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The polarizer is permanently aligned to transmit vertically polarized
light. This maintains the polarization of the IR light as emitted from the
IR head in the standard configuration.
The 1064 nm laser pulse exits the IR head and then different harmonic
wavelengths may be generated if these options have been installed. The
second harmonic at 532 nm is generated by passing the IR beam through
an angle tuned KTP crystal. The Tempest uses Type II phase matching
in KTP to generate the second harmonic, so the polarization of the IR
beam must be adjusted to maximize SHG intensity. Dichroic mirrors
separate the second harmonic from the fundamental light and direct the
beam to the output port. The second harmonic light is vertically
polarized.
The third harmonic at 355 nm may be generated in the Tempest if the
option has been purchased and installed. The third harmonic at 355 nm
is generated by combining one photon at 532 nm with one photon at
1064 nm. Third harmonic generation is accomplished by Type I phase
matching in BBO. The second harmonic must be detuned slightly to
achieve the maximum third harmonic conversion efficiency. The third
harmonic light is separated from the fundamental and second harmonic
using a pair of dichroic mirrors. The third harmonic light is vertically
polarized.
The fourth harmonic of Nd: YAG at 266 nm can be generated by
doubling the 532 nm second harmonic light. This is done by placing the
correct BBO crystal in the optical path and combining two photons at
532 nm to give one photon at 266 nm. The light at 266 nm is separated
using a pair of dichroic mirrors to select only the fourth harmonic light.
The fourth harmonic light is vertically polarized.
The Tempest Nd: YAG laser system can be controlled externally by a
computer using the TTL direct port. TTL commands can be sent to the
laser power supply through the female DB 25 connector.
One internal interlock, one external interlock, and one mechanical
shutter provide protection to the user(s). Opening the laser head trips the
internal interlock. The external interlock connector is located at the rear
of the power supply, and can be shorted with the supplied connector.
The user can install safety interlock to the door or some other device to
provide increased safety when using the laser.
Second Harmonic
Generation
Third Harmonic
Generation
Fourth Harmonic
Generation
External
Computer
Control
Safety
Interlocks
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