Patent Publication Number: US-11644298-B2

Title: Inductive position detection configuration for indicating a measurement device stylus position

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation-in-part of U.S. patent application Ser. No. 16/557,719, entitled “INDUCTIVE POSITION DETECTION CONFIGURATION FOR INDICATING A MEASUREMENT DEVICE STYLUS POSITION” filed on Aug. 30, 2019, now Issued U.S. Pat. No. 10,914,570, which is a continuation-in-part of U.S. patent application Ser. No. 16/178,295, entitled “INDUCTIVE POSITION DETECTION CONFIGURATION FOR INDICATING A MEASUREMENT DEVICE STYLUS POSITION” filed on Nov. 1, 2018, now Issued U.S. Pat. No. 10,866,080, the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Technical Field 
     This disclosure relates to precision metrology, and more particularly to inductive type sensing configurations for use in probes used with coordinate measuring machines. 
     Description of the Related Art 
     Coordinate measurement machines (CMM&#39;s) can obtain measurements of inspected workpieces. One exemplary prior art CMM described in U.S. Pat. No. 8,438,746, which is hereby incorporated herein by reference in its entirety, includes a probe for measuring a workpiece, a movement mechanism for moving the probe, and a controller for controlling the movement. A CMM including a surface scanning probe is described in U.S. Pat. No. 7,652,275, which is hereby incorporated herein by reference in its entirety. As disclosed therein, a mechanical contact probe or an optical probe may scan across the workpiece surface. 
     A CMM employing a mechanical contact probe is also described in U.S. Pat. No. 6,971,183, which is hereby incorporated herein by reference in its entirety. The probe disclosed therein includes a stylus having a surface contact portion, an axial motion mechanism, and a rotary motion mechanism. The axial motion mechanism includes a moving member that allows the contact portion to move in a central axis direction (also referred to as a Z direction or an axial direction) of the measuring probe. The rotary motion mechanism includes a rotating member that allows the contact portion to move perpendicular to the Z direction. The axial motion mechanism is nested inside the rotary motion mechanism. The contact portion location and/or workpiece surface coordinates are determined based on the displacement of the rotating member and the axial displacement of the axial motion moving member. 
     Inductive sensing technologies are known to be environmentally robust, and have various desirable sensing properties. It is known to use precision LVDT&#39;s or the like to measure displacements or positions of various internal elements in mechanical contact probes similar to those referred to above. However, LVDT&#39;s and other known inductive type sensors that are sufficiently accurate for use in CMM probes may be rather large or awkward to incorporate, and the associated motion mechanisms and/or displacement detector arrangements may be relatively expensive and/or susceptible to various “cross coupling” errors (e.g., due to the general configuration and/or mechanism and/or detector imperfections, etc.). U.S. Pat. No. 4,810,966, (the &#39;966 patent) which is hereby incorporated herein by reference in its entirety, discloses an inductive sensor configuration that is relatively planar and relatively economical, and which can detect the three-dimensional position of a nearby conductive target. However, the configurations disclosed in the &#39;966 patent have several design deficiencies relative to providing the accuracy and/or form factors necessary for successful adaptation for use in a CMM scanning probe. In short, the configurations of the &#39;966 patent lack the sophistication and features necessary for providing reasonable levels of accuracy in modern metrology instruments such as a CMM probe. Other issues associated with the use of known inductive sensing systems such as those outlined above in a CMM probe may include signal/response non-linearities that are inherent in the displacement response of the system, position errors resulting from less than perfect assembly and alignment, and signal drift due to environmental effects on mechanical and electrical components (e.g., due to temperature changes, etc.). A need exists for an improved inductive sensing configuration for use in a CMM probe (e.g., wherein the displacement detector configurations may be less susceptible to errors such as those noted above, and/or may be relatively less expensive, etc.). 
     BRIEF SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     A scanning probe responsive in 3 axes is provided for use in a measuring machine (e.g., a CMM). The scanning probe includes a stylus suspension portion, a stylus position detection portion, and signal processing and control circuitry. 
     The stylus suspension portion is attached to a frame of the scanning probe, and includes a stylus coupling portion that is configured to be rigidly coupled to a stylus, and a stylus motion mechanism that is configured to enable axial motion of the stylus coupling portion along an axial direction, and rotary motion of the stylus coupling portion about a rotation center. 
     The stylus position detection portion is arranged along a central axis that is parallel to the axial direction and nominally aligned with the rotational center, and is based on inductive sensing principles. The stylus position detection portion includes a coil board configuration and a disruptor configuration. The coil board configuration comprises a field generating coil configuration that surrounds a hole in the coil board configuration, a top axial sensing coil configuration (TASCC), a bottom axial sensing coil configuration (BASCC), N top rotary sensing coils (TRSC), and N bottom rotary sensing coils (BRSC), where N is an integer greater than 3. 
     The disruptor configuration comprises a cylindrical disruptor element that is configured to move and fit within the hole of the coil board configuration. The cylindrical disruptor element comprises a conductive cylinder that provides a disruptor area and is located along the central axis in a disruptor motion volume. The cylindrical disruptor element is coupled to the stylus suspension portion by a coupling configuration, and moves in the disruptor motion volume relative to an undeflected position in response to a deflection of the stylus suspension portion. The cylindrical disruptor element may be described as moving over operating motion ranges +/−Rz along the axial direction in response to the axial motion, and over respective operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions that are orthogonal to the axial direction in response to the rotary motion. The field generating coil configuration generates a changing magnetic flux generally along the axial direction in the disruptor motion volume in response to a coil drive signal. 
     The signal processing and control circuitry is operably connected to the coils of the stylus position detection portion to provide the coil drive signal, and is configured to input signals from the receiver coil portion comprising respective signal components provided by the respective rotary and axial sensing coils located on the top and bottom coil substrates. It is further configured to output signals indicative of the axial position and the rotary position of the cylindrical disruptor element or the stylus relative to the frame or housing of the scanning probe. 
     Such a configuration, according to the principles disclosed herein, may provide signal components that are particularly advantageous with regard to eliminating or allowing correction of certain signal errors and/or signal cross coupling errors that have limited the accuracy of position determination in known economical three-dimensional position indicators based on inductive sensing. 
     In some implementations, the field generating coil configuration may comprise first and second field generating coil configurations that each surround the hole in the coil board configuration and correspondingly surround the disruptor motion volume. In some such implementations, the first and second field generating coil configurations may comprise a pair of planar field generating coils that are located approximately equidistant from a midplane of the disruptor motion volume along the central axis, and that are nominally planar and orthogonal to the central axis. In some such implementations, the top and bottom axial sensing coil configurations also surround the hole in the coil board configuration and correspondingly surround the disruptor motion volume. 
     In some such implementations, the coil board configuration has top and bottom portions. The top portion includes first, second and third layers which include the top axial sensing coil configuration, the first field generating coil configuration and the N top rotary sensing coils, respectively. The bottom portion mirrors the top portion and correspondingly has first, second and third layers which include the bottom axial sensing coil configuration, the second field generating coil configuration, and the N bottom rotary sensing coils, respectively. The coil board configuration is mounted in the fixed relationship to the frame of the scanning probe with the bottom portion of the coil board configuration closer to the stylus suspension portion. The top and bottom portions of the coil board configuration are nominally parallel to one another and nominally orthogonal to the central axis. The coil board configuration may comprise a normalization coil configuration having a top normalization coil as part of the top portion and a bottom normalization coil as part of the bottom portion. The normalization coil configuration may be utilized to provide a measurement of the changing magnetic flux that is generated by the first and second field generating coil configurations. The top and bottom portions may be part of a single multilayer printed circuit board. 
     In some implementations, a method comprises moving a scanning probe as disclosed herein along a surface of a workpiece and generating three-dimensional position information based on inductive sensing signals generated by the scanning probe as the scanning probe is moved along the surface of the workpiece. 
     In some implementations, a system comprises a scanning probe as disclosed herein, a drive mechanism and an attachment portion configured to couple the drive mechanism to the scanning probe. In some implementations, the system comprises a motion controller which controls movements of the drive mechanism. 
     Previously known inductive sensors utilizing nominally planar sensing elements have been far too inaccurate for application in precision scanning probes. In contrast, inductive sensors utilizing nominally planar sensing elements configured according to the various principles disclosed and claimed herein provide a robust set of signals and may be used to provide sufficient accuracy for application in precision scanning probes. In particular, implementations and/or configurations such as those outlined above may provide signal components that are particularly advantageous with regard to eliminating or allowing correction of certain signal errors and/or signal cross coupling errors that have previously limited the accuracy of position determination in known economical three-dimensional position indicators based on inductive sensing. In various implementations according to the various principles disclosed and claimed herein, the signal components that are provided by the various receiver coils are particularly advantageous in that they may be processed using relatively fast and simple signal processing in order to provide robust and highly accurate three-dimensional position indications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram showing various typical components of a measuring system including a CMM utilizing a scanning probe such as that disclosed herein; 
         FIG.  2    is a block diagram showing various elements of a scanning probe as coupled to a CMM and providing rotary and axial position signals; 
         FIG.  3    is a diagram showing portions of a first exemplary implementation of a stylus suspension portion as coupled to a stylus and a first exemplary implementation of a stylus position detection portion for detecting the position of the stylus suspension portion; 
         FIG.  4    is a diagram showing a cross section of one implementation of the stylus suspension portion of  FIG.  3    as included within a main body frame of a scanning probe; 
         FIG.  5    is a partially schematic isometric diagram of an alternative implementation of the stylus position detection portion shown in  FIGS.  3  and  4   , emphasizing certain aspects according to principles disclosed herein; 
         FIG.  6    is a partially schematic isometric diagram of certain elements of the stylus position detection portion shown in  FIG.  5   , including schematically represented connections to a block diagram of one exemplary implementation of processing and control circuitry according to principles disclosed herein; 
         FIGS.  7 A- 7 E  are diagrams representing respective “4 complementary pair” implementations of patterns of receiver coil portions and disruptor element configurations according to principles disclosed herein, usable in various implementations of the stylus position detection portions shown in  FIGS.  3  and/or  4   ; 
         FIGS.  8 A- 8 F  are diagrams representing respective “3 (or 6) complementary pair” implementations or patterns of receiver coil portions and disruptor element configurations according to principles disclosed herein, usable in various implementations of the stylus position detection portions shown in  FIGS.  3  and/or  4   ; 
         FIGS.  9 A and  9 B  are diagrams showing portions of an exemplary implementation of a stylus position detection portion for detecting the position of the stylus suspension portion; 
         FIG.  10    is a partially schematic isometric diagram of an alternative implementation of the stylus position detection portion shown in  FIGS.  9 A and  9 B , emphasizing certain aspects according to principles disclosed herein; 
         FIG.  11    is a partially schematic isometric diagram of an alternative implementation of the stylus position detection portion shown in  FIG.  10   , emphasizing certain aspects according to principles disclosed herein; 
         FIGS.  12 A and  12 B  are diagrams showing portions of an exemplary implementation of a stylus position detection portion for detecting the position of the stylus suspension portion; 
         FIG.  13 A  is a partially schematic isometric diagram of an exemplary implementation of a stylus position detection portion, emphasizing certain aspects according to principles disclosed herein; 
         FIGS.  13 B to  13 F  are diagrams showing portions of an exemplary implementation of a stylus position detection portion, emphasizing certain aspects according to principles disclosed herein; 
         FIGS.  14 A to  14 D  illustrate example frequency shift and off-axis cross talk characteristics associated with various implementations of a stylus position detection portion; 
         FIGS.  15 A to  15 C  are diagrams showing portions of an exemplary implementation of a stylus position detection portion, emphasizing certain aspects according to principles disclosed herein; 
         FIG.  16    is a partially schematic isometric diagram of an exemplary implementation of a stylus position detection portion, emphasizing certain aspects according to principles disclosed herein; 
         FIGS.  17 A and  17 B  are diagrams showing portions of exemplary implementations of stylus position detection portions, emphasizing certain aspects according to principles disclosed herein; and 
         FIGS.  18 A to  18 C  are diagrams showing portions of an exemplary implementation of a stylus position detection portion, emphasizing certain aspects according to principles disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a diagram showing various typical components of a measuring system  100  including a CMM  200  utilizing a scanning probe  300  such as that disclosed herein. The measuring system  100  includes an operating unit  110 , a motion controller  115  that controls movements of the CMM  200 , a host computer  120  and the CMM  200 . The operating unit  110  is coupled to the motion controller  115  and may include joysticks  111  for manually operating the CMM  200 . The host computer  120  is coupled to the motion controller  115  and operates the CMM  200  and processes measurement data for a workpiece W. The host computer  120  includes input means  125  (e.g., a keyboard, etc.) for inputting, for example, measurement conditions, and output means  130  (e.g., a display, printer, etc.) for outputting, for example, measurement results. 
     The CMM  200  includes a drive mechanism  220  which is located on a surface plate  210 , and an attachment portion  224  for attaching the scanning probe  300  to the drive mechanism  220 . The drive mechanism  220  includes X axis, Y axis, and Z axis slide mechanisms  222 ,  221 , and  223 , respectively, for moving the scanning probe  300  three-dimensionally. A stylus  306  attached to the end of the scanning probe  300  includes a contact portion  348 . As will be described in more detail below, the stylus  306  is attached to a stylus suspension portion of the scanning probe  300 , which allows the contact portion  348  to freely change its position in three directions when the contact portion  348  moves along a measurement path on the surface of the workpiece W. 
       FIG.  2    is a block diagram showing various elements of a scanning probe  300  as coupled to a CMM  200  and providing rotary (e.g., X, Y) and axial (e.g., Z) position signals. The scanning probe  300  includes a probe main body  302  (e.g., comprising a frame) which incorporates a stylus suspension portion  307  and a stylus position detection portion  311 . The stylus suspension portion  307  includes a stylus coupling portion  342  and a stylus motion mechanism  309 . The stylus coupling portion  342  is rigidly coupled to a stylus  306 . The stylus motion mechanism  309  is configured to enable axial motion of the stylus coupling portion  342  and attached stylus  306  along an axial direction, and to enable rotary motion of the stylus coupling portion  342  and attached stylus  306  about a rotation center, as will be described in more detail below with respect to  FIGS.  3  and  4   . Signal processing and control circuitry  380  included in the scanning probe  300  is connected to and governs the operation of the stylus position detection portion  311 , and may perform related signal processing, all as described in greater detail below. 
     As shown in  FIG.  2   , the stylus position detection portion  311  uses inductive sensing principles and includes a receiver coil portion  370 , a field generating coil configuration  360 , and a disruptor element  351  (which may be part of a disruptor configuration  350 , which may include a plurality of parts in some implementations). The receiver coil portion  370  may comprise a rotary sensing coil portion (also referred to as rotary sensing coils) RSC and an axial sensing coil configuration ASCC. Briefly, the moving disruptor element  351  (or more generally, the disruptor configuration  350 ) causes position-dependent variations in a changing magnetic field generated by the field generating coil configuration  360 . The receiver coil portion  370  is responsive to the changing magnetic field and the variations therein caused by the disruptor element  351 . In particular, the rotary sensing coil portion RSC outputs at least first and second rotary signal components RSigs that are indicative of the rotary position (e.g., X and Y position signals) of the stylus coupling portion  342  over corresponding signal lines, and the axial sensing coil configuration ASCC outputs one or more axial signal components ASigs that is indicative of the axial position (e.g., a Z position signal) of the stylus coupling portion  342  over corresponding signal lines, as described in greater detail below with reference to  FIGS.  3 ,  5  and  6   , for example. In various implementations, the signal processing and control circuitry  380  receives the rotary signal components RSigs and the axial signal components ASigs, and may perform various levels of related signal processing in various implementations. For example, in one implementation, the signal processing and control circuitry  380  may cause the signal components from various receiver coils to be combined and/or processed in various relationships, and provide the results in a desired output format as the rotary and axial position signal outputs RPSOut and APSOut, through the attachment portion  224 . One or more receiving portions (e.g., in the CMM  200 , motion controller  115 , host computer  120 , etc.) may receive the rotary and axial position signal outputs RPSOut and APSOut, and one or more associated processing and control portions may be utilized to determine a three-dimensional position of the stylus coupling portion  342  and/or of the contact portion of the attached stylus  306  as its contact portion  348  moves along a surface of a workpiece W that is being measured. 
       FIG.  3    is partially schematic diagram showing portions of a first exemplary implementation of a schematically represented stylus suspension portion  407  as coupled to a stylus  406 , along with a partially schematic cross-section of a first exemplary implementation of a stylus position detection portion  411  for detecting the position of the stylus suspension portion  407  and/or the stylus  406 . It will be appreciated that certain numbered components  4 XX of  FIG.  3    may correspond to and/or have similar operations as similarly numbered counterpart components  3 XX of  FIG.  2   , and may be understood by analogy thereto and as otherwise described below. This numbering scheme to indicate elements having analogous design and/or function is also applied to the following  FIGS.  4 - 8 F . As shown in  FIG.  3   , the stylus suspension portion  407  includes a stylus motion mechanism  409  and a stylus coupling portion  442 . The stylus coupling portion  442  is configured to be rigidly coupled to a stylus  406  which has a contact portion  448  for contacting a surface S of a workpiece W (not shown). 
     As will be described in more detail below with respect to  FIG.  4   , the stylus motion mechanism  409  is attached to a frame of the scanning probe, and is configured to enable axial and rotary motion of the stylus coupling portion  442  and attached stylus  406  so that the contact portion  448  can change its position in three directions along the shape of the surface S. For purposes of illustration, the vertical and horizontal directions on the plane of paper in  FIG.  3    are defined as Z and Y directions, respectively, and the perpendicular direction to the plane of the paper is defined as the X direction. The direction of a central axis CA, also referred to as the axial direction, of the measuring probe  300  coincides with the Z direction in this illustration. 
     In  FIG.  3   , rotary motion portions of the stylus motion mechanism  409  are represented, including a rotating member  436 , a flexure element  440 , and a moving member  412  disposed within the rotating member  436 . As will be described in more detail below with respect to  FIG.  4   , the flexure element  440  enables rotary motion of the rotating member  436  about a rotation center RC. As will be described in more detail below, in various implementations rotary sensing coils TRSCi and BRSCi (where i is an index integer which identifies specific coils) and stylus position detection portion  411  are able to sense the rotated position of the disruptor element  451  and thereby the rotated position of the moving member  412  (e.g., in X and Y directions), and the axial sensing coil configurations (also referred to as the axial sensing coils) TASCC and BASCC are able to sense the axial position of the disruptor element  451  and thereby the axial position of the moving member  412  (e.g., in the Z direction). 
     As shown in  FIG.  3   , a first exemplary implementation of a stylus position detection portion  411  includes a disruptor element  451  (or more generally a disruptor configuration  450 ) that is coupled to the moving member  412  and which moves relative to the scanning probe frame (e.g., wherein the frame is included as part of the scanning probe body, etc.), within a disruptor motion volume MV located between the top and bottom coil substrates  471 T and  471 B, respectively. As shown in  FIG.  3   , the moving member  412  extends through and moves in a hole  472  located along the central axis CA in a bottom coil substrate ( 471 B). The attached disruptor element  451  moves in the disruptor motion volume MV relative to an undeflected position UNDF in response to a deflection of the stylus suspension portion  407  and the moving member  412 . 
     Various other components of the stylus position detection portion  411 , e.g., the receiver coil portion  470  and the field generating coil configuration  460 , may be fixed relative to the frame unless otherwise indicated. In the implementation shown in  FIG.  3   , the field generating coil configuration  460  comprises a single planar field generating coil  461  that is located approximately at a midplane of the disruptor motion volume MV and that is nominally planar and orthogonal to the central axis CA. As previously outlined with reference to  FIG.  2   , the receiver coil portion  470  may generally comprise a rotary sensing coil portion (also referred to as rotary sensing coils) RSC and an axial sensing coil configuration ASCC. The rotary position detection configuration RSC generally includes top rotary sensing coils TRSCi and bottom rotary sensing coils BRSCi. In the cross section shown in  FIG.  3   , only two top rotary sensing coils TRSC 1  and TRSC 2 , and two bottom rotary sensing coils BRSC 1  and BRSC 2 , are shown. These rotary sensing coils may provide signal components indicative of the position of the disruptor element  451  along the Y direction. In particular, their signal components vary depending on an amount of displacement ΔY of the disruptor element  451  along the Y direction, and are therefore indicative of the amount of displacement ΔY. The displacement ΔY determines an associated amount of “overlap” between the disruptor element  451  and the various rotary sensing coils TRSCi and BRSCi, and thereby their amount of coupling to the changing magnetic field generated by the field generating coil  461  (which determines the resultant signal components). Other rotary sensing coils (not shown) may provide signal components which are indicative of the position of the disruptor element  451  along the X axis direction. The various rotary sensing coil signal components may also be undesirably sensitive to their local “operating gap” OG relative to the disruptor element  451 , as represented in  FIG.  3    for the top rotary sensing coil TRSC 2 . However, such undesirable gap sensitivity may be substantially eliminated or compensated according to various principles disclosed herein, as described further below. 
     The axial sensing coil configuration ASCC generally includes a top axial sensing coil configuration TASCC and a bottom axial sensing coil configuration BASCC. In the implementation shown in  FIG.  3   , the top axial sensing coil configuration TASCC comprises a single top axial sensing coil that at least partially surrounds the central axis CA, and the at least one bottom axial sensing coil comprises a single bottom axial sensing coil that at least partially surrounds the central axis, as shown. These axial sensing coils are always completely “overlapped” by the disruptor element  451 . Therefore, their signal components are nominally only responsive to the position of the disruptor element  451  along the axial or Z direction, and are indicative of the position of the disruptor element  451  along the Z direction. The generation of various signal component is described in greater detail below with reference to  FIGS.  5  and  6   . 
     Similarly to operation previously outlined with reference to  FIG.  2   , in operation the moving disruptor element  451  causes position-dependent local variations in a changing magnetic field along the axial direction generated by the field generating coil  461 . The receiver coil portion  470  is responsive to the changing magnetic field and the variations therein caused by the disruptor element  451 , and outputs the rotary signal components RSigs and the axial signal components ASigs that may be processed to determine the rotary position of the disruptor element  451  (e.g., a Y and X position, and corresponding signals) and its axial position (e.g., a Z position), as previously outlined with reference to  FIG.  2   , and as described in detail further below. It will be appreciated that the position of the disruptor element  451  is related by a known geometry to the position of the stylus coupling portion  442  and/or its contact portion  448 . For example, for small rotation angles, for the illustrated movement or displacement ΔY of the disruptor element  451  along the Y direction away from null (e.g., from the undeflected position UNDF):
 
ΔY=Hθ Y   (Eq. 1)
 
where H is the distance from the rotation center RC to the nominal plane of the disruptor element  451 , and θ Y  is the rotary motion tilt of the rotating member  436  (and the moving member  412 ) in a plane parallel to the Y direction (i.e., that is, rotation about an axis parallel to the X axis at the rotation center RC). If a larger rotation angle is used in various implementations, an analogous expression that is accurate for larger rotation angles may be used, as is known in the art. The Y direction movement or displacement Y STYLUS  away from null (e.g., corresponding to the undeflected position UNDF) of the contact portion  448  of the stylus  406  in relation to the rotary motion tilt component θ Y  may be approximated as:
 
Δ Y   STYLUS =θ Y *( h   S   +l   S )  (Eq. 2)
 
where h S  is the distance from the end of the stylus coupling portion  442  to the rotation center RC, and l S  is the length of the stylus  406 . Combining EQUATIONS 1 and 2, the ratio of the displacement ΔY of the disruptor element  451  in relation to the Y direction displacement at the contact portion  448  may be approximated as:
 
 ΔY/ΔY   STYLUS   =H /( h   S   +l   S )  (Eq. 3)
 
     It will be appreciated that the X coordinate motion components are analogous to the above expressions, and will not be explained in further detail herein. The stylus length l S  for various styli may be utilized in the equations (e.g., with respect to the trigonometry of the system) for determining the X-Y position of the contact portion  448  based on the X-Y detected spot position. Regarding the Z coordinate displacement or position component, a displacement ΔZ (not shown) of the disruptor element  451  along the axial or Z direction away from null (e.g., corresponding to the undeflected position UNDF), in relation to the Z direction displacement ΔZ STYLUS  at a stylus contact portion (e.g., the contact portion  448 ) may be approximated as:
 
Δ Z/ΔZ   STYLUS ≈1  (Eq. 4)
 
       FIG.  4    is a partially schematic diagram showing a cross section of one implementation of a stylus suspension portion  407 ′ usable as the stylus suspension portion  407  represented in  FIG.  3   , as well as one implementation of a stylus position detection portion  511  that is similar to the stylus position detection portion  411  shown in  FIG.  3   , and signal processing and control circuitry  480 . The foregoing elements are shown as included within a frame  408  of a probe main body  402  of a scanning probe  400 . The substrates  571 T,  571 B, and the field generating coil  561  or its substrate (e.g., printed circuit type substrates) of the stylus position detection portion  511  may be positioned for proper operation in the scanning probe  400  using alignment and mounting portions  417 , or other known techniques. Various signal connections associated with the stylus position detection portion  511  may be provided by connectors (e.g., flex print and/or wire connections)  419 , or the like, according to known techniques. In some implementations, some or all of the signal processing and control circuitry  480  may be provided as a separate circuit assembly as represented in  FIG.  4   . In other implementations, some or all of the signal processing and control circuitry  480  may be combined on the substrates of the stylus position detection portion  511 , if desired. 
     As shown in  FIG.  4   , the stylus suspension portion  407 ′ includes a stylus motion mechanism  409  and a stylus coupling portion  442  which is coupled to a stylus  406 . The stylus motion mechanism  409  may include a moving member  412 , a rotating member  436 , a flexure element  440  coupled to the main body frame  408  for supporting and enabling rotary motion of the rotating member  436 , and flexure elements  414  and  415  (i.e., referenced as first flexure elements) supporting the moving member  412  and coupling it to the rotating member  436  for enabling axial motion of the moving member  412 . The scanning probe  400  includes the stylus position detection portion  511  having components and operation described in greater detail below with reference to  FIG.  5   , for determining the position and/or motion of the stylus motion mechanism  409  and/or the contact portion  448  of the stylus  406 . 
     The flexure element  440  (i.e., referenced as a second flexure element) may be disposed between the respective planes of a pair of flexure elements  414  and  415  (i.e., referenced as first flexure elements) in the axial direction O. Flexure designs suitable for the flexure elements  414 ,  415  and  440  may be determined according to principles known in the art. For example, one possible implementation is illustrated in copending and commonly assigned U.S. patent application Ser. No. 14/973,376, entitled “Measurement Device With Multiplexed Position Signals”, filed on Dec. 17, 2015, now Issued U.S. Pat. No. 9,791,262, which is hereby incorporated herein by reference in its entirety. The rotating member  436  may have a shape symmetric about the second flexure element  440  and may integrally include: two ring portions  436 A; two connecting portions  436 B; and a cylindrical portion  436 C. Peripheral portions of the first flexure elements  414  and  415  are fixed to the ring portions  436 A. The connecting portions  436 B extend inside of the ring portions  436 A so as to connect to the cylindrical portion  436 C, which has a hollow center. The first flexure elements  414  and  415  may be disposed at a symmetric distance with respect to the second flexure element  440 , although such an implementation is exemplary only and not limiting. 
     An axial motion mechanism  410  including the moving member  412  is supported inside of the rotating member  436 , and the rotating member  436  and the axial motion mechanism  410  together constitute a motion module that is part of the stylus motion mechanism  409 . The axial motion mechanism  410  allows the contact portion  448  to move in the axial direction O. The rotary motion mechanism  434  including the rotating member  436  allows the contact portion  448  of the stylus  406  to move transverse (e.g., approximately perpendicular) to the axial direction O by means of rotary motion about the rotation center RC. 
     The moving member  412  integrally includes: a lower portion  412 A; a rod portion  412 B; and an upper portion  412 C. As previously outlined with reference to  FIG.  3   , and described in more detail below with respect to the stylus position detection portion  511  shown in  FIG.  5   , the disruptor element  551  that is attached to the upper portion  412 C of the moving member  412  functions as both a rotary and axial position indicating element. The rod portion  412 B is disposed between the pair of first flexure elements  414  and  415 . The rod portion  412 B is housed in the rotating member  436 . The lower portion  412 A is formed below the rod portion  412 B and a stylus coupling portion  442  (e.g., a flange member) is attached to the lower portion  412 A. A flange part  444  is provided for attachment of the stylus  406 . The flange part  444  and the stylus coupling portion  442  together may constitute a detachable coupling mechanism (e.g., a known type of kinematic joint or coupling) which allows attachment and detachment between various styli  406  and the stylus coupling portion  442  with repeatable positioning (e.g., in the case of a collision knocking off a stylus, or when intentionally changing styli). 
       FIG.  5    is a partially schematic isometric diagram of an alternative implementation of a stylus position detection portion  511 ′ that is similar to a stylus position detection portion  511  shown in  FIG.  4   , emphasizing certain aspects according to principles disclosed herein. The stylus position detection portions  511 ′ and  511  are similar except for a difference in the field generating coil configuration  560 , as explained further below. In general, the stylus position detection portion  511 ′ includes certain components that are similar to those of the stylus position detection portions  311 ,  411  and  511  of  FIGS.  2 ,  3  and  4   , and will be understood to operate similarly except as otherwise described below. 
     In the implementation shown in  FIG.  5   , the stylus position detection portion  511 ′ comprises the receiver coil portion  570 , the disruptor configuration  550  comprising the disruptor element  551 , and the field generating coil configuration  560 . 
     In various implementations, disruptor element  551  (or more generally the disruptor configuration  550 ) may comprise a conductive plate or conductive loop, or parallel conductive plates or conductive loops (e.g., as fabricated on two sides of a printed circuit substrate, patterned by printed circuit board fabrication techniques), or any other desired operational configuration that provides a disruptor area (e.g., its interior area). The disruptor element  551  is located along the central axis CA in the disruptor motion volume MV between the top and bottom coil substrates  571 T and  571 B and is coupled to the stylus suspension portion  507  by a coupling configuration (e.g., comprising the moving member  512 ). For purposes of explanation, we may describe the disruptor element  551  as moving relative to the undeflected position illustrated in  FIG.  5    (see the undeflected position UNDF, in  FIG.  3   ) in response to a deflection of the stylus suspension portion  507  and/or the stylus  506  and/or the moving member  512 . The disruptor element may be described as moving with displacement increments ΔZ over an operating motion range +/−Rz along the axial direction in response to axial motion, and with displacement increments ΔX and ΔY over respective operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions that are orthogonal to the axial direction (Z direction) in response to rotary motion. The specified or expected operating motion ranges are described in greater detail below. 
     The receiver coil portion  570  may comprise the planar top coil substrate  571 T including N top rotary sensing coils TRSC (e.g., TRSC 1 -TRSC 4 , where N=4) and a top axial sensing coil configuration TASCC (e.g., comprising the single illustrated individual coil in this implementation), and a planar bottom coil substrate  571 B including N bottom rotary sensing coils BRSC (e.g., BRSC 1 -BRSC 4 , where N=4) and a bottom axial sensing coil configuration BASCC (e.g., comprising the single illustrated individual coil in this implementation). The top and bottom coil substrates  571 T and  571 B are mounted in a fixed relationship to the frame of the scanning probe with the bottom coil substrate closer to the stylus  506  and/or the stylus suspension portion  507 . The top and bottom coil substrates  571 T and  571 B may be nominally parallel to one another and nominally orthogonal to the central axis CA, and are spaced apart along the central axis CA with the disruptor motion volume MV located therebetween. It should be appreciated that although the various sensing coils shown in  FIG.  5    are represented by “closed loops” for simplicity of illustration, all coils comprise windings or conductors that have first and second connection ends (e.g., as representing in  FIG.  6   ) that are configured to operate as one or more inductively coupled “turns”. 
     The field generating coil configuration (e.g., the field generating coil configuration  560 ) generally comprises at least a first field generating coil that is located proximate to the disruptor motion volume MV and that is nominally planar and orthogonal to the central axis CA. In contrast to the single planar field generating coil  461  in the implementation shown in  FIG.  3    (which is located approximately at a midplane of the disruptor motion volume MV), in the implementation shown in  FIG.  5   , the field generating coil configuration  560  comprise a pair of planar field generating coils  561 T and  561 B (located on the top and bottom coil substrates  571 T and  571 B, respectively) that are approximately equidistant from a midplane of the disruptor motion volume MV along the central axis CA, and that are nominally planar and orthogonal to the central axis CA. Generally speaking, either of the field generating coil configurations  460  or  560  may be used with the receiver coil portion  570  (or other receiver coil portions disclosed herein) provided that the field generating coil configuration comprises at least a first field generating coil that is configured such that a projection of its coil area along the axial direction (Z direction) encompasses the conductive plate or loop that provides the disruptor area of the disruptor configuration  560  (e.g., of the disruptor element  551 ) and a coil area of all the rotary and axial sensing coils RSCi and ASCC located on the top and bottom coil substrates  571 T and  571 B. In such a case, the field generating coil configuration is configured to generate a changing magnetic flux generally along the axial direction in the disruptor motion volume MV in response to a coil drive signal, as desired for operation of the stylus position detection portion  511 ′. It should be appreciated that, although the various field generating coils shown in  FIG.  5    are represented by a single “closed loop” comprising a wide flat conductive trace (the edges of which are shown) for simplicity of illustration, in an actual device all coils comprise windings or conductors that have first and second connection ends (e.g., as represented in  FIG.  6   ), and are configured to operate as one or more field generating “turns”. 
     As illustrated in  FIG.  5   , a projection of the disruptor element  551  along the axial direction (e.g., as shown by fine dashed lines PRJ in  FIG.  5   ) through an interior coil area of the top axial sensing coil configuration TASCC defines a top axial sensing overlap area TASOA (indicated by a dot pattern filling that interior coil area), and a projection of the disruptor element  551  along the axial direction through an interior coil area of the bottom axial sensing coil configuration BASCC defines a bottom axial sensing overlap area BASOA (indicated by a dot pattern filling that interior coil area). Similarly, a projection of the disruptor element  551  along the axial direction through an interior coil area of any respective top rotary sensing coil TRSCi (e.g., TRSC 1 -TRSC 4 ) defines a respective top rotary coil sensing overlap area TRSCOAi (e.g., TRSCOA 1 -TRSCOA 4 ), as indicated by a dot pattern filling the various respective overlap areas shown in  FIG.  5   , where i is an individual coil identification index in the range 1 to N. A projection of the disruptor element  551  along the axial direction through an interior coil area of any respective bottom rotary sensing coil BRSCi (e.g., BRSC 1 -BRSC 4 ) defines a respective bottom rotary coil sensing overlap area BRSCOAi (e.g., TRSCOA 1 -TRSCOA 4 ), as indicated by a dot pattern filling the various respective overlap areas shown in  FIG.  5   . 
     Regarding axial position detection in a stylus position detection portion (e.g.,  511 ′), according to principles described and claimed herein, the receiver coil portion (e.g.,  570 ) and the disruptor element (e.g.,  551 ) are generally configured to provide a top axial sensing overlap area TASOA and bottom axial sensing overlap area BASOA wherein an amount of each of the overlap areas TASOA and BASOA is unchanged or independent of the position of the disruptor element  551  within operating motion ranges +/−Rz, +/−Rx, and +/−Ry. (It will be appreciated that, for a particular scanning probe, the operating motion ranges may be prescribed or specified in combination with the configuration of the probe&#39;s particular stylus position detection portion, if needed, in order to fulfill this requirement.) In this way, the signal components generated in the top and bottom axial sensing coil configurations TASCC and BASCC are nominally independent of the rotary motion (that is the position of the disruptor element  551  along the X and Y directions), and are nominally sensitive only to variations in “proximity” or gap to the disruptor element  551 , which varies depending on the axial (Z) position or displacement ΔZ of the disruptor element  551 . In operation, currents induced in the disruptor element  551  by the changing magnetic field of the field generating configuration  560  cause opposing magnetic fields. Generally speaking, as the disruptor element  551  moves upward along the axial (Z) direction in  FIG.  5   , the opposing magnetic fields couple more strongly to the top axial sensing coil configurations TASCC, reducing its signal component that arises from the changing magnetic field. Conversely, the opposing magnetic fields couple more weakly to the bottom axial sensing coil configurations BASCC, increasing its signal component that arises from the changing magnetic field. By a convention used in this disclosure, we may refer to a signal component SIGTASCC as the signal component arising from a particular top axial sensing coil configuration (or coil) TASCC, and so on. 
     It will be appreciated that at the undeflected position UNDF, the net signal components SIGTASCC and SIGBASCC may be approximately balanced. For small displacements ΔZ, such as those expected in operation, the net signal components SIGTASCC and SIGBASCC may vary approximately linearly, and inversely compared to one another. Certain considerations related to degree of nonlinearity of such signals are discussed further below. In one implementation, an axial displacement or position ΔZ may be indicated by, or correspond to, the signal relationship:
 
Δ Z =function of [(SIGBASCC−SIGTASCC)/(SIGBASCC+SIGTASCC)]  (Eq. 5)
 
     This signal relationship is exemplary only, and not limiting. In various implementations, this signal relationship may be adjusted or compensated by additional calibration or signal processing operations, including operations that reduce the effects of geometric and/or signal cross-coupling between various displacement directions or signal components, if desired. In various implementations, the top axial sensing coil configuration may comprise at least one top axial sensing coil that is not one of the N top rotary sensing coils and that is arranged closer to the central axis than the top rotary sensing coils, and the at least one top axial sensing coil and the disruptor element are characterized in that the at least one top axial sensing coil has an interior coil area that is smaller than the disruptor element, and a projection of the disruptor element along the axial direction completely fills the interior coil area of the at least one top axial sensing coil for any position of the disruptor element within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, whereby the top axial sensing overlap area TASOA is unchanged by the position of the disruptor element. Similarly, in various such implementations, the bottom axial sensing coil configuration may comprise at least one bottom axial sensing coil that is not one of the N bottom rotary sensing coils and that is arranged closer to the central axis than the bottom rotary sensing coils, and the at least one bottom axial sensing coil and the disruptor element are characterized in that the at least one bottom axial sensing coil has an interior coil area that is smaller than the disruptor element and a projection of the disruptor element along the axial direction completely fills the interior coil area of the at least one bottom axial sensing coil for any position of the disruptor element within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, whereby the bottom axial sensing overlap area TASOA is unchanged by the position of the disruptor element. It may be seen that the particular implementation of the stylus position detection portion  511 ′ shown in  FIG.  5   , wherein the top axial sensing coil configuration TASCC and the bottom axial sensing coil configuration BASCC each comprise a single sensing coil, conforms to this description. It will be appreciated that various configurations of the top and bottom axial sensing coil configurations TASCC and BASCC may be used, and the particular configurations shown in  FIG.  5    are exemplary only and not limiting. Various alternative configurations are described with reference to other figures below. 
     Regarding rotary position detection in a stylus position detection portion (e.g.,  511 ′), according to principles described and claimed herein, the receiver coil portion (e.g.,  570 ) and the disruptor element (e.g.,  551 ) are generally configured to provide N complementary pairs of rotary sensing coils CPi (e.g., CP 1 -CP 4 , where N=4) that each comprise a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi, wherein for any complementary pair CPi, and for any disruptor element displacement increment within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, the magnitude of the change in overlap areas TRSCOAi and BRSCOAi associated with that disruptor displacement increment is nominally the same in that complementary pair. (It will be appreciated that for a particular scanning probe the operating motion ranges may be prescribed or specified in combination with the configuration of its particular stylus position detection portion, if needed in order to fulfill this requirement.) The table CPTable in  FIG.  5    indicates the respective members TRSCi and BRSCi of each respective complementary pair CPi for the implementation shown in  FIG.  5   . 
     By conforming to the foregoing principle, the complementary pairs CPi shown in  FIG.  5    may be used to compensate or eliminate certain cross-coupling errors, and/or to simplify the signal processing required to provide precise rotary position or displacement measurements (e.g., along the X and/or Y directions). In particular, pairs of signal components arising in complementary pairs CPi of rotary sensing coils in the implementation shown in  FIG.  5    may be combined or processed in a relationship that provides a resulting signal that is nominally insensitive to variations in “proximity” or gap between the individual coils of the complementary pair and the disruptor element  551 . That is, the resulting signal may be insensitive to the axial (Z) position or displacement ΔZ of the disruptor element  551 , and nominally only sensitive to a rotary position or displacement (e.g., along the X and/or Y directions), as described in greater detail below. For the particular implementation shown in  FIG.  5   , it may be understood that a displacement of the disruptor element  551  that has a displacement component ΔY along the Y axis direction will increase (or decrease) the overlap areas TRSCOA 2  and BRSCOA 2  in the complementary pair CP 2  and decrease (or increase) the overlap areas TRSCOA 1  and BRSCOA 1  in the complementary pair CP 1 . Similarly, a displacement of the disruptor element  551  that has a displacement component ΔX along the X axis direction will increase (or decrease) the overlap areas TRSCOA 3  and BRSCOA 3  in the complementary pair CP 3  and decrease (or increase) the overlap areas TRSCOA 4  and BRSCOA 4  in the complementary pair CP 4 . 
     As previous outlined, in operation, currents induced in the disruptor element  551  by the changing magnetic field of the field generating configuration  560  cause opposing magnetic fields. Generally speaking, the signal component SIGTRSCi (or SIGBRSCi) generated in any rotary sensing coil TRSCi (or BRSCi), will be reduced as a proximate portion of the disruptor element  551  comes closer to that rotary sensing coil along the axial direction, or increases its overlap TRSCOAi (or BRSCOAi) with the rotary sensing coil. 
     It will be appreciated that for the complementary pairs CP 1 -CP 4  indicated in  FIG.  5    (wherein the coils in a complementary pairs CPi may be identical and aligned along the axial direction), at the illustrated undeflected position UNDF, the signal components in each complementary pair (e.g., SIGTRSC 1  and SIGBRSC 1 ) may be approximately balanced. According to previously outlined principles, for a portion of the disruptor element  551  proximate to a complementary pair (e.g., CP 1 ), for small displacements ΔZ such as those expected in operation, the net signal components (e.g., SIGTRSC 1  and SIGBRSC 1 ) may vary approximately linearly, and inversely compared to one another. Thus, the sum of such signals for a complementary pair CPi may be nominally insensitive to a ΔZ associated with the proximate portion of the disruptor element  551 . Furthermore, in the implementation shown in  FIG.  5   , the edges of the disruptor element  551  may be parallel to the X and Y directions, such that, within the operating motion ranges +/−Rx and +/−Ry, a Y direction displacement component does not alter the rotary coil sensing overlap areas TRSCOA 3 , BRSCOA 3 , and/or TRSCOA 4  and BRSCOA 4 , and an X direction displacement component does not alter the rotary coil sensing overlap areas TRSCOA 2 , BRSCOA 2 , and/or TRSCOA 1  and BRSCOA 1 . Therefore, in one implementation, a rotary displacement or position component ΔX along the X direction may be indicated by or correspond to the following signal relationship, ideally regardless of ΔZ and/or ΔY:
 
Δ X =function of [(SIGTRSC3+SIGBRSC3)−(SIGTRSC4+SIGBRSC4)]÷[(SIGTRSC3+SIGBRSC3)+(SIGTRSC4+SIGBRSC4)]  (Eq. 6)
 
     Similarly, in one implementation, a rotary displacement or position component ΔY along the Y direction may be indicated by or correspond to the following signal relationship, ideally regardless of ΔZ and/or ΔX:
 
Δ Y =function of [(SIGTRSC2+SIGBRSC2)−(SIGTRSC1+SIGBRSC1)]÷[(SIGTRSC2+SIGBRSC2)+(SIGTRSC1+SIGBRSC1)]  (Eq. 7)
 
     These signal relationships are exemplary only, and not limiting. In various implementations, these signal relationships may be adjusted or compensated by additional calibration or signal processing operations, including operations that reduce the effects of geometric and/or signal cross-coupling between various displacement directions or signal components, if desired. 
     In some particularly advantageous implementations, the receiver coil portion (e.g.,  570 ) and the disruptor element (e.g.,  551 ) are configured wherein, for any complementary pair CPi and any disruptor element displacement increment within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, both the magnitude and sign of the change in overlap areas TRSCOAi and BRSCOAi associated with that disruptor displacement increment are the same in that complementary pair. In some such implementations, the receiver coil portion is configured wherein each complementary pair CPi comprises a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi characterized in that the shape of their interior areas nominally coincide when projected along the axial direction. It may be seen that the particular implementation of the stylus position detection portion  511 ′ shown in  FIG.  5    conforms to this description. However, it will be appreciated that various configurations of complementary pairs may be used, and the particular configurations shown in  FIG.  5    are exemplary only and not limiting. Various alternative configurations are described with reference to other figures below. 
     In some particularly advantageous implementations, the receiver coil portion (e.g.,  570 ) and the disruptor element (e.g.,  551 ) may be configured wherein the disruptor element comprises at least N straight sides, and, for any respective complementary pair CPi, a respective one of the straight sides of the disruptor element transects both the top rotary sensing coil TRSCi and the bottom rotary sensing coil BRSCi of that respective complementary pair. In some such implementations, N=4, and the at least N straight sides include 4 sides that are arranged parallel to the sides of a rectangular or square shape. It may be seen that the particular implementation of the stylus position detection portion  511 ′ shown in  FIG.  5    conforms to this description. However, it will be appreciated that various combinations of complementary pairs configurations and disruptor element edge configurations may be used, and the combination of the particular configurations shown in  FIG.  5    is exemplary only and not limiting. Various alternative combinations of configurations are described with reference to other figures below. 
       FIG.  6    is a partially schematic isometric diagram of certain elements of the stylus position detection portion  511 ′ shown in  FIG.  5   , including schematically represented connections CONN to a block diagram of one exemplary implementation of signal processing and control circuitry  680  according to principles disclosed herein. As shown in  FIG.  6   , the signal processing and control circuitry  680  is operably connected to the various coils of the stylus position detection portion  511 ′. In the implementation shown in  FIG.  6   , the signal processing and control circuitry  680  comprises a digital controller/processor  681 , that may govern various timing and signal connection or exchange operations between its various interconnected components, which include a drive signal generator  682 , an amplification/switching portion  683 , a sample and hold portion  684 , a multiplexing portion  685 , and an A/D convertor portion  686 . The digital controller/processor  681  may also perform various digital signal processing operations to determine the output signals APSOut and RPSOut, as previously outlined with reference to  FIG.  2   , and described further below. The design and operation of the signal processing and control circuitry  680  may generally be recognized and understood by one of ordinary skill in the art, according to known principles. For example, in one implementation, the various elements of the signal processing and control circuitry  680  may be designed and operated by analogy to corresponding elements disclosed in U.S. Pat. No. 5,841,274, which is hereby incorporated herein by reference in its entirety. Therefore, the operation of the illustrated signal processing and control circuitry  680  will be described only briefly here. 
     In operation, the drive signal generator  682  is operated to provide a changing coil drive signal Dsig (e.g., a pulse) to the field generating coil configuration  560 , which generates a changing magnetic flux generally along the axial direction in the disruptor motion volume MV in response to the coil drive signal. In the illustrated configuration, the top field generating coil  561 T and the bottom field generating coil  561 B are configured to provide changing magnetic fluxes that reinforce one another. The amplification/switching portion  683  is configured to input the signals RSIGs and ASIGs from the receiver coil portion  570 , comprising respective signal components provided by the respective rotary and axial sensing coils located on the top and bottom coil substrates (e.g., the previously outlined signal components SIGTASCC, SIGBASCC, SIGTRSC 1 -SIGTRSC 4 , and SIGBRSC 1 -SIGBRSC 4 ). In some implementations, the amplification/switching portion  683  may include switching circuits which may combine various analog signals to provide various desired sum or difference signals (e.g., by appropriate serial or parallel connections, or the like), for example as prescribed in the relationships shown in EQUATIONS 5-7, or the like. However, in other implementations, the amplification/switching portion  683  may perform only amplification and signal conditioning operations (and possibly signal inversion operations), with all signal combination operations performed in other circuit portions. 
     The sample and hold portion  684  inputs the various analog signals from the amplification/switching portion  683 , and performs sample and hold operations according to known principles, e.g., to simultaneously sample and hold all respective signal components that arise from the various respective sensing coils of the receiver coil portion  570 . In one implementation, the multiplexing portion  685  may connect various signals to the A/D convertor portion  686  sequentially, and/or in combinations related to various desired signal relationships (for example, as prescribed in the relationships shown in EQUATIONS 5-7, or the like). The A/D convertor portion  686  outputs corresponding digital signal values to the digital controller/processor  681 . The digital controller/processor  681  may then process and/or combine the digital signal values according to various desired relationships (for example, as prescribed in the relationships shown in EQUATIONS 5-7, or the like), to determine and output the output signals APSOut and RPSOut, which are indicative of the axial position and the rotary position of at least one of the disruptor element  551  or the stylus  506  relative to the frame or housing of the scanning probe. In some implementations the digital controller/processor  681  may be configured such that the output signals APSOut and RPSOut directly indicate the three-dimensional position of the stylus  506  or its contact portion  548  relative to the frame of the scanning probe. In other implementations, it may be configured to output signals that indirectly indicate the three-dimensional position of the stylus  506  or its contact portion  548  relative to the frame of the scanning probe, and a host system (e.g., a CMM) inputs such signals and performs additional processing to further combine or refine such signals and determine the three-dimensional position of the stylus  506  or its contact portion  548  relative to the scanning probe and/or relative to a an overall coordinate system used for CMM measurements. 
     It should be appreciated that for implementations of a stylus position detection portion (e.g.,  511 ′) according to the various principles disclosed and claimed herein, the signal components that are provided by the various receiver coils of the receiver coil portion (e.g.,  570 ) are particularly advantageous with regard to eliminating or allowing correction of certain signal errors and/or signal cross coupling errors, while using relatively fast and simple signal processing in order to provide robust and highly accurate three-dimensional position indications. 
     Regarding the use of relatively fast and simple signal processing in order to provide robust and highly accurate three-dimensional position indications, one consideration is the linearity of the position or displacement signal components (or the linearity of certain combined signals, such as the Z signal relationship expressed in EQUATION 5). It should be understood that signals or signal relationships that vary with displacement according to significant 3rd order and/or 5th order signal variation contributions generally require more complex signal processing and/or compensation and/or calibration in order to provide precise displacement or position indications. The inventors have found that certain desirable configurations may tend to suppress higher order signal variation contributions in the axial sensing coil signal components ASigs, and/or combinations thereof. As one way of describing these desirable configurations, the sensing coils of the top and bottom axial sensing coil configurations TASCC and BASCC may be considered as defining an “axial sensing coil region inscribed cylinder” that is defined to be concentric with the central axis CA and to have a radius that is the minimum necessary such that the top and bottom axial sensing coils (e.g., the sensing coils of the top and bottom axial sensing coil configurations TASCC and BASCC shown in  FIG.  5   ) fit within it. A “disruptor inscribed cylinder” may be defined to be concentric with the central axis CA and to have a radius that is the maximum radius that may be inscribed within the edges of the disruptor element (e.g., the disruptor element  551 , or the like). In various implementations it may be desirable (but not required) that the radius of the disruptor inscribed cylinder may be at least 1.1 times the radius of the axial sensing coil region inscribed cylinder. In some implementations, it may be desirable (but not required) that the radius of the disruptor inscribed cylinder may be at least 1.2 or at least 1.5 times the radius of the axial sensing coil region inscribed cylinder. 
       FIGS.  7 A- 7 E  show “plan view” diagrams (looking along the axial or Z direction) representing respective “4 complementary pair” implementations of stylus position detection portion components comprising receiver coil portions  770 A- 770 E and disruptor elements  751 A- 751 E, respectively, according to principles disclosed herein. The illustrated components are usable in various implementations of a stylus position detection portion according to principles disclosed herein. Field generating coils are not shown in  FIGS.  7 A- 7 E , but they will be understood to be provided according to previously disclosed principles. The various components shown in  FIGS.  7 A- 7 E  are similar or analogous to similarly numbered components in the previously described stylus position detection portions  311 ,  411 ,  511  and/or  511 ′, and may generally be understood by analogy thereto. Therefore, only certain unique or important characteristics of the “4 complementary pair” implementations included in  FIGS.  7 A- 7 E  are described below. 
       FIG.  7 A  shows an implementation of a receiver coil portion  770 A and a disruptor element  751 A similar to those previously described with reference to the stylus position detection portion  511 ′, and will be understood by analogy thereto. In addition to showing the circular top and bottom axial sensing coil configurations TASCC and BASCC similar to those previously described with reference to the stylus position detection portion  511 ′,  FIG.  7 A  also shows alternative square top and bottom axial sensing coil configurations TASCC′ and BASCC′, shown in dashed outline. More generally, it will be understood that any desired shape may be used for the top and bottom axial sensing coil configurations provided that they are configured to provide desirable operation according to the various principles disclosed and/or claimed herein. 
     It may be noted that the shape of the disruptor element  751 A includes “trimmed corners”, for compactness. It should be appreciated that in order to fulfill principles previously disclosed herein, wherein the magnitude of the change in overlap areas TRSCOAi and BRSCOAi associated with a disruptor displacement increment is nominally the same in any of the illustrated complementary pairs, the operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions may be prescribed or specified to not extend past the straight edge sections that transect each complementary pair, in order to fulfill this principle. 
       FIG.  7 B  shows an implementation of a receiver coil portion  770 B and a disruptor element  751 B similar to those previously described with reference to  FIG.  7 A , except that the complementary pairs CP 1 -CP 4  in the receiver coil portion  770 B comprise larger rotary sensing coils that overlap the sensing coils of the top and bottom axial sensing coil configurations TASCC and BASCC, which is not prohibited according to the various principles disclosed herein. In order to fabricate such a configuration, the rotary and axial sensing coils may be fabricated on respective layers of a multi-layer printed circuit board, for example. 
       FIG.  7 C  shows an implementation of a receiver coil portion  770 C and a disruptor element  751 C similar to those previously described with reference to  FIG.  7 B , except that the top and bottom axial sensing coil configurations TASCC and BASCC are not provided by axial sensing coils that are separate from the various rotary sensing coils TRSCi and BRSCi. Instead, it will be understood that the top axial sensing coil configuration TASCC comprises a combination of the N (N=4) top rotary sensing coils TRSC 1 -TRSC 4 , wherein the top axial sensing overlap area TASOA comprises a sum of the individual overlap areas TRSCOAi associated with the N top rotary sensing coils. It may be observed that due to the similar shapes of the N top rotary sensing coils TRSC 1 -TRSC 4 , and the two pairs of parallel sides of the disruptor element that overlap them, any overlap area that is lost in the overlap area TRSCOA 1  due to a displacement increment of the disruptor element  751 C is gained in the overlap area TRSCOA 2 , and vice versa. Similarly, any overlap area that is lost in the overlap area TRSCOA 3  is gained in the overlap area TRSCOA 4 , and vice versa. Thus, the sum of the overlap areas TRSCOAi is unchanged or independent of the position of the disruptor element  751 C within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, even though its constituent individual overlap areas TRSCOAi vary depending on the position of the disruptor element  751 C. Similarly, the bottom axial sensing coil configuration BASCC comprises a combination of the N (N=4) bottom rotary sensing coils BRSC 1 -BRSC 4 , wherein the bottom axial sensing overlap area BASOA comprises a sum of the individual overlap areas BRSCOAi associated with the N bottom rotary sensing coils. This sum of the overlap areas BRSCOAi is also unchanged or independent of the position of the disruptor element  751 C within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, even though its constituent individual overlap areas BRSCOAi vary depending on the position of the disruptor element  751 C. Thus, despite its differences from previously described configurations, the implementation shown in  FIG.  7 C  provides a configuration according to a general principle disclosed herein, wherein the receiver coil portion  770 C and the disruptor element  751 C are configured to provide a top axial sensing overlap area TASOA and bottom axial sensing overlap area BASOA wherein an amount of each of the overlap areas TASOA and BASOA is unchanged or independent of the position of the disruptor element within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry. 
       FIG.  7 D  shows an implementation of a receiver coil portion  770 D and a disruptor element  751 D which function in a manner analogous to that previously described with reference to  FIG.  7 C , wherein the axial sensing coil configurations TASCC and BASCC are not provided by axial sensing coils that are separate from the various rotary sensing coils TRSCi and BRSCi. Instead, it will be understood that the top and bottom axial sensing coil configurations TASCC and BASCC comprise respective combinations of the N (N=4) top and bottom rotary sensing coils TRSC 1 -TRSC 4  and BRSC 1 -BRSC 4 , wherein the top axial sensing overlap area TASOA comprises a sum of the individual overlap areas TRSCOAi associated with the N top rotary sensing coils and the bottom axial sensing overlap area BASOA comprises a sum of the individual overlap areas BRSCOAi associated with the N bottom rotary sensing coils. Similarly to the configuration shown in  FIG.  7 C , the sum of the overlap areas TRSCOAi is unchanged or independent of the position of the disruptor element  751 D within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, even though its constituent individual overlap areas TRSCOAi vary depending on the position of the disruptor element  751 D, and the sum of the overlap areas BRSCOAi is also unchanged or independent of the position of the disruptor element  751 D within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, even though its constituent individual overlap areas BRSCOAi vary depending on the position of the disruptor element  751 D. Thus, despite its differences from previously described configurations, the implementation shown in  FIG.  7 D  provides a configuration according to a general principle disclosed herein, wherein the receiver coil portion  770 D and the disruptor element  751 D are configured to provide a top axial sensing overlap area TASOA and bottom axial sensing overlap area BASOA wherein an amount of each of the overlap areas TASOA and BASOA is unchanged or independent of the position of the disruptor element within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry. Due to the illustrated shape of the disruptor element  751 D, it should be appreciated that in order to fulfill principles previously disclosed herein, wherein the magnitude of the change in overlap areas TRSCOAi and BRSCOAi associated with a disruptor displacement increment is nominally the same in any of the illustrated complementary pairs, the operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions may be prescribed or specified such that none of the corners of the disruptor element  751 D move from their illustrated positions to an extent such that they cross any boundary of a sensing coil of any complementary pair CP 1 -CP 4 . 
       FIG.  7 E  shows an implementation of a receiver coil portion  770 E and a disruptor element  751 E similar to those previously described with reference to  FIG.  7 A  (or the stylus position detection portion  511 ′), except that the top and bottom rotary sensing coils of each complementary pair CPi are rotated about the central axis by an angle 2*NAA relative to one another, where NAA is a “non-alignment angle”. However, this implementation becomes increasingly disadvantageous in comparison to the previously outlined configurations (wherein the top and bottom rotary sensing coils of each complementary pair CPi are aligned along the axial direction), as the non-alignment angle NAA increases. The reason it becomes increasingly disadvantageous is that sum of the operating gaps (e.g., the operating gap OG, illustrated in  FIG.  3   ) between the disruptor element  751 E and the top and bottom rotary sensing coils of each complementary pair CPi is not necessarily constant for all displacements of the disruptor element  751 E, since their overlap areas with the disruptor element  751 E are not “co-located”. Thus, the sum of their signals may not be ideally independent of the axial displacement ΔZ, as previously outlined with reference to EQUATION 6. The configuration shown in  FIG.  7 E  and outlined above is nevertheless not prohibited according to the various principles disclosed herein. It should be appreciated that such a configuration may still fulfill the most basic principles disclosed and claimed herein, and provide signal components that at least partially retain the various advantages outlined above in comparison to previously known inductive sensor configurations. As one way of describing the configuration shown in  FIG.  7 E , the receiver coil portion  770 E is configured wherein each complementary pair CPi comprises a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi characterized in that the shape of their interior areas would nominally coincide if the shape of one of them is rotated about the central axis to coincide with an angular location of the other about the central axis (e.g., by an angle 2*NAA), and then projected along the axial direction. In various implementations, the receiver coil portion  770 E and the disruptor element  751 E may be configured wherein the disruptor element  751 E comprises at least N straight sides (e.g., N=4), and, for any respective complementary pair CPi (e.g., CP 1 -CP 4 ), a respective one of the straight sides of the disruptor element  751 E transects both the top rotary sensing coil TRSCi and the bottom rotary sensing coil BRSCi of that respective complementary pair CPi. In such implementations where N=4, the at least N straight sides of the disruptor element  751 E include 4 sides that are arranged parallel to the sides of a rectangular or square shape. 
       FIGS.  8 A- 8 F  show “plan view” diagrams (looking along the axial or Z direction) representing respective “3 (or 6) complementary pair” implementations of stylus position detection portion components comprising receiver coil portions  870 A- 870 F and disruptor elements  851 A- 851 F, respectively, according to principles disclosed herein. The illustrated components are usable in various implementations of a stylus position detection portion according to principles disclosed herein. Field generating coils are not shown in  FIGS.  8 A- 8 F , but they will be understood to be provided according to previously disclosed principles. Various elements shown in “3 (or 6) complementary pair” configurations shown in several of the  FIGS.  8 A- 8 F  are similar or analogous to corresponding elements shown in corresponding “4 complementary pair” configurations previously described with reference to  FIGS.  7 A- 7 E , and they may generally be understood by analogy thereto. Therefore, only certain unique or important characteristics of the “3 complementary pair” implementations included in  FIGS.  8 A- 8 F  are described below. 
       FIGS.  8 A- 8 C  are “3 complementary pair” analogs of their counterpart “4 complementary pair” configurations shown in the corresponding  FIGS.  7 A- 7 C . They may generally be understood by analogy with the description of their counterpart configurations (e.g.,  FIG.  8 A  to its counterpart  FIG.  7 A , and so on), based on the following additional description. 
     The use of 3 complementary pairs oriented at 120 degrees from one another, in contrast with the previously described 4 complementary pairs oriented at 90 degrees from one another (e.g., as shown in  FIG.  7 A ), may be appreciated by considering that any displacement increment or position of a disruptor element (e.g.,  851 A) is just as easily characterized by displacement or position vector components or coordinates oriented along the respective vector component directions VC 1 , VC 2 , and VC 3  shown in  FIGS.  8 A- 8 F  as it is by displacement or position vector components or coordinates oriented along the X and Y axis directions shown in various figures herein. Methods of converting vector components from one coordinate system to another are well known, and need not be discussed in detail here. Based on this, it may be understood that the complementary pairs CPi shown in  FIGS.  8 A- 8 C  are configured according to the same principles outlined in the previous description of complementary pairs, and their respective overlap areas are indicative of the displacement or position of the disruptor element along their corresponding vector component directions VC 1 , VC 2 , and VC 3 . For example, the representative overlap areas TRSCOA 1  and BRSCOA 1  indicated in  FIG.  8 A  result in associated signal components SIGTRSC 1  and SIGBRSC 1  according to previously outlined principles, which are indicative of the displacement or position of the disruptor element along the corresponding vector component direction VC 1 , and so on. For the implementations shown in  FIGS.  8 A- 8 C and  8 E , in one implementation, a rotary displacement or position component ΔVC 1  along the VC 1  direction may be indicated by or correspond to the following signal relationship, which is nominally independent of ΔZ according to previously outlined principles for comparable complementary pairs:
 
Δ VC 1=function of [(SIGTRSC1+SIGBRSC1)−(SIGTRSC1 UNDF +SIGBRSC1 UNDF ],  (Eq. 8)
 
where SIGTRSC 1   UNDF  and SIGBRSC 1   UNDF  are reference signal values resulting from the overlap areas overlap areas TRSCOA 1  and BRSCOA 1  corresponding to the undeflected position UNDF of the disruptor element (e.g.,  851 A, etc.).
 
     Similarly, rotary displacement or position components ΔVC 2  along the VC 2  direction, and ΔVC 3  along the VC 3  direction, may be indicated by or correspond to the following signal relationships:
 
Δ VC 2=function of [(SIGTRSC2+SIGBRSC2)−(SIGTRSC2 UNDF +SIGBRSC2 UNDF ]  (Eq. 9)
 
Δ VC 3=function of [(SIGTRSC3+SIGBRSC3)−(SIGTRSC3 UNDF +SIGBRSC3 UNDF ]  (Eq. 10)
 
     It will appreciated that the axial sensing coil configurations TASCC and BASCC shown in  FIGS.  8 A- 8 C  are substantially the same as those previously describe herein with reference to their counterpart configurations, and may be determined according to the same type of signal components and signal relationship. The signal relationships outlined above are exemplary only, and not limiting. In various implementations, these signal relationships may be adjusted or compensated by additional calibration or signal processing operations, including operations that reduce the effects of geometric and/or signal cross-coupling between various displacement directions or signal components, if desired. 
       FIG.  8 D  shows an implementation of a receiver coil portion  870 D and a disruptor element  851 D similar to those previously described with reference to  FIG.  8 A , except that additional complementary pairs CP 4 -CP 6  are provided that are symmetrically configured across the central axis from the complementary pairs CP 1 -CP 3 , to provide a total of 6 complementary pairs. In particular, CP 1  and CP 4  are oriented opposite one another along the VC 1  direction, CP 2  and CP 5  are oriented opposite one another along the VC 2  direction, and CP 3  and CP 6  are oriented opposite one another along the VC 3  direction. These opposing pairs are analogous to the opposing complementary pairs shown oriented along the X and Y axis directions in  FIGS.  7 A- 7 D . Such a configuration need not depend on the reference signal values (e.g., SIGTRSC1 UNDF , and so on) used in EQUATIONS 8-10. Therefore, such a configuration may be more robust and accurate (e.g., inherently compensating for signal drift due to various causes, and the like). For the implementation shown in  FIG.  8 D , in one implementation, a rotary displacement or position component ΔVC 1  along the VC 1  direction may be indicated by or correspond to the following signal relationships, which are nominally independent of ΔZ according to previously outlined principles for comparable complementary pairs:
 
Δ VC 1=function of [(SIGTRSC1+SIGBRSC1)−(SIGTRSC4+SIGBRSC4)]÷[(SIGTRSC1+SIGBRSC1)+(SIGTRSC4+SIGBRSC4)]  (Eq. 11)
 
Δ VC 2=function of [(SIGTRSC2+SIGBRSC2)−(SIGTRSC5+SIGBRSC5)]÷[(SIGTRSC2+SIGBRSC2)+(SIGTRSC5+SIGBRSC5)]  (Eq. 12)
 
Δ VC 3=function of [(SIGTRSC3+SIGBRSC3)−(SIGTRSC6+SIGBRSC6)]÷[(SIGTRSC3+SIGBRSC3)+(SIGTRSC6+SIGBRSC6)]  (Eq. 13)
 
     It will be appreciated that the “3 complementary pair” implementations shown in  FIGS.  8 B and  8 C  could be similarly adapted to include 6 complementary pairs, and use analogous signal processing with analogous benefits. 
       FIG.  8 E  shows an implementation of a receiver coil portion  870 E and a disruptor element  851 E analogous to those previously described with reference to  FIG.  7 E , and may generally be understood by analogy to that description, in conjunction with the foregoing description of  FIGS.  8 A- 8 C . To briefly paraphrase that description, in  FIG.  8 E  the top and bottom rotary sensing coils of each complementary pair CPi are rotated about the central axis by an angle 2*NAA relative to one another, where NAA is a “non-alignment angle”. This implementation becomes increasingly disadvantageous in comparison to previously outlined configurations (wherein the top and bottom rotary sensing coils of each complementary pair CPi are aligned along the axial direction), as the non-alignment angle NAA increases, as previously described with reference to  FIG.  7 E , where it was explained that the sum of the signals from a complementary pair may not be ideally independent of the axial displacement ΔZ as previously outlined with reference to EQUATION 6. The configuration shown in  FIG.  8 E  is nevertheless not prohibited according to the various principles disclosed herein. It should be appreciated that such a configuration may still fulfill the most basic principles disclosed and claimed herein, and provide signal components that at least partially retain the various advantages outlined above in comparison to previously known inductive sensor configurations. 
       FIG.  8 F  shows an implementation of a receiver coil portion  870 F and a disruptor element  851 F wherein the complementary pairs of sensing coils CPi have a different configuration sensing coils than those of previously described complementary pairs (e.g., as shown in  FIG.  8 A ), in that they are located symmetrical across the central axis relative to one another. Thus, they may be characterized as similar to previously described complementary pairs in that the receiver coil portion and the disruptor element are further configured wherein, for any complementary pair CPi and any disruptor element displacement increment within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, the magnitude of the change in overlap areas TRSCOAi and BRSCOAi associated with the disruptor displacement increment is the same in that complementary pair. Furthermore, in the implementation shown in  FIG.  8 F , the receiver coil portion is configured similarly to some complementary pairs previously described herein, wherein each complementary pair CPi comprises a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi characterized in that the shape of their interior areas would nominally coincide if the shape of one of them is rotated by an offset angle (e.g., 180 degrees) about the central axis to coincide with the angular location of the other about the central axis, and then projected along the axial direction. 
     However, in contrast to previously described complementary pairs, the sign of the change in overlap areas TRSCOAi and BRSCOAi associated with the disruptor displacement increment are the opposite in the complementary pairs shown in  FIG.  8 F . Such an implementation may have certain disadvantages in comparison to implementations wherein the sign of the change in overlap areas TRSCOAi and BRSCOAi associated with a disruptor displacement increment are the same in each complementary pair. However, the configuration shown in  FIG.  8 F  is nevertheless not prohibited according to the various principles disclosed herein. With appropriate signal processing, such implementations may still provide certain advantages for use in a scanning probe, in comparison to known inductive type sensing configurations. The signal processing may need to be more complex than is needed in previously disclosed implementations herein (e.g., using more complex signal component relationships to indicate various displacement or position vector components), in order to correct or compensate for various cross coupling effects or the like. However, for the receiver coil portion  870 F, such effects may generally be compensated based on known geometric and/or signal relationship constraints and the fact that the magnitude of the change in overlap areas for a given displacement of the disruptor element  851 F is the same in the sensor coils of each complementary pair. For example, in the implementation shown in  FIG.  8 F , the disruptor element  851 F comprises 3 pairs of parallel straight sides (e.g., arranged parallel to the sides of a regular hexagon shape), and, for any respective complementary pair CPi, a first one of a pair of parallel straight sides transects the top rotary sensing coil TRSCi, and a second one of that pair of parallel straight sides transects the bottom rotary sensing coil BRSCi of that respective complementary pair. Based on the known rigid body translation and rotation characteristics of the disruptor element  851 F, the respective overlap areas and local operating gaps of each sensing coil are included in the receiver coil portion  870 F to be constrained by known relationships relative to one another, and these known relationships may be used to determine accurate displacement vectors in signal processing for the signal components provided by the receiver coil portion  870 F. 
     It will be appreciated that the variations shown in  FIGS.  7 A- 7 E  and  FIGS.  8 A- 8 F  are indicative of the possibility of further rearranging and/or adjusting the configuration and combination of various elements in a stylus position detection portion according to the various principles disclosed and claimed herein, while retaining many or all of the advantages previously outlined in association with those principles. In general, it will be understood that the various implementations disclosed herein are intended to be exemplary only and not limiting. 
       FIGS.  9 A and  9 B  illustrate an alternative configuration of a stylus position detection portion  911 , which may be employed, for example, in the scanning probe  300  of  FIG.  2    as the stylus position detection portion  311 , in the implementation of  FIG.  3    instead of the stylus position detection portion  411 , in the implementation of  FIG.  4    instead of the stylus position detection portion  511 , etc. The inductive components are illustrated in  FIG.  9 B . The stylus position detection portion  911  uses inductive sensing principles and includes a coil board configuration  990  having a receiver coil portion  970  and a field generating coil configuration  960 , which as illustrated comprises a transmitter coil  961 , and a disruptor configuration  950 , which as illustrated includes first and second disruptor elements  951 . The receiver coil portion  970  may comprise rotary sensing coil portions (also referred to as rotary sensing coils) RSC and axial sensing coil configurations ASCC. Briefly, the moving disruptor elements  951  (or more generally, the disruptor configuration  950 ) cause position-dependent variations in a changing magnetic field generated by the field generating coil configuration  960 . The receiver coil portion  970  is responsive to the changing magnetic field and the variations therein caused by the disruptor elements  951 . 
     The coil board configuration  990  comprises a first board portion  992  including N top rotary sensing coil portions (as illustrated, TRSC 1  to TRSC 4 , for which N=4 in this example) and a top axial sensing coil configuration (as illustrated TASCC), a second board portion  994  including N bottom rotary sensing coil portions (as illustrated, BRSC 1  to BRSC 4 , for which N=4 in this example) and a bottom axial sensing coil configuration (as illustrated BASCC). The coil board configuration  990  also comprises a center board portion  996  positioned between the first board portion  992  and the second board portion  994 . The center board portion  996  includes at least a first field generating coil configuration  960  (as illustrated including transmitting coil  961 ). The coil board configuration  990  is mounted in a fixed relationship to the frame of a scanning probe (see scanning probe  300  of  FIG.  2    and frame  408  of  FIG.  4   ), with the second board portion  994  of the coil board configuration  990  closer to the stylus suspension portion  307 / 407  (see  FIGS.  2  and  3   ). The first board portion  992 , the second board portion  994  and center board portion  996  of the coil board configuration  990  are nominally parallel to one another and nominally orthogonal to a central axis CA (see  FIG.  3   ) of a scanning probe  300  (see  FIG.  2   ). The coil board configuration  990  may comprise, for example, a two-sided substrate or printed circuit board having coils fabricated as printed conductors in layers of the substrate or printed circuit board, free-standing coils fastened to a substrate or printed circuit board, etc., and/or various combinations thereof. 
     In various implementations, the disruptor elements  951  of the disruptor configuration  950  each comprise at least one of a conductive plate or a conductive loop that provides a disruptor area, and the disruptor elements  951  are located along the central axis CA (see  FIG.  3   ) in a disruptor motion volume extending on opposite sides of the coil board configuration  990 . The disruptor elements  951  are coupled to the stylus suspension portion  307 / 407  (see  FIGS.  2  and  3   ) in a fixed relationship relative to one another by a coupling configuration  953 , including an upper portion of a moving member  912  (e.g., similar to the moving member  412  of  FIG.  3   ). The disruptor elements  951  move in the disruptor motion volume relative to an undeflected position in response to a deflection of the stylus suspension portion  307 / 407  (see  FIGS.  2  and  3   ), the disruptor elements moving over operating motion ranges +/−Rz along the axial direction in response to the axial motion, and over respective operating motion ranges +/−Rx and +/−Ry along respective orthogonal X and Y directions that are orthogonal to the axial direction in response to the rotary motion. A projection of a coil area of the first field generating coil  961  along the axial direction encompasses the conductive plates or loops that provide the disruptor areas and a coil area of all the rotary and axial sensing coils located on the coil board configuration  990 . The field generating coil configuration  960  generates a changing magnetic flux generally along the axial direction in the disruptor motion volume in response to a coil drive signal. 
       FIG.  10    is a partially schematic isometric diagram of an implementation of a stylus position detection portion  1011  that is similar to a stylus position detection portion  911  shown in  FIGS.  9 A and  9 B , emphasizing certain aspects according to principles disclosed herein. In general, the stylus position detection portion  1011  includes certain components that are similar to those of the stylus position detection portions  311 ,  411 ,  511  and  911  of  FIGS.  2 ,  3 ,  4 ,  9 A and  9 B , and will be understood to operate similarly except as otherwise described below. The configuration of a stylus position detection portion  1011 , may be employed, for example, in the scanning probe  300  of  FIG.  2    as the stylus position detection portion  311 , in the implementation of  FIG.  3    instead of the stylus position detection portion  411 , in the implementation of  FIG.  4    instead of the stylus position detection portion  511 , in the implementation of  FIGS.  9 A and  9 B  instead of the stylus position detection portion  911 , etc. 
     In the implementation shown in  FIG.  10   , the stylus position detection portion  1011  comprises a coil board configuration portion  1090  and a disrupter configuration  1050 . The coil board configuration portion  1090  includes top and bottom receiver coil board portions  1070 T,  1070 B, with a field generation coil board portion  1060  positioned between the top receiver coil board portion  1070 T and the bottom receiver coil board portion  1070 B. In various implementations, the top and bottom receiver coil board portions  1070 T,  1070 B may also be referenced as first and second board portions  1070 T,  1070 B, and the field generation coil board portion  1060  may also be referenced as a center board portion  1060 . The disruptor configuration  1050  includes disruptor elements  1051 T,  1051 B or scales. In various implementations, the disruptor elements  1051 T,  1051 B may also be referenced as first and second disruptor elements  1051 T,  1051 B. 
     In various implementations, disruptor elements  1051 T,  1051 B (or more generally the disruptor configuration  1050 ) may each comprise at least one of a conductive plate or conductive loop, or parallel conductive plates or conductive loops (e.g., as fabricated on two sides of a printed circuit substrate, patterned by printed circuit board fabrication techniques), or any other desired operational configuration that provides a disruptor area (e.g., its interior area). As illustrated in  FIG.  10   , the disruptor elements  1051 T and  1051 B each comprise a conductive plate. The disruptor elements  1051 T and  1051 B are located along the central axis CA in the disruptor motion volume MV, which extends on opposite sides of the coil board configuration  1090 , and are coupled to a stylus suspension portion  1007  by a coupling configuration (e.g., comprising at least an upper portion of a moving member  1012  that is similar to the moving member  412  of  FIG.  3   ). For purposes of explanation, the disruptor elements  1051 T,  1051 B move relative to the undeflected position illustrated in  FIG.  10    (e.g., similar to the undeflected position UNDF, in  FIG.  3   ) in response to a deflection of a stylus suspension portion  1007  and/or a stylus  1006  and/or the moving member  1012  (e.g., which may be similar or identical to the stylus suspension portion  407 , stylus  406  and moving member  412  of  FIG.  3   ). The disruptor elements  1051 T,  1051 B may be described as moving with displacement increments ΔZ over an operating motion range +/−Rz along the axial direction in response to axial motion, and with respective displacement increments ΔX and ΔY over respective operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions that are orthogonal to the axial direction (Z direction) in response to rotary motion. 
     The top receiver coil board portion  1070 T includes N top rotary sensing coils TRSC (e.g., as illustrated TRSC 1 -TRSC 4 , where N=4) and a top axial sensing coil configuration TASCC (e.g., comprising the single illustrated individual coil in this implementation), and the bottom receiver coil board portion  1070 B includes N bottom rotary sensing coils BRSC (e.g., as illustrated BRSC 1 -BRSC 4 , where N=4) and a bottom axial sensing coil configuration BASCC (e.g., comprising the single illustrated individual coil in this implementation). 
     The coil board configuration  1090  is mounted in a fixed relationship to the frame of the scanning probe (e.g., frame  408  of  FIG.  4   ) with the bottom receiver coil board portion  1070 B closer to the stylus  1006  and/or the stylus suspension portion  1007 . It should be appreciated with respect to the various sensing coils shown in  FIG.  10   , all coils comprise at least one of windings or conductors that have first and second connection ends (e.g., as represented in  FIG.  6   ) that are configured to operate as one or more inductively coupled “turns.” As illustrated, the top and bottom axial sensing coil configurations TASCC and BASCC, as well as the top and bottom rotary sensing coil configurations TRSC and BRSC, are nominally symmetrically spaced with respect to the disruptor configuration  1050  and the corresponding positions of the disruptor elements  1051 T,  1051 B. Other configurations are possible (e.g., the rotary sensing coil configurations TRSC and BRSC may not be nominally centered relative to the disruptor configuration  1050  in some implementations). 
     The field generating coil board portion  1060  generally comprises at least a first field generating coil  1061  and is positioned between the top receiver coil board portion  1070 T and the bottom receiver coil board portion  1070 B. As illustrated in  FIG.  10   , the at least a first field generating coil comprises a single field generating coil  1061  which has an area larger than an area of the disruptor elements  1051 T,  1051 B. The top receiver coil board portion  1070 T, the field generating coil board portion  1060  and the bottom receiver coil board portion  1070 B are nominally planar, nominally parallel to each other and nominally orthogonal to the central axis CA. 
     In the illustrated implementations of  FIGS.  3 ,  4  and  5   , the disruptor element is positioned inside the field generating coil elements (e.g., disruptor element  551  of  FIG.  4    fits inside the field generating coil  561 ), and an area of the disruptor element is smaller than an area of the field generating coil elements. In the illustrated implementations of  FIGS.  9 A,  9 B and  10   , the disruptor elements are positioned parallel to the field generating coil elements (e.g., the disruptor elements  1051 T,  1051 B are positioned above and below the field generating coil  1061 ). The configurations of  FIGS.  9 A,  9 B and  10    provide increased flexibility with respect to the relative sizes of the disruptor elements and the field coil elements. In addition, utilization of a single printed circuit board (e.g., for which the first board portion, the second board portion and the central board portion may comprise portions of a single multilayer printed circuit board) may reduce cost and complexity relative to configurations utilizing multiple printed circuit boards. 
       FIG.  11    is a partially schematic isometric diagram of an alternative implementation of a stylus position detection portion  1111  that is similar to a stylus position detection portion  1011  shown in  FIG.  10   , emphasizing certain aspects according to principles disclosed herein. In general, the stylus position detection portion  1111  includes certain components that are similar to those of the stylus position detection portion  1011  of  FIG.  10   , and will be understood to operate similarly except as otherwise described below. The configuration of a stylus position detection portion  1111 , may be employed, for example, in the scanning probe  300  of  FIG.  2    as the stylus position detection portion  311 , in the implementation of  FIG.  3    instead of the stylus position detection portion  411 , in the implementation of  FIG.  4    instead of the stylus position detection portion  511 , in the implementation of  FIGS.  9 A and  9 B  instead of the stylus position detection portion  911 , in the implementation of  FIG.  10    instead of the stylus position detection portion  1011 , etc. 
     In the implementation shown in  FIG.  11   , the stylus position detection portion  1111  comprises a coil board configuration portion  1190  and a disrupter configuration  1150 . The coil board configuration portion  1190  includes top and bottom receiver coil board portions  1170 T,  1170 B, with a field generation coil board portion  1160  positioned between the top receiver coil board portion  1170 T and the bottom receiver coil board portion  1170 B. In various implementations, the top and bottom receiver coil board portions  1170 T,  1170 B may also be referenced as first and second board portions  1170 T,  1170 B, and the field generation coil board portion  1160  may also be referenced as a center board portion  1160 . The disruptor configuration  1150  includes disruptor elements  1151 T,  1151 B or scales. In various implementations, the disruptor elements  1151 T,  1151 B may also be referenced as first and second disruptor elements  1151 T,  1151 B. The top and bottom receiver coil board portions  1170 T,  1170 B as illustrated are generally similar to the corresponding top and bottom receiver coil board portions  1070 T,  1070 B of  FIG.  10    (more details of conductive vias and pads are illustrated in  FIG.  11   ). 
     In various implementations, disruptor elements  1151 T,  1151 B (or more generally the disruptor configuration  1150 ) may each comprise at least one of a conductive plate or a conductive loop, or parallel conductive plates or conductive loops (e.g., as fabricated on two sides of a printed circuit substrate, patterned by printed circuit board fabrication techniques), or any other desired operational configuration that provides a disruptor area (e.g., its interior area). In various implementations, a configuration with conductive loops may include at least one of concentric loops, a spiral pattern, etc. As illustrated in  FIG.  11   , the disruptors  1151 T and  1151 B each comprise a plurality of concentric conductive loops  1153 , instead of the conductive plates employed in the illustrated implementation of  FIG.  10   . The disruptor elements  1151 T and  1151 B are located along the central axis CA in the disruptor motion volume MV, which extends on opposite sides of the coil board configuration  1190 , and may be coupled to a stylus suspension portion (see stylus suspension portion  1007  of  FIG.  10   ) in a manner similar to that discussed above with reference to  FIG.  10   . 
     The field generating coil board portion  1160  generally comprises at least a first field generating coil. As illustrated, the field generating coil board portion  1160  comprises a top field generating coil portion  1161 T and a bottom field generating coil portion  1161 B, which are positioned between the top receiver coil board portion  1170 T and the bottom receiver coil board portion  1170 B. The top receiver coil board portion  1170 T, the field generating coil board portion  1160  and the bottom receiver coil board portion  1170 B are nominally planar, nominally parallel to each other and nominally orthogonal to the central axis CA. In the example implementation of  FIG.  11   , the field generating coil board portion  1160  comprises a multi-turn field generating coil with two turns and for which the two corresponding field generating coil portions  1161 T and  1161 B are connected by a via and are located approximately equidistant from a midplane of the disruptor motion volume along the central axis, and are nominally planar and orthogonal to the central axis. 
     As illustrated in  FIG.  11   , the top field generating coil portion  1161 T and the bottom field generating coil portion  1161 B have areas which are smaller than the areas of the disruptor elements  1151 T,  1151 B. Employing field generating coils having a smaller area than areas of the disruptor elements facilitates reducing the sensitivity of the stylus position detection portion  1111  to the size of the disruptor elements or scales. Using conductive loops (e.g., concentric loops, a spiral pattern, etc.) in the disruptor elements instead of conductive plates or a single conductive loop also facilitates reducing the sensitivity of the stylus position detection portion  1111  to the size of the disruptor elements or scales, while maintaining good X and Y position signal strength. Reducing the sensitivity of the stylus portion to the size of the disruptor elements or scales may facilitate increased accuracy of measurements, and may reduce processing costs associated with generating results in a desired output format. 
     In some implementations, due to the close proximity of the receiver coils (e.g., coils BRSC 1 -BRSC 4 , TRSC 1 -TRSC 4 ) to the transmitter (e.g., coils  1161 T,  1161 B), non-connected vias/pads may be added to balance offsets that may otherwise be generated by connection traces (e.g., for transmitter and receiver leads) or other elements. As an illustrative example, in the implementation of  FIG.  11   , certain connected vias/pads/leads (e.g., as connected to and/or part of electronic circuitry or configurations) are shown within the coils BRSC 3 /TRSC 3  (e.g., for connection traces) that do not have symmetrical connected counterparts (e.g., symmetrical about the central axis) within the symmetrical coils BRSC 4 /TRSC 4  (e.g., five such vias as well as upper and lower transmitter leads are illustrated within the coils BRSC 3 /TRSC 3  in the example configuration of  FIG.  11   , including three vias for the connections for the axial sensing coil configurations TASCC, BASCC, a via for connecting the portions of the normalization coil R N , a via for connecting the field generating coil portions  1161 T,  1161 B, and the upper and lower transmitter leads for the field generating coil portions  1161 T,  1161 B). In some implementations, such traces/vias/pads/leads may reduce the magnetic field into the receiver coils which can result in a signal offset if not compensated for. In some implementations, such offsets may be addressed by mirroring such features (e.g., on the opposite side of the central axis) within the symmetrical receiver coils with non-connected vias/pads/leads. For example, in one implementation, non-connected vias/pads/leads may be added within the coils BRSC 4 /TRSC 4 , each of which may mirror/be symmetrical with a corresponding connected via/pad/lead within the coils BRSC 3 /TRSC 3  (e.g., five non-connected vias as well as upper and lower pads may be added within the coils BRSC 4 /TRSC 4  that are each symmetrical with/mirror a corresponding connected via/pad/lead illustrated within the coils BRSC 3 /TRSC 3 ). 
     As a specific illustrative example of such concepts, in  FIG.  11    the via for connecting the portions of the normalization coil R N  is designated as an electrically connected via VIA 1 C and is shown within the coils BRSC 3 /TRSC 3 . In accordance with the principles described above, a non-connected via VIA 1 D may be included within the coils BRSC 4 /TRSC 4  that is symmetrical with/mirrors the corresponding connected via VIA 1 C illustrated within the coils BRSC 3 /TRSC 3  (e.g., symmetrical with and mirrored relative to the central axis of the configuration). More specifically, the via VIA 1 D is at a location within the coils BRSC 4 /TRSC 4  that is symmetrical with/mirrors the location of the via VIA 1 C within the coils BRSC 3 /TRSC 3  (e.g., such that a line between the location of the via VIA 1 C and the location of the via VIA 1 D would pass through the central axis of the configuration and for which each location is equidistant from the central axis). The via VIA 1 D balances the offset that could otherwise be generated by the via VIA 1 C as described above. More specifically, the non-connected element VIA 1 D is located within the rotary sensing coils BRSC 4 /TRSC 4  and is symmetrically opposite (i.e., relative to the central axis and/or axial direction) from the similar electronically connected element VIA 1 C which is located within the rotary sensing coils BRSC 3 /TRSC 3 , and for which the non-connected element VIA 1 D reduces a signal offset that would otherwise result in the signal components provided by the rotary sensing coils BRSC 3 /TRSC 3  and BRSC 4 /TRSC 4  due to the presence of the connected element VIA 1 C in the rotary sensing coils BRSC 3 /TRSC 3 . 
     In the implementation of  FIG.  11   , the via VIA 1 C for connecting the portions of the normalization coil R N  is shown to be proximate to the vias for the connections for the axial sensing coil configurations TASCC, BASCC. The normalization coil R N  includes an upper portion and a lower portion, wherein the upper portion is straight and extends radially and is connected by the via VIA 1 C to the lower portion that is also straight and also extends radially (for which the lower portion is located directly below the upper portion but which for simplicity of the illustration is not shown in  FIG.  11    due to being obscured by other elements). In various implementations, the normalization coil R N  is utilized to provide a measurement of the transmitter field (e.g., corresponding to the changing magnetic flux that is generated by the field generating coil configuration  1160 ), for which the measured signal may be relatively independent of (e.g., may be only nominally affected by) the position of the disruptor elements  1151 T,  1151 B. In various implementations, the position measurements may be scaled to this measured signal to make them relatively insensitive to variations in the transmitter amplitude (from the field generating coil configuration  1160 ). In various implementations, such processing may be performed by signal processing and control circuitry (e.g., the signal processing and control circuitry  380  of  FIG.  2   ). 
     With reference to  FIGS.  9 A,  9 B,  10  and  11   , in a manner similar to that described above with reference to  FIGS.  2 - 8 F , the rotary sensing coil portion RSC (as illustrated TRSC 1  to TRSC 4  and BRSC 1  to BRSC 4 ) outputs at least first and second rotary signal components RSigs that are indicative of the rotary position (e.g., X and Y position signals) of the stylus coupling portion  342  (see  FIG.  2   ) over corresponding signal lines, and the axial sensing coil configuration ASCC (as illustrated TASCC and BASCC) outputs one or more axial signal components ASigs that is indicative of the axial position (e.g., a Z position signal) of the stylus coupling portion over corresponding signal lines. In various implementations, signal processing and control circuitry  380  (see  FIG.  2   ) receives the rotary signal components RSigs and the axial signal components ASigs, and may perform various levels of related signal processing in various implementations. For example, in one implementation, the signal processing and control circuitry may cause the signal components from various receiver coils to be combined and/or processed in various relationships, and provide the results in a desired output format as the rotary and axial position signal outputs RPSOut and APSOut, through an attachment portion  224  (see  FIG.  2   ). With reference to  FIG.  2   , one or more receiving portions (e.g., in the CMM  200 , motion controller  115 , host computer  120 , etc.) may receive the rotary and axial position signal outputs RPSOut and APSOut, and one or more associated processing and control portions may be utilized to determine a three-dimensional position of the stylus coupling portion  342  and/or of the contact portion of the attached stylus  306  as its contact portion  348  moves along a surface of a workpiece W that is being measured. The numbers, sizes and shapes of the receiver coils, the field generating coils, and the conductive plates or loops of the disruptor elements employed in various implementations may be selected based on desired operational characteristics, such as improved position sensing and reduced high-order non-linearities. It is noted that low order non-linearities may be calibrated by the CMM. 
     The implementations of  FIGS.  9 A,  9 B,  10  and  11    may facilitate employing fewer mechanical components, as in some implementations only one board needs to be mounted (e.g., flexible cables between separate boards may not be needed). Such implementations also may facilitate improved repeatability and lower assembly costs as the receiver coils may have fewer degrees of freedom with respect to alignment, and thus may be less sensitive to tilt and rotation issues that may arise in multi-board implementations, for example, with respect to XY positioning signals. 
       FIGS.  12 A and  12 B  illustrate an alternative configuration of a stylus position detection portion  1211 , which may be employed, for example, in the scanning probe  300  of  FIG.  2    as the stylus position detection portion  311 , in the implementation of  FIG.  3    instead of the stylus position detection portion  411 , in the implementation of  FIG.  4    instead of the stylus position detection portion  511 , etc. The stylus position detection portion  1211  uses inductive sensing principles and includes a disruptor configuration  1250  and a coil board configuration  1290 . The disruptor configuration  1250  as illustrated comprises a generally cylindrical disruptor  1251 . The coil board configuration  1290  as illustrated comprises a generally disc-shaped structure, and is illustrated in more detail in  FIG.  12 B . 
     As illustrated, the disruptor  1251  is positioned within a center opening  1291  of the coil board configuration  1290 , and extends in the Z direction of the disc-shaped coil board configuration  1290 . In the example of  FIGS.  12 A and  12 B , the disruptor  1251  is illustrated as extending in the Z direction above and below the coil board configuration  1290 , although it will be appreciated that in other implementations this may not be the case (e.g., in various alternative implementations the disruptor  1251  may be even with, or shorter than the coil board configuration  1290  in the Z direction). In various implementations, rather than the height along the Z direction, it is the cylindrical shape of the disruptor  1251  which is the more important factor (e.g., which results in various desirable operating characteristics, as will be described in more detail below, such as with respect to  FIGS.  14 A- 14 D , etc.) 
     The coil board configuration  1290  includes a field generating coil configuration  1260 , as illustrated having two transmission coils  1261 T and  1261 B, and a receiver coil portion  1270 . The receiver coil portion  1270  may comprise rotary sensing coil portions (also referred to as rotary sensing coils) RSC (e.g., for sensing motion transverse to the axial direction, as described above with respect to  FIGS.  3 - 6   , etc.) and axial sensing coil configurations ASCC (e.g., for sensing motion along the axial direction, as described above with respect to  FIGS.  3 - 6   , etc.). 
     Briefly, the moving disruptor element  1251  (or more generally, the disruptor configuration  1250 ) causes position-dependent variations in a changing magnetic field generated by the field generating coil configuration  1260 . The receiver coil portion  1270  is responsive to the changing magnetic field and the variations therein caused by the disruptor element  1251 . 
     As illustrated, the coil board configuration  1290  comprises a first board portion  1292 , including a top axial sensing coil TASCC, and a field generating coil  1261 T, a second board portion  1294 , including a bottom axial sensing coil BASCC, and a field generating coil  1261 B, and a center board portion  1296  positioned between the first board portion  1292  and the second board portion  1294 . The center board portion  1296  includes top rotary sensing coils TRSC 1 - 4 , a top normalization coil TRN, a bottom normalization coil BRN, and bottom rotary sensing coils BRSC 1 - 4 . 
     The coil board configuration  1290  is mounted in a fixed relationship to the frame of a scanning probe (see scanning probe  300  of  FIG.  2    and frame  408  of  FIG.  4   ), with the second board portion  1294  of the coil board configuration  1290  closer to the stylus suspension portion  307 / 407  (see  FIGS.  2  and  3   ). The first board portion  1292 , the second board portion  1294  and center board portion  1296  of the coil board configuration  1290  are nominally parallel to one another and nominally orthogonal to a central axis CA (see  FIG.  3   ) of a scanning probe  300  (see  FIG.  2   ). The coil board configuration  1290  may comprise, for example, a two-sided substrate or printed circuit board having coils fabricated as printed conductors in layers of the substrate or printed circuit board, free-standing coils fastened to a substrate or printed circuit board, etc., and/or various combinations thereof. 
     In various implementations, the disruptor element  1251  of the disruptor configuration  1250  may comprise a conductive cylinder that provides a disruptor area, and the disruptor element  1251  is located along the central axis CA (see  FIG.  3   ) in a disruptor motion volume extending on opposite sides of the coil board configuration  1290 . The disruptor element  1251  is coupled to the stylus suspension portion  307 / 407  (see  FIGS.  2  and  3   ) in a fixed relationship relative to one another by a coupling configuration  1253 , including an upper portion of a moving member  1212  (e.g., similar to the moving member  412  of  FIG.  3   ). The disruptor element  1251  moves in the disruptor motion volume relative to an undeflected position in response to a deflection of the stylus suspension portion  307 / 407  (see  FIGS.  2  and  3   ), the disruptor element moving over operating motion ranges +/−Rz along the axial direction in response to the axial motion, and over respective operating motion ranges +/−Rx and +/−Ry along respective orthogonal X and Y directions that are orthogonal to the axial direction in response to the rotary motion. The field generating coil configuration  1260  generates a changing magnetic flux generally along the axial direction in the disruptor motion volume in response to a coil drive signal. 
     As described above with respect to  FIG.  11   , in various implementations, the top and bottom normalization coils TRN and BRN may be utilized to provide a measurement of the transmitter field (e.g., corresponding to the changing magnetic flux that is generated by the field generating coil configuration  1260 ), for which the measured signal may be relatively independent of (e.g., may be only nominally affected by) the position of the disruptor element  1251 . In various implementations, the position measurements may be scaled to this measured signal to make them relatively insensitive to variations in the transmitter amplitude (from the field generating coil configuration  1260 ). In various implementations, such processing may be performed by signal processing and control circuitry (e.g., the signal processing and control circuitry  380  of  FIG.  2   ). 
       FIGS.  13 A to  13 F  illustrate an implementation of a stylus position detection portion  1311  that is similar to a stylus position detection portion  1211  shown in  FIGS.  12 A and  12 B , emphasizing certain aspects according to principles disclosed herein. 
       FIG.  13 A  is a partially schematic isometric diagram of an implementation of a stylus position detection portion  1311  that is similar to a stylus position detection portion  1211  shown in  FIGS.  12 A and  12 B , emphasizing certain aspects according to principles disclosed herein. In general, the stylus position detection portion  1311  includes certain components that are similar to those of the stylus position detection portions  311 ,  411 ,  511  and  911  of  FIGS.  2 ,  3 ,  4 ,  9 A and  9 B , and will be understood to operate similarly except as otherwise described below. The configuration of a stylus position detection portion  1311 , may be employed, for example, in the scanning probe  300  of  FIG.  2    as the stylus position detection portion  311 , in the implementation of  FIG.  3    instead of the stylus position detection portion  411 , in the implementation of  FIG.  4    instead of the stylus position detection portion  511 , in the implementation of  FIGS.  9 A and  9 B  instead of the stylus position detection portion  911 , in the implementation  FIGS.  12 A and  12 B  instead of the stylus position detection portion  1211 , etc. 
     In the implementation shown in  FIG.  13 A , the stylus position detection portion  1311  comprises a coil board configuration portion  1390  and a disrupter configuration  1350 . In various implementations, disruptor element  1351  (or more generally the disruptor configuration  1350 ) comprises a conductive cylinder, or any other desired operational configuration that provides a disruptor area (e.g., its interior area). As illustrated in  FIG.  13 A , the disruptor element  1351  comprises a conductive cylinder. The disruptor element  1351  is located along the central axis CA in the disruptor motion volume MV, which extends on opposite sides of the coil board configuration  1390 , and is coupled to a stylus suspension portion by a coupling configuration (e.g., comprising at least an upper portion of a moving member  1312  that is similar to the moving member  412  of  FIG.  3   ). For purposes of explanation, the disruptor element  1350  moves relative to the undeflected position illustrated in  FIG.  13 A  (e.g., similar to the undeflected position UNDF, in  FIG.  3   ) in response to a deflection of a stylus suspension portion  1307  and/or a stylus  1306  and/or the moving member  1312  (e.g., which may be similar or identical to the stylus suspension portion  407 , stylus  406  and moving member  412  of  FIG.  3   ). The disruptor element  1351  may be described as moving with displacement increments ΔZ over an operating motion range +/−Rz along the axial direction in response to axial motion, and with respective displacement increments ΔX and ΔY over respective operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions that are orthogonal to the axial direction (Z direction) in response to rotary motion. 
     The coil board configuration  1390  includes a top coil board portion  1390 T and a bottom coil board portion  1390 B. The top coil board portion  1390 T includes a top axial sensing coil configuration TASCC (e.g., comprising the single illustrated individual coil in this implementation), at least a first top field generating coil configuration  1361 T, N top rotary sensing coils TRSC (e.g., as illustrated TRSC 1 -TRSC 4 , where N=4), and a top normalization coil configuration TR N . The bottom coil board portion  1390 B includes a bottom normalization coil configuration BR N , N bottom rotary sensing coils BRSC (e.g., as illustrated BRSC 1 -BRSC 4 , where N=4), at least a first bottom field generating coil configuration  1361 B, and a bottom axial sensing coil configuration BASCC (e.g., comprising the single illustrated individual coil in this implementation). 
     The coil board configuration  1390  is mounted in a fixed relationship to the frame of the scanning probe (e.g., frame  408  of  FIG.  4   ) with the bottom coil board portion  1390 B closer to the stylus  1306  and/or the stylus suspension portion  1307 . It should be appreciated with respect to the various sensing coils shown in  FIG.  13 A , all coils comprise at least one of windings or conductors that have first and second connection ends (e.g., as represented in  FIG.  6   ) that are configured to operate as one or more inductively coupled “turns.” As illustrated, the top and bottom axial sensing coil configurations TASCC and BASCC, as well as the top and bottom rotary sensing coil configurations TRSC and BRSC, are nominally symmetrically spaced with respect to the disruptor configuration  1350  and the corresponding position of the disruptor element  1351 . Other configurations are possible (e.g., the rotary sensing coil configurations TRSC and BRSC may not be nominally centered relative to the disruptor configuration  1350  in some implementations). 
     As illustrated in  FIG.  13 A , the at least a first top field generating coil configuration comprises a single field generating coil  1361 T, which has an area larger than an area of the disruptor element  1351 , the at least a first bottom field generating coil configuration comprises a single field generating coil  1361 B, which has an area larger than an area of the disruptor element  1351 . The top coil board portion  1390 T, and the bottom coil board portion  1390 B are nominally planar, nominally parallel to each other and nominally orthogonal to the central axis CA. 
       FIGS.  13 B to  13 E  illustrate example implementations of coils of the coil board configuration  1390  of  FIG.  13 A .  FIG.  13 F  illustrates an example layering of the coils in the coil board configuration  1390  of  FIG.  13 A .  FIGS.  13 A to  13 E  illustrate connecting pads or vias (see  FIG.  13 B ), which may be similar to connecting pads or vias as discussed above in the description of  FIG.  11   . 
     In  FIG.  13 B , an example implementation of the top axial sensing coil configuration TASCC or of the bottom sensing axial coil configuration BASCC is shown. As illustrated, a single coil is employed as the top axial coil configuration TASCC and a single coil is employed as the bottom axial coil configuration BASCC. 
     In  FIG.  13 C , an example implementation of the top field generating coil configuration  1361 T or of the bottom field generating coil configuration  1361 B is shown. As illustrated, a single coil is employed as the top field generating coil configuration  1361 T and a single coil is employed as the bottom field generating coil configuration  1361 B. 
     In  FIG.  13 D , an example implementation of the top rotary sensing coil configuration TRSC or of the bottom rotary sensing coil configuration BRSC is shown. As illustrated, four coils TRSC 1 - 4  are employed as the top rotary sensing coil configuration TRSC and four coils BRSC 1 - 4  are employed as the bottom rotary sensing coil configuration BRSC. 
     In  FIG.  13 E , an example implementation of the top normalization coil configuration TR N  or of the bottom normalization coil configuration TR B  is shown. As illustrated, a single coil is employed as the top normalization coil configuration TR N  and a single coil is employed as the bottom normalization coil configuration TR B . 
     In  FIG.  13 F , an example implementation of layers of the coil configuration  1390  is shown. As discussed above with reference to  FIG.  13 A , the coil board configuration  1390  includes a top coil board portion  1390 T and a bottom coil board portion  1390 B. The top coil board portion  1390 T, in order, includes a first layer having a top axial sensing coil configuration TASCC, a second layer including at least a first top field generating coil configuration  1361 T, a third layer including N top rotary sensing coils TRSC, and fourth layer including a top normalization coil configuration TR N . The bottom coil board portion  1390 B generally mirrors the top coil board configuration, and includes a first layer having a bottom normalization coil configuration BR N , a second layer having N bottom rotary sensing coils BRSC, a third layer having at least a first bottom field generating coil configuration  1361 B, and a fourth layer having a bottom axial sensing coil configuration BASCC. The disruptor element  1351  as illustrated is a conductive cylinder that extends above and below the coil board configuration. 
     As discussed above, in the illustrated implementations of  FIGS.  3 ,  4  and  5   , the disruptor element is positioned inside the field generating coil elements (e.g., disruptor element  551  of  FIG.  4    fits inside the field generating coil  561 ), and an area of the disruptor element is smaller than an area of the field generating coil elements. In the illustrated implementations of  FIGS.  9 A,  9 B and  10   , the disruptor elements are positioned parallel to the field generating coil elements (e.g., the disruptor elements  1051 T,  1051 B are positioned above and below the field generating coil  1061 ). In the illustrated implementations of  FIGS.  12 A,  12 B, and  13 A to  13 F , the single tall cylindrical disruptor element  1251 / 1351  fits within the hole  1291  which is surrounded by the coil elements, and for which the configuration provides increased flexibility with respect to the relative sizes and positions of the coil configuration board elements, while also utilizing a single printed circuit board (e.g., for which the top board portion and the bottom board portion may comprise portions of a single multilayer printed circuit board) which may reduce cost and complexity relative to configurations utilizing multiple printed circuit boards. In addition, as discussed in more detail below with respect to  FIGS.  14 A to  14 D , in the implementations of  FIGS.  12 A,  12 B, and  13 A to  13 F , significant reductions in the resonant frequency change (RFC) occurring as a result of displacements along the Z axis, as well as reductions in off-axis cross talk, may be obtained, resulting in better overall performance of the CMM. 
     The implementations of  FIGS.  12 A,  12 B, and  13 A to  13 F  may facilitate employing fewer mechanical components, as in some implementations only one board needs to be mounted (e.g., flexible cables between separate boards may not be needed), and a single tall disruptor element may be employed, which does not need to be disassembled to install or remove the board. Such implementations also may facilitate improved repeatability and lower assembly costs as the receiver coils may have fewer degrees of freedom with respect to alignment, and thus may be less sensitive to tilt and rotation issues that may arise in multi-board implementations, for example, with respect to XY positioning signals. Such implementations also may improve off-axis cross talk, frequency stability, and linearity. 
       FIGS.  14 A to  14 C  illustrate example frequency shift and off-axis cross talk errors for the embodiments illustrated in  FIGS.  3 ,  4  and  5   , the embodiments illustrated in  FIGS.  9 A,  9 B and  10   , and the embodiments illustrated in  FIGS.  12 A,  12 B, and  13 A to  13 F .  FIG.  14 A  illustrates an example off-axis cross talk error of the embodiments illustrated in  FIGS.  3 ,  4  and  5    as the displacement of the disruptor (e.g., disruptor  551  of  FIG.  4   ) along the Z axis is swept from −1 mm to +1 mm, and with U,V=1.1 degrees.  FIG.  14 B  illustrates an example off-axis cross talk error of the embodiments illustrated in  FIGS.  9 A,  9 B and  10    as the displacement of the disruptor (e.g., disruptor  950  of  FIG.  9 A ) along the Z axis is swept from −1 mm to +1 mm, and with U,V=1.1 degrees.  FIG.  14 C  illustrates an example off-axis cross talk error of the embodiments illustrated in  FIGS.  12 A,  12 B and  13 A to  13 F  as the displacement of the disruptor (e.g., disruptor  1250  of  FIG.  12 A ) along the Z axis is swept from −1 mm to +1 mm, and with U,V=1.1 degrees. In each of the  FIGS.  14 A- 14 C , the V-shaped Z signal is the primary (linear) positioning signal, and the X and Y signals illustrate the size of the cross talk in the U,V directions. As can be seen, the off-axis cross talk error is highest for the embodiments of  FIGS.  9 A,  9 B and  10   , and is in the range of 32-45 mV/V for the X and Y axes, for which 40% of the nominal signal range is thus cross talk (i.e., (45−32)/32=40%). The embodiments of  FIGS.  3 ,  4  and  5    have off-axis cross talk error in the range of 16-20 mV/V for the X and Y axes, for which 25% of the nominal signal range is thus cross talk (i.e., (20−16)/16=25%), providing some improvement. The off-axis cross talk error is lowest for the embodiments of  FIGS.  12 A,  12 B and  13 A to  13 F , and is in the range of 15-16 mV/V for the X and Y axes, for which 7% of the nominal signal range is thus cross talk (i.e., (16−15)/15=7%). 
       FIG.  14 D  illustrates example resonant transmitter frequency changes as the stylus position detection portion (SPDP) displacement is varied between zero mm and 2 mm for the embodiments illustrated  FIGS.  3 ,  4  and  5   , the embodiments illustrated in  FIGS.  9 A,  9 B and  10   , and the embodiments illustrated in  FIGS.  12 A,  12 B, and  13 A to  13 F . At a displacement of zero mm, the resonant frequency is the same for the various embodiments. The resonant frequency change (RFC) at an SPDP displacement of 2 mm is largest for the embodiments of  FIGS.  9 A,  9 B and  10    (labeled as SPDP  1011  in  FIG.  14 D ), is smallest for the embodiments of  FIGS.  12 A,  12 B and  13 A- 13 F  (labeled as SPDP  1311  in  FIG.  14 D ), with the embodiments of  FIGS.  3 ,  4   , and  5  (labeled as  411  in  FIG.  14 D ) having a RFC slightly larger than that of the embodiments of  FIGS.  12 A,  12 B and  13 A to  13 F , but significantly smaller than that of the embodiments of  FIGS.  9 A,  9 B and  10   . As can be seen, the embodiments of  FIGS.  12 A,  12 B and  13 A to  13 F  have less change in inductance as the displacement along the Z axis is varied, resulting in a small RFC with disruptor position, in addition to having the smallest off-axis cross talk. 
     In various implementations, at least some signal offset errors may occur due to printed circuit board (PCB) manufacturing tolerances, such as layer to layer coil registration errors, particularly for single board implementations. For example, misalignments between field generating coil configurations and rotary sensing coil configurations (RSC) may occur due to PCB manufacturing tolerances. In accordance with principles disclosed herein, one or more misalignment compensation elements may be added to a coil board configuration to compensate for misalignments of coils (e.g., coils of the coil configurations of the first, second and/or center board portions, etc.) with respect to each other. More specifically, as will be described in more detail below, in various implementations one or more misalignment compensation element may be configured/utilized to reduce a signal offset that results from a misalignment of at least one coil of the coil board configuration (e.g., the coil board configuration may comprise a PCB with a plurality of layers in which the coils are located and the misalignment of the at least one coil may result from a registration error, such as within manufacturing tolerances, in a layer to layer registration as part of a fabrication process). 
       FIGS.  15 A to  15 C  illustrate an embodiment in which misalignment compensation elements take a form of shielding added to reduce the effect of registration errors between a field generating coil configuration (e.g., field generating coils  1261 T and  1261 B of  FIG.  12 B ) and a rotary sensing coil configuration (e.g., TRSC 1 - 4  and BRSC 1 - 4  of  FIG.  12 B ).  FIG.  15 A  illustrates an inner shielding  1261 ′ in which copper pads are added to the field generating coils (e.g.,  1261 T and  1261 B of  FIG.  12 B ) and an outer shielding  1263 , in which copper pads are positioned outside the shielded field generating coil  1261 ′.  FIG.  15 B  is a top view illustrating an alignment of a shielded field generating coil  1261 ′ and outer shielding  1263  with a rotary sensing coil configuration RSC (e.g., TRSC 1 - 4  or BRSC 1 - 4 ) with respect to the center axis of the stylus position detection portion (e.g., center axis CA of  FIG.  13 A ). As illustrated, copper pads are added to the field generating coils  1261  to broaden an area of the shielded field generating coils  1261 ′ to generally match an area of inner loops of the rotary sensing coils RSC, and the copper pads of the outer shielding are shaped and positioned to generally match an area of the outer loops of the rotary sensing coils RSC. 
     In  FIG.  15 C , an example implementation of layers of a coil board configuration  1590  is shown. As illustrated, the coil board configuration  1590  includes a top coil board portion  1590 T and a bottom coil board portion  1590 B. The top coil board portion  1590 T, in order, includes a first layer having a top axial sensing coil configuration TASCC, a second layer including at least a first shielded top field generating coil configuration  1261 T′ and an outer shielding  1263 T, a third layer including N top rotary sensing coils TRSC, and fourth layer including a top normalization coil configuration TR N . The bottom coil board portion  1590 B generally mirrors the top coil board configuration, and includes a first layer having a bottom normalization coil configuration BR N , a second layer having N bottom rotary sensing coils BRSC, a third layer having at least a first shielded bottom field generating coil configuration  1261 B′ and outer shielding  1263 B, and a fourth layer having a bottom axial sensing coil configuration BASCC. 
     Some embodiments may employ inner shielding (e.g., shielded field generating coil  1261 ′) without employing outer shielding (e.g., outer shielding  1263 ), some embodiments may employ outer shielding (e.g., outer shielding  1263 ) without employing inner shielding (e.g., shielded field generating coil  1261 ′), some embodiments may employ both inner shielding (e.g., shielded field generating coil  1261 ′) and outer shielding (e.g., outer shielding  1263 ). The shielding  1261 ′,  1263 , makes the field generated smaller and more uniform at the edges of the rotary sensing coils, reducing the effect of registration errors between the field generating coils and the rotary sensing coils. As shown in the table below, including inner and outer shielding may facilitate reducing offsets by 77% with only a 5% reduction in gain. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
               
               
                   
                 XY Gain 
                 Offset per 
                   
                   
                   
               
               
                   
                 (mV/ 
                 100 um mis- 
                 XY_L 
                 Tx_L 
                 Tx_R 
               
               
                 Configuration 
                 V/mm) 
                 registration (%) 
                 (nH) 
                 (nH) 
                 (Ohm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 No Added 
                 53.17 
                 36.5 
                 1656 
                 66.3 
                 0.127 
               
               
                 Shielding 
                   
                   
                   
                   
                   
               
               
                 Inner 
                 50.82 
                 13.26 
                 1621 
                 66.3 
                 0.152 
               
               
                 Shielding 
                   
                   
                   
                   
                   
               
               
                 Inner &amp; 
                 50.63 
                 8.4 
                 1501 
                 60.3 
                 0.152 
               
               
                 Outer 
                   
                   
                   
                   
                   
               
               
                 Shielding 
               
               
                   
               
            
           
         
       
     
     With reference to  FIG.  12 B ,  FIG.  16    illustrates an exemplary implementation of a stylus position detection portion  1211 ′ in which misalignment compensation elements in the form of pins  1298  (e.g., which in various implementations may comprise pins, pads, etc.) are added to a coil board configuration to compensate for signal offset errors by introducing a compensating offset signal. In various implementations, the pins may extend through the entire coil board configuration or through only a portion thereof, or may be positioned in a layer of the coil board configuration. As illustrated, the one or more pins may comprise a plurality of pins positioned on one side of the coil board configuration  1290 ′ with respect to a plane including the central axis (e.g., see  FIG.  13 A ), wherein the pins are generally parallel to the central axis and compensate for a misalignment of one or more rotary sensing coils with respect to a field generating coil configuration. More specifically, in various implementations the placement of the pins may be utilized to either increase or decrease the magnetic field through the individual coils, so as to compensate for a misalignment of the coils. 
     With reference to  FIG.  12 B ,  FIG.  17 A  illustrates an exemplary implementation of a stylus position detection portion  1211 ″ in which a mechanical adjustment mechanism  1297  is employed to adjust a relative position of the coil board configuration  1290 ″ and/or the disruptor configuration  1250  (e.g., a relative X, Y and/or Z position of the coil board configuration  1290 ″ or the disruptor configuration  1250  with respect to each other and/or with respect to the housing/enclosure of the coil board configuration, etc.) In various implementations, the coil board configuration  1290 ″ may include additional spacing (e.g., around the edges and/or in the center, etc.) to allow for the adjustable positioning range. It will be appreciated that the mechanical adjustment mechanism  1297  may be utilized to reduce a misalignment condition. In an exemplary embodiment, gross compensation for a misalignment may be provided using one or more other misalignment compensation elements (e.g., pads or pins  1298  of  FIG.  16   , the shielding  1261 ′,  1263  of  FIGS.  15 A to  15 C , the adjustable coils TASCC of  FIGS.  18 A to  18 C  (discussed below), etc., and/or various combinations thereof), with position fine tuning provided by the mechanical adjustment mechanism  1297 , to reduce any residual misalignment errors or improve the effectiveness of other misalignment compensation elements. 
     As illustrated, the mechanical position adjustment mechanism  1297  comprises set screws  1297 A,  1297 B. A first set screw  1297 A (or multiple first set screws  1297 A) facilitate(s) adjusting a relative XY position of the coil board configuration  1290 ″, and a second set screw  1297 B facilitates adjusting a Z position of the disruptor configuration  1250  relative to the coil board configuration  1290 ″. In various implementations, the set screw(s)  1297 A pass through and adjust the position of an alignment and mounting portion  1217  to which the coil board configuration  1290 ″ is attached or otherwise coupled. An enclosure  1208 ′ (e.g., which may be coupled to or part of a main body frame, such as frame  408  of  FIG.  4   ) encloses the coil board configuration  1290 ″ and includes spacers SP which operate in relation to the relative movement. As described above (e.g., with respect to  FIG.  12 A ), the disruptor element  1251  moves within a hole  1291  of the coil board configuration  1290 ″ and is coupled to a stylus suspension portion (e.g., see the suspension portion  307 / 407 / 407 ′ of  FIGS.  2 - 4   ) by a coupling configuration  1253 , including an upper portion of a moving member  1212  (e.g., similar to the moving member  412  of  FIGS.  3  and  4   ). In various implementations, the second set screw  1297 B may be included as part of, or operate in conjunction with, the coupling configuration  1253  which may thus be at least partially adjustable and for which as noted above the second set screw  1297 B facilitates adjusting a Z position of the disruptor element  1251  relative to the coil board configuration  1290 ″. 
     With reference to  FIG.  4   ,  FIG.  17 B  illustrates an exemplary implementation of a stylus position detection portion  511 ″ in which a mechanical adjustment mechanism  597  is employed to adjust a relative position of a coil board configuration  590 ″ and/or a disruptor configuration  550  (e.g., a relative X, Y and/or Z position of the coil board configuration or the disruptor configuration  550  with respect to each other and/or the housing/enclosure of the coil board configuration, etc.) In various implementations, the coil board configuration  590 ″ (e.g., including the substrates  571 T,  571 B, and the field generating coil  561  and/or its substrate) may include additional spacing (e.g., around the edges and/or in the center, etc.) to allow for the adjustable positioning range. It will be appreciated that the mechanical adjustment mechanism  597  may be utilized to reduce a misalignment condition, similar to the operations described above with respect to  FIG.  17 A . 
     As illustrated, the mechanical position adjustment mechanism  597  comprises set screws  597 A,  597 B. A first set screw  597 A (or multiple first set screws  597 A) facilitate(s) adjusting a relative XY position of the coil board configuration  590 ″, and a second set screw  597 B facilitates adjusting a Z position of the disruptor configuration  550  relative to the coil board configuration  590 ″. In various implementations, the set screw(s)  597 A pass through and adjust the position of an alignment and mounting portion  517  to which the coil board configuration  590 ″ is attached or otherwise coupled. An enclosure  508 ′ (e.g., which may be coupled to or part of a main body frame, such as frame  408  of  FIG.  4   ) encloses the coil board configuration  590 ″ and includes spacers SP which operate in relation to the relative movement. In various implementations, the disruptor element  551  moves within a hole  591  of the coil board configuration  590 ″ (e.g., within the field generating coil  561  and its substrate) and is coupled to a stylus suspension portion (e.g., see the suspension portion  307 / 407 / 407 ′ of  FIGS.  2 - 4   ) by a coupling configuration  553 , including an upper portion of a moving member  412 . In various implementations, the second set screw  597 B may be included as part of, or operate in conjunction with, the coupling configuration  553  which may thus be at least partially adjustable and for which as noted above the second set screw  597 B facilitates adjusting a Z position of the disruptor element  551  relative to the coil board configuration  590 ″. In various implementations, a portion of the second set screw  597 B, the moving member  412  and/or other portions of the coupling configuration  553  may move within a hole  591 B of the substrate  571 B (e.g., and for which in some implementations the substrate  571 T may include a similar hole  591 T, which may provide access to the second set screw  597 B for making adjustments). In regard to  FIGS.  17 A and  17 B , it will be appreciated that certain elements that are illustrated with or without hash lines may include holes or openings (e.g., as enabling certain relative movements, etc.) An example of such relative movements for the disruptor elements  551 ,  1251  within the respective stylus position detection portions  511 ′,  1211 ′ may be understood based at least in part on the illustration of  FIG.  3    with regard to the relative movement of the disruptor element  451  within the stylus position detection portion  411 . 
     With reference to  FIG.  12 B ,  FIGS.  18 A to  18 C  illustrate an exemplary implementation in which misalignment compensation elements in the form of conductive shorts  1299  (e.g., a zero ohm resistor) may be added to a coil board configuration  1290 ″′ to compensate for misalignment errors. More specifically, in various implementations the conductive shorts  1299  may be added (e.g., such as at locations as indicated in  FIGS.  18 B and  18 C ) to adjust the current path and essentially adjust the coil size of one or more adjustable coils of the coil board configuration  1290 ′″, so as to effectively zero or otherwise compensate for certain determined offsets. In various implementations, the adjustable coils are at the top and/or bottom of the coil board configuration at the outer layers (e.g., as proximate to or part of the axial sensing coil configurations TASCC′ or BASCC′ in  FIG.  12 B ), for which the conductive shorts  1299  may be easily added or removed without requiring access to internal layers of the coil board configuration. 
     In various implementations, when a coil board configuration is initially manufactured/produced, certain misalignment compensation elements (e.g., the shielding  1261 ′,  1263  of  FIGS.  15 A to  15 C ) may be included as part of the manufacturing/production (e.g., as a general technique to reduce any misalignment errors that may occur due to any misalignments of the coils). In various implementations, after the coil board configuration is manufactured/produced, measurements may be taken and/or testing may be performed to determine what offsets may exist (e.g., due to coil misalignments that may have occurred during the manufacturing/production). Based on such testing/measurements, certain determinations may be made regarding the application of one or more offset compensation techniques (e.g., such as those described above with respect to  FIGS.  16 ,  17 A,  17 B, and  18 A to  18 C ). For example, in regard to the techniques of  FIGS.  16 ,  18 B and  18 C , based on such testing/measurements, determinations may be made as to where the misalignment compensation elements (e.g., pins, conductive shorts, etc.) should be placed/located/added, in order to compensate for the offsets and to achieve a desired offset compensated configuration. As another example, in regard to the techniques of  FIGS.  17 A and  17 B , based on such testing/measurements (e.g., which may be performed initially and/or after techniques such as of those of  FIGS.  16 ,  18 B and  18 C  have been performed to make larger adjustments and for which the techniques of  FIGS.  17 A and  17 B  are then performed to make finer adjustments), determinations may be made as to what and/or how much of an adjustment or adjustments should be made, in order to compensate for the offsets (e.g., remaining offsets) and to achieve a desired offset compensated configuration. In various implementations, multiple iterations of one or more of the compensation techniques (e.g., including repeated testing and/or active monitoring of any indicated offsets, etc.) may be performed, including continuing to make adjustments until a desired offset compensated configuration is achieved (e.g., a configuration in which respective offset errors have been reduced to an acceptable level, etc.) 
     While  FIGS.  15 A to  15 C,  16 ,  17 A, and  18 A to  18 C  have generally been discussed with reference to  FIGS.  12 B and  13 A , the techniques discussed herein to compensate for and reduce/address offset errors may be employed in other implementations, such as the implementations discussed above with respect to  FIGS.  3 ,  4  and  5   , and with respect to  FIGS.  9 A,  9 B and  10   . 
     In some implementations, a height of a cylindrical disruptor element of a scanning probe as disclosed herein along the Z direction may be equal to or greater than a height of the coil board configuration along the Z direction. In some such implementations, a height of the cylindrical disruptor element along the Z direction may be at least 1.5 times greater than a height of the coil board configuration along the Z direction. 
     In various implementations, the coil board configuration is configured to provide N complementary pairs of rotary sensing coils CPi that each comprise a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi, wherein each complementary pair CPi comprises a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi characterized in that a shape of their interior areas nominally coincide when projected along the axial direction. 
     In various implementations, the coil board configuration is configured to provide N complementary pairs of rotary sensing coils CPi that each comprise a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi, wherein each complementary pair CPi comprises a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi characterized in that a shape of their interior areas would nominally coincide if a shape of one of them is rotated about the central axis to coincide with an angular location of the other about the central axis, and then projected along the axial direction. 
     In some implementations, the scanning probe may comprise a moving member that is coupled to the cylindrical disruptor element and the stylus coupling portion, and which may generally extend along the central axis. 
     In some implementations, a method comprises generating drive control signals to control a drive mechanism that moves a scanning probe as disclosed herein along a surface of a workpiece and generating three-dimensional position information based on inductive sensing signals generated by the scanning probe as the scanning probe is moved along the surface of the workpiece. 
     In some implementations, a system comprises a scanning probe as disclosed herein, a drive mechanism and an attachment portion configured to couple the drive mechanism to the scanning probe. In some such implementations, the system comprises a motion controller which controls movements of the drive mechanism. 
     In various implementations, a field generating coil configuration of a system as disclosed herein comprises first and second field generating coil configurations that each surround a hole in the coil board configuration and correspondingly surround the disruptor motion volume. In some such implementations, the first and second field generating coil configurations comprise a pair of planar field generating coils that are located approximately equidistant from a midplane of the disruptor motion volume along the central axis, and that are nominally planar and orthogonal to the central axis. In some such implementations, the top and bottom axial sensing coil configurations also surround the hole in the coil board configuration and correspondingly surround the disruptor motion volume. In some such implementations, the coil board configuration has top and bottom portions. The top portion includes first, second and third layers, which include the top axial sensing coil configuration, the first field generating coil configuration and the N top rotary sensing coils, respectively. The bottom portion mirrors the top portion and correspondingly has first, second and third layers, which include the bottom axial sensing coil configuration, the second field generating coil configuration, and the N bottom rotary sensing coils, respectively. The coil board configuration is mounted in the fixed relationship to the frame of the scanning probe with the bottom portion of the coil board configuration closer to the stylus suspension portion. The top and bottom portions of the coil board configuration are nominally parallel to one another and nominally orthogonal to the central axis. 
     While preferred implementations of the present disclosure have been illustrated and described, numerous variations in the illustrated and described arrangements of features and sequences of operations will be apparent to one skilled in the art based on this disclosure. Various alternative forms may be used to implement the principles disclosed herein. In addition, the various implementations described above can be combined to provide further implementations. All of the U.S. patents and U.S. patent applications referred to in this specification are incorporated herein by reference, in their entirety. Aspects of the implementations can be modified, if necessary to employ concepts of the various patents and applications to provide yet further implementations. 
     These and other changes can be made to the implementations in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific implementations disclosed in the specification and the claims, but should be construed to include all possible implementations along with the full scope of equivalents to which such claims are entitled.