[Laser] Wicked Lasers Fusion (125mW 532nm) Modulation

[Chuck Hast]

On 9/20/07, Joseph Battaglia <sephail at sephail.net> wrote:
> Hey guys,
>
> I recently purchased a Wicked Lasers Fusion
> (http://www.wickedlasers.com/lasers/Executive_Series-55-3.html - the 532nm
> 125mW model) for use in a raster laser projector I'm building. I've
> successfully pulse-modulated the beam of cheap <5mW red diodes, and now I'm
> trying to use the same interface with the Fusion. I've found, however, that
> unlike some lower-power green pointers I've played with, the output of this
> laser "ramps up" to its full intensity. It takes significantly longer to do
> this than the pulse width of each pixel (a few microseconds), and so I get no
> output when interfaced to the my projecting circuitry.
>
> My questions are as follows:
>
> 1) Is the "ramping" effect due to some internal regulating circuitry of the
> pointer, or is it a characteristic of DPSS lasers?
>
> 2) Is there any way of pulse-modulating the beam by switching the power supply
> of the laser, as I have done with the <5mW red diodes? If not, what is the
> best way of externally modulating the beam? Are the LCD shutters that have a
> fast enough response time (i.e., <1 microsecond)? Etc?
>
> 3) Do pointers like this rely on the internal resistance of the alkaline
> batteries to limit current (as is the case with some LED flashlights)? I.e.,
> is it safe to use an external 3v supply with the pointer without burning out
> the diode?
>

I have observed the same thing. I have seen them with a TTL input and a
max modulation frequency of 1KHz. I am interested in much higher switch-
ing rates so did not even bother with them. I believe that this is a function
of the operation of the diodes as I notice that both green lasers I have also
have a short ramp up on turn on.

Lasermate has them, but does not indicate what the cutoff freq is:
http://www.lasermate.com/DPSSGL.htm

As to the pointers, the cheap ones do depend on the internal resistance of
the circuit and diode to operate with batteries, others have a small circuit
that does the regulation and handles the feedback diode. I have opened
enough of them and it appears that it runs about half and half for the red
lasers, have not opened that many green ones, but the few I have appear
to have a regulation circuit in there.


-- 
Chuck Hast  -- KP4DJT --
To paraphrase my flight instructor;
"the only dumb question is the one you DID NOT ask resulting in my going
out and having to identify your bits and pieces in the midst of torn
and twisted metal."