Compensation techniques for fluid and magnetic bearings

Abstract

A system if used to compensate for guide flatness errors and/or shifting of a support. The system comprises one or more of the supports, an actuating system, the guide, a fluid or magnetic bearing, and a compensation system. The one or more support devices have one or more openings. The support devices are coupled to the actuating system, which is configured to move the support devices. The guide passes through respective ones of the openings. The fluid or magnetic bearings are configured to guide the respective support devices along the guides. The compensation system is coupled to respective ones of the support devices adjacent each of the fluid or magnetic bearings. The compensation system is configured to compensate for any non-straight areas of the guides or shifting (e.g., thermal shifting) of the support devices, which is done through moving of the support devices with respect to the guides during movement of the support devices along the guides

1 . A system, comprising:
 one or more support devices having one or more openings, the support devices being coupled to an actuating system that moves the support devices;   a guide passing through respective ones of the openings;   fluid or magnetic bearings configured to guide the respective support devices along the guides; and   a compensation system coupled to respective ones of the support devices adjacent each of the fluid or magnetic bearings, the compensation system being configured to compensate for any non-straight areas of the guides or shifting of the support devices, which is done through moving of the support devices traverse to the guides during movement of the support devices along the guides.   
   
   
       2 . The system of  claim 1 , wherein:
 the support devices support optical elements, and   the compensation system is configured to move the support devices such that center axes of the optical elements are aligned.   
   
   
       3 . The system of  claim 1 , wherein the compensation system comprises:
 a sensor that determines position of the support device with respect to a datum surface of the guide; and   a compensation device that is configured to output a fluid flow toward the surface of the guide to adjust a position of the support device with respect to the guide based on a signal from the sensor.   
   
   
       4 . The system of  claim 3 , wherein the compensation device is positioned on one side of the guide. 
   
   
       5 . The system of  claim 3 , wherein the compensation device includes first and second compensation devices positioned on opposite sides of the guide. 
   
   
       6 . The system of  claim 3 , wherein the sensor comprises a proximity sensor. 
   
   
       7 . The system of  claim 3 , wherein the sensor comprises a cap gauge sensor. 
   
   
       8 . The system of  claim 3 , wherein the sensor comprises an encoder. 
   
   
       9 . The system of  claim 3 , wherein the sensor comprises an optical sensor. 
   
   
       10 . The system of  claim 3 , wherein the sensor is positioned in a same plane as the air or magnetic bearing. 
   
   
       11 . The system of  claim 3 , wherein the sensor is positioned in a perpendicular plane with respect to a plane of the air or magnetic bearing. 
   
   
       12 . The system of  claim 3 , wherein:
 at least one of the support devices supports an optical element; and   the sensor detects optical characteristics of the optical element.   
   
   
       13 . The system of  claim 3 , wherein:
 a gap between the guide and the compensation system is about five to ten microns; and   the compensation device is configured to maintain a constant size of the gap during movement of the respective support device along the guide.   
   
   
       14 . The system of  claim 1 , wherein the fluid or air bearing is a linear fluid or air bearing. 
   
   
       15 . The system of  claim 1 , wherein the fluid or air bearing is a rotary fluid or air bearing. 
   
   
       16 . The system of  claim 1 , wherein the guide has a circular, rectangular, square, or triangular cross sectional shape. 
   
   
       17 . The system of  claim 1 , wherein the air or magnetic bearing is a compressed air bearing, an air bearing, or a hydraulic bearing. 
   
   
       18 . The system of  claim 1 , wherein:
 first through third ones of the support devices support respective first through third lenses of a zoom system;   the actuating system is coupled to respective ones of the first through third ones of the support devices; and   the compensation system is configured to individually move each of the support devices such that center axes of the lenses remain aligned during a zoom operation.   
   
   
       19 . The system of  claim 1 , wherein the actuating system comprises:
 a motor; and   a screw coupled to the motor and to respective ones of the support devices, such that as the screw rotates the respect ones of the support devices move in one of two directions along the guides.   
   
   
       20 . The system of  claim 1 , wherein each of the support devices includes or is coupled to a counter weight device. 
   
   
       21 . The system of  claim 1 , wherein the compensation system is configured to detect and compensate for thermal shifting of the support devices. 
   
   
       22 . The system of  claim 1 , wherein the support devices, guide, bearing, and compensation system form part of an illumination system configured to condition a beam of radiation. 
   
   
       23 . An illumination system of a lithography apparatus, comprising:
 one or more support devices having one or more openings, the support devices being coupled to an actuating system that moves the support devices;   a guide passing through respective ones of the openings;   fluid or magnetic bearings configured to guide the respective support devices along the guides; and   a compensation system coupled to respective ones of the support devices adjacent each of the fluid or magnetic bearings, the compensation system being configured to compensate for any non-straight areas of the guides or shifting of the support devices, which is done through moving of the support devices traverse to the guides during movement of the support devices along the guides.