Spectra-Physics Tsunami - Opto-Mechanical Controls: fs Configuration

Controls, Indicators and Connections
4-7
Opto-Mechanical Controls
fs Configuration
The following describes the opto-mechanical controls that are present only
on Tsunami lasers configured for femtosecond only operation (Model
3941) or on picosecond systems designed for conversion to femtosecond
operation (Model 3960). Refer to Figure 4-3 and Figure 4-4.
Pr
1
and Pr
4
prisms—in conjunction with Pr
2
and Pr
3
, compensate for posi-
tive GVD in a fs system. Each prism mount has a translation control for
driving the prism into the beam path for fs operation, and completely out of
the beam path for ps operation. Once set, a setscrew on the slide locks each
in position.
M
6
through M
9
prism mirrors—direct the cavity beam from M
5
through
the prisms and into the AOM. Each mirror has vertical and horizontal align-
ment adjustments. The inside control adjusts the mirror vertically, the out-
side control adjusts it horizontally.
Prism dispersion compensation control (Pr
2
and Pr
3
)—adjusts prism-
pair Pr
2
and Pr
3
for overall cavity dispersion balance and shortest output
pulse. It is used interactively with the nearby slit control. The micrometer
control is accessible when the laser head cover is in place.
Slit wavelength selector—selects laser wavelength. The micrometer con-
trol is accessible when the laser head cover is in place.
Slit bandwidth selector—changes the output pulse bandwidth. This Allen
screw adjustment is set at the factory for a specified output, depending on
the optics set installed. Reset it if you change optics set. If set too wide, it
causes cw breakthrough; if set too narrow, it limits bandwidth and produces
long pulses.
M
1
high reflector (HR)—one of two cavity end mirrors that reflect all of
the laser light back into the cavity. The HR replaces the GTI that is used in
the ps configuration. Its vertical and horizontal adjustments allow you to
align the laser cavity and to optimize output power and mode quality. These
controls are accessible when the laser head cover is in place.
Prisms Pr
1
and Pr
4
are pre-aligned at the factory. DO NOT adjust these
prisms until specifically told to do so elsewhere in this manual.
Caution!