Components added to the pcb. Fired it up and as luck would have it, worked first time.
This circuit takes advantage of the hysteresis in the switching characteristics of the 74HC14 inverter IC.
One gate is used to create a 5kHz square wave oscillator with the output charging a capacitor which is in turn discharged by a resistor the time constant of which creates the 1uS pulse through a second gate which is finally inverted through a third gate. Simple.
The upper trace shows the 5kHz oscillator output.
The lower trace shows the 1us pulses repeated every 200uS which is exactly the requirements for the Synrad 'tickle pulse'.
I am still undecided about the controller design but this circuit will at least allow me to test the laser to check that it does indeed work.
Tweakie.