Patent Publication Number: US-2023139114-A1

Title: Multi-axis flexure and tilt mount for laser diode beam generators

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application No. 63/263,316, filed on Oct. 29, 2021, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The disclosure pertains to rotational mounts. 
     BACKGROUND 
     Many optical systems require precise pointing of optical beams, accurate orientation of optical detectors, or proper alignment of optical instruments. In some applications, multi-axis rotational alignment is required, often resulting in the need for multiple adjustments which can be dependent on each other so that setting a rotational alignment about one rotational axis disturbs alignment about other rotational axes. In such applications, providing suitable alignment can be tedious. In optical assemblies to be incorporated into larger systems, this tedious alignment can increase production costs and result in systems in which field re-alignment is difficult, requiring a skilled technician and/or specialized equipment. Moreover, in many cases, providing access to optical assemblies for alignment is challenging as access from multiple directions is required to adjust multi-axis rotations. Thus, an entire assembly may need to be exposed by, for example, removing protective covers and sub-systems which obstruct access. In addition to these challenges associated with multi-axis rotational alignment, practical systems require simple, inexpensive, and easily manufactured components for use in multi-axis rotational stages. For these and other reasons, alternative approaches are needed. 
     SUMMARY 
     Rotational mounts comprise a flexure member defining a base portion, a flexure portion, and a mounting portion, wherein the flexure portion defines a first flexure and a second flexure associated with rotations about a first axis and a second axis, respectively, wherein the second axis is orthogonal to the first axis. At least one clamp is situated to secure an optical system to the mounting portion of the flexure member so that the first flexure and the second flexure are operable to provide rotation about the first axis and the second axis in response to bending at the first flexure and the second flexure, respectively. The first flexure can be defined by a groove in the flexure member, the groove extending parallel to the first axis. The second flexure can be defined by opposing slots in the flexure member, the opposing slots extending parallel to the first axis. The flexure member can be situated between the base portion and the mounting portion. In some examples, the clamp has a cylindrical mounting surface that defines a third axis that is different from the first and second axes, wherein the cylindrical mounting surface is adapted to permit rotation of the optical system about the third axis. At least one ball clamp can be situated to produce bending of the second flexure. The at least one ball clamp can include an adjustment mechanism, a ball, and a retaining surface adapted to receive the ball, wherein the adjustment mechanism is situated to urge the ball against the flexure base to produce a rotation about the second axis. In examples, the at least one ball clamp includes a first ball clamp and second ball clamp, each comprising a respective adjustment mechanism, ball, and retaining surface adapted to receive the ball, wherein the adjustment mechanism of the first ball clamp is operable to urge the ball against the flexure base in a first direction to produce a rotation in a first direction about the second axis and the adjustment mechanism of the second ball clamp is operable to urge the ball against the flexure base in a second direction to produce a rotation in a second direction, opposite first direction about the second axis. 
     In some examples, a base is secured to the flexure member, wherein the base defines cavities situated to receive the balls of the first ball clamp and the second ball clamp, wherein the adjustment mechanisms of the first ball clamp and the second ball clamp are secured to the base. The adjustment mechanisms can include screws situated to contact respective balls and extend parallel to a common axis. In examples, centers of the balls of the first ball clamp and the second ball clamp are situated between the adjustment mechanisms and respective contact surfaces of the flexure member. In examples, the common axis is one of the first axis or the second axis. The adjustment mechanisms can be screws having screw heads that face the common axis. 
     In further examples, the clamp includes a bottom portion and a top portion and at least one fastener situated to secure the bottom portion to the top portion, wherein the at least one fastener extends along the common axis. The clamp can have a cylindrical mounting surface that defines a third axis that is different from the first and second axes, wherein the cylindrical mounting surface is adapted to permit rotation of the optical system about the third axis. 
     Rotational mounts comprise a flexure member having first and second flexures situated to provide rotations above a first rotational axis and a second rotational axis, respectively. A component mount is operable to secure a component to the flexure member and situated to provide component rotation about a third rotational axis, wherein the first, second, and third rotational axes are mutually orthogonal, wherein the flexure member and the component mount are situated to permit rotations about the first, second, and third axes to be provided from a common direction. First and second adjustment mechanisms corresponding to the first and second flexures, respectively, can be provided, wherein the first and second adjustment mechanisms include a first adjustment screw and a second adjustment screw, respectively, having parallel screw axes. In examples, a clamp member is operable to secure the component, wherein the clamp member is adjustable with at least one screw having an axis parallel to the screw axes of the first adjustment screw and a second adjustment screw. 
     Methods comprise rotatably securing a component to a flexure member and adjusting a rotation of the component about first and second axes with adjusters aligned along a common axis, wherein the first axis and the second axis are orthogonal. IN some examples, a rotation of the component about a third axis is adjusted with a third adjuster aligned along the common axis. In representative examples, the common axis is one of the first, second, or third axes. 
     The foregoing and other features and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A- 1 B  are perspective views of a representative unidirectional adjustable stage. 
         FIG.  1 C  is an exploded view of the unidirectional adjustable stage of  FIGS.  1 A- 1 B . 
         FIG.  1 D  is an elevational view of the unidirectional adjustable stage of  FIGS.  1 A- 1 B . 
         FIG.  1 E  is a plan view of the unidirectional adjustable stage of  FIGS.  1 A- 1 B . 
         FIG.  1 F  is a perspective view of a dual-axis flexure member used in the unidirectional adjustable stage of  FIGS.  1 A- 1 B . 
         FIGS.  1 G- 1 H  are perspective and sectional views of a clamp used in a ball adjustor in the adjustable stage of  FIGS.  1 A- 1 B . 
         FIG.  2    illustrates a representative rotational adjustment method. 
         FIG.  3    illustrates a flexure member. 
         FIG.  3 A  is a sectional view of the flexure member of  FIG.  3   . 
         FIG.  3 B  illustrates the flexure member of  FIGS.  3 - 3 A  as secured to a base for angular adjustment. 
         FIG.  4    illustrates an alternative adjustment mechanism and an associated dual-axis flexure. 
         FIG.  5    illustrates an alternative adjustment mechanism and an associated dual-axis flexure. 
         FIG.  6    illustrates another example of a unidirectional adjustable stage. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure pertains generally to rotational stages that permit rotational adjustments about two or more perpendicular or otherwise distinct axes with adjustment mechanisms situated to be accessible from a common direction. Particular examples are shown based on alignment of a laser line beam source that is secured to provide 3-axis rotation adjustments, but other components or systems can be similarly mounted. In some cases, dual-axis adjustments are provided. 
     General Considerations 
     As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the term “coupled” does not exclude the presence of intermediate elements between the coupled items. 
     The systems, apparatus, and methods described herein should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and non-obvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The disclosed systems, methods, and apparatus are not limited to any specific aspect or feature or combinations thereof, nor do the disclosed systems, methods, and apparatus require that any one or more specific advantages be present or problems be solved. Any theories of operation are to facilitate explanation, but the disclosed systems, methods, and apparatus are not limited to such theories of operation. 
     Although the operations of some of the disclosed methods are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed systems, methods, and apparatus can be used in conjunction with other systems, methods, and apparatus. Additionally, the description sometimes uses terms like “produce” and “provide” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms will vary depending on the particular implementation and are readily discernible by one of ordinary skill in the art. 
     In some examples, values, procedures, or apparatus&#39; are referred to as “lowest”, “best”, “minimum,” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, or otherwise preferable to other selections. 
     Examples are described with reference to directions indicated as “above,” “below,” “upper,” “lower,” and the like. These terms are used for convenient description, but do not imply any particular spatial orientation. 
     As used herein, a groove used to define a flexure is a thinned portion of a flexure base, typically elongated and extending from edge to edge of the flexure base permitting bending of the flexure base. A grooved cross-section is typically semicircular but other shapes such as other curved shapes (sections of ellipses, ovals, or other curved surfaces) or polygonal shapes such as squares, rectangles, hexagons, or symmetric or asymmetric polygons can be used, or other shapes defined by combinations of curves and lines. A groove generally permits rotation about an axis that is parallel to a groove length. 
     As used herein, a slot flexure is typically defined by slots in a flexure base that terminate at a flexure portion. The slots can be of the same or different lengths, and typically extend from the flexure portion to edges of a flexure base. Slot flexures can also be defined by single slot that terminates proximate a flexure base edge to leave a flexure portion. Typically, such a slot extends from one edge of the flexure base to the flexure portion. In typical examples, slots of the same dimensions are used and the flexure portion is centered on the flexure base. Such a slot flexure is referred to as a symmetric slot flexure. Slot flexures generally permit rotation about an axis that is perpendicular to a slot base. 
     As used herein, a base is a mounting structure to which a flexure plate can be secured. Such a base can be a component of an optical or other system or can be specially provided for use with a flexure. 
     As used herein, parallel refers to axis directions that are within 1, 2, 5, 10, or 20 degrees of each other. 
     In some examples, opposing adjustors or actuators are used to provide rotations. Opposing actuators can provide adjustments in two directions but in some cases, single adjustors or actuators or used, and in specific examples, springs or other elastic members provide forces opposite to those applied by the single actuator or adjustor. 
     Examples are provided in which multi-axis rotations can be adjusted with adjustors oriented in a common direction. Typically, screws can be used for adjustment and are aligned parallel to a common axis so that screw heads are accessible and adjustable from a common direction. Particular screw heads are shown in some examples for purposes of illustration, but cap, slot, Phillips, or others can be used. Rotational stages that permit adjustment of two or more rotation angles from a common direction are referred to herein as unidirectionally adjustable stages. 
     Example 1 
     Referring to  FIGS.  1 A- 1 H , an optical beam assembly  100  includes a laser beam generator  102  that generally includes a laser diode and one or more beam shaping optical elements such as lenses and apertures. The laser beam generator  102  is secured with a clamp  104  to a dual-axis flexure member  106  and the clamp  104  and dual-axis flexure member  106  are provided with suitable surfaces such as cylindrical surfaces  105 A,  105 B so that the laser beam generator  102  is rotatable about an axis  107  that is parallel to an axis of propagation of an emitted beam  108 . Screws  110 A,  110 B can be used to secure the clamp  104  after a selected rotation of the laser beam generator  102  with the clamp  104 . Rotation of the laser beam generator  102  about the axis  107  can be used to establish an orientation of a line beam or a beam polarization direction. For optical assemblies that include a detector, rotation can permit alignment of detector axes. 
     The dual-axis flexure member  106  defines a first flexure based on channels  112 A,  112 B that separate a flex region  112 C in the dual-axis flexure member  106 . The first flexure provides rotation about an axis  120 . The dual-axis flexure member  106  defines a second flexure based on a groove  122  that permits rotation about an axis  124 . The first flexure and the second flexure are typically arranged so that the axes  120 ,  124  are perpendicular. The flexure base  106  can include a recess  109  to permit rotation of the laser beam generator  102  without contacting the flexure base. Such a recess is not required for some rotations and size of mounted components. 
     The dual-axis flexure member  106  defines a flexure base portion  106 A that can be used to secure the dual-axis flexure member  106  to a base  130  and a mounting portion  106 B that is configured to securing an optical or other assembly for angular positioning and provide rotation of the mounted components about the axis  107 . As shown, the flexure base portion  106 A is secured to the base  130  with screws  132 A,  132 B but can be secured with other fasteners such rivets or adhesives. As shown, the base  130  is provided with clearance holes for use in mounting the base  130  with additional screws such as screws  134 A,  134 B,  136 A,  136 B. The dual-axis flexure member  106  also defines a flexure portion  106 C that include slots, grooves, or other flexible members associated with the first and second flexures, and a mounting portion  106 B that can receive components 
     With the flexure base portion  106 A secured to the base  130 , various adjustment mechanisms can be provided to permit rotation of a component or assembly secured to the mounting portion  106 B. Rotation about the axis  120  can be provided by pressing again surfaces  140 A,  140 B. In one example, ball adjusters  142 A,  142 B are provided that include respective ball clamps  144 A,  144 B, steel balls  146 A,  146 B, mounting screws  148 A,  148 B, and adjustment screws  150 A,  150 B. The mounting screws  148 A,  148 B secure the ball clamps  144 A,  144 B to the base  130  and include cavities  151 A,  151 B that receive the steel balls  146 A,  146   b . The steel balls  146 A,  146 B are situated with respect to the adjustment screws  150 A,  150 B so that the adjustment screws  150 A,  150 B can urge the steel balls  146 A,  146 B against the surfaces  140 A,  140 B, respectively. As shown in  FIG.  1 C , the base  130  can be provided with recesses  147 A,  147 B that retain the steel balls  146 A,  146 B, respectively.  FIG.  1 E  illustrates off-center placement of the adjustment screw  150 A with respect to the steel ball  146 A so that the adjustment screws  150 A is positioned to urge the steel ball  146 A to the surface  140 A and produce rotation about the axis  120 .  FIG.  1 E  also illustrates that the ball clamps  144 A,  144 B are further secured with respective pins  152 A,  152 B that extend into holes  155 A,  155 B in the base  130 . 
     Rotation about the axis  124  can be adjusted with an adjustment screw  154  or other mechanism. The adjustment screw  154  is threaded into the dual-axis flexure member  106  and situated to press again a surface  131  of the base  130 . A tip of the adjustment screw  154  can be shaped to permit motion across the surface  131  of the dual-axis flexure member  106 . A lock screw  156  is received in a threaded hole  158  in the base  130  so that an adjustment can be secured. The lock screw  156  is situated to extend through a slot  160  so that the lock screw  156  does not impede rotation about the axis  120  as controlled by the ball adjusters  142 A,  142 B. 
     The ball clamp  144 A is illustrated in further detail in  FIGS.  1 G- 1 H . A counterbore  168 A is provided so that the screw  148 A can be threaded into the base  130 . The threaded hole  170 A is adapted to receive the adjustment screw  150 A so that it can press against a steel ball in the cavity  151 A. A through hole  153 A is provided for insertion of the pin  152 A that is received by the corresponding hole  155 A in the base  130 . 
     In this example, all adjustment and lock mechanisms are situated to be accessed and adjusted from a single direction, and all are aligned parallel to the axis  120 . Thus, single-direction control is possible, leading to convenient adjustment, particularly as installed in a larger system. In addition, each rotational adjustment can be locked or secured. For example, opposing ball adjusters are provided for rotation about the axis  120  and the rotation about the axis  124  can be secured with the lock screw  156 . In other examples, springs, elastic washers, or other compliant members can be provided and adjustment screws can provide adjustments in one direction that can be opposed the compliant member. For some applications, it is advantageous to secure rotation elements to reduce rotational errors due to vibration or acceleration. In this example, adjustment screws have socket heads, but other types can be used. 
     In some cases, rotations can be described as roll, pitch, or yaw. As used herein, rotations about the axis  107  can be referred to as roll, rotations about the axis  124  can be referred to as pitch, and rotations about the axis  120  can be referred to as yaw. In this example, the dual-axis flexure member permits adjustment of pitch and yaw, and the clamp permits adjustments of roll. 
     Example 2 
     Referring to  FIG.  2   , a representative method  200  includes providing a dual-axis flexure (or other multi-axis flexure) at  202 . At  204 , the flexure is secured to a base and at  206 , adjusters (for example, screws) associated with each axis are situated so that adjustment surfaces (such as screw heads) face a common direction and can be accessed from the common direction to establish rotation angles. A rotational mount associated with a third axis of rotation can be secured to the dual-axis flexure at  208 . At  210 , a selected component of system is secured to the rotational mount. At  212 , rotational adjustments are made for angles of rotation about one, two, or three axes. 
     Example 3 
     Referring to  FIGS.  3 - 3 A , a flexure member  300  includes a flexure base portion  302 , a flexure region  304 , and a mounting portion  306 . The flexure base portion  302  is typically secured to a base so that the flexure region  304  provides rotational adjustments of components secured to the mounting portion  306 . The flexure region  304  includes a first flexure defined by a bridged region  310 C and slots  310 A,  310 B. The first flexure provides rotations about an axis  312  that is perpendicular to the plane of  FIG.  3    but is shown in the sectional view of  FIG.  3 A . A second flexure is defined by a groove, channel, or other thinned region  314  at one or both surfaces of the flexure member  300  and can permit rotation about an axis  316 . The flexure member  300  also includes through holes  320 - 322  for mounting the flexure base portion  302  and a slotted through hole  324  for a lock screws and a tapped hole  326  for an adjustment screw. 
       FIG.  3 B  is a sectional view illustrating the flexure member  300  secured to a base  340  with a screw  342  inserted into the hole  321  and received by a threaded bore in the base  340 . A lock screw  344  is situated to pull the base  304  and the flexure member  300  toward an adjustment screw  346  that establishes an angle of rotation θ about the axis  316  (perpendicular to the plane of  FIG.  3 B ). 
     Example 4 
     Referring to  FIG.  4   , a flexure member  402  is secured to a base  403  at a base portion  404  of the flexure member  402 . The flexure member  402  includes a flexure region  406  that includes a first flexure and a second flexure that can permit rotations about perpendicular axes. The first flexure is defined by a channel or groove  408  or other thinned portion of the flexure member  402  and can provide rotation about an axis  410 . The second flexure is defined by slots  412 A,  412 B and a bridge region  412 C and provides rotation about an axis that is perpendicular to the plane of  FIG.  4   . In this example, a spring  422  is secured to the base  403  and a screw  424  is oriented to urge the flexure member  402  toward the spring  422  to provide component rotation using the second flexure. As shown, access to the screw is in a direction parallel to the axis  410  but a ball clamp adjuster can be used to provide access from above the flexure member  402 . 
     Example 5 
     Referring to  FIG.  5   , a flexure member  502  is secured to a base  503  at a base portion  504  of the flexure member  502 . A flexure is defined by a channel or groove  508  or other thinned portion of the flexure member  502  and can provide rotation about an axis that is perpendicular to the plane of  FIG.  5   . In this example, a screw  524  is 522 is oriented to urge the flexure member  502  toward the base  403  to provide component rotation. As shown, access to the screw  524  is from above the flexure member  502 . A second flexure can be provided as well such as illustrated above. 
     Example 6 
     Referring to  FIG.  6   , a multi-axis rotational stage  600  includes a top plate  604  and a bottom plate  602  that are secured with screws  610 - 612 . An optical system  608  such as a laser beam generator is rotatably secured between the top plate  604  and the bottom plate  602 . The optical system  608  can be secured to or include a spherical mount  606  that is retained by the top plate  604  and the bottom plate  602 , typically in one or more recesses or apertures such as hole  620 ; a corresponding hole or recess can be provided in the bottom plate  602  as well. The rotational stage  600  can be secured as needed with a screw or other fastener at bore  624 . Adjustments with the screws  610 - 612  can be provided from the top and permit 3-axis rotation (roll, pitch, yaw), although the adjustments are not always independent. 
     In view of the many possible embodiments to which the principles of the disclosure may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting the scope of the disclosure.