2 – 14
Getting Started
2.3
Operating the Laser Diode Driver
On the front panel, the “Laser Diode Control” block has five buttons
(see Figure 2.6).
Figure 2.6: The Laser Diode Control block.
The laser control mode can be set to CC (constant current) or CP
(constant power). In CP mode a photodiode is required to sense the
optical intensity. By pressing the [Current
/
Power] button, you can
toggle between modes. For this example we will assume CC mode.
2.3.1
Laser driver configuration
Press the [Config] button to select the laser diode (LD) configuration
menu tree. Here the LD driver will be configured appropriately
for your laser diode. Configurations include output current range,
working bandwidth, photodiode bias voltage and responsivity, and
more.
•
Press [ ] repeatedly to reach the top of the menu tree. Press
[0] to select low range (0 – 250 mA), or press [1] to select high
range (0 – 500 mA). Press [Enter] to accept. The wheel can also
be used to make these selections. The range is indicated by
the
250 mA
or
500 mA
indicator illuminated at the upper right
block of the LDC500, just above the wheel.
•
Press [ ]. Press [1] to enable the analog modulation input,
or press [0] to disable modulation. For optimum noise per-
formance, leave modulation disabled except when needed for
actual analog modulation control.
•
Press [ ] to the “CC BW” item. Press [0] for low bandwidth (DC
– 10 kHz), or [1] for high bandwidth (DC – 1.2 MHz). Band-
LDC500 Series Laser Diode Controllers
