners, or alternating rows (i.e., one row having bubbles  245  and an adjacent equivalent area not having bubbles  245  and so on). 
     Each bubble  245  in the bubble array  242  corresponds to an associated bubble generator  305 . Each bubble generator  305  includes a resistive element (not shown in detail) that may be used to heat the bubble associated with each bubble generator  305 . Each bubble  245  in the array comprises an elastic membrane filled with a gas or liquid well suited to be heated, such as helium, for example. As heat is added to a bubble generator  305 , the corresponding bubble  245  begins to inflate as the liquid or gas enclosed by the membrane expands. Typically, the gas or liquid is a safe and reliable substance able to have a volume that is highly controllable. 
     For example, helium in an enclosed volume, such as within the membrane of a bubble  245 , will necessarily react according to the ideal gas law, PV=nRT, where P=pressure, V=volume, n=number of moles, R=universal gas constant, and T=temperature. Since n and R are constants and it can be assumed that the pressure will not change dramatically (i.e., atmospheric pressure as the elastic membrane only adds a negligible amount of pressure to the enclosed space, hence the reason that the membrane can inflate), the volume will increase as the temperature increases, proportionally. As such, an electric signal through the generator  305  resistor may be tailored to a level that applies a specific amount of heat to the bubble  245  so that the temperature rises, which in turn inflates the bubble  245  to a proportionate volume. 
     As can be seen in  FIG. 3 , a first bubble  245   a  is not inflated and may be at a room temperature such that the gas enclosed in the membrane of the bubble generator  305  remains deflated. That is, the gas still occupies a finite volume, but the volume is entirely below a top plane of the bubble generator  305  such that the bubble  245   a  appears completely deflated. This level may correspond to an adjustment signal from the processor  232  having a discrete level of zero. The next bubble  245   b  is shown inflated to a small degree. This may correspond to the next discrete level, i.e., an adjustment signal from the processor  232  is received that corresponds to a first discrete level. The next bubbles  245   c  and  245   d  again show a slightly larger volumes that may corresponds to yet more discrete adjustment signal levels. Finally, the largest bubble  245   e  may be the larger discrete level wherein the maximum adjustment signal is received at each resistor of each bubble generator  305  such that the volume is maximized with respect to the highest attainable, safe temperature. As such, the processor  232  may generate any number of discrete adjustment signals so as to heat each volume of enclosed gas in each bubble  245  in each bubble generator  305 . Thus, each bubble  245  inflates to a specific volume and the supported sensor array  230  may be raised to a particular focal point with respect to the focus lens ( 210  of  FIG. 2 ). 
     As described above, the differing inflation levels correspond to discrete digital signal levels of the adjustment signal from the processor  232 . Alternatively, the inflation levels may correspond to an analog signal that is transmitted to each bubble generator  305 . The processor generates an adjustment signal as a digital value, but the digital value may be passed to a digital-to-analog converter (not shown) that converts the digital signal to an analog signal. The analog signal is then, in turn, passed to the resistor of each of bubble generator  305 . In this manner, the bubbles generators  305  need not have a resistive element capable of receiving a digital signal such that the digital signal must be interpreted before generating heat for the inflation of the corresponding bubble  245 . 
     In any case, a number of different discrete or analog focus levels may be implemented based on the adjustment signal that is a function of the feedback received from the sensors at the focus strip  235 . The figures below illustrate various contemplated focus levels. 
       FIG. 4  is a diagram of the sensor array  230  and bubble array  242  of  FIG. 2  in zero-inflation state according to an embodiment of the invention. When the auto-focus system  200  is first acquiring data from sensors at the focus strip  235 , the initial starting point is typically a zero-inflation state or focus-at-infinity state. That is, the sensor array  230  is at its lowest point with respect to the focus lens  211  (not shown in  FIG. 4 ) because the bubbles  245  (unable to be seen in  FIG. 4 ) are at a completely deflated level. The completely deflated level corresponds to the lowest value adjustment signal from the processor  232 , and may even be a zero signal or no signal. 
     The zero-inflation state is a convenient starting point for analyzing the sharpness of an incident image since all adjustments based on the feedback can be incrementally increased until the desired sharpness is achieved. Thus, a first adjustment level can be first applied such that the bubbles  245  raise the sensor array  230  a small amount. Then a second analysis, i.e., a second collection of data from the focus strip  235 , may determine that an additional adjustment is necessary, so the processor  232  increases the value of the adjustment signal which causes the sensor array  230  to be raised by the bubble array  242  even more. This iterative process repeats until the feedback data from the sensors at the focus strip  235  indicate a desired sharpness of the incident image. 
       FIG. 5  is a diagram of the sensor array  230  and bubble array  242  of  FIG. 2  in a mid-level inflation state according to an embodiment of the invention. As such, the adjustment signal being transmitted to each resistor of each bubble generator  305  (not shown in detail) is generating a finite amount of heat such that each bubble  245  is inflated to a mid-level volume. Therefore, the sensor array  230  is raised to a mid-level focus level.  FIG. 5  is an example of the possible end-result of the above-described iterative process for determining the optimal sharpness of any incident image at the sensor array  230 . 
     As will be shown below, the bubbles  245  of the bubble array  242  need not all be inflated uniformly. For example, bubbles  245  may inflated to increasing levels across a linear path on the bubble array  242 . 
       FIG. 6  is a diagram of the sensor array  230  and bubble array  242  of  FIG. 2  that illustrates an alternative method for reaching an optimal focus state according to an embodiment of the invention. As can be seen bubbles  245  on the left-hand side of the bubble array  242  are inflated more than the bubbles  245  on the right-hand side of the bubble array  242 . This non-uniform inflation of bubbles  245  results in a tilt of the sensor array  230 . A sensor array  230  tilt may be useful to compensate for a slightly misaligned seating of the sensor array  230  in the first place. That is, the sensor array  230  may have been seated during a manufacturing process such that one corner is seated higher than the rest. As a result, without maneuvering the sensor array  230  by tailoring each individual bubble size to compensate, portions of every image captured would be out of focus, i.e., the portion of the image corresponding to the anomalous corner of the sensor array  230 . By adjusting each bubble individually, problems from anomalous focus areas of a captured image may be alleviated. 
     Additionally, the focus strip  235  may collect data about the image to be captured that, when analyzed, reveals two distinct object depths across the entire image plane. For example, the image to be captured may include a person on the left-hand side standing at a cliff overlooking the ocean on the right-hand side. To correctly focus on the person, the left-side analysis would need to take precedence, but to correctly focus on the ocean, the right-hand side would need to take precedence. Thus, if the bubble array  242  were to receive a pattern of adjustment signals from the processor such that the bubbles  245  of the bubble array  242  position the sensor array similar to  FIG. 6 , then the two separate objects may both be more in focus that without tilting the sensor array  230 . Additionally, two focus strips  235  in an auto-focus system  200  may allow focusing based on three-dimensions to be realized more effectively. That is, so-called 3D functioning is better accomplished using two focus strips  235  in conjunction with a adjustable bubble array  242 .