The answer to your question is right there in the terminology. A pulsed laser is one that emits a series of short pulses rather than a continuous output. Continuous output is self-explanatory.
A pulsed system is typically capable of a much higher maximum power output, but the average output is lower than a CW system. Pulsed lasers can burn if their power is high enough, but for most hobbyist purposes, CW is the way to go for burning power. Visibility can be affected by pulsed operation, but it depends on the frequency of the pulses. The faster the pulses, the more visible the beam.
Pulsed lasers can deliver very high power in a single pulse, but the higher the power, the lower the frequency, and the shorter the pulse. Although it is possible to construct a laser that gives insanely high power, but in a microsecond pulse with ten second cooldown. Good for laboratory purposes, but hobbits should stick with CW
With an Arduino controlling the voltage, or some other analog input control, it should be possible. For example those lab-style lasers on DX that have TTL inputs, they could be given a circuit there that tailors the voltage/current to a sinusoidal form.
Isn't TTL just 5V on and 0V off? :/
But anyway, a sin function takes values between 1 and -1.In the case of AC , these values are multiplied by whatever values, but a laser can't have a negative output so you could only have a pseudo sinusoid that oscilates between max and 0.
Okay, my mistake, it might be binary. However, you could use an Arduino shield to give the laser analog varying voltage.
And yes, it would be between 0 and 100%, no negative, but that's purely academic in our case. You could introduce a rectifier that would make use of the other half of the function, but that would only double the laser repeat frequency though...