9HUVD3XOVH3RZHU6XLWH6HULHV6HUYLFH0DQXDO 7+(25<2)23(5$7,21
5(9%
The flash lamp power circuits include the HVPS, simmer/start controller, IGBT Driver PCB, capacitor bank
circuit, flash lamp IGBT’s and the flash lamps. These circuits operate together to start and simmer the flash
lamps between firings; charge the capacitor bank before firing; and then trigger the discharge of the capacitor
bank through the selected flash lamp via the IGBT.
Simmer - The flash lamps are simmered at a low current (
|150mA) between pulses simply to maintain the
electrical path to the IGBT anode side - i.e., if the lamp was not conducting (open circuit on lamp cathode side)
the IGBT could not be gated on. The lamp is simmering but the rod is not simmering. The simmer/start
controller board provides a separate simmer supply current for each flash lamp, as well as supplying a
transformer coupled RF field around each flash lamp to promote ionization of the flash lamp at turn on. The
RF field is established by connecting a transformer secondary to the cavity housing, which is electrically
isolated from the chassis. The Simmer/start board operates off of B+ supplied by the HVPS.
Charging the Capacitor bank - For the VersaPulse PowerSuite laser, the capacitor bank charges to 800 VDC.
The circuit is monitored by the Frequency to Voltage converter (U13) and is read by the main Analog to digital
converter U31 as V-F_FEEDBACK signal.
There are four identical IGBT driver circuits on the IGBT driver PCB - one for each of the four flash lamp
circuits. Each has an optical fiber input from the Controller PCB, and an output to its associated flash lamp
IGBT. All four circuits are functionally the same - the LAMP I circuit operation will be described in the next
paragraph.
To turn on flashlamp #1, the Controller PCB sends a pulse of infrared light through the optical fiber connected
to RECV 1. RECV turns on, turning on its associated AND gate U9. U9 will enable the appropriate logic
circuit, close the appropriate configuration switches and turn on the IGBT connected between B- and the
cathode of the flash lamp. The IGBT turns on, providing a discharge path for current from the capacitor bank
through the flash lamp and IGBT to capacitor return.
4.6 OPTICS
The optics include all components that act on the aiming and/or treatment beam. This includes the YAG cavity
module; YAG combining optics; folding mirrors; the energy sample optics; shutters; attenuators; aiming beam
laser and combining optics; the fiber focusing lens and blast shield.
To Next Page
Loading...
