Abstract:
Methods and apparatus are provided for rapidly moving a filter into and out of an optical beam. A shuttle carries the filter at a first end and first and second spaced apart pieces of magnetic material near the other end. A low friction guide-way supports the shuttle. A base supports the guide-way and a third magnetic piece and coil between the first and second pieces. When the shuttle is IN the first and third pieces form a first magnetic latch to releasably hold it IN and when the shuttle is OUT the second and third pieces form a second magnetic latch to releasably hold it OUT. Spring(s) between the shuttle and the base store energy when the shuttle is IN or OUT. Activating the coil weakens the magnetic attraction between the latch pieces, freeing the shuttle to move, driven by the spring(s) to the opposite OUT or IN position.

Description:
TECHNICAL FIELD 
   The present invention generally relates to means and methods for rapid linear translation, and more particularly, for rapidly inserting filters or other components into an optical or other path. 
   BACKGROUND 
   Many types of equipment require the temporary insertion (and removal) of filters, lenses, detectors, prisms, screens, isolators and other components. The path into which they are inserted and removed may be an acoustic path or an optical, microwave, x-ray or other electro-magnetic (EM) propagation path For convenience of explanation the word “optical” is used herein to represent any and all such acoustic and EM signals and the words “filter” or “filters” are used herein to represent any and all of the components desired to be rapidly inserted and removed from such a path. The most common arrangement in the prior art for temporarily introducing filters is by means of a rotating filter-wheel assembly. A circular array of filters is often provided, rotating around a shaft or pivot to the side of the optical path such that a circle drawn through the centers of the filters passes through the center of the optical path. As the filter-wheel rotates, different filters are introduced into and removed from the optical path. A limitation of this approach is that the filters must be introduced sequentially according to the order in which they have been placed on the filter-wheel. This is a significant limitation where random rather than sequential filter changes are needed. 
   Another approach used in the prior art is to provide a stack of filters arranged one behind the other off to the side of the optical path. Each filter is coupled to a rotating arm. When actuated the arm flips the filter into or out of the optical path. While this arrangement permits random filter selection it is bulkier and usually heavier than desired because of the need for a separate rotating actuation arm for each filter. 
   Accordingly, it is desirable to provide an improved filter insertion means and method that overcomes some or all of the limitations of the prior art. In particular, it is desirable that the filter transport apparatus be simple, rugged and reliable, not require rotating wheels or arms and the like for insertion and removal, and be able to provide random filter selection. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
   BRIEF SUMMARY 
   An apparatus is provided for rapidly moving a filter or other component IN and OUT of an optical or acoustic beam. The apparatus comprises a shuttle carrying the filter or other component at a first end and first and second spaced apart pieces of magnetic material near the other end. A low friction guide-way moveably supports the shuttle. A base supports the guide-way and supports a third magnetic piece and a first coil preferably located between the first and second pieces. When the shuttle is IN the first and third pieces form a first magnetic latch to releasably hold it IN and when the shuttle is OUT the second and third pieces form a second magnetic latch to releasably hold it OUT. One or more springs between the shuttle and the base store energy when the shuttle is IN or OUT. Activating the first coil weakens the magnetic attraction between the latch pieces, freeing the shuttle to move, driven by the one or more springs to the opposite OUT or IN position. A second coil and armature coupled between the base and the shuttle are desirably provided to aid in resetting the shuttle to the IN or OUT position from any in-between position. 
   A method is provided for rapidly moving a filter or other component into and out of an optical or acoustic beam. In a first embodiment, the method comprises determining whether the shuttle is IN, in-between or OUT. If IN, then sending a first signal to the first coil to release the first magnetic latch and move the shuttle OUT, or if in-between sending a second signal at least to the second coil to move the shuttle OUT. Before, during or after the determining and sending steps, receiving a command directing positioning of the shuttle IN or OUT, and if the command is for OUT, since the shuttle is already OUT repeating the receiving step, or if the command is for IN, sending another signal to the first coil to release the second magnetic latch and thereby move the shuttle to the IN position. In a preferred embodiment, after sending the first signal, checking the shuttle position to determine whether or not the shuttle has moved to the OUT position, and if not, issuing an error report and if so, proceeding to the receiving step. Similarly, after sending the another signal to move the shuttle IN, checking to determine whether the shuttle has moved to the IN position and if not, issuing an error report and if so, returning to the receiving step or locating step. In another embodiment, after determining whether the shuttle is IN or OUT or in-between, if IN or OUT, the actual shuttle position is stored and compared with the commanded position and if different a move shuttle command is issued to relocate the shuttle to agree with the commanded position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and 
       FIG. 1  is a simplified plan view of a rapid insertion assembly of the present invention showing internal construction features and with the filter shuttle in a neutral position; 
       FIG. 2  is a partial cut-away and cross-sectional view of the rapid insertion assembly of  FIG. 1 , at the location  2 - 2  indicated thereon; 
       FIG. 3  is an end view of the rapid insertion assembly of  FIG. 1 ; 
       FIG. 4  is a cross-sectional view of the rapid insertion assembly of  FIG. 1 , at the location  4 - 4  indicated thereon; 
       FIG. 5A  is a plan view and  FIG. 5B  a right side view of the rapid insertion assembly of  FIG. 1  with the filter shuttle in a retracted position; 
       FIG. 6A  is a plan view and  FIG. 6B  a right side view of the rapid insertion assembly of  FIG. 1  with the filter shuttle in an extended position; 
       FIG. 7  is a simplified plan view of an array of rapid insertion assemblies, according to the present invention; 
       FIG. 8A  is a plan view similar to  FIG. 1  but of a rapid insertion mechanism according to a further embodiment of the present invention and  FIG. 8B  is a side view of the mechanism of  FIG. 8A ; 
       FIG. 9A  is a plan view similar to  FIG. 8A  but of a rapid insertion mechanism according to a still further embodiment of the present invention and  FIG. 9B  is a side view of the mechanism of  FIG. 9A ; 
       FIG. 10A  is a simplified electrical schematic block diagram of a system employing a single rapid insertion assembly of the present invention and suitable for carrying out the method of  FIG. 11 , and  FIG. 10B  is a similar diagram for multiple rapid insertion assemblies; 
       FIG. 11A  is a simplified flow chart of the method of the present invention according to a first embodiment; and 
       FIG. 11B  is a simplified flow chart of the method of the present invention according to a further embodiment. 
   

   DETAILED DESCRIPTION 
   The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. As used herein, the words “keeper” and “pole piece(s)” are used interchangeably and refer to materials that are magnetic (e.g., have a magnetic high permeability) but do not retain significant permanent magnetism in the absence of a magnetic field. With respect to materials that are magnetic, ferromagnetic materials are preferred. Where such magnetic materials exhibit permanent magnetism in the absence of an external magnetic field, they are generally referred to as “magnets” and where they do not permanently exhibit such permanent magnetism, they are generally referred to as keepers or pole pieces or merely magnetic materials. 
     FIG. 1  is a simplified plan view,  FIG. 2  is a partial cut-away and cross-sectional view,  FIG. 3  is an end view and  FIG. 4  is a further cross-sectional view, of rapid insertion assembly  10  of the present invention. The cross-sectional views of  FIGS. 2 and 4  are at locations  2 - 2  and  4 - 4  respectively, indicated on  FIG. 1 . Rapid insertion assembly  10  comprises moveable shuttle  12  having region or aperture  14  in which the filter (i.e., any component) desired to be introduced into the optical or acoustic beam is placed. While filter mounting region or aperture  14  is shown as being substantially circular in plan view, this is merely for convenience of explanation and not intended to be limiting Region or aperture  14  can have any convenient shape. Shuttle  12  conveniently slides in preferably but not essentially U-shaped guide-ways or tracks  16 , in the direction shown by arrow  15 . Guide-way tracks  16  are supported and held in substantially parallel alignment by base  18 . Interfaces  13  between shuttle  12  and guide-way tracks  16  are desirably low friction interfaces to permit shuttle  12  to slide in guide-way tracks  16  with little applied force. Magnetic levitation may be used between shuttle  12  and guide-way tracks  16  to minimize or avoid friction at interfaces  13 . Linear bearings are a further example of suitable low friction arrangement. Persons of skill in the art will understand how to provide a low friction guide-way for shuttle  12  in guide-way tracks  16  or equivalent. Shuttle  12  desirably but not essentially has cut-out region  20  located generally at the distal end of shuttle  12  opposite to filter mounting location  14 . Generally U-shaped pole pieces or bar magnets  22 ,  24  are mounted in shuttle  12  at opposite ends of cutout region  20 , with the U-shaped regions facing each other. Pole pieces or magnets  22 ,  24  have their respective poles spaced distance  23  apart and are attached to and move with shuttle  12 . Appropriate magnetic polarities, e.g., north (N) and south (S), are indicated thereon. Persons of skill in the art will understand that where  22 ,  24  are merely pole pieces or keepers, then the indicated magnetic polarities are induced when pole pieces or keepers  22 ,  24  move into proximity with magnet  28 , as explained below. Located within region  20  and attached to portion  26  of base  18  is subassembly  34  comprising coils  30  and magnet  28  with relative N-S magnetic polarities as indicated. Bar or pellet shaped magnet(s)  28  may be a single magnet or multiple magnets and coils  30  may be a single coil or multiple coils. Either arrangement is useful. The magnet(s) and coil(s) should share a common magnetic axis. The respective poles of magnet  28  conveniently have dimension  29  in the direction of arrow  15 . It will be appreciated that the N-S magnetic polarities of magnet  28  are opposite those of pole pieces or magnets  22 ,  24 . As shuttle  12  moves within guideways  16 , pole pieces or magnets  22 ,  24  move with shuttle  12  but subassembly  34  comprising magnet  28 , coils  30  with coil contacts  32  remains fixed to base  18 . 
   Springs  36 ,  38  provide return forces when shuttle  12  is perturbed with respect to sub-assembly  34  from the equilibrium (neutral) position shown in  FIGS. 1-4 . It is desirable that springs  36 ,  38  be resonant springs in combination with shuttle  12  but this is not essential. While two springs  36 ,  38  are preferred, it will be appreciated that in some embodiments only a single spring may be used. Further while springs  36 ,  38  are illustrated as being coil-type springs mounted substantially coaxially with direction  15  this is not essential. For example, springs  36 ,  38  may be off-set from the plane and/or center-line of shuttle  12 . Further, springs  36 ,  38  need not be coil-type springs. Leaf-type springs may also be used, for example, oriented at substantially right angles to shuttle motion direction  15 . The present invention is hereafter described as using coil-type springs  63 ,  68  but this is not intended to be limiting and is merely for convenience of explanation. Persons of skill in the art will understand based on the description herein that many different spring arrangements (e.g., coil, leaf, torsion, etc.) may be used and are intended to be included within the scope of the present invention. 
     FIGS. 5A and 6A  are plan views and  FIGS. 5B and 6B  are right side views of rapid insertion assembly  10  of  FIG. 1  with shuttle  12  in different positions with respect to guide-ways  16  and base  18 . In  FIGS. 5A-B , shuttle  12  is in retracted position  44 , that is, with filter mounting region  14  removed from the optical path. Spring  36  is compressed and spring  38  is extended. Pole piece (or magnet)  24  is in contact with magnet  28  with opposite magnetic polarities facing each other. In this condition, shuttle  12  is magnetically latched in retracted position  44 . In  FIGS. 6A-B , shuttle  12  is in extended position  46 , that is, with filter mounting region  14  encompassing optical path  64 . Spring  38  is compressed and spring  36  is extended. Pole piece (or magnet)  22  is in contact with magnet  28  with opposite magnetic polarities facing each other. In this condition, shuttle  12  is magnetically latched in extended position  46 . Since magnet  28  is a permanent magnet and pole pieces or “keepers”  22 ,  24  are magnetic, shuttle  12  will remain latched in either extended position  46  or retracted position  44  until the holding magnetic force is released. This is accomplished, for example, by supplying a brief pulse of electrical current to coils  30  via contacts  32 , of such a direction to momentarily partially overcome the magnetic field of magnet  28 . As soon as the magnetic attraction of magnet  28  is reduced, springs  36 ,  38  drive shuttle  12  to its opposite extreme position where it is captured by the opposing magnet-keeper combination. In the preferred embodiment, piece  28  is the permanent magnet and pieces  22 ,  24  are merely magnetic pole pieces or keepers. This is preferred because in either latched position, magnet  28  is shorted by the respective pole piece or keeper  22  or  24 . However, the preferred arrangement can be magnetically inverted. That is, pieces  22 ,  24  can be permanent magnets and piece  28  can be the “keeper.” Either arrangement works. In either case, in order to release the magnetic latch, coils  30  only need to provide a magnetic field sufficient to weaken the magnetic attraction holding the magnet-keeper combination together against the force of springs  36 ,  38 , that is, to weaken the field of magnet  28  in contact with keeper  22  or  24  or weaken the field of magnet  22  or  24  in contact with keeper  28 . If all of pieces  22 ,  24  and  28  are permanent magnets, then coils  30  must provide a larger magnetic pulse to cause the magnetic latch to release, but this arrangement is not precluded. 
   For convenience of explanation, it is assumed in the following discussion that piece  28  is a permanent magnet and that pieces  22 ,  24  are keepers, but persons of skill in the art will understand based on the description herein that these roles may be reversed or that all three pieces  22 ,  24 ,  28  may be magnets. Referring now to  FIGS. 5A-B  where shuttle  12  is shown in retracted position  44 , pulsing coils  30  releases the magnetic latch formed by magnet-keeper combination  24 ,  28 . Compressed spring  36  and extended spring  38  then rapidly accelerates shuttle  12  in direction  15 A. When shuttle  12  reaches the midpoint of its journey as illustrated in  FIG. 1 , the spring forces are balanced, but the momentum acquired by shuttle  12  during the first half of its flight is sufficient to compress spring  38  and extend spring  36  bringing shuttle  12  to extended position  46  shown in  FIGS. 6A-B , where magnet-keeper combination  22 ,  28  latches, thereby capturing shuttle  12  in extended position  46 . The opposite occurs when starting in extended position  46 . Pulsing coils  30  to briefly reduce the field of magnet  28 , releases magnet-keeper latch combination  22 ,  28  and compressed spring  38  and extended spring  36  force shuttle  12  in direction  15 B where it is captured by magnet-keeper combination  24 ,  28  which latches it in retracted position  44 . Thus, assembly  10  is a bi-stable fast insertion and retraction mechanism that changes state in response to brief current pulses directed through coils  30 . The current pulses are shorter than the shuttle flight time so that when opposed keeper  22  or  24  on shuttle  12  reaches magnet  28 , the flux canceling pulse has subsided and magnet  28  is once again capable of latching against keeper  22  or  24 . If pieces  22 ,  24  as well as piece  28  are magnets then if the pulse current through coils  30  is increased sufficiently, the permanent magnetic flux of magnet  28  is cancelled and flux reversal takes place, that is, the N-S magnetic polarity of magnet  28  is reversed. Under these circumstances, a repulsive magnetic force can occur. This repulsive force further accelerates shuttle  12 , giving it an extra impetus toward its opposite position. In this manner any energy loss from spring flexure is overcome by the additional energy supplied by coils  30 . While coils  30  are shown as surrounding magnet  28 , this is not essential. Coils  30  may be located in any configuration that permits the magnetic latching force provided by the permanent magnets (e.g.,  28  and/or  22 ,  24 ) to be overcome by sending a current pulse through coils  30 . Further while two coils  30  are convenient, this is not essential and one or more coils may be used. 
   Referring again to  FIG. 1 , filter region opening  14  is of dimension  11  in direction  15  and shuttle  12  has dimension  13  in direction  15  from inboard edge  17  of filter mounting region  14  to outboard edge  19  of shuttle  12 . In order for shuttle  12  to retract completely from the optical path, then shuttle  12  should move inwardly by the amount of dimension  13  or by the width of the optical path. For this circumstance, spacing  23  between faces  50 ,  52  of magnets  22 ,  24  should be such that the magnitude of spacing  23  less thickness  29  of magnet  28  is equal or greater than dimension  13  or the width of the optical path. This allows shuttle  12  with filter mounting region  14  to be fully inserted and retracted. 
     FIG. 7  is a simplified plan view of array  60  of fast insertion assemblies  10 - 1 ,  10 - 2 ,  10 - 3 ,  10 - 4 , each of the type shown in  FIGS. 1-6 . Assemblies  10 - 1 ,  10 - 2 ,  10 - 3 ,  10 - 4  are supported in or on frame  62  around optical path  64 . Shuttle  12 - 1  and filter region  14 - 1  of assembly  10 - 1  is shown as being latched in the extended position with optical path  64  centered in filter region  14 - 1 . Assemblies  10 - 2 ,  10 - 3 ,  10 - 4  are latched in the retracted position. By pulsing control coils  30  of the appropriate assembly, any one of the filters mounted on assemblies  10 - 1 ,  10 - 2 ,  10 - 3 ,  10 - 4  can be rapidly and randomly inserted or removed from optical path  64 . While only four assemblies  10 - 1 ,  10 - 2 ,  10 - 3 ,  10 - 4  are shown in array  60 , persons of skill in the art will understand that more or fewer fast insertion assemblies may be placed in array  60 , so long as adjacent assemblies do not interfere. While array  60  is shown as being substantially circular with the shuttle assemblies mounted symmetrically around the circle, this is merely for convenience of explanation and not intended to be limiting. Array  60  can have any convenient shape that locates the individual fast insertion assemblies where their shuttles can move in and out of the optical beam without interfering with each other. Further, the shuttle assemblies can be mounted at different locations and at any convenient angle in whatever way best accomplishes the particular task faced by the system designer. Also, it is not necessary that the various shuttle assemblies (e.g.,  10 - 1 ,  10 - 2 ,  10 - 3 ,  10 - 4 , etc.) lie in the same plane. For example, shuttle assemblies  10 - 1 ,  10 - 2 ,  10 - 3 ,  10 - 4  can be at different heights perpendicular to the plane of  FIG. 7  so that several can be inserted at the same time without interference. There can be further shuttle assemblies mounted below as well as above frame  62 . By locating various shuttle assemblies so that their shuttles lie in different planes, the number of shuttle assemblies that can be mounted in a compact non-interfering array can be increased. 
     FIG. 8A  is a view similar to  FIG. 1  but of rapid insertion mechanism  78  according to a further embodiment of the present invention, and  FIG. 8B  is a side view of mechanism  78  of  FIG. 8A . Mechanism  78  comprises rapid insertion assembly  10  according to  FIGS. 1-6  combined with reset drive mechanism  80 . Reset drive mechanism  80  comprises generally rod shaped armature  82  that is conveniently coupled to pole piece  22  of shuttle  12 . Armature  82  passes slideably through electromagnetic coil  84  having electrical contacts  86 . Coil  84  is supported on base portion  88  coupled to base  18  of assembly  10 . One or more position monitoring devices  90  are conveniently provided on base  10  for determining the position of shuttle  12  in assembly  10 , that is, in retracted position (see  FIGS. 5A-B , 7), in inserted position (see  FIGS. 6A-B ,  7 ), in neutral position (see  FIGS. 1-2 ), or in some intermediate position depending upon the needs of the designer. Position monitoring device  90  may be located on base  18 ,  88  or on tracks  16  or on shuttle  12 . Either arrangement is useful. While only one position monitoring device  90  is visible in  FIG. 8 , this is not intended to be limiting and persons of skill in the art will understand that multiple position monitoring devices may be placed at any convenient location on the base, track, shuttle or elsewhere. Alternatively, one position monitoring device capable of measuring the position of shuttle  12  with respect to frame  16 , or base  18  or other suitable reference may be used. Position monitoring devices are well known in the art. 
   While armature  82  is illustrated as being a generally rod-shaped device, this is not intended to be limiting and any other convenient shape may also be used. Armature  82  is conveniently made from magnetic material so that it responds to the magnetic field produced by reset coil  84 . When a pulse is applied to reset coil  84  via contacts  86 , the current flowing through reset coil  84  creates a transient magnetic field that, for example, exerts an attractive force on armature  82  causing it to move in direction  83 , that is, to pull shuttle  12  into the retracted position shown in  FIGS. 5A-B  where it is captured by the magnet-keeper combination  28 ,  22  or  22 ,  28 . As previously discussed, shuttle  12  remains in the latched (retracted) position until coil(s)  30  are pulsed thereby breaking the magnetic latch and sending shuttle  12  toward the extended position shown in  FIG. 6A-B . Thus, by use of reset drive mechanism  80 , shuttle  12  may be moved from the neutral or other intermediate position into a latched position. Depending upon the needs of the designer or user, either latched position may be adopted as the “park” position, that is, the position where shuttle  12  is ordinarily stored while awaiting the next repositioning command. 
   While reset drive mechanism  80  is illustrated as comprising drive coil  84  mounted on base  80 ,  18  and armature  82  directly coupled to shuttle  12 , this is not intended to be limiting. Any type of mechanism for pulling or pushing shuttle  12  away from the neutral position toward or into one of the latched positions may be used. non-limiting examples are: a rotary armature coupled to shuttle  12  by a linkage like a crank; a solenoid with a plunger coupled to shuttle  12  by appropriate push or pull levers or arms; a spool and thread or wire arrangement that pulls shuttle  12  toward or into one of the latched positions, and so forth. These arrangements are all capable of positive displacement of shuttle from the neutral position toward or into one or the other of the latched positions. 
   It is not necessary that reset drive mechanism  80  be able to pull (or push) shuttle  12  from the neutral position of  FIGS. 1-2  entirely into the latched position of  FIGS. 5A-B  and  6 A-B. It merely needs to start the shuttle in one direction or the other. By applying a further pulse to coil  84  each time shuttle  12  passes through the neutral position in the correct direction, the amplitude of oscillation of shuttle  12  around the neutral position will increase. By providing a series of appropriately timed pulses the amplitude of oscillation will increase until one of the keeper-magnet combinations latches. Once shuttle  12  is latched in a first position, it may be transferred to the other bi-stable position through normal operation. Reset drive mechanism  80  can also be used to unlatch shuttle  12  from its retracted or extended positions by means of a current pulse through coil  84  of sufficient strength to break the hold of the keeper-magnet latch. Armature  82  may also include permanent magnets. Permanent magnets are especially useful where reset drive mechanism  80  employs a rotating armature and linkage (not shown) to move shuttle  12 . 
     FIG. 9A  is a view similar to  FIG. 8A  but of rapid insertion mechanism  78 ′ according to a still further embodiment of the present invention, and  FIG. 9B  is a side view of mechanism  78 ′ of  FIG. 9A . Mechanism  78 ′ and associated drive mechanism  80 ′ of  FIGS. 9A-B  differ from that illustrated in  FIGS. 8A-B  in that assembly  34  within shuttle  12  is omitted and drive mechanism  80 ′ provides both the shuttle reset and bi-stable capture and release functions. Referring now to  FIGS. 9A-B , shuttle  12  is moveably supported in guide-way  16  and provided with one or more return springs  36 ,  38  already been described. As noted above, mechanism  34  (see FIGS.  1  through  8 A-B) is omitted and springs  36 ,  38  extend between shuttle  12  and support  26 ′ fixedly coupled to base  18 . As shuttle  12  moves in direction  15  with portion  26 ′ fixed to base  18 , springs  36 ,  38  are compressed or extended. Similar to the arrangement in  FIGS. 8A-B , coil  84  with contacts  86  is fixed to base portion  88  coupled to base  18 . As before, armature  82  slideably moves through coil  84  in response to current pulses supplied to coil  84  through contacts  86 . Armature  82  has fixedly mounted thereon, magnetic pieces  24 ′,  22 ′ that are analogous in function to pieces  24 ,  22  of  FIGS. 8A-B . Coil  84  has mounted thereon, magnetic pieces  28 A-B that are analogous in function to magnetic piece  28  of  FIGS. 8A-B . The combination of magnetic pieces  22 ′,  28 B forms a first releasable bi-stable magnetic latch and the combination of magnetic pieces  24 ′,  28 A forms a second releasable bi-stable magnetic latches, analogous to those formed by magnetic pieces  22 ,  28  and  24 ,  28 , respectively in FIGS.  1  through  8 A-B. The previous discussion in connection with FIGS.  1  through  8 A-B with respect to which of magnetic pieces  22 ,  24 ,  28  are permanent magnets and which are merely magnetic keepers also applies to magnetic pieces  22 ′,  24 ′,  28 A,  28 B of  FIGS. 9A-B  with appropriately arrangement magnetic polarities. Magnetic pieces  22 ′,  24 ′,  28 A,  28 B may be rectangular or circular in cross section. Magnetic shunt  28 C may also be provided but this is not essential. In operation, applying one or more current pulses to coil  84  causes armature  82  and therefore shuttle  12  to move in or out until one or the other of bi-stable magnetic latches  22 ′,  28 B or  24 ′,  28 A engages, thereby capturing shuttle  12  in the IN or OUT position. The location of the shuttle may be determined by using position sensor(s)  90  as previously described. Once shuttle  12  is latched in either the IN or OUT position, applying a brief current pulse to coil  84  reduces the magnetic attraction of the corresponding bi-stable magnetic latch, and springs  36 ,  38  drive shuttle  12  to the other OUT or IN bi-stable position. Thus, the arrangement of  FIGS. 9A-B  provides for bi-stable operation of shuttle  12  as has been previously described, but with the advantage that bi-stable capture and release and shuttle reset functions are obtained using a single drive coil. 
     FIG. 10A  is a simplified electrical schematic block diagram of system  92  employing a single rapid insertion assembly  10 ,  78 , of the present invention and suitable for carrying out method  200  of  FIG. 11 . System  92  comprises control function  94  and sensor-actuator function  96 . Sensor-actuator function  96  is associated with rapid insertion assembly  10 ,  60 ,  78 . Sensor-actuator function  96  comprises one or more position sensors  90 - 1 ,  90 - 2 ,  90 - 3  analogous to position sensor  90  of  FIG. 9 . Sensor  90 - 1  is preferably located so as to sense when shuttle  12  is in the retracted position (referred to as “OUT”) such as is illustrated in  FIGS. 5A-B . Sensor  90 - 2  is preferably located so as to sense when shuttle  12  is in the extended position (referred to as “IN”) such as is illustrated in  FIGS. 6A-B . Optional sensor  90 - 3  is preferably located so as to sense when shuttle  12  is in the neutral position (referred to as “NEU”) illustrated in  FIGS. 1-2 . 
   Telemetry (abbreviated TLM) sensors  98  are desirable but not essential. TLM sensors  98  gather data on the state of the various sensors  90 - 1 ,  90 - 2 ,  90 - 3 , etc. and actuators  30 ,  84 , that is, the coils or other motors (collectively “coil” or “coils”) that provide the magnetic pulses to move or latch/unlatch shuttle  12 . Data measured by TLM sensors  98  can include temperature, voltage, current, and other information useful in assessing the “health” of the various components of assemblies  10 ,  60 ,  78 . Techniques for remotely measuring such parameters and communicating them to a monitoring system are well known in the art. Actuator function  96  also includes coils  30 ,  84  that, as has been previously explained, cause shuttle  12  to move and latch and/or be released from a latch position. 
   Control function  94  includes position processor  102  with position input interface  101  that receives data from sensors  90 - 1 ,  90 - 2 ,  90 - 3  via buses or leads  102 - 1 ,  102 - 2 ,  102 - 3  respectively. Control function  94  also includes output processor  104  and associated output drivers  103  that provide the desired magnet drive currents to unlatch coil  30  over leads or bus  104 - 1  and to reset coil  84  over leads  104 - 2 . Control function  94  also includes optional TLM processor  106  with associated TLM input interface  105  receives data from TLM sensors  98  via bus or leads  106 - 1 . Control function  94  further comprises individual mechanism controller  108  that is coupled to position processor  102 , driver output processor  104 , and optional TLM processor  106  via bus or leads  107 . Individual mechanism controller  108  is in turn coupled to outside system bus  110  via bus or leads  109 . 
   Individual mechanism controller  108  performs the following functions:
         monitors the status of rapid insertion assembly  10 ,  60 ,  78  via one or more of sensors  90 - 1 ,  90 - 2 ,  90 - 3 ,  98 , etc., and associated sensor processors  102  and  106  via their respective interfaces  101 ,  105 ;   receives from external system bus  110  various commands directing that a particular shuttle be inserted or removed;   provides the necessary commands to carry out those directions via driver output processor  104  and output drivers  103  to coils  30 ,  84 ;   recovers from a temporary failure that causes shuttle  12  to drop out of either of its bi-stable IN/OUT states into the neutral state or other intermediate state;   parks shuttle  12  in either IN, OUT or NEU position according to the needs of the system designer or user; and   optionally issues execution confirmation reports and/or error reports to external bus  110  using data received from sensors  102 - 1 ,  102 - 2 ,  102 - 3  and  98  so that the external system of which rapid insertion mechanism  10 ,  60 ,  78  is a part can know the unit status.
 
The above-described functions will be understood more fully by reference to the flow charts of  FIGS. 11A-B .
       

     FIG. 10B  a simplified electrical schematic block diagram of system  120  employing N&gt;1 single rapid insertion shuttle assemblies of the present invention where N is the number of single rapid insertion assemblies, e.g.,  10  and/or  78 . For example, system  120  is suitable for controlling system  60  of  FIG. 7 . System  120  comprises multi-shuttle control function  122  and N single rapid insertion shuttle mechanisms  78 - 1  . . . .  78 -N and their associated sensor-actuator functions  96 - 1  . . .  96 -N. Single shuttle assemblies  78 - 1  . . .  78 -N are described in connection with  FIGS. 8-9  and associated sensor-actuator functions  96 - 1  . . .  98 -N are described in connection with  FIG. 10A . System  120  comprises core controller  108 ′ analogous to mechanism controller  108  of  FIG. 10A . System  120  includes individual I/O driver and interface processors  112 - 1 ,  112 - 2  . . .  112 -N that are analogous to the combination of interface units  110 - 102 ,  103 - 104 ,  105 - 106  within outline  112  in  FIG. 10A . There is one such unit  112 -i for each rapid insertion shuttle  78 - 1 ,  178 - 2 , . . .  78 -N and associated sensor-actuator function  96 - 1 ,  96 - 2 , . . .  96 -N. Buses  97 - 1 ,  97 - 2 , . . .  97 -N couple individual I/O drivers and interface processors  112 - 1 ,  112 - 2 , . . .  112 -N to single shuttle assembly&#39;s sensor-actuator functions  96 - 1 ,  96 - 2 , . . .  96 -N, respectively. Units  112 - 1 ,  112 - 2 , . . .  112 -N are in turn coupled to core processor  108 ′ by bus or leads  123 . Core processor  108 ′ is coupled to external command or input bus  110 ′ via bus or leads  109 ′, in much the same way as previously explained for the single shuttle control function of  FIG. 10A . System  120  provides all of the functions previously described in connection with single shuttle system  92  of  FIG. 10A , but for multiple shuttles. In addition to moving individual shuttles IN or OUT in response to movement requests or commands received from external bus or input  110 ′, core processor  108 ′ also monitors command request sequence and timing in order to preclude interference among different shuttles, thereby preventing jams or damage to the units. 
     FIG. 11A  is a simplified flow chart of method  200  of the present invention according to a first embodiment. In  FIGS. 11A-B , the abbreviation “Y” stands for “YES (TRUE)” and the abbreviation “N” stands for “NO (FALSE)” and the abbreviations IN, NEU and OUT represent the following: IN=extended position (in the optical path), NEU=neutral position in-between IN and OUT, and OUT=retracted position (out of the optical path) respectively. Method  200  begins with START  202  that desirably occurs on system power-up. Following START step  202 , two options are available, that is, (i) proceeding via steps  204 ,  206 , to step  210  or (ii) proceeding directly to step  210  as indicated by optional path  203 . Option (i) is preferred wherein COLLECT TLM DATA step  204  is desirably but not essentially executed, in which mechanism controller  108  conveniently polls TLM processor  106  and interface  105  to retrieve the data being reported by TLM sensors  98 . Query  206  follows wherein it is determined whether or not the retrieved TLM data corresponds to safe states or operating conditions. If the result of query  206  is NO (FALSE) then method  200  desirably but not essentially proceeds to step  208  wherein an error report is issued to controller  108  (e.g., from processor  106  to controller  108 ) and/or by controller  108  (e.g., from controller  108  to bus  110 ), and as shown by path  209 , control returns to step  204 . If the outcome of query  206  is YES (TRUE), then method  200  proceeds to step  210  wherein the shuttle position is determined using some or all of sensors  90 - 1 ,  90 - 2 ,  90 - 3  via position processor  102  and controller  108 . If option (ii) is chosen method  200  proceeds directly from START  202  to step  210 . 
   In the discussion that follows, it is assumed for convenience of explanation that the shuttle is desirably parked in the OUT position, but this is not essential. LOCATE SHUTTLE step  210  has three possible outcomes: extended (abbreviated “IN”) as shown in  FIGS. 6A-B  and assembly  10 - 1  in  FIG. 7 , neutral (abbreviated “NEU”) as shown in  FIGS. 1-2 , and retracted (abbreviated “OUT”) as shown in  FIGS. 5A-B  and assemblies  10 - 2 ,  10 - 3 ,  10 - 4  in  FIG. 7 . If the outcome of step  210  is IN or NEU then method  200  proceeds to ISSUE MTO COMMAND step  212  where the abbreviation “MTO” stands for “move to OUT,” that is, retract shuttle  12 . Step  212  is desirably but not essentially followed by queries  214 ,  216 . In query  214  it is determined whether the MTO command issued in step  212  was successful using one or more of sensors  90 . If the outcome of query  214  is NO (FALSE) then method  200  desirably but not essentially proceeds to optional query  216  where it is determined whether the current number (“number” is abbreviated as “NO.” in  FIGS. 1A-B ) of repetitions p of the MTO command equals a predetermined value P. If the outcome of optional query  216  is NO (FALSE) indicating that the MTO command should be repeated, method  200  conveniently loops back to step  212  as shown by path  215 . If the outcome of query  216  is YES (TRUE) indicating that the predetermined number P of trials has been reached without success, then method  200  desirably proceeds to step  218  wherein an error report is issued and then as shown by path  219 , control returns to start  202  and preferably step  204 . If no TLM sensors are provided in sensor-actuator function  96  and steps  204 - 208  are omitted, then method  200  preferably returns to start  202  and step  210 , as shown by alternate path  219 ′. 
   Returning now to query  214 , if the outcome of query  214  is YES (TRUE) indicating that the MTO command succeeded in moving the shuttle to the OUT (retracted) position, then method  200  proceeds to RECEIVE POSITION COMMAND step  220  wherein system  92  awaits receipt of a position command, e.g., via external bus  110 . While external bus  110  is a convenient means of providing such commands to system  92 , any means of doing so may be used, as for example, a simple IN/OUT position switch (not shown) coupled to controller  108 . Returning now to step  210 , if the outcome of LOCATE SHUTTLE step  210  is “OUT” indicating that shuttle  12  is already in the OUT (retracted) position, then method  200  proceeds to RECEIVE POSITION COMMAND step  220 . 
   The outcome of step  220  is either an IN command or an OUT command. Since this embodiment of method  200  insures that shuttle  12  is in the OUT position before step  220  is reached, if the command received is OUT, then shuttle  12  is already in the correct position and method  200  loops back to step  220  as shown by path  221  to await another position command or, alternatively via path  227  to step  210 . Either arrangement is useful. When the outcome of step  220  is IN, then method  200  proceeds to ISSUE MTI COMMAND step  222  where the abbreviation “MTI” stands for “move to IN”, that is move shuttle  12  to the inserted position as shown for example in  FIGS. 6A-B  and for assembly  10 - 1  of  FIG. 7 . Queries  224  and  226  are movement verification and repeat-allowed confirmation steps for the MTI command, analogous to steps  214 ,  216  for the MTO command, and the previous explanation applies here. If the number q of MTI commands is less than a predetermined number Q, then the MTI command is desirably but not essentially, repeated as shown by loop-back path  225 . If the MTI command has failed to shift the shuttle to the IN position and q=Q, then method  200  proceeds to step  218  wherein an error report is desirably issued as before, and control returns to start  202  and step  204  or alternately to step  210  as shown by paths  219 ,  219 ′,  203 . 
   While method  200  has been described for the situation where OUT is assumed to be the “park” position, this is merely for convenience of explanation and not intended to be limiting. If the “park” position is IN rather than OUT or NEU rather than OUT then the corresponding substitution of terms should be made. For example, if “park” is IN then swap OUT for IN in method  200  of  FIG. 1A . If “park” is NEU, then steps  212 ,  214 ,  216  follow step  220  rather than step  210 . Persons of skill in the art will understand based on the description herein how to modify method  200  to suit their particular circumstances. While method  200  has been described for the situation where only one shuttle is being moved, persons of skill in the art will understand based on the description here that it also applies to the situation where multiple shutter assemblies are available and operating under the control of system  120 . 
     FIG. 11B  is a simplified flow chart of method  300  of the present invention according to a further embodiment. Method  300  begins with START  302  that desirably occurs on system power-up. Following START step  302 , two options are available, that is, (i) proceeding via steps  304 ,  306 , to steps  310 ,  312  or (ii) proceeding directly to steps  310 ,  312  as indicated by optional path  303 . Steps  304 ,  306 ,  308  are substantially the same as steps  204 ,  206 ,  208  of FIG.  11 A and the discussion thereof in connection with  FIG. 11A  is incorporated herein by reference. Either via steps  304 ,  306  or via path  303 , method  300  proceeds to LOCATE SHUTTLE step  310  and RECEIVE POSITION COMMAND step  312 . Step  312  may be performed anytime prior to step  316 . Step  310  has two possible outcomes, either “NEU” or “IN/OUT” where “IN/OUT” indicates “either IN or OUT.” If the outcome of LOCATE SHUTTLE step  310  is IN/OUT, then method  300  proceeds to STORE SHUTTLE POSITION step  314 . In subsequent COMPARE step  316 , the stored actual position is compared to the commanded shuttle position received from step  312  leading to query  318  wherein it is determined whether or not the actual shuttle position and the commanded shuttle position agree. If the outcome of query  318  is YES (TRUE) then method  300  preferably but not essentially returns to LOCATE step  310  and RECEIVE step  312  as shown by path  319 . Alternatively, method  300  may return to START  302  as shown by paths  319 ′,  327 . If the outcome of query  318  is NO (FALSE) then method  300  proceeds to ISSUE MOVE COMMAND step  320  where system  92  or  120  or equivalent provides a current pulse to the appropriate latch release coil to send shuttle  12  to the opposite bi-stable position, e.g., if IN then to OUT or if OUT, then to IN. In verification query step  322  it is desirably but not essentially determined whether the shuttle has moved as commanded in step  320 . If the outcome of query  322  is YES (TRUE) then method  300  desirably but not essentially loops back to STORE SHUTTLE POSITION step  314  where it can await a further positioning command from step  312 . If the outcome of query  322  is NO (FALSE) then query  324  is desirably executed to determine whether or not the currently issued number q of MOVE commands equals a predetermined number Q. If the outcome of query  324  is NO (FALSE) then method  300  loops back to ISSUE MOVE COMMAND step  320 , similar to what has been described in connection with analogous move steps in  FIG. 11A . When the number of issued MOVE commands equals Q then the outcome of query step  324  is YES (TRUE), indicating that MOVE commands have been issued Q times without success, and method  300  desirably but not essentially proceeds to ISSUE ERROR REPORT step  326  and returns to START step  302  as indicated by path  327  or to LOCATE step  310  and RECEIVE step  312  as indicated by path  327 ′. 
   Returning now to LOCATE SHUTTLE step  310 , if the outcome of step  310  is NEU, then method  300  proceeds to ISSUE RESET COMMAND step  328  wherein system  92  and/or  120  sends one or more current pulses to the appropriate actuator coil to cause shuttle  12  to move from the NEU position to either IN or OUT, as has been previously described in connection with  FIGS. 8A-B  and/or  9 A-B. Verifications steps  330 ,  332  analogous to steps  214 ,  216  of  FIG. 11A  are executed to determine whether or not the RESET step was successful after one or more attempts. If the outcome of query  330  is YES (TRUE) then method  300  proceeds to STORE SHUTTLE POSITION step  314  where the reset location (either IN or OUT) is stored. If the outcome of query  330  is NO (FALSE) then method  300  proceeds to query  332  where it is determined whether a predetermined number P of RESET attempts has been unsuccessfully executed. If the outcome of query  332  is YES (TRUE) method  300  desirably but not essentially proceeds to ISSUE ERROR REPORT step  326  and returns to START  302  or LOCATE step  310  and RECEIVE step  312 , as has been previously described. While method  300  of  FIG. 11B  does not indicate a preferred “park” position, persons of skill in the art will understand that such can be provided as illustrated in  FIG. 1A . Persons of skill in the art will also understand that systems  92 ,  120  can use the shuttle position information for each shuttle stored in controllers  108 ,  108 ′ or equivalent in step  314  to avoid interference among different shuttles capable of entering the same optical beam in the same location. 
   While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.