Abstract:
A positioning device that is ideally suited for the assembly of optical components, particularly fiber optic components utilizing small-core single-mode optical fiber. The invention teaches a structure that can be used for 3 axis positioning and alignment wherein all of the control actuators are located on a common axis to improve operator adjustment efficiency and reduce repetitive motion strain. The device uses flexible elements to connect relatively movable parts, including parts which move orthogonally relative to each other. The device also has a lever arrangement which provides a mechanical advantage for the control actuators.

Description:
This application claims priority of U.S. provisional application No. 60/222,646 filed Aug. 3, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     In assembling micro-optic structures and in particular those utilizing fiber optic waveguides, it is often necessary to control relative spatial alignments with extremely fine precision. Some optical components use optical fibers having a core region that carries a beam of light that is of the order of 10 microns in diameter (and even smaller in some cases). In order to assemble such a component the optical fibers have to be manipulated with a precision level on the order of {fraction (1/10)} of a micron. 
     2. Prior Art 
     In the past, optical fibers components have been assembled using known 3-axis ball-bearing positioners. Anyone who has attempted to achieve stable alignment using single-mode optical fiber with such known kinds of positioners equipped with micrometer actuators will attest to the lack of required precision. Crossed roller and ball type stages inherently require preload which generates motional friction and have a resolution limit set by the randomness of the required drive force due to dust and surface variations associated with the frictional interfaces and the limited stiffness of actuator mechanisms. 
     Other designs of positioners offer frictionless movement with the use of flexure-based designs but often at the expense of overall mechanical stiffness. A single parallel cantilever pair will generate an arc-error in its trajectory. What is commonly done is to combine two cantilever pairs into a compound cantilever stage so as to have one compensate the other and provide perfect linear motion. Compound cantilever stages are very large for their available travel as conventional designs consist of two separate compound stages that are effectively joined at a centerline to maintain high off-axis stiffness. One of the objects of this invention is to provide a compound cantilever stage that is much smaller than the conventional design. 
     The majority of 3-axis positioning equipment is made up by staging single axis units one on top of each other using angle plates. This results in a structure that has diminished resolution and stiffness as one moves progressively further from the mounting frame of reference. In many designs the stiffness of the overall unit is inadequate to resist the forces required to operate the actuators. In these cases the operator must use a touch and release method where the signal is adjusted and the operator then has to release the actuator to witness the result. Another downfall of a 3-axis positioner made up of three individual orthogonally arranged stages is the fact that the actuators are also arranged in an XYZ configuration, i.e. each has an axis perpendicular to the other two actuators, making prolonged use strenuous due to the required hand movements. 
     An inherent limitation to the resolution of nearly all positioning systems lies in the use of what can be termed simple axial actuators. A micrometer head or a complex piezo micrometer head are examples of simple actuators as they produce a displacement that is used to control the movement of a translation stage in a direct ratio. For example, a 1 micron movement of the shaft of said actuator is used to produce a 1 micron movement of the corresponding translation stage. As a result, all motional errors such as hysteresis or randomness of movement inherent in the actuator itself are passed on directly to the translation stage. The requirement for sub-micron resolution also necessitates the requirement for differential micrometer and micro-stepped stepper-motor driven lead screw drives in order to achieve the necessary resolution since a single thread micrometer under hand control can&#39;t be easily adjusted at such fine a resolution. The general trend towards increased resolution and stability in positioning equipment has been driven by the increased use of small-core single-mode optical fibers over the larger core multimode optical fibers which require less precision in alignment manipulation. In order to remove the effect of operator induced forces, a number of sub-micron resolution remote driven motor driven stages have emerged on the market. Even with fully automated positioning systems where a scan routine is carried out under computer control, some level of operator intervention is required for handling and loading the individual elements to be assembled. In many labor intensive assembly applications the cost of an automated system cannot be justified and would not be considered if an appropriate mechanical positioner were available. 
     SUMMARY OF THE INVENTION 
     It is the object of this invention to realize a 3-axis positioning device ideally suited for, but not limited to, the assembly of single-mode fiber optic components. The invention allows for all of the actuators to be placed in a common orientation to reduce hand fatigue and improve adjustment efficiency. The invention teaches a structure that provides for both coarse and fine movement while using a simple adjustment screw and a single actuator such as a micrometer head or a motorized stepping or DC motor driven actuator. The structure also allows for the fine movement to be a fraction of the travel of the control actuator while increasing movement resolution. Another aspect of the invention includes means of translating motion from one axis of movement to another. In addition, the invention teaches a linear compound flexure stage that provides for large travel and linear motion with high stiffness. In its preferred form, the invention can provide for operator insensitive adjustment when aligning single-mode optical fibers with a resolution limit that is comparable to a closed-loop piezo driven translation stage. 
     The invention is an improvement over a conventional stacked 3-axis unit as the operator adjustment forces act only on a single stiff linear translation stage instead of the sum of the total of all stages. It is thus possible to realize a positioning device that can operate under hand control at resolution and stiffness levels required for single-mode fiber optic alignments wherein the operator does not influence the measured optical signal level during adjustment of the unit. It is also possible with the invention to implement linear motor drive on the second and third axes without affecting the overall sensitivity to hand adjustment forces. 
     According to one aspect of the invention, a positioning device includes: 
     a first, normally fixed support; 
     a movable support mounted on said fixed support and constrained to move in a generally rectilinear manner in a first direction; 
     a first actuator mounted on the fixed support for moving the movable support in the first direction; 
     a second actuator mounted on said movable support in substantially parallel relationship to the first actuator; 
     holding means for an object to be positioned, the holding means mounted on said movable support for movement relative to said movable support in a second direction which is perpendicular to said first direction; and 
     an orthogonal drive conversion system for converting motion of said second actuator in the first direction to movement of the holding means in the second direction. 
     The orthogonal drive conversion system serves to isolate the holding means from manual forces applied to the second actuator. 
     The orthogonal drive conversion system may include an actuator mechanism having a push rod pivoted at a first of its ends to means movable by the second actuator, and at a second end, to motion translation means for converting motion of the push rod to movement of the holding means in the second direction. 
     Preferably, the device includes both second and third actuators mounted on the movable support in parallel relationship to said first actuator; and the holding means is mounted on the movable support for movement relative to the movable support in second and third directions which are perpendicular to the first direction and perpendicular to each other. First and second orthogonal drive conversion systems are provided for converting motion of said second and third actuators respectively to movement of the holding means in said second and third directions. Each orthogonal drive conversion system may include an actuator mechanism including a push rod pivoted at a first end to means movable by the respective second and third actuators, and at its second end to motion translation means for converting movement of the push rod to movement of the holding means in the respective second and third directions. 
     One aspect of the invention is a compound cantilever stage that is one-half of the conventional design, the latter using two separate compound stages that are effectively joined at a centerline to maintain high off-axis stiffness. Traditionally, the one-half arrangement is not used as the intermediate frame of reference would move in response to external loads placed on the system and limit off-axis stiffness. It can be shown however, that if the intermediate frame in a compound cantilever stage were to be forced to move one-half of the overall displacement, then high stiffness can be achieved while requiring only one half of the conventional compound cantilever design. An aspect of this invention is to provide a forcing or control means to set the displacement of the intermediate frame of reference of a compound cantilever stage to one half of the output displacement. In its preferred form, the control means is a beam member connected to the parts by frictionless elastic elements. 
     In accordance with this aspect of the invention, a positioning device includes: 
     a first, normally fixed support; 
     a movable support movable in a generally rectilinear manner in a first direction and carrying holding means for an object to be positioned; 
     an intermediate member which is connected to said first support by a pair of first spaced flexible elements and which is connected to the movable support by a pair of second spaced flexible elements; the arrangement being such that the first flexible elements and the second flexible elements are approximately of the same length: and control means connecting said fixed support, said intermediate member and the movable support so that the movement of the intermediate member is a fixed proportion of the movement of the movable support. 
     Preferably, the control means comprises a rigid member connected to the intermediate member at a position midway between its connections to the fixed support and the movable support, so as to ensure that the movement of the intermediate member is about one-half that of the movable support. 
     Another aspect of the invention provides a lever type mechanical advantage between the actuators and the mechanism producing movement in the second and third directions. In accordance with this aspect, the positioning device includes: 
     a support; 
     holding means for an object to be positioned, the holding means mounted on said support for movement in a particular direction; 
     an actuator mounted on said support, and 
     an orthogonal drive conversion system for converting motion of the actuator to movement of the holding means in said particular direction, said conversion system including an actuator mechanism and a motion translation means; 
     said actuator mechanism including a lever having a first end connector point movably connected to the actuator, the lever having a second end portion which has second and third spaced connector points which form a triangle with the first end connector point, the second spaced connector point being located by a contact element and the third spaced connector point being located by an adjustment screw providing an adjustment which is coarse relative to the actuator, and wherein said lever has a fourth connector point in contact with a push rod which transmits motion of the lever member to the motion translation means. 
     The fourth connector point is positioned so that the movement of the push rod is a fraction of the movement of the actuator. 
     Yet another aspect of the invention relates to the nature of the motion translating means which connect the push rod or like means to the holding means. In accordance with this aspect of the invention, the positioning device includes: 
     a fixed support; 
     a movable support movable in a generally rectilinear manner in a first direction and carrying holding means for positioning an object, and also carrying an actuator, 
     an orthogonal drive positioning conversion system for converting motion of said micrometer type actuator to movement of the holding means in a particular direction which is perpendicular to the axis of the actuator, said conversion system including an actuator mechanism and a motion translation means, said actuator mechanism including a push rod movable by the actuator; and 
     an angularly movable part which is connected to an element fixed to said movable support by two crossing flexible elements which preferably extend perpendicularly to each other, said angularly movable part being also connected to said holding means in such manner that when angularly moved by said push rod the angularly movable element produces movement of said holding means in said particular direction which is perpendicular to the first direction. 
     Preferably, the crossing flexible elements, when viewed along the axis of rotation of the angularly movable part, cross each other between the fixed element and the angularly movable part at the approximate centers of the crossing flexible elements. 
    
    
     DESCRIPTION OF DRAWINGS 
     A preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 shows a perspective view of a 3-axis XYZ positioner in accordance with the invention wherein all of the control actuators are oriented parallel to a common axis; 
     FIG. 2 shows a view of the positioner of FIG. 1 with a top portion displaced relative to a bottom portion; 
     FIG. 3 shows a schematic representation of a compound linear flexure translation stage in accordance with one aspect of the invention wherein a displacement controlling or forcing means has been added; 
     FIG. 4 shows the translation stage in a displaced position relative to that of FIG. 3; 
     FIG. 5 shows perspective view of a system of elements used to generate relative motion that is orthogonal to the motion of a control actuator in accordance with the invention; 
     FIG. 6 shows a view of FIG. 5 with two elements removed. 
     FIG. 7 shows a close up schematic representation of a crossed-cantilever translation stage, one of the elements of the system of elements as shown in FIG. 5; 
     FIG. 8 shows the crossed cantilever translation stage a rotated position relative to its position as shown in FIG. 7 to demonstrate how motion is translated orthogonally from one axis of motion to another in accordance to the invention; 
     FIG. 9 shows a view of a coarse adjustment screw in a displaced position in order to demonstrate the overall motion of the system of elements relative to their respective neutral positions as shown in FIG. 5.; 
     FIG. 10 shows a view of the main control actuator in a displaced position as used to provide fine adjustment control in order to demonstrate the overall motion of the system of elements relative to their respective positions as shown in FIG. 5; and 
     FIG. 11 shows an additional system of elements added to that of FIG. 5 to allow for translation of motion from two control actuators arranged on a common axis to that of two respective orthogonal axis. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The 3-axis positioning device according to the invention is shown in block form in FIG.  1  and is indicated by the number  10  in the drawings. As can be seen, three micrometer type actuators  14 ,  18 ,  20  are oriented parallel to a common axis which simplifies adjustment and reduces operator hand fatigue. It is also possible to arrange the actuators on or about a common central plane which eliminates the need for manufacturing a left-hand and right-hand version of the invention as is the common practice with conventional 3-axis designs. In its entire form, the 3-axis positioner consists of two portions. Firstly, a linear translation stage  12  that is controlled by an actuator  14 , and secondly a top portion  16  that is affixed atop the linear translation stage  12 . Two actuators  18 ,  20  allow for fine movement control at a drive ratio reduced by a lever mechanism to be described, and two adjustment screws  22 ,  24  provide coarse adjustment capability. In the invention as presented, the actuator  18  and adjustment screw  22  in conduction with a series of internal elements generate a relative movement at the mounting plate  26  in a first direction, namely the Y (vertical) direction as defined by the axis designator  28 . The other actuator  20  and adjustment screw  24  generate a relative movement at the mounting plate  26  in the X direction using a second series of internal elements described below with reference to FIGS. 5 to  8 . 
     FIG. 2 shows the top portion  16  of the 3-axis positioning device  10  displaced in the Z direction relative to the linear translation stage  12  on which it mounts. It can be seen that actuators  18 ,  20  mount directly to the top portion  16  which is fastened to a movable support provided by top plate  30  of the linear translation stage  12 . This configuration greatly reduces sensitivity of the overall 3-axis positioning device  10  as the forces generated when adjusting the actuators are transferred directly to the linear travel stage  12 . The system sensitivity to adjustment forces is thus only limited by the stiffness of a single linear translation stage  12 , as compared to the standard stacked XYZ positioner configuration where each stage carries an actuator which will be subject to manual forces. 
     In FIG. 3 there is a side view of a schematic representation of a linear translation stage  12  with all flexible elements in an unstressed state. The stage  12  is shown as a dual cantilever flexure stage, however an alternate form of stage  12  such as a crossed roller bearing stage could be substituted in the complete 3-axis positioning device  10  as shown in FIG. 1 without altering the utility of other aspects of the invention. The linear translation stage  12  as shown is comprised of two preferably parallel cantilever stages, the first one formed by two thin flexible plate elements  38  which have one end affixed to a stationary support or reference frame  34  and the other respective ends fastened to an intermediate member or movable plate  32 . In the preferred arrangement, the two flexible elements  38  are of approximately equal length and under displacement the relative motion between the movable plate  32  and the fixed reference frame  34  will then be a parallel arcing motion. A similar second parallel cantilever stage is formed by the intermediate member or movable plate  32  which is connected to the top movable plate  30  by a second pair of thin flexible plate elements  36  having their respective ends affixed to the plates  30 ,  32  as indicated. The relative motion between the intermediate member or plate  32  and the top plate  30  is also a parallel arcing motion provided that the flexible elements  36  are of approximately equal length. The preferred relationship is such that the flexible plate elements  36  and  38  are of substantially equal length. An actuator  14  shown as a micrometer head acts on an anvil block  40  which is affixed to the top moveable plate  30 . 
     A novel feature of this arrangement is a forcing or control means  42  which acts upon the structure to control the relative motion of the moveable plates  30 ,  32 . The control means in its preferred form is elastic and frictionless but can also be made up of rigid linkages with frictional bearing joints without altering the scope of the invention. The control means  42  includes rigid beam member  44  having attached near one end a first flexure element  46  that mounts to a first termination block  52  at the other end, said termination block  52  being fastened to the stationary reference frame or support  34  with one or more fastening elements  58  or alternate attachment means such as adhesives. Affixed to the beam member  44  at or near its center is a second flexure element  48  that mounts at its other end to a second termination block  54  that is fastened to the intermediate movable plate  32 . Affixed to the beam member  44  near the opposite end is a third flexure element  50  that has its other end affixed to a third termination block  56  that is fastened to the top moveable plate  30 . It would be also possible to implement one or more of the flexure elements  46 , 48 , 50  as integral parts being made directly of the same portion of material as the support  34  and plates  32 ,  34  respectively. Preferably, the spacing between first flexure element  46  and the second flexure element  48  in Y direction as defined by the axis designator  60  is of approximately the same as the spacing between the second flexure element  48  and the third flexure element  50 ; i.e. the connection to the intermediate member or plate  32  is midway between the other connection points. 
     FIG. 4 shows the stage  12  of FIG. 3 in a deflected position with the moveable plate  30  having been displaced in the Z direction by a distance d 1  by a corresponding movement of the actuator  14 . The control means  42  in its preferred form as defined in FIG. 3 will impart a displacement d 2  that is one half that of d 1  onto the moveable plate  32  which is elastically mounted in Z direction by flexible plate elements  36 , 38 . If the control element  42  were removed then the top moveable plate  30  would still move in a perfect linear trajectory in the Z direction provided that the flexible elements  36  and the flexible elements  38  were of equal length and flexure stiffness in the Z direction and no external load in the Y direction were applied to the top moveable plate  30 . If the stiffness were not equal or an external load were present then the control means  42  would be required to ensure that the displacement d 2  was half that of d 1  which is the condition required to ensure that the arc error motion of the first parallel cantilever stage is equal to that of the second parallel cantilever stage. The two arc error motions of the two parallel cantilever stages are opposite in relative direction and cancel each other when the aforementioned conditions are met resulting in linear motion at the top moveable plate  30 . 
     FIG. 5 shows a perspective view of an orthogonal drive positioning system  62  in accordance with the invention. The system is contained in the top portion  16  of FIGS.  1 , 2  having its cover plates removed for viewing, and which is mounted on the top movable plate or support  30 . The system  62  is shown in a nominal mid-position with all flexible elements in an unstressed state. The system  62  provides means for controlling a resultant motion in a direction that is orthogonal to the axis of movement of an actuator. In this embodiment, movement from a second actuator  18 , which is oriented in the Z direction, is used to control a resultant motion  84  in the Y or vertical direction as defined by the axis the designator  66 . The shaft of the actuator  18  pushes on a contact element shown as a partial spherical element  70  having a flat engagement surface and a body portion that rests in a contact seat that is part of a pivoting plate or lever  71 . A partial spherical element  70  is shown to facilitate the use of a rotating shaft type actuator as the contact interface formed between the actuator  18  and the flat surface of the partial spherical element  70  can accommodate both relative rotation and relative lateral shear displacement in the XY plane. The pivoting plate  71  has formed in it three additional contact seats that contact spherical elements  72 ,  74 ,  76 . A first spherical element  72  and a second spherical element  74  are located on an axis of rotation defined by their respective centers, and form a triangle with the contact seat for element  70 . The partial spherical element  70 , first spherical element  72  and second spherical element  74  are co-located on a plane defined by their respective centers. A third spherical element  76  forms a ball joint between the pivoting plate  71  and an axial push rod  80 . A fourth spherical element  78  forms a ball joint between the other end of the push rod  80  and a contact seat located in motion translation means provided by a crossed cantilever translation stage  82 . The fourth spherical element  78  moves essentially in the Z direction and causes an angularly movable part  108  of translation stage  82  to rotate which results in a movement  84  of moving plate  86  in the Y direction as will be described below. 
     A parallel cantilever flexure stage is depicted as the preferred type of connection between the fixed plate  88  and the movable plate  86 . Other types of movement stages could be used in conduction with the translation stage  82  but would invariably limit the resolution of the orthogonal drive conversion system  62  as defined by the invention. The parallel cantilever flexure stage is comprised of the fixed plate  88 , to which are attached two flexure elements each having a thin flexible portion  90  on each side of a plate portion  92 . The plate portion  92  between the flexible portions  90  serves to enhance the stiffness in the off-axis directions X and Z of the moving plate  86  that is affixed to the other ends of the flexure elements. 
     A mounting plate  68  is fastened to the top moveable plate  30  and both mounts the actuator  18  and transfers adjustment forces directly to the linear translation stage  12  as shown internally in FIGS. 3,  4 . The orthogonal drive conversion system  62  may also be used with the moveable plate  30  as a stationary reference plate or mounting base to allow the conversion system  62  to be used as a stand-alone single axis system. 
     FIG. 6 is identical to that of FIG. 5 except that the pivoting plate  71  and the axial push rod  80  have been replaced by respective line representations. A reference plane  98  defined by three points is formed by and passes through the centers of the partial spherical element  70 , first spherical element  72  and a second spherical element  74 . The reference plane  98  is also coincident with an identical reference plane formed by contact seats in the pivoting plate  71 . The three spherical elements  70 ,  72 ,  74  are held in a reference plane  98  having a geometric spacing that is constant in relation to each other as defined by the respective contact seats of the elements  70 ,  72 ,  74  in the pivoting plate  71 . A spatially stable arrangement of the three spherical elements  70 ,  72 ,  74  is achieved in the following preferred manner. The second spherical element  74  is located in a contact seat formed into an end portion of an adjustment screw  22 . The first spherical element  72  rests in a seat that is preferably slightly elongated in the X direction. Either or both of the spherical elements  72 , 74  can be made moveable being located by the tip of an adjustment screw or similar adjustment means. The partial spherical element  70  has a flat surface that forms a sliding interface with the end of the actuator  18 . It is a preferred aspect of the invention that the reference plane  98  be substantially orthogonal with the axis formed by the third spherical element  76  and the fourth spherical element  78  when the actuator  18  and adjustment screw  22  are at the center of their respective travel ranges. The third spherical element  76  is ideally located on the reference plane  98  to minimize cosine errors resulting from movement of the reference plane  98  as the actuator  18  and adjustment screw  22  are moved away from the center of their respective travel ranges. 
     As the adjustment screw  22  is moved, the second spherical element  74  also moves in the Z direction which will result in a rotation about a first axis of rotation  100  formed by the partial spherical element  70  and the first spherical element  72 . The ratio of the shortest distance from the third spherical element  76  and the first axis of rotation  100  to the shortest distance from the second spherical element  74  to the first axis of rotation  100  determines the ratio of the movement of the axial push rod  80  to that of the adjustment screw  22  in the Z direction. In a preferred embodiment, the adjustment screw  22  is used to provide a coarse adjustment feature where a typical ratio would be between 0.5 and 1 although any ratio can be selected depending on where the third spherical element  76  is placed relative to the other spherical elements  70 ,  72 ,  74 . As the actuator  18  is moved, the partial spherical element  70  moves primarily in the Z direction which will result in a rotation about a second axis of rotation  102  formed by the first spherical element  72  and the second spherical element  74 . The ratio of the shortest distance from the third spherical element  76  and the second axis of rotation  102  to the shortest distance from the partial spherical element  70  to the second axis of rotation  102  determines the ratio of the movement of the axial push rod  80  to that of the actuator  18  in the Z direction, i.e. the mechanical advantage between the actuator and the push rod. In a preferred embodiment, the micrometer actuator  18  is used to provide fine adjustment control. If, for example, a ratio of 1/25.4 is chosen, then a standard imperial micrometer head with a travel range of 0.500 inches and graduations of 0.001 inch per division can be converted to read in microns per division over a ½ millimeter range of travel. Of course other ratios can be selected. 
     FIGS. 7 and 8 show details of the crossed cantilever translation stage or motion translating means  82 . As shown, an elastic hinge is formed by arranging at least one first flexure element  112  and at least one second flexure element  114  preferably in an orthogonal configuration such that their physical centers are substantially coincident when seen along the axis of the angularly movable part  108 , and define an imaginary center of rotation  115  about the X-axis. The lengths of the flexure elements  112 ,  114  need not be the same but are shown as such. The structure serves as a hinge for limited rotational displacements in the range say of +/−10 degrees. The part  108  is connected by a flexible web  116  to a second moveable block  110 , which is in turn attached to moveable plate  86 . Each individual elastic element  112 ,  114 ,  116  is long and thin in geometry having low flexure stiffness about the X-axis as defined by the axis designator  60  and a relatively high axial stiffness. The elastic elements  112 , 114  thus serve to compliment each other&#39;s weak direction and form a high-stiffness elastic hinge. It is a unique curiosity of the structure that if the elastic elements are positioned as described in this preferred embodiment, then the overall flexure stiffness of the stage  82  is the sum of the individual flexure elements. The elements  112 , 114  can also be arranged with their centers non-coincident but this will increase the flexure stiffness of the overall stage  82 . Functionally, the angularly movable part or block  108  is constrained by crossed cantilever flexure elements  112 ,  114  having at least one of each in each direction such that the block  108  rotates about a center of rotation  115  that is oriented about the X-axis. Orthogonal motion is coupled into and out of the movable block  108  by engaging the block  108  with a displacement or force from one direction and engaging the block  108  by a second displacement or force from a second orthogonal direction. One such engagement point on the block  108  is that of the flexure element or web  116  that is attached to the block  108  at a distance away in the Z direction from the rotational center  115 . The other end of the flexible web  116  is attached to a second movable block  110  which is affixed to and imparts displacement to a moving plate  86  as seen in FIGS. 9 and 10. Plate  86  also constrains the second movable block  110  from rotation. A second engagement point  107  is indicated as a dashed line which represents a contact seating surface fabricated into the block  108  that is shown in FIGS. 5,  6 ,  7  and  8  to engage a fourth spherical element. 
     The preferred embodiment uses a spherical engagement point  107  to permit the use of an axial push rod  80  which allows relative rotation at the engagement point  107  about more than one axis as will be shown in FIG.  11 . When only one direction of relative movement or rotation about a single axis is required an attachment system similar to that of the flexible web  116  and movable block  110  can be used in place of the contact seat  107  and the respective element  78 . It would also be possible to replace the elastic elements  112 ,  114 ,  116  with frictional hinges without altering the scope of other aspects of the invention. In a preferred embodiment, all or most of the elements of the translation stage  82  are fabricated in a cost effective and efficient manner from a single block of a suitable material. 
     FIG. 8 shows an example of the crossed cantilever translation stage  82  of FIG. 7 in a rotationally displaced position. With reference to FIGS. 9,  10  one can see how the axial push rod  80  engages the angularly movable block  108  of the stage  82  through engagement of the intermediate fourth spherical element  78 . As the engagement point  107  moves principally in the Z direction by an arbitrary displacement  118  (indicated in FIG.  8 ), a rotation is imparted onto the angularly movable block  108  which in turn causes a displacement of the flexible web  116  and the affixed movable block  110 . The final result is a displacement  84  in the orthogonal Y direction. 
     FIG. 9 is virtually the same as FIG. 5 except that the adjustment screw  22  has been moved in the Z direction from its center position in order to demonstrate how movement in an orthogonal direction results from movements of said screw  22 . The second spherical element  74  having been moved in the Z direction imparts a rotation to the pivoting plate  71  about a first axis  100  formed by the partial spherical element  70  and the first spherical element  72 . As the third spherical element  76  is in contact with the pivoting plate  70  in accordance with the geometric arrangement of FIG. 6, the element  76  also moves in the Z direction and imparts movement to the axial push rod  80  which is in contact with a third spherical ball  78 . The third spherical ball  78  is in contact with the crossed cantilever stage  82 , which imparts an orthogonal movement to the moving plate  86  to which it is affixed. The moving plate  86  is part of a system of elements that form a parallel cantilever flexure stage, the stage consisting of a fixed plate  88  to which are attached the ends of two flexure elements  90  which are in turn fastened to two plate portions  92  and then to two more flexible portions  90  which are attached at their other ends to the moving plate  86 . The moving plate  86  is guided by the affixed elements  90 , 92  and moves in a constrained parallel arcing motion as can be seen from the relative movement of parts  90 ,  92 ,  86  when FIG. 9 is compared to FIG.  5 . The cosine error motion resultanting from the constrained arcing motion of the moving plate  86  will be in the Z direction, which in a typical optical alignment setup represents the focus direction and is the least sensitive to such an error. In accordance with the invention, the adjustment screw  22  is used to control a resultant movement  84  that is in an orthogonal direction. 
     FIG. 10 is similar to FIG.  9  and demonstrates the movement of the overall system except that the actuator  18  in FIG. 10 has been adjusted in the Z direction and the adjustment screw  22  has been returned to its nominal center position. The movement of the actuator  18  also causes an overall displacement  84  of the stage  62  in the Y direction of the moving plate  86  through a similar series of linked movements to that of FIG.  9 . In FIG. 10, the movement of the actuator  18  can be seen to cause a rotation of the pivoting plate  71  about a second axis of rotation formed by the centers of a first spherical element  72  and a second spherical element  74 . It can be seen in FIG. 10 that the contact element shown as a partial spherical element  70  moves concurrently in an arc with the pivoting plate as evidenced by the slight relative displacement in the Y direction between the partial spherical element  70  and the end of the shaft of the actuator  18  as compared to FIGS. 5,  6 . Other contact elements besides a partial spherical element  70  can be used such as the end of a spherical tipped actuator that directly engages the pivoting plate  71  or an actuator that engages an intermediate linkage similar to a push rod  80 . As discussed in FIG. 6, almost any ratio between the magnitude of the overall displacement  84  and that of the actuator  18  can be chosen based on the geometric positioning of the spherical elements  70 ,  72 ,  74 ,  76 . The ratio shown in FIG. 10 is ⅕ and was chosen to exaggerate the overall movement  84  that results from a large movement of the actuator  18 . It should be noted that the invention can be configured for very small ratios of, say, 1/25.4 to give a resolution of movement comparable to or better than that of the most precise differential micrometer. It is of course possible for the actuator  18  and the adjustment screw  22  to be positioned simultaneously over any portion of their respective travel ranges. It is also possible for the first spherical element  72  to be made moveable by locating it in an additional adjustment screw similar to the adjustment screw  22  that is shown. 
     FIG. 11 demonstrates how a single axis stage  62  as shown in FIGS. 5,  6 ,  9  and  10  may be added to in order to realize a two-axis orthogonal drive conversion system  120 . FIG. 11 is similar to FIG. 5 with a second orthogonal drive conversion system added to provide control of motion in the X direction having its actuator  20  and adjustment screw  24  also both oriented in the Z-axis. In order to realize a second axis of movement, a second parallel cantilever stage is added to that of FIG. 5 as follows. Two flexure elements, each having a plate portion  136  and two flexible portions  134  were added, one end affixed to a first moving plate  86  and the other end affixed to second moving plate  138 . The plate portion  136  is shown as being of a greater thickness than the flexible portions  134  but need not be. The members  134 , 136  could be of continuous geometry becoming in effect a single part. The second flexure element  134 ,  136  is obscured from view by a stage  125  and is located behind said stage  125  in a similar orientation and offset in the negative X direction, the two flexure elements  134 ,  136  being similar in form to the other two flexure elements  90 ,  92  as shown in FIG.  5 . The two flexure elements  134 ,  136  are oriented to allow flexure about the Y-axis only and a resultant relative motion in the X direction between a second moving plate  138  and the first moving plate  86 . The overall system  120  is thus capable of displacement  140  in both the X and Y directions at the second moving plate  138  which provides holding means for an optical fiber or other object being positioned. Movement of the system  120  in the Y direction is illustrated in FIG.  5 . Movement in the X direction of the system  120  is illustrated with reference to FIG. 5 as follows. When either the actuator  20  or the adjustment screw  24  are moved, a displacement in the Z direction of a second axial push rod  122  results which in turn engages a first angularly movable block  130  through an intermediate spherical element  126  that is located in contact seats at each respective interface. 
     A second crossed cantilever translation stage  125  has been mounted in the XZ plane to provide translation of motion from the Z direction to the X direction. The translation stage  125  has a fixed block  128  fastened to a first moving plate  86  and a second movable block  132  fastened to the second moving plate  138 . The two-axis stage  120  is capable of movement  140  in both X and Y directions from a neutral center position if appropriate preload elements such as springs are added to the stages. Preload elements have not been shown as they are commonly known. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Table of Reference Designations 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 10 
                 3 Axis positioning device 
               
               
                 12 
                 linear translation stage 
               
               
                 14 
                 first actuator, Z-Axis 
               
               
                 16 
                 top portion 
               
               
                 18 
                 second actuator, Y-Axis 
               
               
                 20 
                 third actuator, X-Axis 
               
               
                 22 
                 adjustment screw, Y-Axis 
               
               
                 24 
                 adjustment screw, X-Axis 
               
               
                 26 
                 mounting plate or holding means 
               
               
                 28 
                 axis designator 
               
               
                 30 
                 second movable plate or movable support 
               
               
                 32 
                 first movable plate or intermediate member 
               
               
                 34 
                 stationary reference frame; fixed support 
               
               
                 36 
                 thin flexible plate element 
               
               
                 38 
                 thin flexible plate element 
               
               
                 40 
                 anvil block 
               
               
                 42 
                 forcing means; control means 
               
               
                 44 
                 beam member 
               
               
                 46 
                 first flexure element 
               
               
                 48 
                 second flexure element 
               
               
                 50 
                 third flexure element 
               
               
                 52 
                 first termination block 
               
               
                 54 
                 second termination block 
               
               
                 56 
                 third termination block 
               
               
                 58 
                 fastening element 
               
               
                 60 
                 axis designator 
               
               
                 62 
                 orthogonal drive conversion system; 
               
               
                 66 
                 axis designator 
               
               
                 68 
                 mounting plate 
               
               
                 70 
                 contact element, partial spherical element 
               
               
                 71 
                 pivoting plate 
               
               
                 72 
                 first spherical element 
               
               
                 74 
                 second spherical element 
               
               
                 76 
                 third spherical element 
               
               
                 78 
                 fourth spherical element 
               
               
                 80 
                 axial push rod 
               
               
                 82 
                 crossed cantilever translation stage 
               
               
                 83 
                 fastening element 
               
               
                 84 
                 movement designator 
               
               
                 86 
                 moving plate 
               
               
                 88 
                 fixed plate 
               
               
                 90 
                 flexible portion 
               
               
                 92 
                 plate portion 
               
               
                 98 
                 reference plane defined by three points 
               
               
                 100  
                 first axis of rotation 
               
               
                 102  
                 second axis of rotation 
               
               
                 106  
                 fixed block 
               
               
                 107  
                 engagement point 
               
               
                 108  
                 first movable block; angularly movable part 
               
               
                 110  
                 second movable block 
               
               
                 112  
                 first flexure element 
               
               
                 114  
                 second flexure element 
               
               
                 115  
                 center of rotation 
               
               
                 116  
                 third flexure element; flexible web 
               
               
                 118  
                 arbitrary displacement 
               
               
                 120  
                 two axis orthogonal drive conversion system 
               
               
                 125  
                 second crossed cantilever translation stage 
               
               
                 126  
                 spherical element 
               
               
                 128  
                 fixed block 
               
               
                 130  
                 first movable block, angularly movable part 
               
               
                 132  
                 second movable block 
               
               
                 134  
                 flexible portion 
               
               
                 136  
                 plate portion 
               
               
                 138  
                 second moving plate; holding means 
               
               
                 140  
                 movement designator