Operation
41
3) Remove the 532 nm dichroic mirror set closest to the exit aperture
and install the 266 nm dichroic mirror set using the same alignment
pins and screw holes.
4) Adjust the wave plate on the second harmonic generator housing to
maximize the 266 nm energy, Figure 4-5. The adjustment that
maximizes 266 nm energy for one laser head will also maximize it
for the second laser head.
5) Adjust the external screw on the 4HG housing to optimize the crystal
angle, maximizing 266 nm energy. The crystal angle may be adjusted
using a trim pot adjustment tool. This adjustment maximizes 266 nm
energy for both laser heads.
6) Reinstall the laser head harmonic generator housing (front) cover.
NOTE: DO NOT DISASSEMBLE THE THIRD OR FOURTH
HARMONIC GENERATORS. THE CRYSTALS INSIDE ARE
HYGROSCOPIC. DUST, DIRT AND HUMIDITY WILL
DESTROY THE CRYSTALS.
Use the following procedure to remove UV harmonic generators and return
the Gemini to 532 nm operation.
1) Remove the laser head harmonic housing cover.
2) Remove the third or fourth harmonic generator.
1) Remove the 355 nm or 266 nm dichroic mirror set. Install the 532
nm dichroic mirror set.
2) Release the half wave plate set screw on the top of the second
harmonic generator housing, Figure 4-5. Rotate the half wave plate
to maximize the green energy (532 nm) output.
3) Rotate the second harmonic generator crystal to optimize the phase
matching angle and maximize the 532 nm energy. The crystal angle
may be adjusted using a trim pot adjustment tool or small
screwdriver, Figure 4-6.
4) Reinstall the laser head harmonic generator housing cover.
Return to 532 nm
operation
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