Improved Single-Crystal Cathodoluminescent Lamp
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Single-crystal phosphors like Ce:YAG offer much improved "coulomb lifetime" and thermal performance over conventional powder phosphors. Assuming quench-temperature-limited operation of the phosphor, the limits on flux and brightness are set by thermal resistances. While YAG itself has a large thermal conductivity, N0.13 W/CMŒK, copper is 30 times as good. The best thermal geometry is one in which the electron-bombarded single crystal surface lies as close to the copper heatsink as possible, such as when the phosphor crystal is a thin plate bonded onto a massive copper block and irradiated from above (Fig. 1). The bottom of the garnet is used to remove heat, leaving the top to accept electrons from the beam and emit the cathodoluminescent light.