Laserscope pulse duration and repetition rate?

[dave]

Does anybody have an idea of the pulse duration for one of these?

Repetition is around 20hHz right?

Also, what IR powers can I expect, peak and average on a ceramic cavity beastie?

[weartronics]

Hi Dave,

If you have the NEOS Q-switch driver, the rep. rate is adjustable from 100 Hz to 100 kHz. If you have the Crystal Technologies Q-switch driver, the rep. rate is adjustable from 6 kHz to 12 kHz. The actual pulse duration depends on a combination of pump power and rep. rate. Also, remember that the pulse shape is like a lumpy decay, it's not close to square.

For beams (where you don't care about the relationship between the Q-switching and the artwork), you can tune the rep. rate for maximum average power. For graphics, you probably want to turn the rep rate up to 15-20kHz to minimise the dotted-line effect (at the cost of slightly reduced average power).

The physics dictates that to get the maximum average power, you will have to suffer some off-time. If you modulate the Q-switch using e.g. the DAC intensity channel, you can choose where the off-time is though. That would let you move the dots and dashes around in alternating frames and other effects. I haven't actually tried this, so I don't know if it's worthwhile in practice.

The Kuizenga patents have some charts of lamp current vs. intra-cavity power. I think you should expect something like 100-150W of intra-cavity 1064nm.

Best regards,

weartronics

[LesioQ]

Hi,

I think trying 100 Hz repetition is like asking for troubles as these will be very strong pulses, being able to burn coatings on optics. If equipped with FPS, such slow pulses would be shallowed by FPS, so not much of use.

For my ex-setup (now sold) I was using 4kHz-50kHz repetition, with constant 2us RF-off time. Peak avg. power was around 12kHz. Single NE555 was used.

Piotr.K