Laserscope blanking (again)

[weartronics]

Over on Sam's FAQ (http://www.repairfaq.org/sam/laserstr.htm) I read:

CAUTION: On the Laserscope or any Q-switched high power YAG (or other SS laser), don't think you can get away with blanking it (as you might want to do for laser show applications) by using the gate to the Q-switch. Some people have tried and quickly found out that it's the quickest way to destroy your optics. If you blank very quickly with your Q-switch, there is no way to get effective first pulse suppression, and you end up with giant first pulses drilling all your optics, starting with the most expensive ones. Use other means for blanking like an external galvo

The first pulse suppression on the early mods of the Laserscope Q-switch drivers (the units with the gate pulse circuitry mounted on a board exterior to the RF section) is kinda iffy. If you are thinking of using it for blanking, don't do it very fast (i.e., don't use it for blanking during a show, but turning the beam on and and off during a show, or for alignment, etc., is OK). The newer Q-switch modules have far better first pulse suppression, and I have been told by the manufacturer that you can blank up to a few hundred hertz with the Q-switch enable input, but I have not done this personally in a Laserscope type system.

I confirmed the expected operation of the FPS using an oscilloscope for DC on/off test signals, but I don't understand why the FPS operation doesn't extend to kHz frequencies. Does anybody have experience actually using the Laserscope Q-switch for graphics blanking?

Best regards,

weartronics

[weartronics]

Actually, I found a document by Sintec Optronics which can answer my own questions.

http://www.sintecoptronics.com/qswit...PSguidance.pdf

[andythemechanic]

Hi,

this confuses me, isn't the giant pulse not the thing one wants from q-switching? Why suppress it?

[mixedgas]

Hi,

this confuses me, isn't the giant pulse not the thing one wants from q-switching? Why suppress it?

yag has a upper lifetime state of 800 uSecs. It can store for a long, long time. The first time you open the qswitch and unblock the cavity, you get a massive pulse of stored energy that can pop your doubling crystal or blow a coating off a optic.

So when you start the pulse train, you want to open that floodgate in some controlled manner.

Once running in steady state, the build up time nevr gets long enough to do that again unless you stop pulseing, ie you actually run at 10 khz or more.

Steve

Steve

[Laser Zone]

Steve if you adjust the q switch freq down or up will it give you more output power ?

[Laserman532]

10 khz will give you more power, 15 khz is safer with less power, 20 is best but lower power, 25 is safest with the lowest power

I use 15khz good balance of power vs damaging optical components.

[Laser Zone]

Thanks Pat !!