Stanford Research Systems LDC500, Руководство по эксплуатации и обслуживанию

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2.3 Operating the Laser Diode Driver 2 – 15
width controls the intrinsic bandwidth of the current source,
and limits the response to analog modulation. The e
ff
ective
output impedance of the current source is higher (sti
ff
er) in
high-bandwidth mode, but this comes at the cost of slightly
higher current noise. For lowest output noise, select [0].
The next configuration menu items are specific to the photodiode
circuit, and are optional for CC mode since photodiode feedback is
not involved in this mode. To properly configure a photodiode for
monitoring purposes in CC mode, see section 2.3.4
2.3.2 Laser settings
Press the [Set] button to select the LD Settings menu tree.
•
Press [ ] repeatedly to reach the top of the menu tree.
•
Press [ ] to the “LD Ilim:” item. Enter the desired current limit
(in milli-amperes) for your laser diode, and press [Enter] to
accept. The laser current will be limited to this value at all
times, including when adding analog modulation.
•
Press [ ] twice, to the “LD Vlim:” item. Enter the maximum
voltage for your laser diode. The LD driver will uncondition-
ally shut down if the operating voltage on the laser diode ever
exceeds this value.
•
Press [ ] repeatedly to return to “LD I:”.
Now
you may enter
the desired operating current, followed by [Enter].
2.3.3 Operating the laser in CC mode
Before turning the laser driver on, determine whether active TEC
cooling is required for your laser. If so, turn on the TEC controller
and wait for the temperature to stabilize (see section 2.2). To turn on
the laser driver, press the [LASER On
/
O
ff
] button. This will begin a
3 second delay period, during which the LASER ON indicator will
blink. To abort turning the laser on during this delay, press [LASER
On
/
O
ff
] again. Once the delay is completed, the shorting relay will
be heard to open, and the laser current source will quickly ramp up
to the programmed current setting.
To change the current setting, press [Set] to navigate to the LD Set-
tings tree, and navigate (with [ ]) to the “LD I:” item. Enter a new
current setting (either with the numeric keypad or the wheel) and
press [Enter] to accept.
Output current can be dynamically adjusted with the wheel by press-
ing the [Live Entry] button, entering “live” mode. Pressing any key
LDC500 Series Laser Diode Controllers