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Table 3. Demonstrated wavefront correction of the DM/WFS closed-loop system
Focusing
Short pulse experiments use non-standard beam delivery, so users should contact MEC scientists to discuss the best focusing options and expected performance for their experiment. An inventory of off-axis parabolic mirrors (OAPs) is given in table 4. Note that the standard full-power (1 J, <50 fs) beam size is roughly 65 cm, and so OAP 4 is incompatible with this mode. Recent example measurement of the focus from OAP 3 is given in figure 4.
MEC OAP Inventory for Run 20Focusing of the short pulse laser is achieved with an off-axis parabolic mirror. In table 4 below, OAP3 represents the optic used in the standard beam delivery for full intensity. See the description of the beam delivery on the MEC Components page of the LCLS website (until the Confluence page is updated). OAP1 and OAP2 use narrow angles and are thus difficult to use with most target frames. OAP4 has a smaller clear aperture and will clip the full energy beam.
| Name | CA (mm) | Effective focal length(mm) | Off-axis angle (deg) | coating | notes |
|---|---|---|---|---|---|
| OAP1 | 99 | 311.66 | 17.55 | Dielectric | Incompatible with standard target mount |
| OAP2 | 99 | 311.66 | 17.55 | Dielectric | Incompatible with standard target mount |
| OAP3 | 99 | 330.4 | 35.31 | Silver | Primary OAP for full intensity |
| OAP4 | 50 | 500.58 | 34.41 | Silver | For long focal length and low power. Only compatible with reduced beam size and power. |
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