OsTech electro-optical-instruments Laser- und ... - Hy-Line

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� The External Pulse-Mode will run by entering the 'LMDX'-command. If this tag is
activated and the laser-current and compliance voltage is entered as in CW-Mode
you can run the laser by the 'LR'-command. The laser then is activated with an TTL
high-level at the DMOD input and vv. . With the 'LMDXN[R|S]'-commands you may
negate these logic, that means: the laser will be activated by TTL low-level.
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� The Analog Modulation-Mode will run by entering the 'LMAX'-command. If this tag is
set and the laser is activated by the 'LR'-command, the compliance Voltage must be
set before, the laser current can be controlled by the voltage at the AMOD input
with 0.5V/A.
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(in cw-mode!)
The Power Control Loop consits of two independent parts:
1. The photo current control loop, which works independent and
2. The Laser Power top, which in fact does nothing than a translation from
a power value into a value for the photo current
To initiate the Power Control you must first prepare the laser for proper operation
in cw-mode. Don't forget to adjust the Laser Current Limit.
When the laser runs you must connect the photosensor between the PDC-(Cathode) and
the GND(Anode) pins at the laser connector. After this you should test whether the
sensor works well. For this run the laser and check with the 'LPCA'-command (Laser
Photo Current Actual) it's operation. The maximum photo current is (default) 700µA,
but can be increased on request.
When all this is working start the 'LPCCC'-command (LaserPhoto Current Calibration),
the driver searches about 1 minute for the threshold current, the slope and internal
offsets. After this the control loop is working already with photo current values.
Give in your target photocurrent with 'LPCT'-command. Initialise the photocurrent
control mode by 'LPCCR'-command (Laser Photo Current Controll Run). Now you have
merely to run and stop the laser by 'LR' and 'LS'.
In the moment you start the laser the current is setup with a target photo current
calculated by the found coefficients, so that (power) is initiated at once. After
this the driver begins continuosly to track and guide the photo current.
The second step is to adjust the power coefficients, so that you can use power
values in Watt. For this:
1. Adjust a 'LPT'-value (Laser Power Target), it should have a typical or a maximum
..value
2. Now run the laser in normal cw-mode and set up the current until the laser
emitts exact the target laser power. An external power-meter is necessary for
this. Now execute the 'LPF'-command to fix the actual photocurrent value to
this laser power.
Now you can get the laser power by 'LPA'-command, set the power target by
'LPT'-command, run the power control mode by 'LPCCR'-command. Start and stop the
laser by
'LR' and 'LS'.
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