Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/35—Optical coupling means having switching means
  • G02B6/3564—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
  • G02B6/3566—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details involving bending a beam, e.g. with cantilever
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/007—Optical devices or arrangements for the control of light using movable or deformable optical elements the movable or deformable optical element controlling the colour, i.e. a spectral characteristic, of the light
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
  • G02B7/18—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors
  • G02B7/182—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/35—Optical coupling means having switching means
  • G02B6/351—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/35—Optical coupling means having switching means
  • G02B6/3564—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
  • G02B6/358—Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system

Definitions

• This invention generally relates to optical elements, and more specifically relates to mechanisms for high speed switching of optical elements.
• wheel mechanisms optical elements are arranged around the perimeter of a wheel. As different elements are needed, a motor or other driver rotates the wheel, stopping when the desired element is in the optical path. This allows different optical elements to inserted into optical path as desired.
• wheel mechanisms suffer from several significant disadvantages. For example, the amount of time and energy used to switch from one element to another can be unacceptable for many applications. This is an especially significant issue when the wheel switches from one element to another that is on the opposite side of the wheel, hi some cases it can be difficult to rotate the wheel fast enough to switch it from one side of the wheel to the other. Additionally, the amount of power required to move the wheel from one end of the other can be excessive. These limitations all arise from the fact that the traditional wheel provides a sequential rather than random access to the elements at the edges of the wheel.
• the present invention provides an optical element switching mechanism that overcomes many of the disadvantages found in the prior art.
• the switching mechanism uses a balanced arm, with an optical element attached at one end of the arm.
• the arm is suspended on a axis that allows it to rotate from a first position to a second position.
• the arm is balanced to provide low force disturbance during this movement.
• a spring is coupled to the arm that provides the rotational energy to move the arm.
• the spring is coupled such that its neutral position is between the first and second positions, and thus the spring provides the energy to move the arm from the first position to the second position and vice versa.
• a latch mechanism is also provided for selectively holding the arm in the first position or second position. Additionally, the latch mechanism can provide additional energy needed to catch and move the arm into final position.
• the latch mechanism When the latch mechanism is released, the tension on the arm provided by the spring starts the rotational movement of the arm its axis toward the opposite position. As the arm approaches the opposite position, the latch mechanism provides the additional energy to complete rotation to the new position, and catches and holds the arm in the new position. [0009]
• the switching mechanism thus provides the ability to rapidly move an optical element in and out of the transmission path with limited power.
• multiple switching mechanisms are combined together to provide a switching system with the ability to switch multiple optical elements in and out of the optical path.
• the switching mechanisms are configured to allow one arm to swing into the optical path as the another arm swings out.
• the latch mechanism for the optical element currently in the transmission path and the latch mechanism for the desired optical element both release.
• the springs on the switching mechanisms cause the current optical element to swing out of the optical path, and the desired optical element to swing in.
• the latch mechanism for the desired optical element catches and holds the arm with the desired optical element in the optical path.
• the latch mechanism for the other element catches and holds the arm in the opposite position. The opposite movements of the arms provides cancellation of the disturbance moments that would otherwise result from the arm movement.
• the two switching mechanisms together allow one optical element to be quickly substituted for another with limited power consumption and force disturbance outside the system.
• FIG. 1 is a perspective view of an optical element switching mechanism
• FIGS. 2-4 are top schematic views of an optical element switching system
• FIG. 5 is a position diagram charting arm position for an optical element switching system
• FIG. 6 top schematic views of an optical element switching system
• FIG. 7 is a cross-section top view of a latch mechanism.
• the present invention provides an optical element switching mechanism that overcomes many of the disadvantages found in the prior art.
• the switching mechanism uses a balanced arm, with an optical element attached at one end of the arm.
• the arm is suspended on an axis that allows it to rotate from a first position to a second position.
• the arm is balanced to provide low force disturbance during this movement.
• a spring is coupled to the arm that provides the rotational energy to move the arm.
• the spring is coupled such that its neutral position is between the first and second positions, and thus the spring provides the energy to move the arm from the first position to the second position and vice versa.
• a latch mechanism is also provided for selectively holding the arm in the first position or second position. Additionally, the latch mechanism can provide additional energy needed to catch and move the arm into final position.
• FIG. 1 an exemplary optical element switching mechanism
• Switching mechanism 100 includes an arm 102, an axis 104, a spring 105 coupled to the arm, an optical element 106 and two latch mechanisms 108a and 108b.
• the arm 104 can be any structural member designed to accept the optical element.
• the arm preferably is made with sufficient rigidly to effectively control the position of optical element 106.
• the optical element 106 can be any device or combination of devices that is desirable to selectively insert into the optical path. Common devices that could be used as optical ⁇ element 106 include various types and combinations of filters and mirrors and optical sources such as black body sources.
• the axis 104 can be any axis that provides for positioning and rotational movement of the arm 102.
• suitable axis 102 include flex pivots, bearings or flexural elements that provide suitable rotational movement.
• the spring 105 is coupled to the arm 102 provides the rotational energy for moving the arm 102 in and out of the optical path.
• the spring 105 can be any suitable spring structure that provides sufficient energy to move the arm within desired time constraints.
• the spring is coupled such that its neutral position is substantially centered with the arm being between the optical path and the outside position. Thus, the spring 105 can provide for moving the arm 102 in both directions.
• Examples of springs that can be used for spring 105 include rotational springs such as coil, helical or torsion bars, or translational tension or compression springs.
• the latch mechanisms 108a and 108b provide the ability to selectively hold the arm in both positions.
• Each latch mechanism 108 can comprise any suitable mechanism for catching and holding the arm 102 in position. Examples of mechanisms that can be used for latch mechanism 108 include magnetic devices that provide the ability to selectively hold the arm 102. Additionally, the latch mechanism 108 can be configured to provide any additional energy needed to catch and move the arm into final position during rotation. In the alternative, a separate rotational mechanism can be added to provide the rotational energy needed to complete rotation.
• the latch mechanisms 108 hold the arm 102 in position until switching is desired.
• a latch mechanism 108 such as 108a
• the tension on the arm 102 provided by the spring 105 starts the rotational movement of the arm 102 on the axis 104 toward the opposite position.
• the opposite latch mechanism 108 such as 108b
• the switching mechanism 100 thus provides the ability to rapidly move an optical element 106 in and out of the optical path with limited power consumption and limited physical disturbance.
• an optical switching system 200 that utilizes multiple switching mechanisms 100 that are combined together to provide the ability to switch multiple optical elements 106 in and out of the optical path, h the illustrated example, three switching mechanisms 100 are configured to allow three different optical elements 106 to be selected. Of course, this is- just an example, and optical switching systems can be desired with any number of switching mechanisms 100 within space limitations.
• the optical switching system 200 is desired to allow one optical element 106 to swing into the optical path as another optical element 106 swings out.
• the latch mechanism 108 for the optical element 106 currently in the optical path and the latch mechanism 108 for the desired optical element 106 both release.
• the springs 105 on the switching mechanisms 100 cause the current optical element 106 to swing out of the optical path, and the desired optical element 106 to swing in.
• the optical switching system 200 is illustrated after the latch mechanism 108 for the optical element 106 currently in the optical path and the latch mechanism 108 for the desired optical element 106 have released, and the arms 102 are being rotated by springs 105 on the respective switching mechanisms 100. both release.
• the spring 105 for the old optical element 106 is providing the rotational energy to move the old optical element 106 out of the optical path.
• the spring 105 for the new optical element 106 is likewise providing the rotational energy to move the new optical element 106 into the optical path.
• the arms are being moved in opposite directions at the same time, and thus together provide cancellation of the disturbance forces that would otherwise result from the arm movement. With matched individually balanced arms, matched springs and equal deflection angles the system produces no external forces, moments or unbalanced momentum.
• the optical switching system 200 is illustrated after the latch mechanism 108 for the old optical element 106 has caught and held the arm 102 in its new position with the old optical element 106 out of the optical path. Likewise, the latch mechanism 108 for the new optical element 106 has caught and held the arm 102 in its new position with the new optical element 106 in the optical path.
• the optical system has provided the ability for one optical element to be quickly substituted for another with limited power consumption and force disturbance outside the system.
• FIG. 5 a timing diagram is illustrated that charts the position of the arm during movement from a first position to a second position, and back to the first position.
• the latch mechanism is released and the spring starts the movement of the arm.
• the parameters of the sinusoidal movement would be determined by the specific parameters of the system, such as the spring constant, rotational stiffness and the inertia of the arm, optical element, latch mechanism and any balancing weights.
• the inertia of these elements and the spring constant would be selected to have a first rotational mode mechanical resonance such that the natural period of the resulting oscillation is twice the switching speed that is required.
• the first mode of the system is designed to be at least 20Hz, with some additional settling time and margin typically provided by increasing the mode slightly above 20Hz.
• the arm passes the natural center of the spring. From this point on the spring is no longer providing additional energy to the arm and instead the spring acts to slow the arm and store potential energy for the next switch.
• the kinetic energy provided by the spring has been substantially expended. However, due to unavoidable frictions in the system, the arm has not yet been completely moved to the second position. Accordingly at time T3, the latch mechanism engages the arm to provide the additional energy needed to move the arm the rest of the way to the second position. Thus, at time T4 the arm comes to rest at the second position.
• the optical switching system can be implemented in many different configurations.
• the arms can be arranged so that multiple arms move in the same plane (although optical elements in the same plane must be inserted only at different times). Additional optical elements can be added beyond this point by adding additional planes on either side of the first. The additional planes are slightly displaced to allow clearance with the first plane and the additional planes are rotated around the beam slightly to provide non-interference for the springs. .
• FIG. 6 a optical element switching system is illustrated in which a second group of three switching mechanisms 100 have been added in a different plane than the original group of three.
• an exemplary design layout could include three planes of optical elements, with three optical elements in each plane. Using this layout allows for random access to any of the nine optical elements at any time. It should be noted that while this layout could be structured to allow only one optical element in the path at a time, it could also be constructed to allow different elements from different planes to be placed in the optical path at the same time.
• the arms are preferably designed to identical deflection angles, inertia's, springs, and natural frequencies. This can be accomplished is several ways, for example, by selecting springs that are similar in stiffness and then tuning each arm to the same natural frequency. The system is operated where one filter is always inserted as a second is removed. The two resulting moments, forces, and momentum thus essentially cancel. By having each arm balanced the external forces generated by the arm movement is minimized.
• the latch mechanism are preferably designed to provide both arm holding and to provide additional kinetic energy to the arm.
• Each arm is switched (into and out of the optical path) through its own natural resonance where the limits of its harmonic motion are positions fully into the optical path and fully out of the optical path. To make switching consume as little power as possible, it is desirable for this resonance to have low damping (high Q).
• the latch mechanisms are used to hold the arm at each extreme. Without the latch mechanisms, the arm would simply oscillate through natural harmonic motion between the two extremes, where kinetic energy (motion) and potential energy (spring force) are exchanged.
• the latch mechanisms provide the extra kinetic energy needed to make up for losses in the system due to structural damping, windage and such.
• the latch mechanism can be either mechanical or magnetic, and its purpose is to hold the arm at either extreme of motion, agamst the force of the spring. It is desirable, but not necessary that this mechanism be able to hold the arm with no power consumption. It is also advantageous but not required that this mechanism add energy to the system to make up for losses.
• the preferred implementation of the latch mechanism is using a permanent magnet along with an electromagnetic coil so that the magnet can hold the arm and the electromagnetic coil can oppose the permanent magnet, thus releasing the arm. Since a counter-weight is typically needed to balance the optical filter the preferred implementation is placing the iron on the opposite side of the arm from the optical element.
• FIG. 7 a cross-sectional top view of a preferred latch mechanism 108 is illustrated.
• the latch mechanism 108 includes an electro-magnetic coil 706 surrounding a permanent magnet 708. Surrounding the magnets is a iron casing 704 that completes the flux path. Iron 702 is included on the end of the arm 102.
• the iron 702 serves as to add both magnetic attraction to the arm and can act as a counter-weight to balance the arm. It should be noted that although iron is preferred, other suitable ferromagnetic materials could also be used.
• the permanent magnet 708 serves to hold the arm in place and does so without requiring the consumption of power.
• a pulse is provided to the electro-magnet 706. This causes the electro-magnet 706 to temporarily turn on and overwhelm the magnetic force of the permanent magnet 708, and thus releases the arm 102.
• the spring force causes the arm 102 to move away from before the electro-magnet 706 is turned off.
• a second implementation of the latch mechanism is to instead locate the permanent magnet on the arm, with the electro-magnetic coil again located on the stop. This allows power-off holding at both extremes of motion and the use of much more sophisticated control schemes. For example, the arm could be pushed at the release to add energy to the system and the capture magnet shut-off until the arm arrives and stops. Once stopped, the opposing coil is deactivated and the permanent magnet holds the arm in place.
• a latch mechanism implemented as such can have the additional benefit of providing a way to restart the arm should it settle to the center, zero energy position. Specifically, by controlling the electro-magnets to be alternately energized at the natural resonance frequency of the arm, the natural harmonic motion of the arm can be built up until its amplitude is high enough to relatch the arm.
• the latch mechanism that holds the arm in position is also used to provide the additional kinetic energy needed to make up for losses, the energy could instead be provided by other rotational energy mechanisms. Examples of other mechanisms include torque motors and other such devices.
• the use of a motor to provide the additional energy allows the use of alternate latch mechanisms that don't add energy to the system such as mechanical latches.
• the present invention thus provides an optical element switching mechanism that overcomes many of the disadvantages found in the prior art.
• the switching mechanism uses a balanced arm, with an optical element attached at one end of the arm.
• the arm is suspended on an axis that allows it to rotate from a first position to a second position.
• the arm is balanced to provide low force disturbance during this movement.
• a spring is coupled to the arm that provides the rotational energy to move the arm.
• the spring is coupled such that its neutral position is between the first and second positions, and thus the spring provides the energy to move the arm from the first position to the second position and vice versa.
• a latch mechanism is also provided for selectively holding the arm in the first position or second position. Additionally, the latch mechanism can provide additional energy needed to catch and move the arm into final position. When the latch mechanism is released, the tension on the arm provided by the spring starts the rotational movement of the arm its axis toward the opposite position. As the arm approaches the opposite position, the latch mechanism provides the additional to complete rotation to the new position, and catches and holds the arm in the new position. [0040]
• the switching mechanism thus provides the ability to rapidly move an optical element in and out of the transmission path with limited power consumption and limited physical disturbance.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Astronomy & Astrophysics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Mechanical Light Control Or Optical Switches (AREA)
• Lens Barrels (AREA)
• Blocking Light For Cameras (AREA)
• Structure And Mechanism Of Cameras (AREA)

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Citations (6)

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• 2002
  • 2002-03-20 US US10/103,534 patent/US7013057B2/en not_active Expired - Lifetime
• 2003
  • 2003-03-20 AU AU2003218290A patent/AU2003218290A1/en not_active Abandoned
  • 2003-03-20 JP JP2003578993A patent/JP2005521097A/ja active Pending
  • 2003-03-20 DE DE60307069T patent/DE60307069T2/de not_active Expired - Lifetime
  • 2003-03-20 EP EP03714284A patent/EP1485745B1/en not_active Expired - Lifetime
  • 2003-03-20 WO PCT/US2003/008523 patent/WO2003081317A1/en not_active Ceased

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