Changes

Figure 6 shows two columns of broad asymmetric patterns in a diamond sample cut using only a single lens for a varying number of laser pulses. Figure 7 shows the improvement in beam shape gained after using the three lens setup.

Figure 6 shows two columns of broad asymmetric patterns in a diamond sample cut using only a single lens for a varying number of laser pulses. Figure 7 shows the improvement in beam shape gained after using the three lens setup.

If the focal spot that created these patterns was rastered over an entire diamond it would result in a radiator with large surface variations rendering it unusable for GlueX. The focus of the laser defines the cutting tool with which the diamond is shaped. An ill-defined focused will ablate non-uniformly as the diamond is rastered across it making it extremely difficult to cut uniformly to 20 µm thickness without cracking the thin diamond membrane. The geometry of the focus also determines the fluence (laser energy per cm2 ) incident on the diamond surface. A tightly focused beam spot increases the available fluence, increasing the rate of ablation. It is therefore very important to measure the waist of the beam after L3 in the three lens system.

If the focal spot that created these patterns was rastered over an entire diamond it would result in a radiator with large surface variations rendering it unusable for GlueX. The focus of the laser defines the cutting tool with which the diamond is shaped. An ill-defined focused will ablate non-uniformly as the diamond is rastered across it making it extremely difficult to cut uniformly to 20 µm thickness without cracking the thin diamond membrane. The geometry of the focus also determines the fluence (laser energy per cm2 ) incident on the diamond surface. A tightly focused beam spot increases the available fluence, increasing the rate of ablation. It is therefore very important to measure the waist of the beam after L3 in the three lens system.