Tsunami Mode-Locked Ti:sapphire Laser
11-6
Symptom: Poor Long-term Stability
Possible Causes Corrective Action
Chiller mishap or is not on. Turn on the chiller.
Check that the reservoir water level is filled to the proper level.
Check temperature setting; should be set to 18°C.
Check for a water flow obstruction in the chiller and Tsunami laser head.
Tsunami is not optimized. Adjust M
1
and M
10
as described in Chapter 6, “Alignment: Cavity Alignment.”
Optics are dirty. Inspect the optics for dirt or contamination. If dirty, clean the optics using the
cleaning procedure in Chapter 9, “Maintenance.” If an optic is dirty, an IR viewer
will show unusual scatter.
System is not properly
aligned.
Check that the pump beam is centered on M
2
and M
3
(the side facing the Ti:Sap-
phire rod). Avoid parallax error.
Check for beam centering on mirrors M
1
through M
5
, prisms, AOM and OC.
Check for the location of the cavity beam on M
6
through M
9
(M
8
should be a mir-
ror image of M
7
).
SF-10 prism (G0360-000 (apex ∼60° 42’)) use in systems without the Blue set, a
must for X-long systems.
At 800 nm, the beam should be centered on M
7
and M
8
.
LaFn28 Prism (G0383-000 (apex ~ 59° 15’)) used in Blue, Broadband and
USP options.
At 800 nm, the beam should be
3
/4 of the way toward PR
2
/Pr
3
assembly.
Poor pump laser mode
quality.
Check pump laser power and mode (requires TEM
00
pump mode).
Dirty optics and/or beam
splitters in the pump laser.
Clean the optics if necessary. Refer to the cleaning procedure in the pump laser
user’s manual.
Environmental problem Verify that any heat source (e.g., power supplies, chiller, etc.) are exhausting
away from under the table.
Avoid temperature swings ≥ ± 1° C.
Avoid turbulent airflow over the entire system.
For ion pump systems, avoid cooling water temperature swings of ± 2° C.
Improper alignment of the
routing mirror assemblies.
Check the alignment of the routing mirror assemblies between the pump laser
and the Tsunami laser. The dust tubes may be binding against the mirrors.
There is contact between
the routing mirror housing
and screws.
Relocate the housing to avoid contacting the adjustment screw(s).
A dust tube in the routing
mirror assembly is not
properly installed.
Each tube should slide freely inside the mirrors, over the laser snout or input win-
dow, and with respect to each other. All tubes should be at the same height and
parallel with the table, and the beam should be centered in the tubes. Refer to
Chapter 5, “Installation: Set up the Routing Mirrors.”
A mirror in the Tsunami is
not properly seated.
Optimize Tsunami laser output, then, one at a time, tap the back side of each mir-
ror holder while watching the output power level. If the power falls, you have a
seating problem with that mirror. Reseat the mirror, then optimize the laser out-
put by adjusting that mirror before proceeding on to the next mirror.
Loose mechanics. Optimize Tsunami laser output, then systematically verify that all the mechanics
are secured. Start with the ion laser locknuts on the feet, then proceed to the
lock-down clamps, and the routing mirror assemblies. Next, check the internal
Tsunami mechanics, then its locknuts and, finally, its foot clamps.
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