Patent Publication Number: US-11650080-B2

Title: Optical-path folding-element with an extended two degree of freedom rotation range

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation from U.S. patent application Ser. No. 17/829,722 filed Jun. 1, 2022 (now allowed), which was a continuation of U.S. patent application Ser. No. 17/013,561 filed Sep. 5, 2020 (now U.S. Pat. No. 11,359,937), which was a continuation application from U.S. patent application Ser. No. 16/615,310 filed Nov. 20, 2019 (now U.S. Pat. No. 11,268,829), which was a 371 application from international patent application PCT/IB2019/053315 filed Apr. 22, 2019, and is related to and hereby claims the priority benefit of commonly-owned and U.S. Provisional Patent Application No. 62/661,158 filed Apr. 23, 2018, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The subject matter disclosed herein relates in general to a folded-lens and to digital cameras with one or more folded lens. 
     BACKGROUND 
     In recent years, mobile devices such as cell-phones (and in particular smart-phones), tablets and laptops have become ubiquitous. Many of these devices include one or two compact cameras including, for example, a main rear-facing camera (i.e. a camera on the back face of the device, facing away from the user and often used for casual photography), and a secondary front-facing camera (i.e. a camera located on the front face of the device and often used for video conferencing). 
     Although relatively compact in nature, the design of most of these cameras is similar to the traditional structure of a digital still camera, i.e. it comprises a lens module (or a train of several optical elements) placed on top of an image sensor. The lens module refracts the incoming light rays and bends them to create an image of a scene on the sensor. The dimensions of these cameras are largely determined by the size of the sensor and by the height of the optics. These are usually tied together through the focal length (“f”) of the lens and its field of view (FOV)— a lens that has to image a certain FOV on a sensor of a certain size has a specific focal length. Keeping the FOV constant, the larger the sensor dimensions (e.g. in a X-Y plane), the larger the focal length and the optics height. 
     A “folded camera module” structure has been suggested to reduce the height of a compact camera. In the folded camera module structure, an optical path folding element (referred to hereinafter as “OPFE” that includes a reflection surface such as a prism or a mirror; otherwise referred to herein collectively as a “reflecting element”) is added in order to tilt the light propagation direction from a first optical path (e.g. perpendicular to the smart-phone back surface) to a second optical path, (e.g. parallel to the smart-phone back surface). If the folded camera module is part of a dual-aperture camera, this provides a folded optical path through one lens module (e.g. a Tele lens). Such a camera is referred to herein as a “folded-lens dual-aperture camera” or a “dual-aperture camera with a folded lens”. In some examples, the folded camera module may be included in a multi-aperture camera, e.g. together with two “non-folded” camera modules in a triple-aperture camera. 
     A folded-lens dual-aperture camera (or “dual-camera”) with an auto-focus (AF) mechanism is disclosed in Applicant&#39;s US published patent application No. 20160044247. 
     SUMMARY 
     According to one aspect of the presently disclosed subject matter there is provided an actuator for rotating an OPFE in two degrees of freedom in an extended rotation range a first sub-assembly, a second sub-assembly and a stationary sub-assembly, the first sub-assembly configured to rotate the OPFE relative to the stationary sub-assembly in an extended rotation range around a yaw rotation axis and the second sub-assembly configured to rotate the OPFE relative to the first sub-assembly in an extended rotation range around a pitch rotation axis that is substantially perpendicular to the yaw rotation axis; a first sensor configured to sense rotation around the yaw rotation axis and a second sensor configured to sense rotation around the pitch rotation axis, the first and second sensors being fixed to the stationary sub-assembly, wherein at least one of the first sensor or the second sensor is a magnetic flux sensor; and a voice coil motor (VCM) comprising a magnet and a coil, wherein the magnet is fixedly attached to one of the first sub-assembly or the second sub-assembly, wherein the coil is fixedly attached to the stationary sub-assembly, wherein a driving current in the coil creates a force that is translated to a torque around a respective rotation axis, and wherein the second sensor is positioned such that sensing by the second sensor is decoupled from the rotation of the OPFE around the yaw rotation axis. 
     In addition to the above features, the actuator according to this aspect of the presently disclosed subject matter can optionally comprise one or more of features (i) to (xxv) listed below, in any technically possible combination or permutation:
         i. wherein the actuator is adapted to be installed and operable in a folded digital camera for rotating the OPFE within the camera,   ii. wherein the actuator comprises a first actuation mechanism (including a first VCM) configured to rotate the first sub-assembly around the yaw rotation axis and a second actuation mechanism (including a second VCM) configured to rotate the second sub-assembly around the yaw rotation axis,   iii. wherein the actuator comprises a first sensing mechanism that comprises the first sensor and a respective first magnet configured to sense the rotation around the yaw rotation axis and a second sensing mechanism that comprises the second sensor and a second magnet configured to sense the rotation around the pitch rotation axis,   iv. wherein the yaw rotation axis passes through the second sensor to thereby decouple the second sensor from rotation around the yaw axis,   v. wherein the yaw rotation axis passes through a center of the second sensor,   vi. wherein the actuator further comprises a first curved ball-guided mechanism operative to enable the rotation around the pitch axis, and a second curved ball-guided mechanism operative to enable the rotation around the yaw axis,   vii. wherein the actuator further comprises a curved ball-guided mechanism operative to enable the rotation around the yaw axis, the curved ball-guided mechanism is located on a side of the OPFE which is opposite to side facing an image sensor,   viii. wherein the extended rotation range is equal to or greater than ±5 degrees around the pitch and yaw rotation axes,   ix. wherein the extended rotation range is equal to or greater than ±10 degrees the pitch and yaw rotation axes,   x. wherein the extended rotation range is between ±15-40 degrees around the pitch and yaw rotation axes,   xi. wherein the extended rotation range around the pitch rotation axis is different from the extended rotation range around the second rotation axis,   xii. wherein the at least one voice coil motor includes a pitch magnet and a coil dedicated for generating the rotation around the pitch rotation axis and wherein the pitch magnet is designed with a flat surface facing the coil,   xiii. wherein the magnetic sensor is a magnetic flux sensor such as a Hall sensor.   xiv. wherein the actuator comprises a sensing mechanism that includes the first sensor and a magnet (e.g. yaw sensing magnet), the magnet is shaped or formed such that a central part of the sensing magnet is further away from a projection line of motion of the first sensor, relative to an end of the sensing magnet,   xv. wherein the actuator comprises a sensing magnet (e.g. yaw sensing magnet) shaped such that width of a cross section of the sensing magnet increases from a point substantially at its center towards each end of the magnet, thereby resulting in a variable distance between the first sensor and the magnet when relative movement occurs between the sensing magnet and the sensor,   xvi. wherein the actuator further comprises a first magnet-yoke pair which pulls the first sub-assembly to the second sub-assembly in a radial direction relative to the pitch rotation axis and a second magnet-yoke pair which pulls the first sub-assembly to the stationary sub-assembly in a radial direction relative to the yaw rotation axis,   xvii. wherein the first sub-assembly comprises a middle moving frame, the second sub-assembly comprises an OPFE holder, and the stationary sub-assembly comprises a base; wherein the first magnet-yoke pair pulls the OPFE holder to middle moving frame and the second magnet-yoke pair pulls the middle moving frame to the base,   xviii. wherein the first sub-assembly comprises a middle moving frame and the second sub-assembly comprises an OPFE holder, and the stationary sub-assembly comprises a base; wherein rotation around the yaw rotation axis is generated by rotating the middle moving frame relative to the base and rotation around the pitch rotation axis is generated by rotating the OPFE holder relative to the middle moving frame,   xix. wherein the actuator comprises a magnet characterized by a cut sphere shape and a coil characterized by a circular shape, the coil is symmetrically positioned around the cut sphere,   xx. wherein the actuator comprises a single magnet that is used for creating an actuation force for rotation around the yaw rotation axis, creating a pre-load force in a magnet-yoke pair for holding together the first sub-assembly and the stationary sub-assembly, and sensing the rotation around the yaw rotation axis.   xxi. wherein the actuator comprises only one magnetic flux sensor that is used for sensing rotation around the yaw rotation axis,   xxii. wherein the single magnet is a polarization magnet characterized by continuous changes in direction of a magnetic field of the magnet along the magnet&#39;s length. wherein the first and second sensing mechanisms are decoupled from each other,   xxiii. wherein the actuator is designed to be installed in a folded camera that comprises a lens module accommodating a plurality of lens elements along an optical axis; wherein the OPFE redirects light that enters the folded camera from a direction of a view section along a first optical path to a second optical path that passed along the optical axis,   xxiv. wherein the actuator comprises a pitch magnet located at a side of the OPFE that is opposite to the side facing the view section,   xxv. wherein the actuator comprises a yaw magnet located at a side of the OPFE that is opposite to the side facing the lens module,       

     According to another aspect of the presently disclosed subject matter there is provided a folded camera comprising the actuator according to the previous aspect. 
     In addition to the above features, the folded camera according to this aspect of the presently disclosed subject matter can optionally comprise one or more of features (i) to (xxv) listed above, in any technically possible combination or permutation. 
     According to yet another aspect of the presently disclosed subject matter there is provided an actuator for rotating an OPFE with a first degree of freedom (DOF) around a first rotation axis and a second DOF around a second rotation axis, comprising: 
     a) a first actuation mechanism for rotation in the first DOF; 
     b) a first sensing mechanism for sensing movement in the first DOF; 
     c) a second actuation mechanism for rotation in the second DOF; and 
     d) a second sensing mechanism for sensing movement in the second DOF; 
     wherein first and second actuation mechanisms are configured to rotate the OPFE around the respective first or second rotation axis in an extended rotation range, 
     and wherein in some examples the first and second actuation mechanism are voice coil motors and the second sensing mechanism comprises a sensor positioned such that rotation of the OPFE around the first rotation axis is decoupled from the second sensor. 
     In addition to the above features, the camera according to this aspect of the presently disclosed subject matter can optionally comprise one or more of features (i) to (xxv) listed above, in any technically possible combination or permutation. 
     According to another aspect of the presently disclosed subject matter there is provided a sensing mechanism for sensing rotation movement around a rotation axis, comprising a magnet and a magnetic sensor configured to detect a magnetic flux of the magnet and to determine a relative shift between the magnet and the magnetic sensor based on change in the detected magnetic flux, wherein the magnet is shaped such that a cross section of the magnet has a width that increases from a point substantially at a center of the magnet towards each end of the magnet, thereby increasing a range of detectable change in the magnetic flux and increasing a corresponding detectable range of the relative shift between the magnet and the magnetic sensor. 
     In addition to the above features, the actuator according to this aspect of the presently disclosed subject matter can optionally comprise one or more of features (i) to (iv) listed below, in any technically possible combination or permutation:
         i. wherein the detectible range of relative shift between the magnet and the magnetic sensor is of more than 0.8 mm,   ii. wherein the detectible range of relative shift between the magnet and the magnetic sensor is of more than 1.0 mm,   iii. wherein the detectible range of relative shift between the magnet and the magnetic sensor is of more than 2.0 mm, and   iv. wherein the magnetic sensor is a Hall bar sensor.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting examples of the presently disclosed subject matter are described below with reference to figures attached hereto that are listed following this paragraph. Identical structures, elements or parts that appear in more than one figure may be labeled with the same numeral in the figures in which they appear. The drawings and descriptions are meant to illuminate and clarify embodiments disclosed herein, and should not be considered limiting in any way. 
         FIG.  1 A  illustrates a folded camera with an optical path folding element (OPFE) with an extended 2 degrees-of-freedom (DOF) rotation range, according to some examples of the presently disclosed subject matter; 
         FIG.  1 B  shows the folded camera of  FIG.  1 A  with an OPFE actuator, according to some examples of the presently disclosed subject matter; 
         FIG.  1 C  shows a dual-camera the includes a folded camera as in  FIG.  1 A  together with an upright (non-folded) camera, according to according to some examples of the presently disclosed subject matter; 
         FIG.  2 A  shows an OPFE actuator of the folded camera of  FIG.  1    in an isometric view, according to some examples of the presently disclosed subject matter; 
         FIG.  2 B  shows the actuator in  FIG.  2 A  without a shield, according to some examples of the presently disclosed subject matter; 
         FIG.  3 A  shows a top actuated sub-assembly of the actuator of  FIGS.  2 A and  2 B  from one side, according to some examples of the presently disclosed subject matter; 
         FIG.  3 B  shows the top actuated sub-assembly of  FIG.  3 A  from an opposite side, according to some examples of the presently disclosed subject matter; 
         FIG.  3 C  shows the top actuated sub-assembly of  FIG.  3 A  in an exploded view, according to some examples of the presently disclosed subject matter; 
         FIG.  4 A  shows a bottom actuated sub-assembly of the actuator of  FIGS.  2 A and  2 B  from one side, according to some examples of the presently disclosed subject matter; 
         FIG.  4 B  shows the bottom actuated sub-assembly of  FIG.  4 A  from an opposite side, according to some examples of the presently disclosed subject matter; 
         FIG.  4 C  shows the bottom actuated sub-assembly in an exploded view, according to some examples of the presently disclosed subject matter; 
         FIG.  5 A  shows the top and bottom actuated sub-assemblies installed together in an isometric view, according some examples of the presently disclosed subject matter; 
         FIG.  5 B  shows the top and bottom actuated sub-assemblies installed together in a cut along a line A-B shown in  FIG.  5 A , according to some examples of the presently disclosed subject matter; 
         FIG.  6 A  shows a stationary sub-assembly of the actuator of  FIGS.  2 A and  2 B  from one side, according to some examples of the presently disclosed subject matter; 
         FIG.  6 B  shows the stationary sub-assembly of  FIG.  6 A  from an opposite side, according to some examples of the presently disclosed subject matter; 
         FIG.  6 C  shows the stationary actuated sub-assembly in an exploded view, according to some examples of the presently disclosed subject matter; 
         FIG.  7    shows the actuator of  FIG.  2 B  along a cut along line A-B shown in  FIG.  2 A , according to some examples of the presently disclosed subject matter; 
         FIG.  8    shows details of an electronic circuitry included in the stationary sub-assembly of  FIGS.  6 A- 6 C , according to some examples of the presently disclosed subject matter; 
         FIG.  9 A  shows a pitch actuation and sensing mechanism of the actuator in  FIGS.  2 A- 2 B  in an isometric view, according to some examples of the presently disclosed subject matter; 
         FIG.  9 B  shows a side cut along a line A-B shown in  FIG.  9 A  of the pitch actuation and sensing mechanism of  FIG.  9 A , according to some examples of the presently disclosed subject matter; 
         FIG.  10 A  shows a pitch actuation and sensing mechanism of the actuator in  FIGS.  2 A- 2 B  in an isometric view, according to other examples of the presently disclosed subject matter; 
         FIG.  10 B  shows a side cut of the pitch actuation and sensing mechanism of  FIG.  10 A  along a line A-B shown in  FIG.  10 A , according to some examples of the presently disclosed subject matter; 
         FIG.  11 A  shows a yaw sensing mechanism of the actuator in  FIGS.  2 A- 2 B , according to some examples of the presently disclosed subject matter; 
         FIG.  11 B  shows a yaw rotation range β, a distance R YAW  between a yaw Hall bar element and a yaw rotation axis, and a trajectory of a yaw sensing magnet of the yaw sensing mechanism of  FIG.  11 A  in the Y-Z plane, according to some examples of the presently disclosed subject matter; 
         FIG.  11 C  shows one magnetic configuration for the yaw sensing magnet of  FIG.  11 B  in a cut along a line A-B shown in  FIG.  11 A , according to some examples of the presently disclosed subject matter; 
         FIG.  11 D  shows another magnetic configuration for the yaw sensing magnet of  FIG.  11 B  in a cut along a line A-B shown in  FIG.  11 A , according to some examples of the presently disclosed subject matter; 
         FIG.  11 E  shows yet another magnetic configuration for the yaw sensing magnet of  FIG.  11 B  in a cut along a line A-B shown in  FIG.  11 A , according to some examples of the presently disclosed subject matter; 
         FIG.  11 F  shows the magnetic field as a function of rotation along a given trajectory for the cases presented in  FIGS.  11 C-E , according to some examples of the presently disclosed subject matter; 
         FIG.  11   - i  to  FIG.  11   - vi  show various possible alternative examples of magnetic configuration for the yaw sensing magnet. 
         FIG.  12 A  shows a yaw magnetic actuation mechanism in an isometric view from one side, according to some examples of the presently disclosed subject matter 
         FIG.  12 B  shows the yaw magnetic actuation mechanism of  FIG.  12 A  in an isometric view from another side, according to some examples of the presently disclosed subject matter; 
         FIG.  12 C  shows magnetic field directions in a Y-Z plane along a cut A-B in  FIG.  12 A , according to some examples of the presently disclosed subject matter; 
         FIG.  13    shows additional magnetic yoke positioned next to yaw magnet, according to some examples of the presently disclosed subject matter; 
         FIG.  14 A  is a schematic illustration of a stitched image generated from four Tele images, according to some examples of the presently disclosed subject matter; 
         FIG.  14 B  is a schematic illustration of a stitched image generated from six Tele images, according to some examples of the presently disclosed subject matter; 
         FIG.  14 C  is a schematic illustration of a stitched image generated from nine Tele images, according to some examples of the presently disclosed subject matter; 
         FIG.  15 A  is a cross section of top actuated sub-assembly and bottom actuated sub-assembly installed together along a cut along line A-B shown in  FIG.  15 B , according to other examples of the presently disclosed subject matter; 
         FIG.  15 B  is an isometric view of top actuated sub-assembly and bottom actuated sub-assembly installed together of the example shown in  FIG.  15 A , according to other examples of the presently disclosed subject matter; 
         FIG.  15 C  is an isometric view of top actuated sub-assembly and bottom actuated sub-assembly installed together, showing an external yoke, according to other examples of the presently disclosed subject matter; 
         FIG.  15 D  is a schematic illustration of a single polarization magnet, according to some examples of the presently disclosed subject matter; and 
         FIG.  15 E  is a schematic illustration of the magnetic field lines directions in a Y-Z plane of the single polarization magnet illustrated in  FIG.  15 D , according to some examples of the presently disclosed subject matter. 
     
    
    
     DETAILED DESCRIPTION 
     For the sake of clarity, the term “substantially” is used herein to imply the possibility of variations in values within an acceptable range as would be known to a person skilled in the art. According to one example, the term “substantially” used herein should be interpreted to imply possible variation of up to 10% over or under any specified value. According to another example, the term “substantially” used herein should be interpreted to imply possible variation of up to 5% over or under any specified value. According to a further example, the term “substantially” used herein should be interpreted to imply possible variation of up to 2.5% over or under any specified value. For example, the phrase substantially perpendicular should be interpreted to include possible variations from exactly 90°. 
       FIG.  1 A  illustrates a folded camera  100  with a 2 degrees-of-freedom (DOF) optical path folding element (OPFE) with an extended rotation range, according to an example of the presently disclosed subject matter. An orthogonal X-Y-Z coordinate (“axis”) system shown applies also to all following drawings. This coordinate system is exemplary only and should not be construed as limiting. In some examples, the term “extended rotation range” used herein is used to describe a rotation range larger than the 2-3 degrees necessary for another application, for example optical image stabilization (OIS). In an example, an extended rotation range may be a range equal to or greater than ±5 degrees in each DOF relative to an OPFE zero state (as defined below). According to another example, an extended rotation range may be a range equal to or greater than ±10 degrees in each DOF relative to an OPFE zero state (as defined below). According to yet another example, an extended rotation range may be a range between ±15-40 degrees in each DOF relative to an OPFE zero state (as defined below). The extended rotation range may or may not be equal in the two DOF. In an example, the extended rotation range may be twice or more in the yaw DOF than in the pitch DOF, because the optical effect (shift of image on the image sensor) of pitch rotation is double the optical effect of yaw rotation. 
     Camera  100  includes a lens assembly or lens module (or simply “lens”)  102 , an OPFE  104  and an image sensor  106 . In general lens module  102  comprises a plurality of lens elements positioned along an optical axis, for example between 3 to 7 lens elements. In some examples, lens  102  has a fixed focal length “f”. In other examples, lens  102  has a variable focal length (zoom lens). In some examples, lens  102  may be a lens designed for folded cameras described for example in co-owned U.S. Pat. No. 9,392,188. OPFE  104  has a reflection surface (e.g. it may be a mirror or a prism). 
     OPFE  104  folds light from a first optical path  108  to a second optical path  110 . First optical path  108  extends from the direction of a view section  114  (facing an object or scene) towards OPFE  104  and is substantially parallel to the X axis (in the exemplary coordinate system). Second optical path  110  extends from OPFE  104  towards image sensor  106  and is substantially parallel to the Z axis (in the exemplary coordinate system). 
     View section  114  may include, for example, one or more objects, a scene and/or a panoramic view, etc. According to the illustrated example, axis  110  is aligned with the optical axis of lens  102 , and therefore is also referred to herein as “lens optical axis” Image sensor  106  may be aligned with a plane substantially perpendicular to axis  110  (a plane that includes the X and Y axes). Image sensor  106  may output an output image. The output image may be processed by an image signal processor (ISP—not shown), the processing including for example, demosaicing, white balance, lens shading correction, bad pixel correction and other processes that may be carried out by an ISP. In some embodiments, the ISP (or some functionalities of the ISP) may be part of image sensor  106 . 
     It is noted that while the OPFE and some of the parts described below may be configured to rotate in two DOF, all the figures, the description and the directions therein show the OPFE in a “zero” state (without rotation) unless otherwise mentioned. 
     For the sake of clarity of the description and by way of a non limiting example only, it is defined that at zero state the first optical path  108  extending from the direction of view section  114  towards the OPFE  104  is perpendicular to a zero plane. The term “zero plane” as used herein refers to an imaginary plane on which an actuator  202  described below is positioned and is parallel to the lens optical axis. For example, in a mobile phone, the zero plane is a plane parallel to the screen of the phone. 
     Furthermore, in zero state the reflecting surface of the OPFE is positioned such that light along the first optical path  108  is redirected to a second optical path  108  that coincides with lens optical axis  110 . Notably, the above definition is assumed to be true for the center of the field of view (FOV). 
     Yaw rotation can be defined as rotation around an axis substantially parallel to the first optical path in zero state. Pitch rotation can be defined as rotation around an axis substantially perpendicular to the yaw rotation axis and the lens optical axis. 
     In some examples, camera  100  may further include a focus or autofocus (AF) mechanism (not shown), allowing to move (or “shift” or “actuate”) lens  102  along axis  110 . The AF mechanism may be configured to adjust the focus of the camera on view section  114 . Adjusting the focus on view section  114  may bring into focus one or more objects and/or take out of focus one or more objects that may be part of view section  114 , depending on their distance from OPFE  104 . For simplicity, the description continues with reference only to AF mechanisms, with the understanding that it also covers regular (manual) focus. 
     An AF mechanism may comprise an AF actuation mechanism. The AF actuation mechanism may comprise a motor that may impart motion such as a voice coil motor (VCM), a stepper motor, a shape memory alloy (SMA) actuator and/or other types of motors. An AF actuation mechanism that comprises a VCM may be referred to as a “VCM actuator”. Such actuation mechanisms are known in the art and disclosed for example in Applicant&#39;s co-owned international patent applications PCT/IB2015/056004 and PCT/IB2016/055308. In some embodiments, camera  100  may include an optical image stabilization (OIS) actuation mechanism (not shown) in addition to, or instead of, the AF actuation mechanism. In some embodiments, OIS may be achieved by shifting lens  102  and/or image sensor  106  in one or more directions in the X-Y plane, compensating for tilt of camera  100  around the Z and Y directions. A three-degrees of freedom (3-DOF) OIS and focus actuation mechanism (which performs two movements for OIS and one for AF) may be of VCM type and known in the art, for example as disclosed in international patent application PCT/US2013/076753 and in US patent application 2014/0327965. In other embodiments, OIS may be achieved by shifting the lens in one direction (i.e. the Y direction), perpendicular to both the first and second optical paths, compensating for tilt of camera  100  around the Z direction (lens optical axis). In this case, a second OIS operation, compensating for tilt of camera  100  around the Z direction may be done by tilting the OPFE around the Y axis, as demonstrated below. More information on auto-focus and OIS in a compact folded camera may be found in Applicant&#39;s co-owned international patent applications PCT/IB2016/052143, PCT/IB2016/052179 and PCT/IB2016/053335. 
     Camera  100  is designed with a capability to rotate OPFE  104  with at least two DOF (2-DOF) in an extended rotation range. Rotation can be done for example using OPFE actuator  120 , seen in  FIG.  1 B . Two-DOF rotation may be used to describe rotation of the prism around two axes (each axis being a DOF); in camera  100 , the degrees of freedom are a yaw rotation  132  around yaw rotation axis  122  which is parallel to first optical path  108  (X axis) when in zero state as defined above, and a pitch rotation  134  around a pitch rotation axis  124  which is parallel to the Y axis. In camera  100 , yaw rotation axis  122  and pitch rotation axis  124  may intersect, which may reduce coupling between a pitch sensing mechanism and yaw rotation, as described below with reference to  FIG.  9   . In camera  100 , lens optical axis  110  intersects the intersection point of yaw rotation axis  122  and pitch rotation axis  124 . In other embodiments, this may not be the case. 
     As shown in  FIG.  1 C , camera  100  may be a part of a dual-camera  180 . Dual-camera  180  comprises camera  100  and an upright camera  190 . Upright camera  190  includes a lens  192  and an image sensor  194 . Upright camera  190  may further include other parts such as a shield, a focus or AF mechanism, and/or an OIS mechanism (all of which are not shown), as known in the art. Cameras  100  and  190  may share some or all of respective fields of view (FOVs). According to some examples, camera  190  may have a wider FOV than camera  100 . In such an example, camera  100  will be referred as a “Tele camera”, while camera  190  will be referred as a “Wide camera”. In such an example, a scanning mechanism of camera  100  may be used to cover some or all of the FOV of camera  190 , as explained in the description below of  FIGS.  14 A- 14 C . In other examples, camera  100  may be a part of a multiple aperture camera (multi-camera) comprising more than two cameras, e.g. comprising two or more additional upright and/or two or more additional folded cameras. Notably, while characterized by extended rotation ranges, camera  100  and actuator  120  may also be capable of performing small range (1-2 degree) actuations with high accuracy, which enable OIS around any position in the extended rotation range. 
       FIGS.  2 A-B  show OPFE actuator  120  with more details according to some non-limiting examples of the presently disclosed subject matter.  FIG.  2 A  shows OPFE actuator  120  in an isometric view. OPFE actuator  120  may be covered by a shield  202  with an opening  204  through which light can enter into OPFE  104  and an opening  206  through which light can exit from OPFE  104 .  FIG.  2 B  shows actuator  120  without shield  202 . Actuator  120  further includes a bottom actuated sub-assembly  220  (also referred to herein as “yaw sub-assembly” or “first sub-assembly”), a top actuated sub-assembly  210  (also referred to herein as “pitch sub-assembly” or “second sub-assembly”), and a stationary sub-assembly  230 . Top actuated sub-assembly  210  may be operable to be rotated, and thus rotate OPFE  104 , around the pitch rotation axis (parallel to the Y axis) relative to bottom actuated sub-assembly  220  (pitch rotation  134 ), as described below. Bottom actuated sub-assembly  220  may be operable to be rotated, and thus rotate OPFE  104 , around the yaw rotation axis (parallel to the X axis) relative to stationary sub-assembly  230  (yaw rotation  132 ), as described below. 
     As described in more detail below, according to one example, the bottom (yaw) actuated sub-assembly  220  rotates relative to a stationary sub-assembly and the top (pitch) actuated sub-assembly  210  rotates relative to the bottom sub-assembly, thus the bottom sub-assembly acts as a master and the top sub-assembly acts as a slave. Applicant has found that this design, with the bottom actuated sub-assembly used for yaw rotation and the top actuated sub-assembly used for pitch rotation, and with the bottom actuated sub-assembly serving as a master and the top actuated sub-assembly serving as a slave, enables to maintain a lower overall height of the actuator and thus to mitigate a penalty on the folded camera height. 
       FIGS.  3 A-C  show top (pitch) actuated sub-assembly  210  with more details in an isometric view from one side ( FIG.  3 A ), an isometric view from another side ( FIG.  3 B ), and an exploded view ( FIG.  3 C ), according to some non-limiting examples of the presently disclosed subject matter. Top actuated sub-assembly  210  includes an OPFE, holder (or carrier)  302  that can be made, for example, by a plastic mold that fits the shape of OPFE  104 . Top actuated sub-assembly  210  further includes a permanent (fixed) pitch magnet  304 . Pitch magnet  304 , as well as all other magnets in this application, can be for example a permanent magnet, made from a neodymium alloy (e.g. Nd 2 Fe 14 B) or a samarium-cobalt alloy (e.g. SmCo 5 ), and can be made by sintering. According to one example, pitch magnet  304  is fixedly attached (e.g. glued) to OPFE carrier  302  from below (negative X direction in  FIG.  3 A ). Hereinafter, the term “below” used with reference to the position of OPFE  104  refers to a side of the OPFE opposite to the side facing the view section (in the negative X direction relative to the view). Details of pitch magnet  304  and its operation are given below. In some examples, OPFE carrier  302  includes (e.g. is molded with) two pins  308 . 
     Sub-assembly  210  may further include two ferromagnetic yokes  306 . Ferromagnetic yokes  306  may be attached (e.g. glued) to OPFE holder  302  on pins  308 . Ferromagnetic yokes  306  may be made of a ferromagnetic material (e.g. iron) and have an arced (curved) shape with a center on pitch rotation axis  124 . Ferromagnetic yokes  306  are pulled by pitch-pull magnets  408  (see  FIGS.  4 A,  4 C ) to attach top actuated sub-assembly  210  to bottom actuated sub-assembly  220  as described below with reference to  FIGS.  5 A- 5 C . OPFE holder  302  may further include (e.g. is molded with) two parallel arc-shaped (curved) grooves  310   a  and  310   b  ( FIG.  3 B ) positioned at two opposite sides of OPFE holder  302 , each arc-shaped groove having an angle α′&gt;α, where angle α is a desired pitch stroke, as defined by optical needs. Angle α′ is shown in  FIG.  5 B . Arc-shaped grooves  310   a  and  310   b  have a center of curvature on pitch rotation axis  124  (see  FIGS.  3 A,  5 A,  5 B ). OPFE holder  302  further includes (e.g. is molded with) two stoppers  312  ( FIG.  3 A ) positioned at two opposite sides of OPFE holder  302 . Stoppers  312  are used to stop OPFE  104  in a required position. 
       FIGS.  4 A-C  show bottom (yaw) actuated sub-assembly  220  with more details in an isometric view from one side ( FIG.  4 A ), an isometric view from another side ( FIG.  4 B ), and an exploded view ( FIG.  4 C ). Bottom actuated sub-assembly  220  includes a middle moving frame  402  which can be made, for example, by a plastic mold. Bottom actuated sub-assembly  220  further included four permanent (fixed) magnets: a yaw actuation magnet  404 , a yaw sensing magnet  406 , and two pitch-pull magnets  408 . All magnets are fixedly attached (e.g. glued) to middle moving frame  402 . Notably, yaw magnet  404  is located on a side of the OPFE that is opposite to the side facing lens module  102  in camera  100 . Details of all magnets and their operation are given below. 
     Bottom actuated sub-assembly  220  further includes two stoppers  410 , made for example from a non-magnetic metal. Stoppers  410  are fixedly attached (e.g. glued) to middle moving frame  402 . Stoppers  410  help to prevent top actuated sub-assembly  210  from detaching from bottom actuated sub-assembly  220  in case of a strong external impact or drop, as described in more detail below. Middle moving frame  402  includes (i.e. is molded with) two parallel arc-shaped (curved) grooves  412  ( FIG.  4 A ) positioned at two opposite sides of middle moving frame  402 , each arc-shaped groove having an angle α″&gt;α. Angle α is shown in  FIG.  5 B . Arc-shaped grooves  412  have a center of curvature on yaw rotation axis  122  ( FIG.  5 B ) in common with arc shaped grooves  310 . Middle moving frame  402  further includes (e.g. is molded with) two parallel arc-shaped (or “curved”) grooves  414  ( FIG.  4 B ) positioned at a back side of middle moving frame  402  (negative Z axis), each arc-shaped groove having an angle β′&gt;β, where angle ( 3  is a required yaw stroke, as defined by optical needs. Angle β′ is shown in  FIG.  7   . Arc-shaped grooves  414  have a center of curvature on yaw rotation axis  122  ( FIG.  7   ). 
       FIGS.  5 A-B  show top actuated sub-assembly  210  and bottom actuated sub-assembly  220  installed together.  FIG.  5 A  shows an isometric view and  FIG.  5 B  shows a cut along line A-B in  FIG.  5 A . The figures also show various elements described above.  FIG.  5 B  shows actuator  120  with three balls  512   a ,  514   a  and  516   a  positioned in the space between grooves  310   a  and  412   a , and three balls  512   b ,  514   b  and  516   b  positioned in the space between grooves  310   b  and  412   b .  FIG.  5 B  shows only balls  512   b ,  514   b  and  516   b  and grooves  310   b  and  412   b , while balls  512   a ,  514   a  and  516   a  and grooves  310   a  and  412   a  are not seen (being in the unseen back side of the drawing), with understanding of them being symmetric along plane Z-Y. The number of balls (here 3) shown in the drawing is for the sake of example only and should not be construed as limiting. In other embodiments, an actuator such as actuator  120  may have more or fewer of three balls (e.g. 2-7 balls) in the space between adjacent grooves. The balls may be made of Alumina, another ceramic material, metal, plastic or other suitable materials. The balls may have for example a diameter in the range of 0.3-1 mm. In actuator  120 , grooves  310   a ,  301   b ,  412   a ,  412   b  and balls  512   a ,  512   b ,  514   a ,  514   b ,  516   a  and  516   b  form a curved ball-guided mechanism  560  operative to impart a rotation or tilt movement to an optical element (e.g. OPFE  104 ) upon actuation by the VCM actuator (see below). More details on ball-guided mechanisms in actuators may be found in co-owned international patent applications PCT/IB2017/052383 and PCT/IB2017/054088. 
     In some embodiments, balls having different sizes (e.g. two different ball sizes) may be used to provide smoother motion. The balls can be divided into a large diameter (LD) group and a small diameter (SD) group. The balls in each group may have the same diameter. LD balls may have for example a 0.1-0.3 mm larger diameter than SD balls. A SD ball may be positioned between two LD balls to maintain the rolling ability of the mechanism. For example, balls  512   b  and  516   b  may be LD balls and ball  514   b  may be a SD ball (and similarly for balls  512   a - 516   a ). As described above, two metallic ferromagnetic yokes  306  that may be fixedly attached to OPFE holder  302  face two pitch-pull magnets  408  that may be attached to middle frame  402 . Ferromagnetic yokes  306  may pull magnets  408  (and thus pull top actuated sub-assembly  210  to bottom actuated sub assembly  220 ) by magnetic force and hold a curved ball-guided mechanism  560  from coming apart. The magnetic force (e.g. acting between yoke  306  and magnets  408 ) that is used for preventing two parts of a moving mechanism to be detached is referred to herein as “pre-load force”. A pitch-pull magnet  408  and its respective yoke  306  may be referred to as “first magnet-yoke pair”. Ferromagnetic yokes  306  and pitch-pull magnets  408  both have arc shapes, with a center on pitch rotation axis  124 . The magnetic direction of pitch-pull magnets  408  is along pitch rotation axis  124 , e.g. with a north pole toward OPFE  104  and a south pole away from OPFE  104 . Due to the geometric and magnetic design presented, the magnetic force (pre-load force) between ferromagnetic yokes  306  and pitch-pull magnets  408  is kept substantially in a radial direction  520  with a center on pitch rotation axis  124 , and negligible tangent force, at all rotation positions, as can be seen in  FIG.  5 A . 
     Balls  512   a - 516   a  and  512   b - 516   b  prevent top actuated sub-assembly  210  from touching bottom actuated sub-assembly  220 . Top actuated sub-assembly  210  is thus confined with a constant distance from bottom actuated sub-assembly  220 . Curved ball-guided mechanism  560  further confines top actuated sub-assembly  210  along pitch rotation axis  124 . Top actuated sub-assembly  210  can only move along the path defined by curved ball-guided mechanism  560 , namely in a pitch rotation  134  around pitch rotation axis  124 . 
       FIGS.  6 A-C  show stationary sub-assembly  230  with more details, in an isometric view from one side ( FIG.  6 A ), an isometric view from another side ( FIG.  6 B ) and an exploded view ( FIG.  6 C ). Stationary sub-assembly  230  includes a base  602  that can be made, for example, by plastic mold. Stationary sub-assembly  230  further includes electronic circuitry  608  attached to base  602 , shown in  FIG.  6 C . Details of electronic circuitry  608  are given below with reference to  FIG.  8   . Stationary sub-assembly  230  further includes a ferromagnetic yoke  606 . Ferromagnetic yoke  606  is made by ferromagnetic material (e.g. iron) and is pulled by yaw actuation magnet  404  (see  FIGS.  6 B and  7 C ) to attach bottom actuated sub-assembly  220  to stationary sub-assembly  230  as described in more detail below. Ferromagnetic yoke  606  and yaw actuation magnet  404  may be referred to as “second magnet-yoke pair”. 
     Stationary actuated sub-assembly  230  further include a stopper  610 . Stopper  610  is made for example from a non-magnetic metal. Stopper  610  is attached (e.g. glued) to based  602 . Stopper  610  helps to prevent bottom actuated sub-assembly  220  from detaching from base  602  in case of a strong external impact or drop, as described in more detail below. In some examples, base  602  includes (i.e. is molded with) two parallel arc-shaped (curved) grooves  612   a - d  ( FIG.  6 A ), each arc-shaped groove having an angle β″&gt;β, where angle β is a required tilt stroke, as defined by optical needs. Angle β″ is shown in  FIG.  7   . Arc-shaped grooves  612   a - d  may further include a center of curvature on yaw rotation axis  122  ( FIGS.  2 C,  6 A and  7   ), in common with arc-shaped grooves  414   a - b.    
       FIG.  7    shows actuator  120  without the shield along a cut along line A-B seen in  FIG.  2 A . Grooves  612   a - d  are shown to share a center with grooves  414   a - b  on yaw rotation axis  122  ( 612   c  and  612   d , which are shown in  FIGS.  6 B and  6 C  are hidden in  FIG.  7   ). Angles β′ and β″ are demonstrated. Groves  612   a - b  are adjacent to groove  414   a  while grooves  612   c - d  are adjacent to groove  414   b . Four balls  712  (two are shown in  FIG.  7   ) are positioned between adjacent groove pairs  612   a  and  414   a ,  612   b  and  414   a ,  612   c  and  414   b , and  612   d  and  414   b , one ball between each adjacent groove pair. In other embodiments, actuator  120  may have more than one ball pair in each adjacent groove pair, e.g. in the range of 1-4 balls. The considerations for size and materials of all balls are similar to those described above. Grooves  414   a - b ,  612   a - d  and balls  712  form a second curved ball-guided mechanism  760  of actuator  120 . As shown in  FIG.  6    and  FIG.  7   , the second curved ball-guided mechanism is situated such that the grooves  612  for rotating around the yaw axis are located behind OPFE  104  i.e. in the positive direction along the Z axis relative to OPFE  104  (a side opposite to the side facing the lens module). 
     As described above, ferromagnetic yoke  606  is fixedly attached to base  602  facing magnet  404  (illustrated for example in  FIG.  4   a    and  FIG.  4   c   ). Ferromagnetic yoke  606  pulls magnet  404  (and thus pulls bottom actuated sub-assembly  220 ) to stationary sub-assembly  230  by magnetic force  702  (pre-load force) and thus holds curved ball-guided mechanisms  760  from coming apart. The direction of magnetic force  702  is marked in  FIG.  7    as the Z direction. Balls  712  prevent bottom actuated sub-assembly  220  from touching stationary sub-assembly  230 . Bottom actuated sub-assembly  220  is thus confined with a constant distance from stationary sub-assembly  230 . Second curved ball-guided mechanism  760  further confines bottom actuated sub-assembly  220  along the Y-axis. Bottom actuated sub-assembly  220  can only move along the path defined by the curved ball-guided mechanism  760 , namely in a yaw rotation around yaw rotation axis  122 . 
     The curved ball-guided mechanisms  560  and  760  disclosed herein provides flexibility when defining the pitch and yaw rotation axes respectively, as the curve can be adapted to the required rotation axis. Furthermore, curved ball-guided mechanisms  560  and  760  enable to execute movement of the top actuated sub-assembly and the bottom actuated sub-assembly by rolling over the balls confined within the grooves (rails) along the path prescribed by the grooves, and thus help to reduce or eliminate friction that may otherwise exist during movement between the balls and the moving parts. 
       FIG.  8    shows electronic circuitry  608  with more details, according to some examples of the presently disclosed subject matter. Electronic circuitry  608  includes a printed circuit board (PCB)  802  and may include processing circuitry. PCB  802  allows sending input and output currents to coils  806  and  804  and to Hall bar elements  808  and  810  (described below), the currents carrying both power and electronic signals needed for operation. PCB  802  may be connected electronically to host camera (camera  100  or similar cameras) or host device (e.g. phone, computer, not shown) e.g. by wires (not shown). PCB  802  may be a flexible PCB (FPCB) or a rigid flex PCB (RFPCB) and may have several layers (e.g. 2-6) as known in the art. Electronic circuitry  608  further includes three coils, a pitch coil  804  and two yaw coils  806 . Electronic circuitry  608  further includes two Hall bar sensing elements, a pitch Hall bar element  808  and a yaw Hall bar element  810 . Coils  804  and  806  and Hall bar elements  808  and  810  are all connected (e.g. soldered) to PCB  802 . In actuator  120 , pitch coil  804  and pitch Hall bar element  808  are positioned below pitch magnet  304 . Notably, some of the components mentioned as part of the electronic circuitry are also considered as part of an actuation and sensing mechanism. 
     Notably, yaw rotation axis  122  is positioned as closely as possible to the pitch sensor (e.g. Hall bar element  808 ). According to one example, yaw rotation axis  122  passes through pitch sensor  808 , in order to decouple the sensing of the pitch sensor from the rotation around the yaw axis. When decoupled, the influence on the sensing of the pitch sensor by rotation around the yaw axis is reduced or eliminated. More specifically, according to one example, yaw rotation axis  122  passes through the center of pitch sensor  808 . By positioning the yaw rotation axis so it passes through the center of the pitch sensor, the influence of yaw rotation on the sensing of pitch sensor can be completely eliminated. In addition, in some designs, yaw rotation axis  122  may optionally pass through the center of pitch coil  804 . 
       FIGS.  9 A-B  show an example of a pitch actuation and sensing mechanism (PAASM)  900  that includes pitch magnet  304 , pitch coil  804  and pitch Hall bar element  808 . PAASM  900  may be included in actuator  120 . In some embodiments, PAASM  900  may be used only for actuation (acting as an actuation mechanism for one DOF).  FIG.  9 A  shows PAASM  900  in an isometric view and  FIG.  9 B  shows a side cut of pitch magnet  304  along a line A-B. According to one example, pitch magnet  304  may be symmetric along a plane that includes pitch rotation axis  124  and first optical axis  108 . In an example, pitch magnet  304  may be fabricated (e.g. sintered) such that it has a changing magnetic field direction along its mechanical symmetry plane, e.g. a north magnetic field facing the positive X direction on the left side and a north magnetic field facing the negative X direction on the right side. Pitch magnet  304  may have a length R PITCH  of a few millimeters (for example 2-6 mm) in parallel to pitch rotation axis  124  and substantially longer than pitch coil  804 , such that its magnetic field on most lines parallel to pitch rotation axis  124  may be considered constant. Upon driving a current in pitch coil  804 , a Lorentz force is created on pitch magnet  304 ; a current in a clockwise direction will create force in the positive Z direction (along the Z axis), while a current in counter clockwise direction will create a force in the negative Z direction. Any force on pitch magnet  304  is translated to torque around pitch rotation axis  124 , and thus top actuated subassembly  210  will rotate relative to bottom actuated sub-assembly  220 . 
     Pitch Hall bar element (sensor)  808 , which is positioned inside pitch coil  804 , can sense the intensity and direction of the magnetic field of pitch magnet  304  radially directed away from pitch rotation axis  124 . In other words, for any pitch orientation of top actuated sub-assembly  210 , pitch Hall bar measures the intensity of the magnetic field directed in the X direction only. Since yaw rotation axis  122  passes through pitch Hall bar element  808 , the effect of the yaw rotation of bottom actuated sub-assembly  220  on the magnetic field in the X direction applied by pitch magnet  304  is reduced (e.g. eliminated) and thus any change on the measurement of pitch Hall bar element  808  is reduced (e.g. eliminated) as well. By positioning the Hall bar element  808  such that the yaw rotation axis  122  passes through its center, the effect of the yaw rotation of bottom actuated sub-assembly  220  on the magnetic field in the X direction applied by pitch magnet  304  is reduced (e g minimized) and thus any change on the measurement of pitch Hall bar element  808  is mitigated. Pitch Hall bar element  808  can thus measure the respective pitch rotation of top actuated sub-assembly  210  while being unaffected by the yaw rotation of bottom actuated sub-assembly. 
       FIGS.  10 A-B  show another exemplary embodiment of a PAASM numbered  1000 , similar to PAASM  900 . PAASM  1000  may be included in actuator  120 , to replace PAASM  900 . According to one example, a pitch magnet  1004  replaces pitch magnet  304 . Pitch magnet  1004  is a cut of a sphere with its center positioned substantially on the intersection point of yaw rotation axis  122  and pitch rotation axis  124 . According to one example, a pitch coil  1006  that replaces pitch coil  804  has a circular shape with a center substantially on yaw rotation axis  122  (in some examples the yaw rotation axis passes exactly through the center of the coil). Pitch coil  1006  may be made (fabricated) with similar considerations presented above for pitch coil  804 . Due to the symmetry of the pitch magnet around yaw rotation axis  122 , any yaw rotation will not influence the magnetic field of the pitch coil and thus will not change the force applied by pitch coil  1006  on pitch magnet  1004 . Having a constant force for various yaw positions may facilitate and simplify pitch position control (close loop control or open loop control). As mentioned above, yaw rotation axis passes through sensor  808  to thereby reduce the effect of yaw rotation of bottom actuated sub-assembly  220  on the magnetic field in the X direction applied by pitch magnet  1004 . 
       FIG.  11 A  shows a yaw sensing mechanism numbered  1100 . Yaw sensing mechanism  1100  includes yaw sensing magnet  406  and yaw Hall bar element  810 . Yaw Hall bar element  810  can measure the intensity and direction of the magnetic field of yaw sensing magnet  406  directed along yaw rotation axis  122 . In other words, Hall bar element  810  measures the intensity of magnetic field directed in the X direction only. 
       FIG.  11 B  shows a yaw rotation range β, a distance R YAW  between yaw Hall bar element  810  and yaw rotation axis  122 , and a trajectory  1108  of yaw sensing magnet  406  in the Y-Z plane. In some examples, yaw rotation range β is more than 10 degrees. The distance R YAW  is e.g. in the range of 2-5 mm. As an example, a case in which β=40° (meaning ±20° from the “zero” position) and R YAW =2.75 mm is analyzed in  FIGS.  11 C-F  below. As bottom actuated sub-assembly  220  is yaw-rotated, trajectory  1108  is in the Y-Z plane. Trajectory  1108  has an arc projection in the Y-Z plane ( FIG.  11 B ) with length β×R YAW , where β is calculated in radians. Trajectory  1108  has a line shape projection on the X-Y plane ( FIGS.  11 C-E ) with length 2×R YAW ×cos(β). 
     Yaw sensing magnet  406  is designed such that is has dimensions along Z-Y directions and such that it covers trajectory  1108  from the top view (Y-Z plane). Yaw sensing magnet  406  can have different configurations. 
       FIGS.  11 C-E  show three different examples of magnetic configurations for yaw sensing magnet  406  in a cross section along X-Y plane of yaw sensing mechanism  1100 . In the configuration of  FIG.  11 C , yaw sensing magnet  406  has a rectangular cross section and the magnetic field of yaw sensing magnet  406  changes direction in the middle, e.g. the north magnetic field facing the positive X direction on the left side and the north magnetic field facing the negative X direction on the right side. In the configuration of  FIG.  11 D , yaw sensing magnet  406  has a rectangular cross section, and the magnetic field of yaw sensing magnet  406  is directed in the Y direction. 
     In the configuration shown in  FIG.  11 E , yaw sensing magnet  406  is characterized, along the Y direction, by a thinner cross section (the Y-X plane) in the middle and a thicker cross section on the sides. The varying width results in a varying distance between the sensor and the magnet positioned near the magnet (the sensor is located towards the negative X direction relative to the magnet) and thus a varying magnetic field along a projection of trajectory  1108  (line  1114 ) on the Y-X plane. In some examples, the variation around the magnetic field is symmetrical around its center such that the thickness of the cross section of the magnet increases from a point substantially at its center towards each end of the magnet. Various examples of magnets constructed according to this principle are illustrated in  FIGS.  11   - i  to  11 - vi.    
     In addition, in some examples of the configuration of  FIG.  11 E  (or any one of  FIGS.  11   - i  to  11 - vi ), the magnetic field of yaw sensing magnet  406  changes direction in the middle, e.g. the north magnetic field faces the positive X direction on the left side and the north magnetic field faces the negative X direction on the right side. This results in zero magnetic field in the X direction in yaw hall bar element  810  facing the center of magnet  406  (along the center line). 
       FIG.  11 F  shows the magnetic field as a function of rotation along trajectory  1108 , for the 3 cases presented in  FIGS.  11 C-E . The projection of trajectory  1108  on plane X-Y (representing a lateral shift component of the magnet shift relative to the sensor) is shown by line  1110  in  FIG.  11 C , line  1112  in  FIG.  11 D  and line  1114  in  FIG.  11 E . For line  1110 , the maximal magnetic field change along ±20 degrees trajectory is ±0.28 Tesla. However, most of the magnetic field change is obtained in a ±7 degrees trajectory and the magnetic field gradient at higher yaw angles is lower than at lower yaw angles. This limits the ability to sense changes with high accuracy in high yaw angles. For projection line  1112 , the magnetic field gradient is more uniform along the trajectory of ±20, comparing to projection line  1110 . However, the magnetic field total change is limited to under ±0.08 Tesla. For projection line  1114  the magnetic field gradient is more uniform than for both lines  1110  and  1112 , and the total magnetic field change is ±0.25 Tesla, which can give high accuracy for position measurements. Thus, the magnetic configuration presented in  FIG.  11 E  is superior for position sensing at large strokes, relative to the distance between the Hall bar and the corresponding magnet (e.g. in 1-4 mm range) using changes in magnetic field. Thus, by shaping the magnet with a variable thickness as shown in  FIGS.  11 E and  11   - i  to  11 - vi , the range of detectable change in magnetic flux in increased. Accordingly, the corresponding detectable range of relative (lateral) shift of the magnet and sensor is increased as well. 
       FIG.  12 A-C  shows a yaw magnetic actuation mechanism numbered  1200 . This actuation mechanism is for a second DOF.  FIG.  12 A  show isometric view from one side,  FIG.  12 B  shows isometric view from another side. Yaw magnetic actuation mechanism  1200  include yaw actuation magnet  404 , yaw coils  806  and ferromagnetic yoke  606 .  FIG.  12 C  shows the magnetic field directions is Y-Z plane, along a cut A-B in  FIG.  12 A . Yaw actuation magnet  404  may be sintered such that its magnetic field is pointed toward negative Z direction. Each of coils  806  has one part ( 1202 ,  1204 ) which is positioned in close proximity to yaw actuation magnet  404  (e.g. distance of 100-300 μm), and one part ( 1206 ,  1208 ) which is further apart from yaw magnet  404 . Coils  806  may be connected in serial, such that the current in the two coil is equal. When current in  1202  is in the positive X direction the current in  1204  is also in the positive X direction, and the current in parts  1206  and  1208  is in the negative X direction. Upon driving a current in Yaw coils  806 , a Lorentz force is created on the yaw magnet  404 , according to d{right arrow over (F)}=Id{right arrow over (l)}×{right arrow over (B)}. The direction of the magnetic field is demonstrated in  FIG.  12 C . The Lorentz force is translated into torque around yaw rotation axis  122 . 
     In some examples, an additional magnetic yoke  1302  may be located next to yaw magnet  404 . This yoke may increase the intensity of the magnetic field in coils  806  and increase the torque created by yaw magnetic actuation mechanism  1200 .  FIG.  13    shows this case. 
     In some examples, rotation of the reflecting element around one or two axes moves the position of the camera FOV, wherein in each position a different portion of a scene is captured in an image having the resolution of the digital camera. In this way a plurality of images of adjacent camera FOVs (e.g. partially overlapping FOVs) are captured and stitched together to form a stitched (also referred to as “composite”) image having an overall image area of an FOV greater than digital camera FOV. 
     In some examples the digital camera can be a folded Tele camera configured to provide a Tele image with a Tele image resolution, the folded Tele camera comprising a Tele image sensor and its Tele lens assembly is characterized with a Tele field of view (FOV T ). 
     According to some examples, the folded Tele camera is integrated in a multiple aperture digital camera that comprises at least one additional upright Wide camera configured to provide a Wide image with a Wide image resolution, being smaller than the Tele image resolution, the Wide camera comprising a Wide image sensor and a Wide lens module with a Wide field of view (FOV W ); wherein FOV T  is smaller than FOV W , wherein rotation of the OPFE moves FOV T  relative to FOV W , for example as shown in of co-owned international patent applications PCT/IB2016/056060 and PCT/IB2016/057366. 
     The description of these PCT applications includes a Tele camera with an adjustable Tele field of view. As described in PCT/IB2016/056060 and PCT/IB2016/057366, rotation of the reflecting element around one or two axes moves the position of Tele FOV (FOV T ) relative to the Wide FOV (FOV W ), wherein in each position a different portion a scene (within FOV W ) is captured in a “Tele image” with higher resolution. According to some examples, disclosed in PCT/IB2016/056060 and PCT/IB2016/057366, a plurality of Tele images of adjacent non-overlapping (or partially overlapping) Tele FOVs are captured and stitched together to form a stitched (also referred to as “composite”) Tele image having an overall image area of an FOV greater than FOV T . According to some examples, the stitched Tele image is fused with the Wide image generated by the Wide camera. 
     Digital camera  100  can further comprise or be otherwise operatively connected to a computer processing circuitry (comprising one or more computer processing devices), which is configured to control the operation of the digital camera (e.g. camera CPU). The processing circuitry, can comprise for example a controller operatively connected to the actuator of the rotating OPFE configured to control its operation. 
     The processing circuitry can be responsive to a command requesting an image with a certain zoom factor and control the operation of the digital camera for providing images having the requested zoom. As mentioned in applications PCT/IB2016/056060 and PCT/IB2016/057366, in some examples a user interface (executed for example by the processing circuitry) can be configured to allow input of user command being indicative of a requested zoom factor. The processing circuitry can be configured to process the command and provide appropriate instructions to the digital camera for capturing images having the requested zoom. 
     In some cases, if the requested zoom factor is a value between the FOV W  of a wide camera and FOV T  of a tele camera, the processing circuitry can be configured to cause the actuator of the reflecting element to move the reflecting element (by providing instruction to the controller of the actuator) such that a partial area of the scene corresponding to the requested zoom factor is scanned and a plurality of partially overlapping or non-overlapping Tele images, each having a Tele resolution and covering a portion of the partial area, are captured. The processing circuitry can be further configured to stitch the plurality of captured imaged together in order to form a stitched image (composite image) having Tele resolution and an FOV greater than the FOV T  of the digital camera. Optionally the stitched image can then be fused with the Wide image. 
       FIG.  14 A  is a schematic illustration of an example of a stitched image  1400  generated by scanning, capturing and stitching together four Tele images with FOV T , compared to the FOV W  of a Wide camera, as in the example of  FIG.  1 C , where camera  190  represents a Wide FOV camera with a FOV W  coupled to folded Tele camera  100  with a FOV T . In  FIG.  14 A,  1402    denotes FOV W ,  1404  denotes FOV T  at the center of FOV W  and  1406  indicates the size of the requested zoom factor. In the illustrated example, four partially overlapping Tele images  1408  are captured. 
     Notably, the overall area of captured Tele images  1408  is greater than the area of the zoom image  1406  in the requested zoom. The central part of the captured Tele images is extracted (e.g. by the computer processing circuitry as part of the generation of the stitched image) for generating stitched image  1400 . This helps to reduce the effect of image artefacts resulting from transition from an image area covered by one image to an image area covered by a different image. 
       FIG.  14 B  is a schematic illustration of an example of a stitched image  1400 ′ generated by capturing and stitching together six Tele images.  FIG.  14 C  is a schematic illustration of an example of a stitched image  1400 ′ generated by capturing and stitching together nine Tele images. The same principles described with reference to  FIG.  14 A  apply to  FIGS.  14 B and  14 C . Notably, the output image resulting from the stitching can have a different width to height ratio than the single image proportion. For example, as illustrated in  FIG.  14 B , a single image can have a 3:4 ratio and the output stitched image can have a 9:16 ratio. 
     It is noted that image stitching per se is well known in the art and therefore it is not explained further in detail. 
     An alternative design of the top and bottom actuated sub-assemblies described above is now described with reference to  FIGS.  15 A- 15 E . Notably, as would be apparent to any person skilled in the art, unless stated otherwise, some of the details described above with reference to the previous figures can also be applied to the example described with reference to  FIGS.  15 A- 15 E . 
     According to this design, a single magnet  1510  serves for three purposes: 1) as a pre-load magnet in magnet-yoke pair, dedicated for fastening the bottom actuated sub-assembly to the stationary sub-assembly; 2) as a yaw actuation magnet dedicated for generating yaw movement of bottom actuated sub-assembly; and 3) as a yaw sensing magnet for sensing yaw movement. 
       FIG.  15 A  shows a magnet  1506  and a yoke (e.g. a ferromagnetic plate such as iron)  1504 , where the magnet and yoke are pulled together by pre-load force (indicated by black double head arrow) and thus fasten top actuated sub-assembly  210  to bottom actuated sub-assembly  220 . In some examples, magnet  1506  and yoke  1504  are positioned substantially at the center (relative to the Y axis direction) of the top actuated sub-assembly. Pitch rotation axis relative to the bottom actuated sub-assembly is demonstrated by the circular arrow  1508 . 
       FIG.  15 B  shows top and bottom actuated sub-assemblies in isometric view.  FIG.  15 B  illustrates magnet  1510  located at the internal part of bottom actuated sub-assembly, sensor  1512  and a coil  1514 , which is located at the back of bottom actuated sub-assembly (in the positive Z direction relative to magnet  1510 ). According to one example, a single coil can be used for actuation. 
     As shown in  FIG.  15 C , yoke  1516 , is fastened to the stationary sub-assembly. Magnet  1510  and yoke  1516  are attracted by pre-load force to thereby fasten bottom actuated sub-assembly  220  to stationary sub-assembly  230 . Coil  1514  is positioned in close proximity to yaw actuation magnet  1510  (e.g. distance of 100-300 μm). When current is applied in coil  1514 , a Lorentz force is created on yaw magnet  1510  according to d{right arrow over (F)}=Id{right arrow over (l)}×{right arrow over (B)}, where the Lorentz force is translated into torque around yaw rotation axis  122  (not shown) as explained above. 
     Magnet  1510  moves along the yaw direction as part of the bottom actuated sub-assembly. In addition of being more compact, this type of yaw actuation mechanism also provides better efficiency, as it does not generate force in the opposite direction to the desired yaw movement. 
     As explained above, in some examples top actuated sub-assembly  210  includes an OPFE holder (or carrier)  302  and bottom actuated sub-assembly includes a middle moving frame  402 . According to an example, yoke  1504  is attached (e.g. glued) to the holder and the first magnet-yoke pair ( 1506 - 1504 ) pulls the OPFE holder to the middle moving frame. Alternatively, the position of the magnet and yoke can be switched. The stationary sub-assembly includes a base and the yoke is attached to the based in a manner that the second magnet-yoke pair ( 1510 - 1516 ) pulls the middle moving frame to the base. Also, in an example coil  1514  and sensor  1512  are fixed (e.g. glued) to the base. 
     According to some examples of the presently disclosed subject matter yaw magnet  1510 , which also serves as yaw sensing magnet, is made to have an increased detection range. To this end, magnet  1510  is made to have a single magnetic polarization direction as indicated by the back arrow extending from the south pole to the north pole of magnet  1510  shown in  FIG.  15 D . The directions of the magnetic field lines are indicated by arrows a-e in  FIG.  15 D  and in more detail in  FIG.  15 E , which is a top view of magnet  1510 . As indicated by arrows a-e, as a result of the single magnetic polarization direction of magnet  1510 , the angle of the magnetic field relative to the magnet surface changes continuously along the length of magnet. The illustration shows the angle changing from being substantially perpendicular in the positive direction at one end, to being in a parallel direction at the magnet center and to being substantially perpendicular in the negative direction at the other one. Since the relative changes (e.g. of magnetic flux) are detectable at each of the points where change in the direction of the magnetic field occurs, yaw movement of the magnet relative to sensor  1512  can be detected over an increased range. The increased detection range of the yaw magnet as disclosed herein enables to use the same magnet for both actuation and sensing, eliminating the need for two separate magnets. 
     Note that unless stated otherwise terms such as “first” and “second” as used herein are not meant to imply a particular order but are only meant to distinguish between two elements or actions in the sense of “one” and “another”. 
     While this disclosure has been described in terms of certain embodiments and generally associated methods, alterations and permutations of the embodiments and methods will be apparent to those skilled in the art. The disclosure is to be understood as not limited by the specific embodiments described herein, but only by the scope of the appended claims. 
     All references mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual reference was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present application.