
B–70115EN/03
E. CONTROL SEQUENCES
IN LASER OSCILLATOR
APPENDIX
451
[SQ 10]
This is the state after power is turned on in which intra–tube gas pressure
equals atmospheric pressure.
[SQ16, 17, 18]
Setting the laser start switch (RUN) to ON starts evacuation, which
continues until the pressure designated by PRM No. 15240 [235]
(evacuation completion pressure) is reached. As soon as this pressure has
been detected, gas pressure control is applied. Then, the intra–tube
pressure increases to that designated by PRM No. 15241 [237] (intra–tube
pressure setting at the start of discharge) and is stabilized there. Forty five
seconds after the start of pressure control, the intra–tube pressure is
checked to confirm whether it conforms to the value set with PRM No.
15241 [237], an error of "20 (="266 Pa) being allowed. If the error
exceeds the allowable range, an alarm is issued. Once this check has been
completed the turbo blower starts, reaching the specified speed within
about 70 seconds. Once the specified speed has been reached, LRDY is
set to 1, at which point the laser enters the discharge start preparation
completion state. If the frequency reached signal is not issued by the
inverter within 120 seconds of the turbo blower being started, an alarm
is issued.
[SQ 20]
This is the state of discharge start preparation completion (LRDY=1) and
HV(high voltage command) is read.
[SQ 26, 27, 28]
This sequence begins when HV is turned on after discharge start
preparation completion (LRDY=1).
Applying high voltage leads to base discharge in the tube. Gas pressure
control begins simultaneously and the pressure changes from the value of
PRM No. 237 to the one of PRM No. 236 (intra–tube pressure at base
discharge). The error tolerance is "100 (="1330 Pa). When it is so, the
calculation of power calibration coefficient begins and if not so alarm
appears.
[SQ 30]
This is oscillation preparation completion state(LSTR=1) in which laser
oscillation is ready.
[SQ 23]
By turning off HV, intra–tube pressure shifts from the value of PRM No.
236 to the value of PRM No. 237. Here discharge is extinguished and
laser leaves oscillation preparation completion state and enters discharge
start preparation completion state.