Planar rotary air bearing stage

Abstract

Various embodiments of the present technology generally relate to precise rotary motion control systems. More specifically, some embodiments relate to systems, methods, and means for providing pressure to a non-contact rotary system. In some embodiments, the rotary system comprises a rotary shaft that can rotate three hundred and sixty degrees continuously. In order for the rotary system to be entirely non-contact with any surfaces of surrounding components or housing, pressure must be supplied to a rotary air bearing that floats the rotary unit above a surface. In some examples, the bottom air bearing is a vacuum preloaded (VPL) air bearing. As such, the VPL air bearing requires a supply of positive pressure and a supply of negative pressure to stabilize the rotary unit. The present technology provides a mechanism for providing pneumatic air to the air bearing without a physical connection to the rotary shaft or air bearing.

1 . A frictionless rotary union comprising:
 a bearing comprising:
 a first port that provides a first pressure to a first aperture of a rotary unit, wherein the frictionless rotary union is non-contact with the rotary unit; and 
 a second port that provides a second pressure to a second aperture of the rotary unit. 
   
     
     
         2 . The frictionless rotary union of  claim 1 , further comprising the rotary unit, wherein the rotary unit is a vacuum preloaded air bearing. 
     
     
         3 . The frictionless rotary union of  claim 1 , wherein:
 the first pressure is a positive pressure; and   the second pressure is a negative pressure.   
     
     
         4 . The frictionless rotary union of  claim 3 , wherein the first pressure and the second pressure are used by the rotary unit to maintain a vertical stability of the rotary unit. 
     
     
         5 . The frictionless rotary union of  claim 1 , wherein the frictionless rotary union is mounted to a housing, the housing comprising at least one radial air bearing that maintains stability of the rotary unit in an x direction and a y direction. 
     
     
         6 . The frictionless rotary union of  claim 1 , wherein:
 the first aperture of the rotary unit is located within a first groove of the rotary unit;   the second aperture of the rotary unit is located within a second groove of the rotary unit; and   the frictionless rotary union creates a first air seal between the first port and the first aperture, wherein the first air seal enables the first pressure to be provided to the first aperture.   
     
     
         7 . The frictionless rotary union of  claim 1 , wherein:
 the frictionless rotary union creates a first air seal between the first port and the first aperture, wherein the first air seal enables the first pressure to be provided to the first aperture without leaking; and   the frictionless rotary union creates a second air seal between the second port and the second aperture, wherein the second air seal enables the second pressure to be provided to the second aperture without leaking.   
     
     
         8 . An assembly comprising:
 a first air bearing that maintains stability of a rotary air bearing in an x direction and a y direction; and   a second air bearing comprising at least one port, wherein the at least one port provides a first pressure to an aperture of the rotary air bearing.   
     
     
         9 . The assembly of  claim 8 , further comprising the rotary air bearing, wherein the rotary air bearing rotates about a vertical axis without contacting either one of the first air bearing and the second air bearing. 
     
     
         10 . The assembly of  claim 9 , further comprising:
 a housing, wherein the housing comprises the first air bearing and the second air bearing; and   a base, wherein the rotary air bearing rotates about the vertical axis without contacting the base.   
     
     
         11 . The assembly of  claim 8 , wherein:
 the rotary air bearing is a positive pressure air bearing; and   the first pressure is a positive pressure.   
     
     
         12 . The assembly of  claim 8 , wherein the rotary air bearing is a vacuum preloaded air bearing and the first pressure is a positive pressure. 
     
     
         13 . A method comprising:
 providing, via a first port of a frictionless rotary union, a first pressure to a first aperture of a rotary unit, wherein providing the first pressure to the first aperture comprises creating a first air seal between the first port of the frictionless rotary union and the first aperture of the rotary unit; and   providing, via a second port of the frictionless rotary union, a second pressure to a second aperture of the rotary unit, wherein providing the second pressure to the second aperture comprises creating a second air seal between the second port of the frictionless rotary union and the second aperture of the rotary unit.   
     
     
         14 . The method of  claim 13 , further comprising, via at least one rotary air bearing, maintaining a horizontal stability of the rotary unit. 
     
     
         15 . The method of  claim 13 , further comprising:
 floating the rotary unit above a base using the first pressure provided to the first aperture of the rotary unit, wherein the first pressure is a positive pressure; and   holding the rotary unit directly above the base using the second pressure provided to the second aperture of the rotary unit, wherein the second pressure is a negative pressure.   
     
     
         16 . The method of  claim 13 , wherein the rotary unit is a vacuum preloaded air bearing. 
     
     
         17 . A system comprising:
 a means for providing a first pressure to a first aperture of a rotary unit without contacting the rotary unit;   a means for maintaining a horizontal stability of the rotary unit; and   a means for maintaining a vertical stability of the rotary unit.   
     
     
         18 . The system of  claim 17 , further comprising a means for providing a second pressure to a second aperture of the rotary unit without contacting the rotary unit. 
     
     
         19 . The system of  claim 17 , wherein the rotary unit is a vacuum preloaded air bearing. 
     
     
         20 . The system of  claim 17 , wherein the first pressure, at least in part, is used to maintain a vertical stability of the rotary unit.