Abstract:
The present invention is a bistable optical element actuator device utilizing a powered means to move an actuation arm, to which an optical element is attached, between two stable positions. A non-powered means holds the actuation arm in either of the two stable positions. The optical element may be a electromagnetic (EM) radiation or particle source, an instrument, or EM radiation or particle transmissive reflective or absorptive elements. A bearing is used to transfer motion and smoothly transition the actuation arm between the two stable positions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 09/418,477, filed Oct. 15, 1999, now U.S. Pat. No. 6,144,506. 
    
    
     STATEMENT OF GOVERNMENT INTEREST 
     The United States Government has rights in this invention pursuant to Contract No. W-7405-END-48 between the United States Department of Energy and the University of California for Management of the Lawrence Livermore National Laboratory. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to optical actuator positioning devices, and particularly to bi-stable optical actuator devices. 
     1. Description of Related Art 
     It is known in the art of bi-stable optical actuator devices to move an optical clement into and out of the path of a beam of electromagnetic radiation or particles, or to position a source such as a laser with respect to a target. However, two-state devices that switch a component from a first stationary position to a second stationary position typically leave the power on while the component is stationed at one of the positions, or may depower one position and retain power in the second position. This overuse of power can cause unnecessary heat and wear to components as well as cause thermal air disturbances to the light beam transmitted. In addition, there is a need for a device wherein at the end of the optical clement&#39;s travel there is a minimum of vibration experienced by the optical element. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a bi-stable optical device that does not require power to maintain the device in either of two stable positions, and wherein the direction of motion of the optical element is reversible between either of the two stable positions. 
     It is a further object of the present invention to provide a bi-stable optical actuator device that imparts a minimum amount of vibration to an optical element when the optical element is moved from one stable position to a second stable position. 
     It is a further object of the present invention to provide a bi-stable optical actuator device that can handle a variety of optical elements, including EM radiation or particle sources, EM radiation or particle instruments, elements capable of reflecting, absorbing or transmitting EM radiation or particles, and targets or workpieces upon which the EM radiation or particles will act. 
     According to one aspect of the present invention, there is provided a bi-stable optical actuator device, comprising a mounting base; an actuation arm having first and second positions and having a first end, a second end, and a middle region, said middle region being rotatably connected to said mounting base, said First end including an elongated opening, said second end having an attached optical element; a driver bar having first and second positions for driving said actuation aim between actuation arm First and second positions, said driver bar having a first end rotatably connected to said mounting base and a second end on which is mounted a bearing for engaging and traveling within said elongated opening, so that when said driver bar pivots in a given direction said actuation arm is driven in an opposite rotational direction by said bearing; a non-powered means for restraining said driver bar in either of its first and second positions which maintains said actuation arm in either of its first and second positions (and thus the optical element in either of its first and second positions); and powered means for driving said driver bar from its first to its second position, so that said actuation arm is driven from its first to its second position, and the optical element is moved from its first to its second position. The optical element may be a source, an instrument, an clement capable of reflecting, transmitting or absorbing EM radiation or particles, or a target or workpiece upon which EM radiation or particles impinge. 
     According to another aspect of the present invention, the optical element interacts with the flux from a source (preferably a beam source) emitting EM radiation or particles. In one aspect, the optical element receives none of the emission while it is initially held outside of the path of the flux by the non-powered means. The optical element is subsequently moved into the path of the flux when the driver bar is driven by the powered means to its second position and thus the optical element receives at least a portion of said source emission. In another aspect, the optical element initially receives at least a portion of said emission while it is held in the path of the flux by the non-powered means. The optical element is subsequently moved out of the flux when the driver bar is driven by the powered means to its second position. 
     In a further aspect of the present invention, the optical element is a source (preferably a beam source) emitting EM radiation or particles, wherein at least a portion of said emission initially impinges upon a second optical clement. As the driver bar is driven by the powered means, the second optical element receives no emission from the source. In another aspect, the second optical element initially receives no emission from the source, and subsequently receives at least a portion of said emission when the driver bar is driven by the powered means to its second position. 
     Other objects and features of the present invention will be apparent from the following detailed description of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B illustrate the front and side views for an embodiment of the present invention wherein the non-powered means and the powered means operate on an output rod connected to the driver bar. 
     FIGS. 1C and 1D illustrate front views for the two positions for the driver bar for embodiments of the present invention as the driver bar is driven from its first position ( 1 C) to its second position ( 1 D). 
     FIG. 2 illustrates the front view for an embodiment of the present invention wherein the non-powered means comprises a spring or a permanent magnet that cooperates with the second end of the driver bar. 
     FIG. 3 illustrates the front view for an embodiment of the present invention wherein the non-powered means comprises gravity. 
     FIGS. 4A and 4B illustrate an aspect of the present invention which further comprises a source (preferably a beam source) emitting a flux of EM radiation or particles. In FIG. 4A, the optical clement is initially not in the path of the emitted flux while the driver bar is held in the first position by a non-powered means, and in FIG. 4B, the optical element intercepts at least a portion of the emitted flux when the driver bar is moved to its second position by a powered means. 
     FIGS. 5A and 5B illustrate an aspect of the present invention wherein the optical element comprises a source emitting a flux of EM radiation or particles. In FIG. 5A at least a portion of the emitted flux impinges upon a second optical element while the driver bar is in its first position, and in FIG. 5B, the EM radiation or particles no longer impinge on the second optical element when the driver bar is moved to its second position by a powered means. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Definitions 
     beam source—a source emitting a beam of particles or electromagnetic (EM) radiation directed in a particular direction. 
     EM radiation—electromagnetic radiation 
     first position—initial stable position of the driver bar, actuation arm or optical element prior to the driver bar being driven by the powered means 
     instrument—an instrument capable of measuring, sensing or detecting FM radiation or particles 
     non—powered means—means to apply a restraining force to the driver bar by which the driver bar is held in either of its first or second positions without power. 
     opposite rotational direction—simultaneous motion by the driver bar and the actuation arm, such that the end of the driver bar including the bearing and the end of the actuation arm including the elongated slot pivot along opposing arcs. 
     optical element—a) a source emitting EM radiation or particles; b) an instrument to measure or detect EM radiation or particles; c) an clement capable of reflecting, transmitting or absorbing EM radiation or particles. Examples of such elements include but are not limited to shields, mirrors, lenses, filters, collimators, absorbing glass, polarizers, polarization rotating elements, prisms, and alignment fiducials; d) an item desired to interact with a source emitting EM radiation or particles, including a workpiece whose material properties (surface and/or bulk) are modified. 
     particles—subatomic, atomic or molecular particles, in either charged or neutral states. 
     power source—a device or connection that supplies electric current, or other type of power, to the powered means. The power source may be alternating or direct current at a variety of strengths (voltages). Other sources of power may include hydraulic and pneumatic. 
     powered means—means to apply a driving force to the driver bar by which the driver bar is moved from a first position to a second position via the use of power. 
     second position—ending stable position of the driver bar, actuation arm or optical element after the driver bar has been driven by the powered means 
     source—one or more sources of electromagnetic radiation or particles, emitted in all directions or as a beam. 
     DESCRIPTION 
     Embodiment One 
     FIGS. 1A and 1B illustrate front and side views for an embodiment of the present invention. A bi-stable optical element actuator device  100  of the present invention comprises a mounting base  102 , a driver bar  108  having first and second ends, and an actuation arm  116  having first and second ends. The first end (driven end)  106  of driver bar  108  is connected via output rod  104  to mounting base  102 . The second end (working end)  114  of driver bar  108  is mechanically linked to the actuation arm  116 , by a bearing  118  that slides within an elongated slot  120  in the first end  122  (driven end) of actuation arm  116 . 
     Powered means  138  applies a torsional driving force to driver bar  108  via output rod  104  to cause driver bar  108  to pivot from a first position to a second position. Powered means  138  is preferably a rotary actuator, but may also include electric motors, electric engines, rotary solenoids and electromagnets. A preferred rotary actuator is part no. RA35A-2P12.9726 manufactured by Shindengen of Japan. Electromagnets may be positioned relative to each other or to ferromagnetic materials, as is well known in the art, so that repulsive (or attractive) magnetic forces are generated. 
     Non-powered means  140  applies a torsional restraining force to driver  108  via output rod  104  which urges driver bar  108  to remain in either of the driver bar&#39;s first or second positions. Non-powered means  140  preferably comprises combinations of permanent magnets aligned with each other or with respect to ferromagnetic materials, so that the magnetic forces urge said driver bar  108  to remain in either of its first or second positions. 
     As driver bar  108  pivots from the first position shown in FIG. 1C, bearing  118  is forced to slide within elongated slot  120  toward a middle portion  124  of actuation arm  116 . As bearing  118  slides within elongated slot  120 , bearing  118  exerts a force on either a wall  126  or a wall  128  of slot  120 , causing actuation arm  116  to pivot about a pivot  130 . As bearing  118  moves from one side to the other of device  100 , bearing  118  travels in a path defined by a curved outline  132  shown in FIG.  1 A. As driven end  122  of actuation arm  116  is forced to move to the left by bearing  118 , the second end  134  of actuation arm  116  moves from the left, the position shown in FIG. 1C, to the right, the position shown in FIG.  1 D. Mounted on the actuation arm second end  134  is an optical element  136 . As actuation arm second end  134  moves from the position shown in FIG. 1C to the position shown in FIG. 1D, optical element  136  not only moves from left to right in an arc, but also rotates in a clockwise direction. Optical element  136  may be fixed or removably attached to actuation arm second end  134  by means well known in the art. 
     As shown in the embodiment of the present invention shown in FIGS. 1C and 1D, the driver bar and actuation arm are preferably at angle of 90° with respect to each other when the driver bar is in either of its first and second positions. It is further preferred that the distance from the output rod to the bearing on the driver bar (length  1 ) be equal to the distance from the bearing to the actuation arm pivot (length  2 ). If length  1  is made shorter than length  2 , then the driver bar would need to travel more than 90 degrees to meet the initial zero angular velocity criteria. The optical element would not move as fast nor rotate as much as in the 90 degrees case. Also, as can be seen in FIGS. 1C and 1D, pivoting the driver bar 90° causes the actuation arm to be pivoted 90° in the opposite rotational direction. By arranging the driver bar and actuation arm 90° to one another when the actuation is in the first position, when the driver bar is pivoted, the actuation arm is accelerated by the driver arm and bearing from zero angular velocity at the actuation arm first position, to a maximum angular velocity at 45° of rotation and then decelerated back to zero velocity at 90° of rotation, when the actuation arm reaches the second stationary position. This design locks the actuation arm in either the first or second positions until the actuation arm is pivoted in the reverse direction. It may also be noted that output rod  104  is aligned with pivot  130 . The position of driver bar  108  may be detected via first and second position sensors  1   10  and  112  respectively. 
     Embodiment Two 
     FIG. 2 illustrates a front view for a second embodiment of the present invention. Powered means  238  applies a driving force to driver bar  208  at the working end  214  of driver bar  208  to pivot driver bar  208  from a first position to a second position. The power source for powered means  238  may comprise electric, hydraulic or pneumatic. The powered means  238  may comprise solenoids and electromagnets. 
     Non-powered means applies a restraining force to driver bar  208  at the working end  214  of driver bar  208  which urges driver bar  208  to remain at either of its first or second positions. Non-powered means  240  comprises at least one spring, preferably a helical tension or compression spring. It is understood that the present invention encompasses configurations for the various other types of springs that are well known in the art, including but not limited to helical, Belleville, leaf, extension, volute, and conical springs. Non-powered means  241  may also comprise one or more permanent magnets or a combination of one or more permanent magnets and ferromagnetic materials. 
     Embodiment Three 
     FIG. 3 illustrates the front view for an embodiment of the present invention wherein the non-powered means  340  comprises gravity. Locating the composite center of gravity (CG)  342 , for the optical element  336  and actuation arm  316 , between pivot  330  and actuation arm second end  334  means that gravity acting on the CG  342  will urge the driver bar  308  to remain in either of driver bar&#39;s position one or position two. 
     Embodiment Four 
     FIGS. 4A and 4B illustrate an aspect of the present invention comprising a bi-stable optical element actuator device  400  cooperating with a source  444  (preferably a beam source) emitting a flux  446  of EM radiation or particles. In FIG. 4A, the optical element  436  is initially not in the path of the flux  446  while the actuation arm  416  is in its first position. As shown in FIG. 4B, the optical element  436  intercepts at least a portion of said emitted flux  446  when the actuation arm  416  is moved to the second position by various powered means (as described earlier). One application (but not limited to) of this embodiment would be as a shutter, wherein the optical element  436  is a shield that moves into the path of the flux  446  partially or completely blocking the transmission of the flux. It is understood that this embodiment also encompasses the configuration wherein the optical element  436  initially intercepts at least a portion of said emitted flux  446  while the actuation arm  416  is in its first position, and subsequently gets moved out of the path of the flux  446  (actuation arm second position). One application (but not limited to) of this embodiment would be as a switch, wherein the optical element  436  is a shield which moves out of the path of the flux  446 . 
     Embodiment Five 
     FIGS. 5A and 5B illustrate an aspect of the present invention comprising a bistable optical element actuator device  500  in which optical element  536  comprises a source (preferably a beam source) of EM radiation or particles a portion of whose flux impinges on a second optical element item  548 . In FIG. 5A, the second optical element  548  intercepts at least a portion of flux  546  from the optical element  536  while the actuation arm  516  is in its first position. In FIG. 5B, when the actuation arm  516  is moved to the second position by various powered means (as described earlier), the second optical element  548  no longer intercepts the flux  546  from optical element  536 . If the source  536  is not a beam source, then additional shielding (not shown) may be needed to shield the second optical element  548  when the actuation arm is moved to position two. Although the embodiment illustrated was for the scenario that the second optical element  548  receives flux when the actuation arm is in the first position, it is understood that the present invention also encompasses the scenario wherein the second optical element  548  receives at least a portion of the flux when the actuation arm is in the second position, and the second optical element  548  receives no flux in the actuation arm First position. 
     It is understood that since the device is stable in two (first and second) positions, the first and second positions arc denoted for illustrative purposes for a given driving force direction. In FIGS. 1C and 1D, the driver bar motion is shown as moving from the right side (first position) to the left (second position). The first position could equally have been set as being on the left side, with the driver bar moving to the right (second position). As described earlier, the first and second positions only signify the initial and ending stable positions, before and after the driver bar has been driven by the powered means. As the driving force direction is reversed, the positions designated as first and second positions arc also reversed. It is to be understood that the present invention as described herein may be operated wherein the direction of the driver bar motion is repeatedly reversed (cycled). 
     In general, the mounting base of the present invention serves as a platform to which the components of the optical actuator device of the present invention are secured. The mounting base may be made of metal, or another sufficiently strong, non-deformable material. 
     The driver bar of the present invention is a component to which restraining and driving forces are applied. The driver bar may be made of metal, or other strong, non-deformable material. 
     The actuation arm of the present invention is the portion of the optical actuator device that is driven by the driver bar and pivots in an opposite rotational direction. The actuation arm is preferably made of a strong, non-deformable material, most preferably a machinable, high-strength plastic such as DELRIN. 
     Obviously numerous modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described therein.