System and method for transferring articles between vacuum and non-vacuum environments

1. A system for transferring articles between an atmospheric pressure environment and a vacuum pressure environment, the system comprising:

a vacuum enclosure including a wall separating the atmospheric pressure environment from the vacuum pressure environment;

a transfer shaft extending through the wall from the atmospheric pressure environment to the vacuum pressure environment, the transfer shaft having an atmospheric transfer port in communication with the atmospheric pressure environment, a vacuum transfer port in communication with the vacuum pressure environment, and an intermediate port disposed in communication with a channel in the wall;

a transfer carriage disposed within the transfer shaft, the transfer carriage having an access port for providing access to an interior of the transfer carriage, the transfer carriage being movable within the transfer shaft;

a first differential pumping region formed in the wall on a first side of the channel and a second differential pumping region formed in the wall on a second side of the channel opposite the first side, each of the first and the second differential pumping regions comprising a groove configured to draw gas out of a space between the transfer carriage and the transfer shaft;

and

an air bearing associated with the transfer carriage, the air bearing configured to maintain a gap between the transfer carriage and the transfer shaft.

2. The system of claim 1 , wherein the transfer carriage is movable between an atmospheric position in which the access port of the transfer carriage is aligned with the atmospheric transfer port of the transfer shaft, an intermediate position in which the access port of the transfer carriage is aligned with the intermediate port of the transfer shaft, and a vacuum position in which the access port of the transfer carriage is aligned with the vacuum transfer port of the transfer shaft.

3. The system of claim 1 , the transfer carriage further including a third differential pumping region formed in the transfer carriage and comprising a groove configured to draw gas out of a space between the transfer carriage and the transfer shaft.

4. The system of claim 3 , wherein the groove of the third differential pumping region comprises a continuous, annular channel formed in an exterior of the transfer carriage.

5. The system of claim 2 , wherein the groove comprises a continuous, annular channel formed in an interior of the transfer shaft.

6. The system of claim 1 , further comprising a linear actuator disposed within the transfer shaft and configured to move the transfer carriage between several predetermined positions within the transfer shaft.

7. The system of claim 6 , wherein the intermediate port is configured to draw gas out of the transfer carriage when the transfer carriage is in an intermediate position.

8. The system of claim 6 , wherein the intermediate port is configured to pump gas into the transfer carriage when the transfer carriage is in an intermediate position.

9. The system of claim 1 , wherein the air bearing comprises a plurality of air outlets through which the pressurized gas is expelled into a space between the transfer carriage and the transfer shaft.

10. A system for transferring articles between an atmospheric pressure environment and a vacuum pressure environment, the system comprising:

a transfer shaft extending between the atmospheric pressure environment and the vacuum pressure environment, the transfer shaft having an intermediate port disposed in communication with a channel in a wall separating the atmospheric pressure environment from the vacuum pressure environment;

a transfer carriage disposed within the transfer shaft, the transfer carriage having an access port for providing access to an interior of the transfer carriage;

a first differential pumping region formed in the wall on a first side of the channel and a second differential pumping region formed in the wall on a second side of the channel opposite the first side, each of the first and the second differential pumping regions comprising a groove configured to draw gas out of a space between the transfer carriage and the transfer shaft;

and

an air bearing mounted to the transfer carriage and configured to expel pressurized gas into a space between the transfer shaft and the transfer carriage for maintaining a gap between the transfer carriage and the transfer shaft.

11. The system of claim 10 , wherein the transfer carriage is movable between an atmospheric position in which the access port of the transfer carriage is aligned with an atmospheric transfer port of the transfer shaft, an intermediate position in which the access port of the transfer carriage is aligned with the intermediate port of the transfer shaft, and a vacuum position in which the access port of the transfer carriage is aligned with a vacuum transfer port of the transfer shaft.

12. The system of claim 10 , further comprising a third differential pumping region formed in the transfer carriage, the third differential pumping region comprising a groove configured to draw gas out of the transfer shaft.

13. The system of claim 10 , further comprising a linear actuator disposed within the transfer shaft and coupled to the transfer carriage.

14. The system of claim 10 , wherein the air bearing is configured to expel gas radially outwardly from the transfer carriage.