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Home Electro-optics Avalanche Transistor-based Pockels Cell Drivers Q-switch Driver PCD-04

Q-switch Driver PCD-04

Generation of quasi-rectangular, High-Voltage Pulses for the control of E-O Q-switches (Pockels Cells) in a Solid-State Laser.

Driver can be used for ultrafast optical beam modulation and deflection, control of laser regenerative amplifiers and pulse pickers.

Distinctive Features

  • High-Voltage Pulse is formed by a symmetrical, bi-polar output in «Switch-on» Operational mode;
  • HV amplitude up to 6kV;
  • Nanosecond rise and fall times;
  • Controlled pulse duration;
  • Pulse jitter is less than 500 psec;
  • Built-in pulsed high voltage source;
  • Pulse amplitude adjustment by trimmer or external analog signal;
  • Trigger pulse 5 V, impedance 50 Ω;
  • Pulse repetition rate up to 1000 Hz;
  • Excellent pulse-to-pulse stability.

Technical Specifications

    • Output voltage amplitude1 ………………………………………………………………..  3200 ÷ 5800 V
    • Output voltage pulse-to-pulse instability ……………………………………  1 %
    • Max pulse current …………………………………………………………………………………  40 A
    • Max load capacitance ………………………………………………………………………….  30 pF
    • HV pulse rise time2 ………………………………………………………………………………  1 ÷ 2 nsec
    • HV pulse fall time2 ………………………………………………………………………………..  1 ÷ 2 nsec
    • HV pulse duration3 ………………………………………………………………………………  40 ÷ 1000 nsec
    • Max HV pulse repetition rate …………………………………………………………..  1 kHz
    • Trigger voltage (input impedance is 50 Ohms) ………………………..  4.5 ÷ 5.5 V   (+5V)
    • Output pulse delay vs. trigger pulse 4 ………………………………………….  10 ÷ 20 nsec
    • HV pulse jitter ………………………………………………………………………………………..  < 0.5 nsec
    • External powering requirements:
    • DC supply voltage…………………………………………………………………………………. 4.75 ÷ 5.25 V   (+5V)
    • DC supply current ………………………………………………………………………………..  400 mA max
    • Operating temperature range ………………………………………………………….  –40 ÷ +60 °C
    • Dimensions (see dimensional drawing below)…………………………. 80 × 50 × 12 mm3
    • Mounting hole pattern (Æ3.2 mm) ………………………………………………..  74 × 44 mm

1 Is set from the built-in potentiometer.
2 Depends on the load impedance and output voltage amplitude.
3 Determined by an external trigger-generator.
4 Delay depends on the trigger pulse. The shorter trigger rise and higher trigger amplitude the shorter delay.

Connector J1 (input) – DF13-6P-1.25H (Hirose):
Pin 1   – power supply + 5V & 400 mA max;
Pin 2   – power supply GND;
Pin 3   – trigger input +5V; input impedance 50Ω; duration >40 nsec;
Pin 4   – trigger GND;
Pin 5   – measurement of the output voltage amplitudes; DC voltage scale 1:10000;
Pin 6   – output voltage measure GND.

Connector J2 (output) – SM02B-BHSS (JST):
Pin 1   – first high voltage output;
Pin 2   – second high voltage output.

Pins 5 and 6 can be used for the remote adjustment of the HV pulse’ amplitude relative to the value set by potentiometer RV46 within a range of +2% to -20%.

That is, if a voltage of U=0V is applied from the external source to pin 5, – then HV amplitude would be ~2% higher than nominal setting.If U=5V is applied to pin 5, then amplitude would be lower by ~20%. The input impedance of the pin 5 is ~45kΩ.

BLOCK DIAGRAM OF PCD-04 – PULSE DURATION IS DETERMINED BY THE TRIGGER PULSE

 

TIMING DIAGRAM OF MODIFIED PCD-04 FOR TWO-STEPS, HALF-WAVE VOLTAGE APPLICATIONS IN THE REGENERATIVE AMPLIFIERS (RA)

PULSE I [V(λ/4)] – INJECTION SEEDING OF THE RA
PULSE II [V(λ/2)] – EJECTION (“DUMPING”) OF THE AMPLIFIED LASER PULSE OUT OF RA

As an option, the driver PCD-04 can produce HV pulses of a different polarity, if duration of the trigger-pulse exceeds 50 μsec. If rectangular trigger pulses of 500 μsec duration are applied with 1 msec period, then driver will produce HV pulses of the opposite polarity with frequency 1kHz (see Fig. on page 4). This will require 12 VDC supply and a conventional pulse generator.

OUTPUT WAVEFORM OF PCD-04 (TRIGGER PULSE DURATION > 100 μsec)