Flow tubes and flow plates are used in water-cooled Nd:YAG lasers to channel cool water at high-velocity across the surface of the lamp and rod. Velocity is the key consideration for transporting heat away from the lamp and rod.

Materials
Pyrex is the most popular flow tube material because it is inexpensive, transmits well in the Nd:YAG pump bands and effectively filters ultraviolet light.

Cerium Doped Quartz is the next most common flow tube material. Quartz is more mechanically rugged than Pyrex, and is more resistant to thermal cracking. The Cerium dopant filters UV almost as well as Pyrex and has the added advantage of fluorescing in the Nd:YAG absorption bands. Cerium Doped Quartz flow tubes yield better YAG efficiencies and last longer than Pyrex, but they are more expensive.

Samarium Doped Glass is an even more effective optical filter and fluorescent material. However, its high cost limits its application mainly to military and scientific applications.

**For more information about flow tube operation, see our catalog page 115. (click here to view the catalog , *.pdf)