WO2009106094A1 - Device and method for positioning an optical element - Google Patents

Device and method for positioning an optical element

Info

Publication number
WO2009106094A1
WO2009106094A1 PCT/EP2008/001541 EP2008001541W WO2009106094A1 WO 2009106094 A1 WO2009106094 A1 WO 2009106094A1 EP 2008001541 W EP2008001541 W EP 2008001541W WO 2009106094 A1 WO2009106094 A1 WO 2009106094A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
plate
positionable
coils
system
base
Prior art date
Application number
PCT/EP2008/001541
Other languages
French (fr)
Inventor
Biesen Marc Van
Original Assignee
Newson Engineering
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B7/00Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/18Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors
    • G02B7/182Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors
    • G02B7/1822Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors comprising means for aligning the optical axis
    • G02B7/1827Motorised alignment
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B26/00Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light, e.g. switching, gating, modulating
    • G02B26/08Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light, e.g. switching, gating, modulating for controlling the direction of light
    • G02B26/0816Optical devices or arrangements using movable or deformable optical elements for controlling the intensity, colour, phase, polarisation or direction of light, e.g. switching, gating, modulating for controlling the direction of light by means of one or more reflecting elements
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B7/00Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G02B7/023Mountings, adjusting means, or light-tight connections, for optical elements for lenses permitting adjustment

Abstract

A device for positioning on optical element (1) in 1, 2 or 3 dimensions comprising elevation and two-dimensional tilting. Said device comprises a positionable plate (2) whereon said optical element (1) is mounted. Said positionable plate (2) comprises a number of electrical conductive coils (6) serving as actuation elements positioned around the geometrical centre of said positionable plate (2). A base plate (3) comprising permanent magnets (5) forming electromotive pairs with said coils (6) is supporting said positionable plate (2) by means of a bearing system (4). When current is driven through said coils (6) over electrical conductive mechanically flexible connections (8), electromotive forces, all substantially normal to said positionable plate (2), are formed at said coil positions. Said forces can be compiled in a two-dimensional tilt torque and an elevation force capable, by means of said bearing system (4), to tilt in two dimensions and/or elevate the positionable plate (2) relative to the base plate (3). Regulators (9), comprising error signals derived from a deviation between instantaneous and desired (10) position of said positionable plate (2) relative to said base plate (3), are used to control said currents.

Description

Description

Device and Method for Positioning an Optical Element Technical Field

[0001] The present invention relates to a device and a method for positioning an optical element, being a mirror or a lens. Said positioning comprises two- dimensional tilting of said optical element or elevation of said optical element or two-dimensional tilting combined with elevation of said optical element.

Background Art

[0002] Positioning a focused laser beam in a planar field is frequently required in industrial optical applications. A large number of laser-based marking systems and laser-based micro machining systems are installed worldwide. In most of those machines the laser beam is positioned on the work piece by means of a deflection system. This means that during processing the work piece is standing still while the laser beam is moving. The beam needs to be positioned in three dimensions: X, Y and Z. The Z movement is needed for keeping the laser light in focus while it moves over the work piece. This focusing can be achieved by a flat field objective mounted between XY-deflection system and the work piece or by a dynamically moving lens mounted between laser and XY-deflection system or a combination thereof.

[0003] Using two rotational servo systems is a common used straight forward and easy to understand solution for deflecting a laser beam in X-Y directions. The first servo system is holding the X mirror while the second one is holding the Y mirror. This dual mirror approach has some disadvantages. Due to the fact that the second mirror always has to catch the light from the first one, it is generally larger. When the aperture of the overall system has to be large, the Y mirror becomes huge. Single mirror solutions for deflecting a laser beam in X-Y directions, lead to smaller mirrors. The present state of the art also includes single mirror solutions for deflecting laser beams, as in the following patents: US WO/2003/076977 (GLIMMERGLASS NETWORKS, INC.) 18/09/2003 , US US4157861 (US NAVY) 6/12/1979 , EP 0790512 A (EL.EN.S.P.A.) 20/08/1997 .

[0004] In general the main load of a tilting system is the mass of the moving part of the system. Each positioning of the mirror is a sequence of accelerations. The lower the mass to be accelerated the smaller the force one needs to do this acceleration. Any design in which the weight of the moving parts is minimised will likely result into a fast system. Most of the dual axis tilting designs that are based on electromotive forces have a layout in which permanent magnets or ferromagnetic parts are mounted on the moving side of the system. The advantage of this approach is that the actuation elements, mainly electrical conductive coils, can be on the static side. This construction allows easy electrical and thermal connections to those coils. However, a large disadvantage of this layout is the fact that permanent magnets and ferromagnetic parts are relatively heavy, which makes it somewhat difficult to get fast accelerations.

[0005] On the other hand actuation elements, for example electrical conductive coils routed on a printed circuit board, are relatively light and more suited to be accelerated quickly. A deflection system wherein the positionable part comprises said actuation elements is likely to be faster than a similar system wherein the magnets are moving. The weight advantage of a deflection system wherein the moving part comprises the actuation elements increases with the size of the aperture to be positioned. Present state of the art shows examples supporting said theory embedded in rotational servo systems, ref. EP 1373964 B (NEWSON ENGINEERING N.V.) 8/02/2006 . A large system also provides space needed for the flexible electrical connection between the static part of said deflection system and the coils mounted on the positionable part of said deflection system. Furthermore applications using a X-Y deflection system combined with a dynamically moving lens for controlling the focal position could be compiled into a single device able to tilt and elevate a mirror to some extent.

Disclosure of Invention

[0006] The present invention is related to a device for positioning an optical system according to claim 1 and a method according to claim 5 and 6. Said device comprises a positionable plate whereon said optical system is mounted. The main technical aspect of the present invention is the use of electrical conducting coils mounted on said positionable plate around the centre of said positionable plate. Each coil is paired with a permanent magnet mounted beneath said coil on a base plate and spaced thereof. Said spacing allows relative movability between said coils and said magnets. When an electrical current is driven through said coils, electromotive forces are generated at each pair of said coils and said magnets. Said forces are substantially normal to the positionable plate and located in the geometrical centre of each coil. By controlling said currents in said coils all those forces can be modulated independently. Said device further comprises position measurement devices able of measuring the instantaneous position of said positionable plate relative to said base plate and regulators comprising error signals, derived from a deviation between instantaneous and desired position of said positionable plate relative to said base plate. Said desired position may vary dynamically in time. Said regulators are connected through electrical conductive mechanically flexible connections with said coils whereby said currents are controlled by said regulators. By grouping the coils, by means of electrical interconnections, into a number of actuation elements equal to the number of dimensions of the required movability of said optical system, the number of said regulators needed to drive said currents is minimised.

[0007] A system providing two-dimensional tilt together with elevation comprises a positional plate comprising three actuation elements resulting in a system controlled by three regulators. Each of said actuation elements comprise a number of coils located within a 120°-pie segment of said positionable plate. Winding direction of said coils and magnetic polarisation of their paired permanent magnets are arranged in such a way that the electromotive forces, generated when current is driven through said coils, are all pointing substantially in the same direction, normal to said positionable plate. Said forces of each of the three actuation elements can be compiled into a two-dimensional tilt torque and a force substantially normal to the positionable plate.

[0008] A system providing two-dimensional tilt comprises one actuation element for tilting in X direction and one actuation element for tilting in Y direction resulting in a system controlled by two regulators. Said actuation elements comprise coils located at opposite side of the geometrical centre of the positionable plate. Winding direction of said coils and magnetic polarisation of their paired permanent magnets are arranged in such a way that the electromotive forces, generated when current is driven through said coils, are all pointing substantially normal to said base plate, whereby opposite coils generate opposite electromotive forces. Said forces can be compiled into a tilt torque, one tilt torque for said actuation element tilting the X direction and one tilt torque for said actuation element tilting the Y direction.

[0009] A system providing elevation comprises one actuation element. All coils mounted on the positionable plate are grouped into said actuation element. Winding direction of said coils and magnetic polarisation of their paired permanent magnets are arranged in such a way that the electromotive forces, generated when current is driven through said coils, are all substantially normal to said positionable plate and pointing in the same direction.

Brief Description of Figures in the Drawings

[0010] The invention will be more clearly understood from the non-limitative description and the attached drawings showing modes for carrying out the invention. In said drawings:

[001 1]

Figure 1 shows a schematic three-dimensional view of a best mode for carrying out the invention; Figure 2 shows a schematic three-dimensional view of a mode for carrying out the invention;

Figure 3 shows a schematic three-dimensional view of a mode for carrying out the invention.

Best Mode for Carrying Out the Invention

[0012] Figure 1 shows a device for positioning an optical mirror (1). Said mirror (1) is mounted on a positionable plate (2). A base plate (3) is supporting said positionable plate (2) by means of a bearing system (4). Said bearing system (4) is providing movability of said positionable plate (2) relative to said base plate (3) in three dimensions being two-dimensional tilting and elevation.

[0013] The positionable plate (2) comprises a printed circuit board comprising a number of actuation elements each comprising a number of coils (6) routed on said printed circuit board. Said coils (6) are positioned around the geometrical centre of the positionable plate (2). Figure 1 shows a positionable plate (2) comprising six coils (6) placed around the centre of said positional plate (2). Said coils (6) are grouped into three actuation elements each comprising two coils.

[0014] Beneath each coil (6), a permanent magnet (5) is mounted on the base plate (3). When currents are driven through said coils (6) electromotive forces are generated by magnetic interaction between said magnets (5) and said coils (6). Said forces are substantially normal to said positionable plate (2) and can be compiled into a two-dimensionial tilt torque between said positionable plate (2) and said base plate (3) and an elevation force between said positionable plate (2) and said base plate (3). Said permanent magnets (5) are mounted beneath said coils (6) of said positionable plate (2) in an alternating sequence: S-pole of permanent magnet 1 pointing towards coil 1 , N-pole of permanent magnet 2 pointing towards coil 2, S-pole of permanent magnet 3 pointing towards coil 3, and so on... whereby the electromotive efficiency is maximised. [0015] Three regulators (9) are connected to said coils (6) by means of electrical conductive mechanically flexible wires (8). The instantaneous position of the positionable plate (2) relative to the base plate (3) is measured by a three-dimensional position sensing device. Figure 1 shows a said position sensing device comprising three single dimension position sensing devices (7). Said regulators comprise error signals derived from the difference between said instantaneous position and the desired position

(10) and control the current in said actuation elements.

[0016] The range of movability of the positionable plate (2) relative to the base plate (3) of a device as shown in figure 1 , is mainly limited by: the measurement range of the position sensing device, the spacing between coils and permanent magnets, the spacing between said positionable plate and said base plate, the travel range of the bearing system and the size of the permanent magnets.

Mode for Carrying Out the Invention

[0017] Figure 2 shows a device for positioning an optical mirror (11). Said mirror

(11) is mounted on a positionable plate (12). A base plate (13) is supporting said positionable plate (12) by means of a bearing system (14). Said bearing system (14) is providing movability of said positionable plate

(12) relative to said base plate (13) in two dimensions being two- dimensional tilting.

[0018] The positionable plate (12) comprises a printed circuit board comprising a number of actuation elements each comprising a number of coils (16) routed on said printed circuit board. Said coils (16) are positioned around the geometrical centre of the positionable plate (12). Figure 2 shows a positionable plate (12) comprising four coils (16) placed around the centre of said positional plate (12). Said coils (16) are grouped into two actuation elements each comprising two coils.

[0019] Beneath each coil (16), a permanent magnet (15) is mounted on the base plate (13). When currents are driven through said coils (16) electromotive forces are generated by magnetic interaction between said magnets (15) and said coils (16). Said forces are substantially normal to said positionable plate (12) and can be compiled into a 2-dimensionial tilt torque between said positionable plate (12) and said base plate (13). Said permanent magnets (15) are mounted beneath said coils (16) of said positionable plate (12) in an alternating sequence: S-pole of permanent magnet 1 pointing towards coil 1 , N-pole of permanent magnet 2 pointing towards coil 2, S-pole of permanent magnet 3 pointing towards coil 3, and so on... whereby the electromotive efficiency is maximised.

[0020] Two regulators (19) are connected to said coils (16) by means of electrical conductive mechanically flexible wires (18). The instantaneous position of the positionable plate (12) relative to the base plate (13) is measured by a two-dimensional position-sensing device. Figure 2 shows a said position sensing device comprising two single dimension position sensing devices (17). Said regulators (19) comprises error signals derived from the difference between said instantaneous position and the desired position (20) and control the current in said actuation elements.

[0021] The range of tilting of the positionable plate (12) relative to the base plate (13) of a device as shown in figure 2, is mainly limited by: the measurement range of the position sensing device, the spacing between coils and permanent magnets, the spacing between said positionable plate and said base plate, the travel range of the bearing system and the size of the permanent magnets. In average mechanical tilting will be limited to the arc tangent of "height permanent magnets" divided by "average distance permanent magnets to geometrical centre of said positionable plate".

Mode for Carrying Out the Invention

[0022] Figure 3 shows a device for the positioning of an optical lens (21). Said optical lens (21) is mounted on a positionable plate (22). A base plate (23) is supporting said positionable plate (22) by means of a bearing system (24). Said bearing system is providing movability of said positionable plate (22) relative to said base plate (23) in one dimension being elevation.

[0023] The positionable plate (22) comprises a printed circuit board comprising a number of actuation elements, each comprising a number of coils (26) routed on said printed circuit board, and an opening in the geometrical centre of said positionable plate (22). Said coils (26) are positioned around the geometrical centre of the positionable plate (22). Said opening together with an opening in the base plate (23) are arranged to provide a clear optical aperture through said device. Figure 2 shows a positionable plate (22) comprising six coils (26) placed around the geometrical centre of said positional plate (22). Said coils (26) are grouped into one actuation element comprising three coils.

[0024] Beneath each coil, a permanent magnet (25) is mounted on the base plate (23). When currents are driven through said coils (26) electromotive forces are generated by magnetic interaction between said magnets (25) and said coils (26). Said forces are substantially normal to said positionable plate (22) and can be compiled into an elevation force between said positionable plate (22) and said base plate (23). Said permanent magnets (25) are mounted beneath said coils (26) of said positionable plate (22) in an alternating sequence: S-pole of permanent magnet 1 pointing towards coil 1 , N-pole of permanent magnet 2 pointing towards coil 2, S-pole of permanent magnet 3 pointing towards coil 3, and so on... whereby the overall electromotive efficiency is maximised.

[0025] One regulator (29) is connected to said coils (26) by means of electrical conductive mechanically flexible wires (28). The instantaneous elevation of the positionable plate (22) relative to the base plate (23) is measured by one single dimension position sensing device (27). Said regulator (29) comprises error signals derived from the difference between said instantaneous position and the desired position (30) and control the current in said actuation element.

[0026] The range of elevation of the positionable plate (22) relative to the base plate (23) of a device as shown in figure 3, is mainly limited by: the measurement range of the position sensing device, the spacing between coils and permanent magnets, the spacing between said positionable plate and said base plate, the travel range of the bearing system and the size of the permanent magnets. In average mechanical elevation will be limited to the height of the permanent magnets.

[0027] It should be apparent that the disclosure of the present invention show only three modes provided solely as a practical demonstration of the invention, and that this invention may be varied in its forms and dimensions without departure from the scope of the guiding principle of the invention.

[0028] Any presence of reference numbers in the attached claims has the purpose of facilitating reading of the claims with reference to the description and to the drawings, and does not limit the scope of protection represented by the claims.

Claims

Claims
1. A device for positioning an optical element (1 ), comprising: a positionable plate (2) comprising a number - 1 , 2, 3, 4 or more - of electrical conductive coils (6) placed around the geometrical centre of said positionable plate (2), each said coil (6) comprising an electrical conductive wire traced in turns mounted on said positionable plate (2), said coils (6) grouped to form 1 , 2 or 3 actuation elements; electrical conductive mechanically flexible connections (8) to said coils (6); a base plate (3) positioned below said positionable plate (2), said base plate (3) comprising a number - 1 , 2, 3, 4 or more - of permanent magnets (5) placed below the centre areas of said electrical conductive coils (6) and spaced thereof, whereby electrical currents driven through said electrical conductive coils (6) over said electrical conductive mechanically flexible connections (8) will generate electromotive forces substantially normal to said positionable plate (2); a bearing system (4) mechanically connecting said positionable plate (2) to said base plate (3) providing movability of said positionable plate (2) relative to said base plate (3) in 1 , 2 or 3 dimensions comprising elevation and two- dimensional tilting; a means (7) to measure the instantaneous position of said positionable plate (2) relative to said base plate (3); a number - 1 , 2 or 3 - of regulators (9) to drive said electrical currents in said coils (6), said regulators (9) comprising error signals derived from a deviation between instantaneous and desired (10) position of said positionable plate (2) relative to said base plate (3), wherein said desired position may vary in time; a means to mechanically mount said optical element (1) to said positionable plate (2).
2. The device as claimed in claim 1 wherein the bearing system is a pivot bearing (14) whereby the movability of the positioning plate (12) relative to the base plate (13) is limited to two-dimensional tilting.
3. The device as claimed in claim 1 wherein the bearing system is a linear bearing (24) whereby the movability of the positioning plate (22) relative to the base plate (23) is limited to elevation.
4. The device as claimed in claim 3 wherein the positioning plate (22) comprises a hole located in the geometrical center of said positioning plate (22) and the base plate (23) comprises a hole beneath the geometrical centre of said positional plate (22), whereby an opening is created in said device to allow an optical aperture going through.
5. A method for deflecting an optical aperture wherein said optical aperture is deflected by a mirror mounted on the positionable plate (2) of a device as claimed in claim 1.
6. A method for shifting the focal plane of an optical lens system wherein one or more lenses are mounted on the positionable plate (22) of a device as claimed in claim 4.
PCT/EP2008/001541 2008-02-27 2008-02-27 Device and method for positioning an optical element WO2009106094A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2008/001541 WO2009106094A1 (en) 2008-02-27 2008-02-27 Device and method for positioning an optical element

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2008/001541 WO2009106094A1 (en) 2008-02-27 2008-02-27 Device and method for positioning an optical element

Publications (1)

Publication Number Publication Date
WO2009106094A1 true true WO2009106094A1 (en) 2009-09-03

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ID=39967671

Family Applications (1)

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PCT/EP2008/001541 WO2009106094A1 (en) 2008-02-27 2008-02-27 Device and method for positioning an optical element

Country Status (1)

Country Link
WO (1) WO2009106094A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2437382A1 (en) 2010-09-30 2012-04-04 Newson Engineering N.V. Electromagnetic motor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4157861A (en) * 1977-08-03 1979-06-12 The United States Of America As Represented By The Secretary Of The Navy Optical beam steering system
EP0579471A1 (en) * 1992-07-13 1994-01-19 State Of Israel Ministry Of Defence Rafael Armament Development Authority Scanning apparatus
US20010000130A1 (en) * 1998-03-26 2001-04-05 Kazuhiko Aoki Laser pointing apparatus and on-fulcrum movement drive apparatus
WO2001078096A2 (en) * 2000-04-07 2001-10-18 Microsoft Corporation Magnetically actuated microelectromechanical systems actuator
US20030058550A1 (en) * 2001-09-21 2003-03-27 Ju Chae Min Position control unit for lens of optical pickup device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4157861A (en) * 1977-08-03 1979-06-12 The United States Of America As Represented By The Secretary Of The Navy Optical beam steering system
EP0579471A1 (en) * 1992-07-13 1994-01-19 State Of Israel Ministry Of Defence Rafael Armament Development Authority Scanning apparatus
US20010000130A1 (en) * 1998-03-26 2001-04-05 Kazuhiko Aoki Laser pointing apparatus and on-fulcrum movement drive apparatus
WO2001078096A2 (en) * 2000-04-07 2001-10-18 Microsoft Corporation Magnetically actuated microelectromechanical systems actuator
US20030058550A1 (en) * 2001-09-21 2003-03-27 Ju Chae Min Position control unit for lens of optical pickup device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2437382A1 (en) 2010-09-30 2012-04-04 Newson Engineering N.V. Electromagnetic motor

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