C O M M A N D R E F E R E N C E
GPIB Command Reference
02_03
LDC-3926339
53
C H A P T E R
4
The LASER:MDI command sets the laser monitor photodiode current (MDI) setpoint.
Parameters
An <nrf value> which represents the photodiode current setpoint, in
µ
A.
Notes
In constant monitor diode current ("MDI") mode, the output current is controlled so that the monitor
diode current remains constant at the MDI setpoint. See the "Laser:Mode" command for more
information.
Monitor diode current is sometimes referred to as "photodiode feedback current". On the front
panel, monitor diode current is referred to as IPD.
Examples
Laser:Mdi 40-action: The laser monitor photodiode current setpoint is set to 40
µ
A.
Laser:MDI 200.5-action: The laser constant-monitor photodiode current setpoint is set to 200.5
µ
A.
The LASER:MDI? query returns the value of the laser photodetector (monitor photodiode) current
measurement, in
µ
A.
Parameters
None. The response is an <nrf value>.
Notes
The response is in
µ
A, and is valid even when the unit is not in MDI mode.
This measurement is updated approximately once every 600 msec.
Examples
Laser:MDi?-response: 57.3, means 57.3
µ
A of photodetector current was measured in the laser
monitor photodiode circuit.
The LASER:MDP command sets the value of the laser optical power set point, in mW.
Parameters
An <nrf value> which represents the optical power setpoint, in mW.
Notes
In constant optical power ("MDP") mode, the output current is controlled so that the optical power
remains constant at the MDP setpoint. See the "Laser:Mode" command for more information.
If CALPD is 0, the actual MDP set point will be approximately 0.
On the front panel, the monitor photodector power is referred to as PPD.
Examples
Laser:Mdp 40-action: The laser power setpoint is set to 40 mW.
The LASER:MDP? query returns the value of the laser photodetector power measurement, in mW.
Parameters
None. The response is an <nrf value>.
Notes
The response is in mW. The response is valid, even when the unit is not in constant power mode.
This measurement is derived from the monitor photodiode current (MDI): it is calculated by dividing
MDI by CalPD. If CalPD is 0, this query returns a -1.0. This measurement is updated approximately
once every 600 msec.
Examples
Laser:MDp?-response: 100.0, means Laser's optical power is calculated to be 100 mW.
LASER:MDI
LASER:MDI?
LASER:MDP
LASER:MDP?
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