© 2015 Thorlabs
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LDC200C Series
3.8 Disabling the Beeper
If audible signals are unwanted, the beeper can be disabled in this way:
·
Press and hold the key “UP” (F18).
·
Press the key “Down” (F17). Now the beeper state is displayed:
·
“Sd.On” - Sound ON
·
“Sd.OFF” - Sound OFF
To change the beeper state, hold the key “UP” pressed and toggle the beeper state by pressing
"DOWN" key.
3.9 Remote Operation
Although the LDC200C Series Controllers do not provide a standard computer interface, a
limited remote operation is possible using the TTL input or the analog inputs and outputs.
The following control or read out functions are available:
LD REM
This digital input allows to switch on/off the laser independent of the key “LASER ON”. A rising
edge at this input switches the laser on (if being in off state), a falling edge switches the laser
off (if being in on state). The threshold voltages are TTL compatible and feature hysteresis.
When using the “LD REM” input, the key “LASER ON” remains fully functional.
Interlock
If a relay contact or an open collector transistor is inserted into the interlock line (refer to section
"
"), the output can be switched off remotely at any time.
Note
The interlock is usable only for switching off. After the interlock path was interrupted, the
LDC200C Series Controller can be switched on again only manually, provided the Interlock is
closed.
Setting the laser diode current
The analog modulation input “MOD IN” input (R2) is DC coupled; the input voltage ranges from
-10V to + 10V. The input resistance of the input “MOD IN” is >10 k
W
.
A voltage applied to this input is converted to a current value, which is then superposed to the
LD set value, adjusted with the rotary knob F9. The conversion coefficient depends on the max.
nominal output current of the controller and can be calculated to
k
MOD
= I
max
/10V
[mA/V]
where I
max
is the max. output current for the given controller.
Example:
For a LDC202C with a max. output current of 200mA the conversion coefficient k
MOD
is equal to
20mA/V.
If the adjusting knob (F9) is set to it's left stop position, corresponding to a zero injection
current, the laser diode set current value can be controlled externally by an analog DC voltage
of (0...+10) V applied to the “MOD IN” input (R2).
If knob F9 is at its right stop position (corresponding to the max. injection current), a DC voltage
of (-10…0) V can be used to decrease the injection current.
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