Polarity Of The Laser Diode (Ld Pol); Polarity Of The Monitor Diode (Pd Pol); Bias Voltage Of The Monitor Diode (Bias) - THORLABS ITC502 Operation Manual

2.7 Polarity of the laser diode (LD POL)

2.7 Polarity of the laser diode (LD POL)
The laser diode can either be operated with anode or cathode connected to ground.
If you have chosen the right pins of the output jack, you also have to select the right
polarity with the button LD POL in the field SETUP at the front panel.
AG means laser diode anode is connected to ground.
CG means laser diode cathode is connected to ground.
The corresponding LED indicates the selection.

2.8 Polarity of the monitor diode (PD POL)

The monitor diode can either be operated with anode or cathode connected to
ground. If you have chosen the right pins of the output jack, you also have to select
the right polarity with the button PD POL in the field SETUP at the front panel.
If the polarity has been chosen correctly the display of the photo current is positive.
If the chosen polarity is wrong the display of the photo current is negative when
driving the laser diode above the threshold current. In this case you must never
switch on the bias voltage.

2.9 Bias voltage of the monitor diode (BIAS)

If required the monitor diode may be driven with a bias voltage of 0 ... 10 V.
By pressing the button PD POL again the bias voltage is in standby, indicated by the
LED BIAS in the field SETUP at the front panel. The LED PRESET indicates that the
bias voltage is switched on and off simultaneously with the laser diode current. When
the bias voltage is present, the LED PRESET extinguishes.
ITC500 / page 36