- Laser Current Feedback
- Auxiliary Feedback to Temperature or PZT
- Double Integrators to Eliminate Drift
- Peak Lock Option
- Smooth Lockup
- Frequency Jumping and Lockup via Computer Control
- Internal Ramp Generator
- High Bandwidth (10 MHz)
- Reconfigurable PI2D Loop Parameters
- Lock Guard & Ramp Centering included on all models
Lock Guard monitors the servo output and when it detects an Unlock Point (a fast change in the servo output; see arrow on the red trace), it disengages the servo and returns the output to the last known valid value. Lock Guard waits for the Hold Time (shorter interval on blue trace) and then re-engages the lock. Lock Guard waits for the Settle Time (longer interval on blue trace) and if it detects that the system is still out of lock it will reset the servo output again. In the image, Lock Guard made three relock attempts before the challenge was removed and relock was achieved. (The beam was actually blocked and unblocked during this time.) The Lock Guard control parameters Unlock Point and Hold & Settle Times are all user adjustable for maximum flexibility and optimized performance.
The D2-125 has the flexibility to optimize its performance for your experiment. The Peak Lock option provides an adjustable-amplitude 4 MHz dither which can directly modulate a diode laser or drive an external modulator. The incoming error signal is then demodulated at this same 4 MHz (with adjustable phase.) The resulting first derivative error signal allows the user to lock a laser to the peak of the error feature instead of the side without the implementation of an external modulator and lock-in amplifier, simplifying and reducing the cost of many experimental configurations.
In most cases, the D2-125 will be powered by the D2-005 linear power supply. The D2-005 will power up to 4 servos or D2-100 lasers and so is quite convenient. But some situations call for a dedicated servo with a small footprint. The Internal Power option integrates a smaller linear supply into the D2-125 chassis, minimizing precious space needed for the locking electronics.
Ramp Centering is now included on all units and allows the user to bias the servo output while preparing the system for lock up. This is useful, for instance, when servoing a PZT or other transducer that does not operate around a zero set point.
View a typical configuration of a D2-125 servoing a D2-100-DBR laser.
D2-125 Demonstration Videos:
|Bandwidth||> 10 MHz|
|Input Impedance||50 Ω|
|Input Voltage Noise||< 5 nV / √ Hz|
|Output Voltage||±10 V|
|Proportional Gain||-40 to +32 dB|
|ωI (Integrator One)||Off, 10 Hz – 200 kHz|
|ωPI (Integrator Two)||Off, 100 Hz – 2 MHz|
|ωD (Differential)||Off, 500 Hz – 10 MHz|
|Differential Gain||5 to 15 dB|
|Temp. / PZT Output||Integral: 60 msec to 6 sec|
|DC Error, AC Error, Input, Ramp, Ramp TTL, Servo Output|
|-IP||Internal Power Supply. (Please specify input line voltage.)|