Laser Diode Driver LD8000
8
Ver. 1.0
Interlock
The interlock safety feature implements a possibility to turn the
laser off, when a remote switch is beeng activated. For example, a
door switch turns the laser off, when a person enters the room. The
jack is a standard 3.5mm mono phone jack (TS). The switches
should be of the normaly closed type.
Multiple switches can be used by series connection (wired-AND).
If the feature is not needed, a shorted dummy jack should be
plugged into the connector (one is shipped with the device).
Figure 7. Interlock connector
pinout
Photo diode input
The voltage at the inner pin of the BNC connector 10 (Figure 4) is measured and converted to a
digital value. The constant power function holds this value by tracking the target current.
Please note, that the value representing the photo diode signal is neither calibrated nor it has a
unit.
Some custom modifications may have this signal internally connected to pin 23 (Figure 6) of the
laser head connector. In such cases, the photodiode is integrated into the laser head, and a high
impedance input voltmeter or scope can be connected to this connector to monitor the power.
Modulation input
In external analog modulation mode, voltage at the inner pin of this connector is converted to
diode current with amplification ratio of 2 Amperes of diode current per 1 Volt modulation
voltage.
TTL output
In pulsed modes (internal or external), the level at the inner pin of this connector indicates
wether the laser is driven with the Target current (High) or the Base current (Low).
TTL input
In external pulse mode, the level at the inner pin of this connector determines wether the laser
should be driven with the Target current (High) or the Base current (Low).
In modes with internal pulse generation (s. 4.3 Laser modulation modes) and enabled gate mode,
the level at the inner pin of this connector determines wether pulses of Target current (High) or
the Base current (Low) should be driven through the laser.
Indicators
All buttons on the front panel have integrated LEDs, indicating the state.
•
The laser ON indicator (7) lights green, when the laser is on.
•
The laser OFF indicator (6) lights red, when the laser is off.
•
The buttons Up, Down and OK are enlighten blue, if their operation makes sense in the
current state. These indicators are dimmed, if manual control has been disabled by remote
control.
