Pneumatic connection to carrier head

1. A chemical mechanical polishing system, comprising:

a carrier head having a flexible membrane and a plurality of chambers to apply pressure to the flexible membrane;

a motor to rotate the carrier head;

a drive shaft connecting the motor to the carrier head, the drive shaft having a plurality of passages connected to the plurality of chambers;

a pressure control system; and

a rotary union to connect the plurality of passages in the drive shaft to the pressure control system, wherein the rotary union includes a substantially cylindrical body, a plurality of fittings arranged in a vertical line along the body, and a plurality of flexible tubes connected to the plurality of fittings and extending in a curve around a portion of the body to connect to the pressure control system.

2. The polishing system of claim 1 , wherein the plurality of flexible tubes connect to a second plurality of fittings arranged in a second vertical line.

3. The polishing system of claim 1 , comprising a plurality of optical sensors located along the tubes.

4. The polishing system of claim 3 , wherein the optical sensors are clipped to the exterior of the tubes.

5. The polishing system of claim 3 , wherein each tube of the plurality of flexible tubes includes a substantially identical portion of tubing.

6. The polishing system of claim 5 , wherein the substantially identical portion of tubing of each respective tube of the plurality of flexible tubes is different in at least one of color, material or thickness than a remainder of the respective tube of the plurality of flexible tubes.

7. The polishing system of claim 5 , wherein the substantially identical portion of tubing comprises plastic, glass or quartz.

8. The polishing system of claim 3 , comprising a controller configured to detect the presence of a contaminant in the flexible tubes.