[Laser] DPSS Laser weirdness

[Sresal]

-In some cases, I've seen the pump diode tune out of the optimal
absorption band of the Nd host if the diode gets too hot, then the
output power drops because it is wing-pumping the crystal.

On 7/3/07, Chuck Hast <wchast at gmail.com> wrote:
> On 7/3/07, Terry Morris W5TDM <w5tdm at hotmail.com> wrote:
> > Chuck,
> > I would second Bob's comments. Probably KTP SHG has become misaligned from
> > the Nd:YVO4 crystal. If this is a battery operated handheld unit, the two
> > crystals are just bonded together in some very precision fixturing. The
> > chance you can realign,hold,and then bond with the correct optical adhesive
> > is not great. At the same time you have to deal with the high power 808nm
> > pump not taking out an eye.
> >
> > Might be better to salvage the 808nm diode for Laser communications, spend
> > the repair time on doing another construction job so you can buy another
> > DPSS pointer.
> >
> > If it is not a cheap hand pointer, you might have a chance for realignment
> > if it has mechinacal adjustments on the KTP crystal.
> >
> > Good luck,
> > Terry W5TDM
> >
> >
> > >From: Bob Blick <bbblick at sbcglobal.net>
> > >Reply-To: Free Space LASER Communications <laser at mailman.qth.net>
> > >To: Free Space LASER Communications <laser at mailman.qth.net>
> > >Subject: Re: [Laser] DPSS Laser weirdness
> > >Date: Tue, 3 Jul 2007 09:00:36 -0700 (PDT)
> > >
> > >--- Chuck Hast <wchast at gmail.com> wrote:
> > > > I have a DPSS green laser, it worked fine up until a
> > > > few weeks ago, I noticed
> > > > after it was on for about 2-3 seconds the power
> > > > would drop. It is a 30mw
> > > > laser, after the power drops it is only a 10mw
> > > > laser. I checked the current
> > > > and it stays the same, so not sure if the laser
> > > > diode is at fault or if it s the
> > > > freq conversion crystals. It does it regardless of
> > > > temp. Indeed the cooler it
> > > > is the faster it appears to have the problem. Prior
> > > > to this happening it worked
> > > > just fine for as long as I kept it on (usually at
> > > > most 10 -15 seconds)
> > >
> > >Hi Chuck,
> > >
> > >Since you probably have not overheated the unit,
> > >chances are there has been some mechanical shift.
> > >Depending on the design, there is sometimes a way to
> > >tweak it. But that will require disassembly and also
> > >safety precautions to be taken to protect you against
> > >the almost 1/2 watt IR laser diode inside, like repair
> > >inside a box using a video camera.
> > >
> > >But if it's an inexpensive unit it is probably just
> > >glued together inside and there's not much hope of
> > >repairing it.
> > >
> Thanks folks. I am going to call the seller, it has  a guarantee on it so I
> will see what they want me to do. I figured that something had to be done
> with the crystals, of course the 1/2 watt diode is a fearsome device without
> protection. It has been a very handy device as I explained.
>
>
> --
> 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."
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