RTC
®
5 PC Interface Board
Rev. 1.9 e
7 Basic Functions for Scan Head and Laser Control
132
Notes
• The LASER1 and LASER2 signals are activated by
setting the pulse length to a nonzero value and
are deactivated by setting the pulse length to
zero (default setting).
• The signals LASER1 and LASER2 have a constant
relative phase shift of 180° (half an output
period). LASER2 can be used for the control of a
second laser tube. With set_laser_control
(bit#1=1), both signals can be exchanged with
each other. To control laser power, the pulse
length of the LASER1 and LASER2 signals can be
varied. Both signals share the same pulse lengths
and output frequencies.
•Note that half of the output period must be
specified for the LASER1 and LASER2 signals, i.e.
the shift between the two laser signals.
•The commands set_laser_pulses and
set_laser_timing are list commands. They can be
used within a list, for instance, for changing the
laser power at any time between two list
commands.
• The actual output period and the pulse lengths of
laser signals LASER1 and LASER2 (but not the
laser delays) are dependent on the time base.
For RTC
®
5 mode, this is fixed at 64 MHz (1 bit
equals 1/64 µs).
For RTC
®
4 compatibility mode (for “laser active”
operation), the time base can be set via
set_laser_timing (but not via set_laser_pulses
or set_laser_pulses_ctrl) for either 1 MHz (1 bit
equals 1 µs) or 8 MHz (1 bit equals 1/8 µs). For
RTC
®
4 compatibility mode, SCANLAB generally
recommends setting the time base to 8 MHz (via
set_laser_timing(..,..,..,1)
). A time base of
1 MHz should only be chosen if necessary.
The time base for standby signals is always
1/64 µs (in RTC
®
5 mode) or 1/8 µs (in RTC
®
4
compatibility mode).
The command set_laser_control (bit#0) can be used
to specify whether a (for “laser active” operation)
started modulation pulse (LASER1 or LASER2) should
execute to completion or be cut off when it has not
yet fully executed when the LASERON signal is
switched off (see figure 48). This cannot be specified
for standby signals; if applicable, these will be cut off.
7.4.4 YAG Modes
With set_laser_mode( [1, 2, 3 or 5] ) one can choose
between four different YAG laser control modes. The
laser control timing diagram figure 49 on page 134
shows the corresponding signals.
In all four YAG modes, for “laser active” operation (if
applicable after a LaserOn delay and if enabled via
set_laser_control or enable_laser)
• The LASERON signal is switched on,
•A Q-Switch signal with variable pulse length and
frequency is provided at the LASER1 output and
• A programmable FirstPulseKiller signal is
provided at the LASER2 output.
For “laser standby” operation (if applicable after a
LaserOff delay)
• The LASERON signal is switched off and
• Standby pulses are provided at the LASER1
output (but not at the LASER2 output) with pulse
lengths and periods that can be defined via
set_standby or set_standby_list.
The LASER1 signal is activated by setting the pulse
length to a nonzero value and is deactivated by
setting the pulse length to zero (default setting).
Q-Switch Signal
The Q-Switch signal is available for control of the
laser’s Q switch. The Q-Switch period and pulse
length are set with the commands set_laser_pulses,
set_laser_pulses_ctrl or set_laser_timing.
Notes
•Note that half of the Q-Switch output period
must be specified.
• The actual Q-Switch output period and the pulse
length (but not the laser delays) are dependent
on the time base.
For RTC
®
5 mode, this is fixed at 64 MHz (1 bit
equals 1/64 µs).
For RTC
®
4 compatibility mode, the time base can
be set via set_laser_timing (but not via
set_laser_pulses or set_laser_pulses_ctrl) for
either 1 MHz (1 bit equals 1 µs) or 8 MHz (1 bit
equals 1/8 µs). For RTC
®
4 compatibility mode,
SCANLAB generally recommends setting the time
base to 8 MHz (via
set_laser_timing(..,..,..,1)
). A time base of
1 MHz should only be chosen if necessary.
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