Alignment
6-21
There are two birefringent filter (bi-fi) sets that cover the Tsunami ps wave-
length range. The “A” plate bi-fi has a yellow dot on the filter ring, the “B”
plate bi-fi has a white dot. Use the “A” plate with the blue, standard, long,
or extra-long optic sets. Use the “B” plate with the midrange optic set.
After you choose an operating wavelength, select a filter from Table 6-3
and follow this procedure to install and align the filter.
A monochromator is required for this procedure.
1. Close the pump laser shutter.
2. Set the bi-fi micrometer to its maximum clockwise position.
3. Install the appropriate filter in the holder.
a. Back out the clamping setscrew and place the filter into the holder.
b. Rotate the filter until the pair of setscrew holes on the outer edge of
its ring (Figure 6-15) is near the position listed in Table 6-3 for
your wavelength. Note: the “12 o'clock” position is the highest
point and is nearest to you as seen from the output bezel. The posi-
tion listed is your “starting” position.
c. Open the pump laser shutter.
d. While watching the monochromator, rotate the filter slightly clock-
wise by hand until you obtain the lower wavelength listed in Table
6-3.
e. Close the pump laser shutter.
f. Tighten the clamping setscrew to hold the filter in place.
4. Open the pump laser shutter.
5. Recenter the beam on the M
1
GTI using the M
2
vertical and horizontal
mirror controls.
6. Adjust
M
1
to overlap the fluorescent spots and reestablish lasing.
7. Rotate the micrometer counterclockwise as far as needed to verify the
Tsunami reaches the upper wavelength listed in Table 6-3.
This completes the bi-fi alignment.
Table 6-3: Bi-Fi Alignment for Picosecond Operation
Optic Set Plate Type/
Dot Color
Setscrew
Position (o’clock)
Lowest
Wavelength
Highest
Wavelength
Blue (B) A/Yellow 1:00 688 nm 790 nm
Standard (S) A/Yellow 12:00 715 nm 850 nm
Mid-range (M) B/White 1:00 775 nm 900 nm
Long (L) A/Yellow 1:00 835 nm 1000 nm
X-Long (X) A/Yellow 12:00 965 nm 1080 nm
Broadband NA/Yellow-Red 12:00 695 nm 1005 nm
The alignment of each filter stack is set at the factory and does not
require adjustment. Never try to disassemble the stack.
Caution!
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