Rev A Nov 2017
Page 18
Chapter 3
Getting Started
3.3.11 Using the Safety Interlock and Key Switch
The Controller is fitted with a functional interlock and key switch. The key switch must
be turned on, and a short circuit must be applied across the terminals of the interlock
(pins 1 and 5) before the unit can be enabled.
If the unit is used with a Thorlabs LM14S2, LDM21, LDM56 or LDM90 laser diode mount,
the interlock connection is integral within the mount (cable CAB400 required). Alternatively,
the contact can be controlled externally; the user can connect the pins to a remote actuated
(normally open) switch (e.g. an open door indicator), which must be closed before the unit
can operate. In this case, the resistance of the connection must be <430
Ω..
The interlock input also doubles up as an external ‘Laser On’ LED driver output. For visual
indication of the laser operating, it is possible to connect an LED to the interlock input. If
this option is required, any standard LED can be used that has a forward voltage of less
than 3 Volts. Most common red, orange, yellow and green LEDs meet this condition.
Fig. 3.9 Interlock Connection Options
Note
When open circuit, the INTERLOCK pin (pin 1) is at about +5.0V. When shorted, the
current is typically 10mA.
430
Ω
No LED, interlock only
Interlock with laser ON LED
No interlock, Laser ON LED
No interlock
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