Self-aligning vacuum feed-through for liquid nitrogen

1. A light source, comprising:

a rotatable drum;

an exhaust tube coupled to the rotatable drum to exhaust nitrogen gas from an interior of the rotatable drum;

a feed tube situated within the exhaust tube to provide liquid nitrogen to the interior of the rotatable drum;

a casing to surround at least a portion of the exhaust tube;

a rotary air bearing between the exhaust tube and the casing, to allow the exhaust tube to rotate with the rotatable drum; and

a motor, coupled to the rotatable drum independently of the exhaust tube, to rotate the rotatable drum.

2. The light source of claim 1 , wherein:

the exhaust tube and the feed tube extend vertically;

the rotatable drum is vertically translatable; and

the rotary air bearing allows the exhaust tube to translate vertically with the rotatable drum.

3. The light source of claim 2 , wherein:

the motor is a first motor; and

the light source further comprises a second motor, coupled to the rotatable drum independently of the exhaust tube, to translate the rotatable drum vertically.

4. The light source of claim 3 , wherein:

the second motor is situated below the rotatable drum; and

the exhaust tube and the feed tube extend above the rotatable drum.

5. The light source of claim 2 , further comprising:

a flange to level the casing; and

a linear air bearing between the casing and the flange.

6. The light source of claim 5 , further comprising bellows having a first end connected to the flange and a second end connected to the casing.

7. The light source of claim 2 , further comprising a gimbal coupled to the casing, to accommodate tilt of the casing and the exhaust tube.

8. The light source of claim 7 , wherein the gimbal comprises bushings to accommodate horizontal translation of the casing and the exhaust tube.

9. The light source of claim 1 , wherein the exhaust tube comprises thermal insulation.

10. The light source of claim 9 , wherein the thermal insulation comprises titanium.

11. The light source of claim 9 , wherein the thermal insulation comprises a vacuum gap between a first layer of the exhaust tube and a second layer of the exhaust tube.

12. The light source of claim 9 , further comprising:

a chamber to receive the nitrogen gas from the exhaust tube, wherein the exhaust tube terminates in the chamber and the chamber has an output to vent the nitrogen gas; and

a heater block between the chamber and the casing, to thermally isolate the casing from the chamber.

13. The light source of claim 1 , further comprising a nut to couple the exhaust tube to the rotatable drum.

14. A method of operating a light source, comprising:

rotating a drum using a motor;

providing liquid nitrogen to an interior of the drum through a feed tube;

exhausting nitrogen gas from the interior of the drum through an exhaust tube coupled to the drum, wherein the feed tube is situated within the exhaust tube; and

allowing the exhaust tube to rotate with the drum, using a rotary air bearing between the exhaust tube and a casing that surrounds at least a portion of the exhaust tube, wherein the motor is coupled to the drum independently of the exhaust tube.

15. The method of claim 14 , wherein the exhaust tube and the feed tube extend vertically, the method further comprising:

vertically translating the drum while rotating the drum; and

allowing the exhaust tube to translate vertically with the drum, using the rotary air bearing.

16. The method of claim 15 , further comprising accommodating horizontal translation of the casing and the exhaust tube with respect to a flange, using a linear air bearing between the casing and the flange; wherein:

the flange levels the casing; and

the horizontal translation comprises translation from run-out of the drum.

17. The method of claim 15 , further comprising accommodating tilt of the casing and the exhaust tube, using a gimbal coupled to the casing.

18. The method of claim 17 , wherein the gimbal comprises bushings, the method further comprising accommodating horizontal translation of the casing and the exhaust tube using the bushings, the horizontal translation comprising translation from run-out of the drum.

19. A light source, comprising:

a vertically translatable, rotatable drum;

an exhaust tube coupled to the drum to exhaust nitrogen gas from an interior of the drum, wherein the exhaust tube extends vertically;

a feed tube situated within the exhaust tube to provide liquid nitrogen to the interior of the drum, wherein the feed tube extends vertically;

a casing to surround at least a portion of the exhaust tube;

a rotary air bearing between the exhaust tube and the casing, to allow the exhaust tube to rotate with the drum and to translate vertically with the drum;

a flange to level the casing; and

a linear air bearing between the casing and the flange.