01cooperl:
I am trying to output a predefined analog pulse with a duration of ~0.5ms from an Arduino Uno I have recently bought.
The term 'analog' can mean many different things, especially in an Arduino environment where it can also mean a PWM square wave output, which is not at all what most people expect 'analog' to mean.
Can you explain exactly what sort of output you're trying to produce? Are you trying to generate a variable DC voltage, reproduce a wave form, output a sequence of digital pulses, or what?