Tsunami - Beckman Institute Laser Resource Center

4
Tsunami
Beam %
2 mm (0.08 in.)
Prism
Figure 7-4: Placement of Pr, and Pr4 in beam
5. Move prisms Prl and Pr4 SO that the beam passes through them about
2 mm from their apices (Figure 7-4). For x-long wavelengths, ensure
the beam is not clipped by these prisms.
6. Use the prism dispersion compensation control to adjust Pr2 and Pr3
so the beam also passes through them about 2 mm from the their
apices.
7. Verify the beam is in the center of M1 0. Adjust M5 if necessary, then
repeat steps 5 and 6.
8. Refer to "Optimizing Laser Output" earlier in this chapter to "walk
the beam" and optimize laser output.
9. Purge the system with clean, dry nitrogen gas when you are operating
within water and oxygen absorption regions (Figure 7-1).
10. Push the STATUS mode locker enable button (the ENABLE LED should
be lit).
11. Set up an autocorrelator such as the Model 409 -08 according to its
user's manual, then maximize the signal by adjusting the angle of the
nonlinear crystal for the optimum phase-matching condition.
12. Maximize the intensity of the autocorrelated waveform by adjusting
the coarse and fine PHASE controls.
Refer to chapter 6, "Alignment: Coarse Phase Adjustment ...," for
information on setting the coarse and fine PHASE controls.
13. Adjust the GTI POSITION control to obtain a pulse.
14. Optimize system performance by iterating between the following
adjustments:
a. Adjust the fine PHASE control.
b. Adjust ion laser output power to obtain a stable pulse.
c. Adjust the GTI POSITION control, prisms Pr2 and Pr3, the slit width,
and pump source interactively to obtain the desired pulse width. I -"
I