40 Chapter 4 Laser Diode Driver Module Operation
4.2 Laser Safety Features
4.2.1 Conditions Which Can Automatically Shut Off the Laser
Output.
• Laser Open Circuit
1
• Laser Compliance Voltage Limit
1
• Laser Hard Current Limit
1
• Laser Interlock State Changed
1
• Laser Photodiode High Current Limit
• Laser Photodiode High Power Limit
• Laser Intermittent Contact (if enabled, default disabled)
• A Linked Function
With the exception of the linked functions, some of these conditions can be disabled
by clearing the appropriate bits in the Laser OUTOFF register. See the Computer
Interfacing Manual for additional information on the OUTOFF register.
4.2.2 Key switch Interlock
The
LASER ENABLE
key switch on the front panel will shutoff, or not allow to be
turned on, any laser outputs while in the OFF position, per CDRH requirements.
1
This condition will always shutdown the laser output, and cannot be disabled.
PD Anode
(pin 7)
.1 uF
.01 uF
LD Anode
(pin 8,9)
LD Cathode
(pin 4,5)
(pin 6)
PD Cathode
EGND
(pin 3)
LDD Connector
D-Sub 9
.1 uF
LD
PD
1
2
3
3.5 uH Ferrite Beads
Mouser P/N 542-FB73-287
Figure 21 - Laser Diode Protection Circuit
When applying high
speed modulation to the
laser diode, this circuit
will reduce the maximum
modulation frequency.
Note: The temperature controlled
mount is earth grounded through pins 5
and 6 of the TEC connector D-sub 15.
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