초록 ▼

A positioning device of the type described characterised by the incorporation of the puck into a closed circuit gas system from which the puck establishes the flow of fluid to provide the fluid cushion. Typically the positioning device is characterised by the provision of a heat transfer mechanism i

A positioning device of the type described characterised by the incorporation of the puck into a closed circuit gas system from which the puck establishes the flow of fluid to provide the fluid cushion. Typically the positioning device is characterised by the provision of a heat transfer mechanism incorporated in the closed circuit to provide for heat exchange between the heat transfer mechanism and gas flowing around the system. The puck is coupled to a lens and a mask to provide for close following of a surface of a work-piece so as to keep a magnified image of the mask stable; the combination of puck, lens and mask forming a unit counterbalanced by a counterweight acting to provide for adjustment of focus of the laser beam relative to the surface of the work-piece.

대표청구항 ▼

1. A positioning device for positioning a focusing or imaging lens to a working datum position at a predetermined distance relative to a first surface of a work piece in micro-machining by a laser beam, said laser beam being focused by the focusing or imaging lens onto the first surface of the work

1. A positioning device for positioning a focusing or imaging lens to a working datum position at a predetermined distance relative to a first surface of a work piece in micro-machining by a laser beam, said laser beam being focused by the focusing or imaging lens onto the first surface of the work piece, said positioning device comprising a distance sensing device comprising a body member riding on a fluid cushion on the first surface of the work piece, said fluid cushion being established by a flow of fluid such as to maintain the body member at a predetermined distance from said first surface, wherein the body member is incorporated into a closed circuit gas system by which the body member is used to establish said flow of fluid to provide said fluid cushion,a heat transfer means is provided which is incorporated in the closed circuit gas system to provide for heat exchange between the heat transfer means and gas flowing around the closed circuit gas system for controlling a temperature of the surface of the work piece during the micro-machining and said positioning device being configured such that, in the event that the body member is displaced due to a variation in thickness of the work piece, any change in position of said body member, Perpendicular to the first surface, moves the focusing or imaging lens so as to cause a corresponding change in a current datum position of the focusing or imaging lens to restore the current datum position to the working datum position. 2. The positioning device according to claim 1, wherein the body member is coupled to the focusing or imaging lens and a mask to provide for close following of a surface of a work-piece so as to keep a magnified image of the mask stable; the combination of the body member, the focusing or imaging lens and the mask forming a unit counterbalanced by a counterweight acting to provide for adjustment of focus of the laser beam relative to the surface of the work-piece. 3. The positioning device according to claim 1, wherein the body member of the distance sensing device includes a column supporting a focusing or imaging lens unit above the surface of a work piece; the column being fed gas from the closed circuit gas system and comprising an aperture at the foot of the column such as to establish the fluid cushion enabling to support the body member at a closely specified clearance above the work piece; the focusing or imaging lens unit providing for focusing the laser beam at a point on the surface of the work piece. 4. The positioning device according to claim 3, wherein the body member includes a further column which in combination with the column serves to support the lens unit above the surface of a work piece; the further column is fed gas from the closed circuit gas system; the further column is provided with an aperture at the foot of the further column; the column and the further column in combination serving to support the body member at a closely specified clearance above the work piece; the lens unit providing for focusing of the laser beam at a point on the surface of the work piece. 5. The positioning device according to claim 1, wherein the body member is provided with an inlet pipe for a gas flow and an outlet pipe to provide for an extraction flow from the body member separately from the closed circuit gas system. 6. The positioning device according to claim 1, wherein the closed circuit gas flow system is fed into and passes out of the body member by at least two inlets and two outlets. 7. The positioning device according to claim 1, having a body member incorporating an electrostatic device for positioning close to a surface of a work-piece. 8. The positioning device according to claim 7, wherein the body member is fabricated from an insulating material. 9. The positioning device according to claim 1, wherein the distance sensing device locates a contact mask at a very small distance from the work-piece close to, but not in contact with, the work surface. 10. The positioning device according to claim 1, wherein the body member is shaped to closely correspond to a curved surface of a work piece so as to cause the body member to float relative to the surface of the work piece by the gas flow of air so as to enable the body member to compensate for manufacturing errors in the work piece. 11. A positioning device for a focusing lens that focuses a laser beam, which is emitted by a laser, at a working datum position on a surface of a work piece for micro-machining the work piece with the laser, the positioning device comprising: a distance sensing device comprising a body memberthat communicates with the focusing lens, the body member comprising a central aperture through which the laser beam passes, a gas inlet aperture, a gas return aperture and at least one gas outlet aperture;a closed circuit gas system comprising a delivery conduit and an evacuation conduit, the delivery conduit mates with the gas inlet aperture of the body member to supply the body member with a flow of gas, the evacuation conduit mates with the gas return aperture to direct a first portion of the flow of gas from the body member to the closed circuit gas system, the at least one gas outlet aperture of the body member is aligned with the work piece to direct a second portion of the flow of gas from the body member at the surface of the work piece;the second portion of the flow of gas from the body member directed at the surface of the work piece establishes a fluid cushion between the body member and the surface of the work piece and maintains the body member at a predetermined distance from the surface, such that any change in the predetermined distance perpendicular to the surface induces corresponding movement of the focusing lens to maintain the focus of the laser beam at the working datum position on the surface of the work piece; andthe closed circuit gas system comprises a heat exchanger which either heats or cools the flow of gas supplied to the body member through the delivery conduit and the gas inlet aperture to control a temperature of the surface of the work piece during micro-machining. 12. The positioning device according to claim 11, wherein the body member comprises first, second, third and fourth gas outlet apertures arranged radially about the body member, the first and the third gas outlet apertures are arranged on the body member opposite each other and define a diametrical line that is normal to a diametrical line that is defined by the second and the fourth gas outlet apertures that are arranged on the body member opposite each other, the arrangement of the first, the second, the third and the fourth gas outlet apertures about the body member facilitate adjusting at least one of lateral movement of the body member along the surface of the work piece and a direction of debris extraction from the surface of the work piece. 13. The positioning device according to claim 11, wherein the body member further comprises at least one gas bore which is open to the central aperture and which directs a further portion of the flow of gas to the central aperture and toward the surface of the work piece. 14. The positioning device according to claim 11, wherein a pump is located within the gas system and coupled to the delivery conduit and the evacuation conduit, the pump operating to feed the flow of gas into and extract the flow of gas from the body member. 15. The positioning device according to claim 11, wherein the body member comprises a pair of columns and each of the columns has one of the at least one gas outlet apertures, the columns are supported on opposite lateral sides of the body member and the focusing lens, each of the columns comprises a gas inlet aperture which mates with the delivery conduit and receives the flow of gas, the pair of columns direct the flow of gas out a respective gas outlet aperture at the surface of the work piece to support the body member at a closely specified clearance above the surface of work piece. 16. A positioning device for a focusing lens that focuses a laser beam, which is emitted by a laser, at a working datum position on a surface of a work piece for micro-machining the work piece with the laser, the positioning device comprising: a distance sensing device comprising a body member that communicates with the focusing lens, the body member comprising a central aperture through which the laser beam passes, a gas inlet aperture, a gas return aperture and at least one gas outlet aperture, the gas inlet aperture, the gas return aperture and the at least one gas outlet aperture being in fluid communication with each other;a closed circuit gas system being connected to the gas inlet aperture and the gas return aperture of the body member, the gas system comprising a gas pump and a heat exchanger, the gas pump directs a flow of gas to the body member through the gas inlet aperture and removes a flow of gas from the body member through the gas return aperture, the at least one gas outlet aperture being located on the body member adjacent the surface of the work piece to direct an axial flow of gas at the surface of the work piece;a fluid cushion being formed between the body member and the surface of the work piece by the axial flow of gas as the axial flow of gas impinges on the surface of the work piece, the fluid cushion maintains the focus of the laser beam at the working datum position on the surface of the work piece; andthe heat exchanger either heats or cools the flow of gas, directed through the gas inlet aperture, and the axial flow of gas to control a temperature of the surface of the work piece during micro-machining.