Abstract:
The disclosure relates to measuring a distance from a mobile device to a remote surface. An energy emitter directs an energy signal onto an energy splitter, the energy splitter partitions the energy signal into a first energy beam having a first wavelength and a second energy beam having a second wavelength, a reflector array reflects the first energy beam at a first angle and the second energy beam at a second angle different from the first angle and projects the first energy beam and the second energy beam onto the remote surface, a receiver measures a first propagation time of the first energy beam reflected off of the remote surface and a second propagation time of the second energy beam reflected off of the remote surface, and a processor estimates the distance to the remote surface based on the first propagation time and the second propagation time.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present Application for Patent is a continuation of U.S. patent application Ser. No. 13/797,449, now U.S. Pat. No. 8,798,959, entitled “SMALL FORM-FACTOR DISTANCE SENSOR,” filed Mar. 12, 2013, which is a continuation of U.S. patent application Ser. No. 12/560,176, now U.S. Pat. No. 8,396,685, entitled “SMALL FORM-FACTOR DISTANCE SENSOR,” filed Sep. 15, 2009, assigned to the assignee hereof and hereby expressly incorporated by reference in their entirety herein. 
    
    
     BACKGROUND 
     1. Field 
     The subject matter disclosed herein relates to determining a distance from a mobile device to a remote object or a size of the remote object. 
     2. Information 
     A device may measure a distance to a remote surface by measuring a propagation time of sound, light, infrared (IR) and/or radio-frequency (RF) energy projected to the surface and reflected back to the device. For example, a hand-held device may project a light beam toward a surface several meters away to measure its distance. Unfortunately, an angle at which such a device is aimed at the surface typically affects a distance measurement. Additionally, such a device typically measures a distance to a point on the surface at which the device is aimed, which is not necessarily the closest point on the surface to the device. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Non-limiting and non-exhaustive features will be described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures. 
         FIG. 1A  is a schematic diagram showing a distance sensor to measure a distance to a surface, according to an implementation. 
         FIG. 1B  is a schematic diagram showing a distance sensor held at an angle relative to a surface of which a distance may be measured, according to an implementation. 
         FIG. 2  is a diagram depicting a handheld device measuring several distances to a surface, according to an implementation. 
         FIG. 3  is a flow diagram of a process for determining a shortest distance to a surface, according to an implementation. 
         FIG. 4  is a schematic diagram showing distance measurement points on a surface for a shortest distance determination, according to one implementation. 
         FIG. 5  is a schematic diagram showing a distance sensor for measuring distances to multiple measurement points on a surface, according to one implementation. 
         FIG. 6  is a schematic diagram showing an emitter system to emit light energy toward multiple directions simultaneously, according to one implementation. 
         FIG. 7  is a diagram depicting a handheld device measuring several distances to a surface, according to an implementation. 
         FIG. 8  is a detailed view showing a handheld device measuring several distances to a surface, according to an implementation. 
         FIG. 9  is a flow diagram of a process for determining a distance on a remote surface, according to an implementation. 
         FIG. 10  is a flow diagram of a process for determining a distance on a remote surface, according to another implementation. 
         FIG. 11  is a schematic diagram showing a distance sensor for measuring distances to multiple measurement points on a surface, according to one implementation. 
         FIG. 12  is a schematic diagram showing a distance sensor for measuring a distance to a measurement point on a surface, according to one implementation. 
         FIG. 13  is a diagram depicting a non-stationary handheld device measuring several distances to a surface, according to an implementation. 
     
    
    
     SUMMARY 
     In one particular implementation, a method comprises rotating a rotatable micro-reflector to direct energy toward a remote surface, wherein the rotatable micro-reflector may be disposed in a mobile device, and wherein the rotating is relative to the mobile device; and measuring a distance based at least in part on reflected energy from the remote surface resulting from the directed energy. It should be understood, however, that this is merely an example implementation and that claimed subject matter is not limited to this particular implementation. 
     DETAILED DESCRIPTION 
     Reference throughout this specification to “one example”, “one feature”, “an example” or “a feature” means that a particular feature, structure, or characteristic described in connection with the feature and/or example is included in at least one feature and/or example of claimed subject matter. Thus, the appearances of the phrase “in one example”, “an example”, “in one feature” or “a feature” in various places throughout this specification are not necessarily all referring to the same feature and/or example. Furthermore, the particular features, structures, or characteristics may be combined in one or more examples and/or features. 
     In an implementation, a handheld device, such as a cellular phone, PDA, and the like, may include a distance sensor to determine a closest distance to a remote surface. For example, such a distance sensor may include an emitter and a receiver to emit and receive sound, light, IR and/or RF energy, a time module to determine a propagation time of the emitted energy as it travels to and from the remote surface, and a processor adapted to determine distances to multiple points on the surface. In particular, such a distance sensor may determine the closest, or shortest, distance among multiple determined distances to the surface. Additionally, such a distance sensor may have a sufficiently small form factor in order to fit in a handheld device such as a cellular phone or PDA, for example. In a particular implementation, a distance sensor may be capable of emitting sound, light, IR and/or RF energy along multiple angles. Individual angles may respectively correspond to particular distance measurement points on the remote surface. Determining distances to the remote surface along individual angles may yield multiple distance measurements. The shortest distance among such measurements may correspond to the shortest distance to the remote surface, as explained in further detail below. Such an implementation may be useful, for example, if a handheld device that includes a distance sensor making such distance measurements is held at a skewed angle towards a remote surface. In this case, a distance measurement along only the skewed angle may not necessarily comprise the shortest distance to the remote surface. This idea is discussed in reference to  FIGS. 1A and 1B  below. 
       FIG. 1A  is a schematic diagram showing a distance sensor  100  to measure a distance to a surface  140 , according to an implementation. Such a distance sensor may be disposed in a handheld device, such as a cell phone for example, as mentioned above. In one particular implementation, distance sensor  100  may transmit and receive sound energy comprising substantially directed sound waves having subsonic or supersonic frequencies. In another particular implementation, distance sensor  100  may transmit and receive electromagnetic (EM) energy comprising RF radiation, and/or laser light having visible or IR wavelengths. Of course, such descriptions of sound and EM energy are merely examples, and claimed subject matter is not so limited. Distance sensor  100  may emit such energy  110  toward a point  130  on surface  140 . Energy  110  may comprise a pulse of energy, e.g., a relatively short wave-train of sound and/or EM energy having a begin and end time. Such a pulse may be encoded, for example, to provide a means for distinguishing multiple received pulses from one another. Subsequently, energy  120  reflected from surface  140  may travel back to distance sensor  100 , where a measurement of time elapsed between emission and reception at the receiver may be performed. Such an elapsed time may be referred to as propagation time. Using knowledge of the speed of sound and/or EM energy emitted and received by the distance sensor and the measured propagation time, a distance from the distance sensor to the remote surface may be determined. As shown in  FIG. 1B , distance sensor  100  may be held at a skewed angle  125  relative to surface  140 . For example, such an angle may not be perpendicular to remote surface  140 . At such an angle, distance sensor  100  may emit energy  150  at point  170  on surface  140 , though point  180  may be the closest point of surface  140  to distance sensor  100 . Accordingly, emitted energy  150  and reflected energy  160  along angle  125  may travel a greater distance relative to a distance to and from closest-point  180 . Unfortunately, a resulting measured distance to surface  140  may then be greater than the closest distance to surface  140 . In a particular implementation, a user may operate such a distance sensor disposed in a handheld device at a skewed angle without being aware of such a skewed angle, since even relatively small skewed angles that are difficult to observe may introduce substantial distance measurement errors. In another particular implementation, a distance sensor may be capable of emitting sound and/or EM energy along multiple angles so that a closest distance to a remote surface may be determined whether or not the distance sensor is held at a skewed angle to the surface, as discussed in detail below. 
       FIG. 2  is a diagram depicting a handheld device  210  measuring several distances to a surface  220 , according to an implementation. Handheld device  210  may comprise a cell phone, a PDA, and the like, and include a distance sensor  230 . Such a distance sensor, as mentioned above, may have a small form factor to enable the distance sensor to fit in handheld device  210  As shown in  FIG. 2 , such a distance sensor  230  may emit sound and/or EM energy along multiple angles toward multiple distance measurement points on surface  220 . In a particular implementation, distance sensor  230  may include one or more rotatable micro-reflectors mounted on a semiconductor device. Such rotatable micro-mirrors, which are explained in more detail below, may provide the small form factor mentioned above, for example. Of course, such a description of a distance sensor in conjunction with handheld device  210  is merely an example, and claimed subject matter is not so limited. In an example, a user  240  may inadvertently hold handheld device  210  at a skewed angle toward surface  220  to direct an energy beam D1 at surface  220 . However, energy beam D1 may not be directed toward a point on surface  220  that is closest to the handheld device  210 , so that a resulting distance measurement may be greater than such a measurement to the closest point. 
     In a search for such a distance to the closest point, distance sensor  230  may then redirect an energy beam D2 to another point on surface  220  to measure a distance to surface  220  along the direction of energy beam D2. Such a redirecting process may continue such as for energy beams D3 and D4, for example. After such a process, distance sensor  230  may have measured multiple distances to surface  220  along multiple directions. Accordingly, the shortest measured distance may correspond to the shortest distance to surface  220 . In a particular implementation, accuracy of measuring the shortest distance to a surface may be improved by increasing the number of distance measurements to the surface while redirecting energy beams through smaller angles, as discussed below in more detail. Of course, such processes of a distance sensor are merely examples, and claimed subject matter is not so limited. 
       FIG. 3  is a flow diagram of a process  300  for determining a shortest distance to a surface, and  FIG. 4  is a schematic diagram showing distance measurement points on a surface  400  for a shortest distance determination, according to one implementation. A distance sensor, such as distance sensor  100  shown in  FIG. 1  for example, may emit energy, such as sound and/or EM energy, sequentially toward points  430 A,  430 B,  430 C, and  430 D arranged substantially linearly along a line  410 . A first point  430 A and the direction along which line  410  lies may be based, at least in part, on an orientation of the distance sensor, which may be held by a user that may select such a direction.  FIG. 2  may depict such a case, for example, wherein such a direction may be at least partially randomly selected since a user may hold a distance sensor manually. The particular direction of line  410  need not be of importance in process  300 , as explained in detail below. At block  310 , initial point  430 A on line  410  may be selected and its distance measured. At block  320 , a portion, such as an emitter portion, of the distance sensor may rotate through a step angle to emit energy toward a subsequent point  430 B. A step angle of such a rotation, and a corresponding spacing between points  430 A and  430 B on surface  400  may be selected based at least in part on a desired resolution and/or accuracy of a particular process  300 , as discussed in detail below. Such a step angle may comprise a constant value that is used for subsequent rotations of emitted energy until a direction of such a rotation is reversed, as at block  360  described in detail below. 
     Subsequently, at block  330 , at least a portion of energy emitted toward point  430 B may reflect back to the distance sensor, where the reflected energy may be received. A distance to point  430 B may be determined based at least in part on a measured propagation time of the emitted/received energy. At block  340 , a determination may be made whether the subsequently measured distance, e.g., to point  430 B, is greater than the previously measured distance, e.g., to point  430 A. If not, then process  300  may return to block  320  where a portion of the distance sensor may again rotate through the same step angle as for the previous rotation to direct energy toward a subsequent point  430 C. Again, at block  340 , a determination may be made whether the subsequently measured distance, e.g., to point  430 C, is greater than the last previously measured distance, e.g., to point  430 B. If not, then process  300  may again return to block  320  where the emitter portion of the distance sensor may again rotate through the same step angle as for the previous rotation to direct energy toward a subsequent point  430 D. Such a process of directing energy toward a point on a surface, rotating through a step angle, directing energy toward another point on the surface, and so on may repeat each time a subsequently measured distance is less than the previously measured distance. Such a repeating process may allow the distance sensor&#39;s emission angle to approach a point along line  410  on surface  400  that is closest to the distance sensor. A measured distance to such a point may be referred to as a relative minimum since the measured distance may be the smallest value among measured distances to points along line  410 . On the contrary, an indication that the distance sensor&#39;s emission angle has passed such a point on line  410  may occur if the last measured distance is greater than a previously measured distance. 
     In the present example illustrated in  FIG. 4 , a distance to point  430 D, measured at block  330 , is greater than the distance measured to point  430 C, as determined at block  340 . Accordingly, at block  350 , a determination may be made as to whether the angle of rotation corresponds to a resolution limit imposed on the distance sensor, for example. If not, then a search for a shorter distance to a point on surface  400  than the distance to point  430 D may be performed. Such a point corresponding to a shorter distance may be assumed to be on line  410  between points  430 C and  430 D. Accordingly, the emitter portion of the distance sensor may reverse its direction of rotation and reduce its step angle by half or other fraction from previous step angles, for example, as at block  360 . Of course, other step angle reduction amounts are possible, and claimed subject matter is not so limited. In this fashion, a distance to a point  430 E may be determined, as at block  330 . At block  340 , a determination may be made whether the subsequently measured distance, e.g., to point  430 E, is greater than the previously measured distance, e.g., to point  430 D. If so then, at block  350 , a determination may be made as to whether the current angle of rotation corresponds to a resolution limit imposed on the distance sensor, for example. If not, then a search for a shorter distance to a point on surface  400  than the distance to point  430 E may be performed. However, if such a resolution limit is reached, then a process to search for a closest point on surface  400  along a line  420  that is substantially orthogonal to line  410  may then be performed, as at block  370 . 
     In a particular implementation, line  420  being substantially orthogonal to line  410  may lead to a relatively fast process to determine a closest point on surface  400 , as compared to the case where line  420  is at an oblique angle to line  410 , for example. Such orthogonality may provide an efficient process of measuring points on surface  400  in a trial-and-error fashion until a closest distance is determined. The process at block  370  may comprise actions similar to those of blocks  310  through  360 , for example. In particular, the emitter may rotate to direct energy toward a point  440 A so that a distance to this point may be determined Continuing with the example depicted in  FIG. 4 , the emitter may rotate through a step angle to direct energy toward a point  440 B after determining that the distance to point  440 A is greater than the distance to point  430 E. As described above for the process of determining distances to points  430 C,  430 D, and  430 E, distances to points  440 C,  440 D, and  440 E may be measured to determine a closest point on surface  400  along line  420 . A measured distance to such a point may be referred to as a relative minimum since the measured distance may be the smallest value among measured distances to points along line  420 . Since line  420  may include point  430 E, which was determined to be the closest point on surface  400  along line  410 , a closest point along line  420  may be selected as the closest point on the surface  400 , within a measurement resolution limit, as at block  380 . In the example depicted in  FIG. 4 , point  440 E is the closest point. 
       FIG. 5  is a schematic diagram showing a distance sensor  500  for measuring distances to multiple distance measurement points on a surface  550 , according to one implementation. Upon receiving emitted energy from emitter  510 , a rotatable reflector  520  may direct energy  540  via opening  530  towards various distance measurement points on surface  550 . A processor  508  may transmit information to a rotation controller  525  that may send signals to rotatable reflector  520  that determine at least in part the angular position of the rotatable reflector. In one particular implementation, rotatable reflector  520  may comprise a reflector to reflect EM energy emitted by emitter  510 . Such a reflector may be rotated by a stepper motor that receives signals from rotation controller  525 , for example. In another particular implementation, rotatable reflector  520  may comprise a micro-reflector array to reflect EM energy emitted by emitter  510 . The angle of reflection of such an array may be determined at least in part by signals from rotation controller  525  that operate on multiple micro-reflectors in the array, for example. Rotation controller  525  may operate on such an array of micro-reflectors in unison so that multiple micro-reflectors have identical reflecting angles, or individual micro-reflectors may have reflecting angles different from one another, as will be discussed below. In yet another particular implementation, rotatable reflector  520  and emitter  510  may be combined into a rotating emitter (not shown) to direct sound energy at various angles. The angle of such a rotating emitter may be determined at least in part by signals from rotation controller  525  that may operate a motor such as a stepper motor, for example. Of course, such emitters are merely examples, and claimed subject matter is not so limited. 
     In an implementation, rotatable reflector  520  may comprise two or more degrees of rotational freedom orthogonal from one another. For example, rotatable reflector  520  may comprise a degree of rotational freedom in the plane of  FIG. 5 , as shown. Additionally, rotatable reflector  520  may comprise a degree of rotational freedom perpendicular to the plane of  FIG. 5  (not shown). Accordingly, rotatable reflector  520  may reflect energy  540  in one or more directions across surface  550 , such as orthogonal lines  410  and  420  on surface  400  in  FIG. 4 , for example. 
     Receiver  515  may receive energy  545  reflected from surface  550  after a propagation time delay from when energy  540  was emitted from emitter  510 . Such a delay may be measured by time module  505 , which may monitor signals transmitted from processor  508  to emitter  510  that initiate the emitter to emit energy  540 , for example. Accordingly, time module  505  may measure a time difference between when energy  540  is emitted and energy  545  is received. Of course, such methods of measuring propagation time of energy are merely examples, and claimed subject matter is not so limited. Returning to  FIG. 5 , user I/O  518  may provide user access and/or control to distance sensor  500  via processor  508 . 
     In an implementation, an emitter may include a mechanically rotatable reflector capable of directing sound, light, IR and/or RF energy along multiple angles toward a surface to be measured, for example. Such a rotatable reflector may comprise a micro-reflector device, such as a micro-mirror array mounted on a semiconductor device, also known as a digital mirror device, for example. Depending on what type of energy is to be reflected, such a rotatable reflector may include various coatings and/or treatment to improve reflectance. Such a rotatable reflector may also include various reflecting-surface shapes, such as planar, spherical, parabolic, concave, convex, and so on. Such a rotatable reflector may have a relatively small form factor, allowing the rotatable reflector, among other things, to fit in a handheld device, for example. Of course, such a micro-reflector device is merely an example of a small form factor rotatable reflector, and claimed subject matter is not so limited. 
       FIG. 6  is a schematic diagram showing an emitter system  600  to emit light energy toward multiple directions at the same time, according to one implementation. Such a system may be included in a distance sensor such as distance sensor  500  shown in  FIG. 5 , for example. Emitter system  600  may include emitter  610  configured to emit light energy  615  comprising multiple wavelengths, such as a first wavelength and a second wavelength for example. Light energy  615  from emitter  610  may encounter wavelength splitter  618  configured to partition light energy into distinct wavelengths. Accordingly, light energy  615  may be partitioned into light beam  630  having a first wavelength and light beam  640  having a second wavelength. Micro-reflector array  620  may comprise micro-mirrors, such as those of a digital mirror device for example, whose angle may be individually set. Such partitioned light beams may travel along substantially the same paths or diverging paths, though in either case such beams may be incident on one or more portions of micro-reflector array  620 . 
     In a particular implementation, a portion of micro-reflector array  620  may be set at a first angle while another portion may be set at a second angle, for example. As a result, light beam  630  may be reflected at a first angle leading to beam  635  and light beam  640  may be reflected at a second angle leading to beam  645 . Beam  635  may be projected onto a distance measurement point on surface  650  along a first line, and beam  645  may be projected onto a distance measurement point on surface  650  along a second line orthogonal to the first line. First and second lines may be similar to orthogonal lines  410  and  420  on surface  400  in  FIG. 4 , for example, which may be used for process  300  in  FIG. 3 . In this fashion, distances to points along the first and second lines may be measured simultaneously, thus shortening a time it may take to measure a closest distance to surface  650 . Multiple wavelengths and/or encoded pulses of beams  635  and  645  may allow a receiver (not shown) to distinguish a reflection from surface  650  of beam  635  from that of beam  645 . Such a receiver may measure propagation time of beams  635  and  645 , as discussed above. Of course, such methods of partitioning energy to distinguish among multiple energy beams reflected from a surface are merely examples, and claimed subject matter is not so limited. 
     In another implementation, a handheld device, such as a cellular phone, PDA, and the like, may include a size sensor to determine a distance between two point on a surface of a remote object. If the two points correspond to edges of such a remote object, then a distance between the two points may comprise a size of the object, for example. Such a size sensor may comprise a distance sensor that includes an emitter and a receiver to emit and receive sound, light, IR and/or RF energy, and a time module to determine a propagation time of the emitted energy as it travels to and from the remote surface. A size sensor may also include a special purpose processor adapted to determine distances to points on the surface and to use such determined distances to calculate a distance between two such points. Additionally, such a size sensor may have a sufficiently small form factor in order to fit in a handheld device such as a cellular phone or PDA, for example. In a particular implementation, a distance sensor may be capable of emitting sound, light, IR and/or RF energy along multiple angles. Individual angles may respectively correspond to particular distance measurement points on the remote surface. Determining distances to the remote surface along individual angles may yield multiple distance measurements. Two such measurements, for example, may be used to calculate a distance between two corresponding points on the remote surface. 
       FIG. 7  is a diagram depicting a user  720  holding a handheld device  740  a distance from a remote surface  750 . The handheld device may include a distance sensor  730  measuring several distances to surface  750 , according to an implementation. Such a distance sensor may comprise a portion of a distance sensor that is disposed in handheld device  740 , such as a cell phone for example, as mentioned above. In one particular implementation, similar to distance sensor  100  shown in  FIG. 1 , distance sensor  730  may transmit and receive with sound energy comprising substantially directed sound waves having subsonic or supersonic frequencies. In another particular implementation, distance sensor  730  may transmit and receive with electromagnetic (EM) energy comprising RF radiation, and/or laser light having visible or IR wavelengths. Of course, such descriptions of sound and EM energy are merely examples, and claimed subject matter is not so limited. Again, similar to distance sensor  100  shown in  FIG. 1 , distance sensor  730  may emit such energy toward a point  705  and/or  710  on surface  750 . Such energy may comprise a pulse of energy, e.g., a relatively short wave-train of sound and/or EM energy having a begin and end time. Such a pulse may be encoded, for example, to provide a means for distinguishing multiple received pulses from one another. Subsequently, energy reflected from surface  750  may travel back to distance sensor  730 , where a measurement of time elapsed between emission and reception at the receiver may be performed. Such an elapsed time may be referred to as propagation time. Using knowledge of the speed of sound and/or EM energy emitted and received by the distance sensor and the measured propagation time, a distance from the distance sensor to the remote surface may be determined. As shown in  FIG. 7 , distance sensor  730  may be held at a skewed angle  725  relative to surface  750 . For example, such an angle need not be perpendicular to remote surface  750 . At such an angle, distance sensor  730  may be adapted to emit energy toward either point  705  or  710  on surface  750  without user  720  changing a position of distance sensor  730 . In other words, distance sensor  730  may redirect emitted energy toward various directions without rotating handheld device  740 . 
       FIG. 8  is a detailed view showing a handheld device  840  measuring several distances to a surface  850 , according to an implementation. Handheld device  840  may comprise a cell phone, a PDA, and the like, and include a distance sensor  830 . Such a sensor, as mentioned above, may have a small form factor to enable the sensor to fit in handheld device  840  As shown in  FIG. 8 , such a distance sensor  830  may emit sound and/or EM energy along multiple angles toward multiple distance measurement points on surface  850 . In a particular implementation, distance sensor  830  may include one or more rotatable micro-reflectors mounted on a semiconductor device. Such rotatable micro-mirrors, which are explained in more detail below, may provide the small form factor mentioned above, for example. Of course, such a description of a distance sensor in conjunction with handheld device  840  is merely an example, and claimed subject matter is not so limited. In an example, a user  820  may hold handheld device  840  toward surface  850  to direct an energy beam along a distance D1 to point  805  on surface  850  to measure distance D1. Distance sensor  830  may then redirect an energy beam along distance D2 to another point  810  on surface  850  to measure a distance to surface  850  along the direction of D2. An angle  825  of such a redirection may be measured by distance sensor  830 , as explained in detail below. After such a process of measuring distances D1 and D2, distance sensor  830  may calculate a distance D3 between two points  805  and  810  on surface  850 . Such a calculation may involve measured distances D1 and D2 and measured angle  825 . Of course, such a process involving a distance sensor is merely an example, and claimed subject matter is not so limited. 
       FIG. 9  is a flow diagram of a process  900  for determining a distance on a remote surface, according to an implementation. Returning to the implementation shown in  FIG. 8 , such a surface may include surface  850  for example. At block  910 , a user  820  holding a handheld device  840  may direct energy toward a first point  805  on a surface. Such energy may be emitted by an emitter included in a distance sensor  830  on board the handheld device for example. As described above, the emitter may emit an energy beam toward the first point. Accordingly, at block  920 , a distance D1 to the first point may be measured. In one particular implementation, user  820  may select the first point to be along an edge of an object (not shown) and subsequently select a second point to be along an opposite edge of the object in order to measure a size of the object. In another particular implementation, a user may select first and second points anywhere on a surface of an object in order to measure a distance between the two points. Returning to process  900  at block  930 , distance sensor  830  may include one or more micro-reflectors ( FIGS. 11 and 12 ) that may be rotated to redirect a measurement direction toward a second point. Such a rotation may be performed by user  820  activating one or more controls (not shown) on handheld device  840 , for example. Such controls may actuate a rotation of the one or more micro-reflectors. An angle of rotation, such as angle  825  shown in  FIG. 8  for example, may be measured and stored by the distance sensor. In a particular implementation, the user may hold the handheld device substantially stationary in the position used to aim the device toward the first point. At block  940 , the user may measure the distance to the second point using the redirected energy. At block  950 , using measured distances to first and second points and the rotation angle of the micro-reflectors subtended from the first point to the second point, a distance between the first and second points may be calculated using a geometrical relation, such as the Law of Cosines, for example. 
       FIG. 10  is a flow diagram of a process  1000  for determining a distance on a remote surface, according to an implementation. Returning again to the implementation shown in  FIG. 8 , such a surface may include surface  850  for example. At block  1010 , a user  820  holding a handheld device  840  may aim an emitter, which may be included in a distance sensor  830  on board the handheld device for example, toward a first point  805  on a surface. As described above, the emitter may emit an energy beam toward the first point. Accordingly, at block  1020 , a distance D1 to the first point may be measured. At block  1030 , user  820  may rotate handheld device  840  to consequently rotate an emitted energy beam toward a second point in order to measure distance D2 to the second point. In a particular implementation, distance sensor  830  may include angle and/or direction-measuring transducers, such as a clinometer and/or a compass. Using such transducers, the angle, such as angle  825 , at which handheld device  840  is rotated from a direction of the first point to that of the second point may be measured. Distance sensor  830  may then store such an angle. At block  1040 , the user may measure the distance to the second point using the redirected energy. At block  1050 , using measured distances to first and second points and the rotation angle of the handheld device subtended from the first point to the second point, a distance between the first and second points may be calculated using a geometrical relation, such as the Law of Cosines, as mentioned above. 
       FIG. 11  is a schematic diagram showing a mobile device  1100  that includes a distance sensor for measuring distances to multiple distance measurement points on a surface  1150 , according to one implementation. Such a mobile device may include a two-way communication system  1128 , such as a cellular communication system, Bluetooth, RFID, and/or WiFi, just to name a few examples, which may transmit and receive signals via antenna  1122 . Upon receiving emitted energy from an emitter  1110 , a rotatable reflector  1120  may direct energy  1140  via opening  1130  toward various distance measurement points on surface  1150 . A special purpose processor  1108  may transmit information to a rotation controller  1125  that may send signals to rotatable reflector  1120  that determine at least in part the angular position of the rotatable reflector. In one particular implementation, rotatable reflector  1120  may comprise a reflector to reflect EM energy emitted by emitter  1110 . Such a reflector may be rotated by a stepper motor that receives signals from rotation controller  1125 , for example. In another particular implementation, rotatable reflector  1120  may comprise a micro-reflector array to reflect EM energy emitted by emitter  1110 . The angle of reflection of such an array may be determined at least in part by signals from rotation controller  1125  that operate multiple micro-reflectors in the array, for example. Rotation controller  1125  may operate such an array of micro-reflectors in unison so that multiple micro-reflectors have substantially identical reflecting angles, or individual micro-reflectors may have reflecting angles different from one another, as will be discussed below. In yet another particular implementation, rotatable reflector  1120  and emitter  1110  may be combined into a rotating emitter (not shown) to direct sound energy at various angles. The angle of such a rotating emitter may be determined at least in part by signals from rotation controller  1125  that may operate a motor such as a stepper motor, for example. Of course, such emitters are merely examples, and claimed subject matter is not so limited. 
     Receiver  1115  may receive energy  1145  reflected from surface  1150  after a propagation time delay from when energy  1140  was emitted from emitter  1110 . Such a delay may be measured by a time module  1105 , which may monitor signals transmitted from processor  1108  to emitter  1110  that initiate the emitter to emit energy  1140 , for example. Accordingly, time module  1105  may measure a time difference between when energy  1140  is emitted and energy  1145  is received. Of course, such methods of measuring propagation time of energy are merely examples, and claimed subject matter is not so limited. Returning to  FIG. 11 , user I/O  1118  may provide user access and/or control to distance sensor  1100  via processor  1108 . For example, such control may comprise a rotation control of rotatable reflector  1120  to redirect energy  1140  from a first point on a surface to a second point on the surface, as described above. 
     In an implementation, an emitter, such as emitter  1110 , may include a mechanically rotatable reflector capable of directing sound, light, IR and/or RF energy along multiple angles toward a surface to be measured, for example. Such a rotatable reflector may comprise a micro-reflector device, such as a micro-mirror array mounted on a semiconductor device, also known as a digital mirror device, for example. Depending on what type of energy is to be reflected, such a rotatable reflector may include various coatings and/or treatment to improve reflectance. Such a rotatable reflector may also include various reflecting-surface shapes, such as planar, spherical, parabolic, concave, convex, and so on. Such a rotatable reflector may have a relatively small form factor, allowing the rotatable reflector, among other things, to fit in a handheld device, for example. Of course, such a micro-reflector device is merely an example of a small form factor rotatable reflector, and claimed subject matter is not so limited. 
       FIG. 12  is a schematic diagram showing a mobile device  1200  that includes a distance sensor for measuring distances to multiple distance measurement points on a surface  1250 , according to one implementation. Such a mobile device may include a two-way communication system  1228 , such as a cellular communication system, Bluetooth, RFID, and/or WiFi, just to name a few examples, which may transmit and receive signals via antenna  1222 . Upon receiving emitted energy from an emitter  1210 , a reflector  1220 , which may be fixed with respect to the mobile device, may direct energy  1240  via opening  1230  toward various distance measurement points on surface  1250 . A special purpose processor  1208  may receive information from one or more transducers  1260  adapted to measure angles in various planes of motion. For example, transducers  1260  may comprise one or more compasses and/or clinometers. Accordingly, such information communicated from transducers  1260  to processor  1208  may comprise angles of rotation of mobile device  1200 . In a particular implementation, reflector  1220  may comprise a micro-reflector array to reflect EM energy emitted by emitter  1210 . Of course, such a description of a mobile device is merely an example, and claimed subject matter is not so limited. 
     Similar to a process described for  FIG. 11 , receiver  1215  may receive energy  1245  reflected from surface  1250  after a propagation time delay from when energy  1240  was emitted from emitter  1210 . Such a delay may be measured by a time module  1205 , which may monitor signals transmitted from processor  1208  to emitter  1210  that initiate the emitter to emit energy  1240 , for example. Accordingly, time module  1205  may measure a time difference between when energy  1240  is emitted and energy  1245  is received. Of course, such methods of measuring propagation time of energy are merely examples, and claimed subject matter is not so limited. Returning to  FIG. 12 , user I/O  1218  may provide user access and/or control to distance sensor  1330  via processor  1208 . 
       FIG. 13  is a diagram depicting a non-stationary handheld device  1340  measuring several distances to a surface  1350 , according to an implementation. Such movement of a handheld device may arise, for example, from the time when a distance to a first point  1305  on a surface is measured to the time when a distance to a second point  1310  on the surface is measured. Perhaps a user&#39;s unsteady hand holding the handheld device results in such a movement, and/or a user may be in motion while performing distance measurements. As for the implementation shown in  FIG. 8 , a handheld device  1340  may comprise a cell phone, a PDA, and the like, and include a distance sensor  1330 . Such a sensor, as mentioned above, may have a small form factor to enable the sensor to fit in handheld device  1340 . Such a distance sensor  230  may emit sound and/or EM energy along multiple angles toward multiple distance measurement points on surface  1350 , as described above. 
     In a particular implementation, distance sensor  1330  may include one or more rotatable micro-reflectors mounted on a semiconductor device. Such rotatable micro-mirrors, explained above, may provide the small form factor mentioned above, for example. Of course, such a description of a distance sensor in conjunction with handheld device  1340  is merely an example, and claimed subject matter is not so limited. In an example, a user  1320  may hold handheld device  1340  toward surface  1350  to direct an energy beam along a distance D4 to point  1305  on surface  1350  to measure distance D4. Distance sensor  1330  may then redirect an energy beam along distance D5 to another point  1310  on surface  1350  to measure a distance to surface  1350  along the direction of D5. In another implementation, user  1320  may redirect the energy beam to another point  1310  by rotating handheld device  1340 , wherein handheld device need not include a rotatable reflector, for example. An angle of such a redirection may be measured by angle and/or direction-measuring transducers, such as a clinometer and/or a compass, which handheld device  1340  may include. In other words, such transducers may measure the angle at which handheld device  1340  is rotated from a direction of the first point to that of the second point. Distance sensor  1330  may then store such an angle. 
     Handheld device  1340  may be adapted to measure its position using various positioning systems, including a satellite positioning system (SPS), such as the Global Positioning System (GPS), the Wide Area Augmentation System (WAAS), and the Global Navigation Satellite System (GLONASS), for example, which may provide position, velocity, and/or time information. In a particular implementation, position information may be provided to handheld device  1340  by acquisition of SPS signals or signals from positioning technologies other than SPS, such as WiFi signals, Bluetooth, RFID, Ultra-wideband (UWB), Wide Area Network (WAN), digital TV, and/or cell tower ID, just to name a few examples. Such signals may be received via antenna  1222  shown in  FIG. 12 , for example. Accordingly, handheld device  1340  may be adapted to measure a position displacement ΔXYZ from a position where D4 is measured to a position where D5 is measured. After such a process of measuring distances D4 and D5, ΔXYZ, and the angle of redirection from first point  1305  to second point  1310 , distance sensor  1330  may calculate a distance D6 between two points  1305  and  1310  on surface  1350 . Of course, such a process involving a distance sensor is merely an example, and claimed subject matter is not so limited. 
     Methodologies described herein may be implemented by various means depending upon applications according to particular features and/or examples. For example, such methodologies may be implemented in hardware, firmware, software, and/or combinations thereof. In a hardware implementation, for example, a processing unit may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, electronic devices, other devices units designed to perform the functions described herein, and/or combinations thereof. 
     For a firmware and/or software implementation, methodologies may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. Any machine-readable medium tangibly embodying instructions may be used in implementing the methodologies described herein. For example, software codes that represent electronic signals, such as digital electronic signals, may be stored in a memory, for example the memory of a mobile station, and executed by a specialized processor, such as processors  508  or  1108  in  FIG. 5  or  11 , respectively. Memory may be implemented within the processor or external to the processor. As used herein the term “memory” refers to any type of long term, short term, volatile, nonvolatile, or other memory and is not to be limited to any particular type of memory or number of memories, or type of media upon which memory is stored. 
     In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code that represent signals on a computer-readable medium. Computer-readable media includes physical computer storage media. Transmission media includes physical transmission media. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. 
     While there has been illustrated and described what are presently considered to be example features, it will be understood by those skilled in the art that various other modifications may be made, and equivalents may be substituted, without departing from claimed subject matter. Additionally, many modifications may be made to adapt a particular situation to the teachings of claimed subject matter without departing from the central concept described herein. Therefore, it is intended that claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter may also include all aspects falling within the scope of appended claims, and equivalents thereof.