Re: My picosecond laser is flakier than your picosecond laser

Phil,

The "dead chicken" sounds like a really great idea! Maybe I could use it in
my lab?
Have you patented the process or is it a trade secret? How much are you
asking to
license the process?

Mike


"Phil Hobbs" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Having gone straight and been a CW guy all my life, I now have a bit of
> a pulse problem that I can't seem to shake.  A year or so ago, I got an
> EKSPLA tunable picosecond source, consisting of a 30-ps, 100-mJ YAG
> laser, tripled, driving a seeded OPO/OPG and difference frequency
> generator (DFG).  When it works, it is a thing of great beauty--100-uJ
> to 1-mJ in 20-ps pulses, continuously tunable from 420 nm to 10 um, with
> an inconsequential dip near 710 nm (twice the pump wavelength).  The
> pulse length is a near-perfect compromise between time resolution and
> spectral width for my application.  It can do wavelength scans under
> computer control, which is what I need it for.  And all for $150k,
> installed, and $4k per year for a service contract.
>
> When I got it, I was worried about how to keep the OPG alive, but, silly
> me, the pump laser is the killer. This gizmo has three cavities, three
> Pockels cells, active and passive mode locking, different kinds of
> feedback control, separate oscillator and amplifier rods, a Faraday
> rotator, two temperature-controlled KT*P crystals, perspulex running
> boards, liquid-sodium-cooled laser rods, four-barrel unobtainium
> flashlamps, built in subwoofer, you name it.
>
> There are three basic problems.
>
> 1.  The pulse to pulse noise of the pump laser is very inconsistent.
> When the engineer has just been working on it--he's a good guy, very
> responsive to emails, but he lives in Lithuania--it works great.
> Gradually, over a period of a week in operation or a month idle, the
> pulse-to-pulse variation gets worse and the oscillator-section pulse
> energy declines.  Changing the Q-switch dye helps sometimes, but is a
> pain.  Other times, I have to wave a dead chicken over it, adjust wave
> plates, move the beam around on the amplifier rod.  I understand how it
> works in theory, but the complexity of the interactions is very great.
>
> 2.  The aiming varies a great deal with time, or at least I have to keep
> readjusting the oscillator cavity mirrors to keep it going.  This is a
> moderately long-frame laser (about 150 cm), but it's on an air table and
> has a temperature-stabilized cast-aluminum optical bench inside.
>
> 3.  It's arranged parallel to the OPG box, so that the pump light has to
> go in a U-shaped path to get into the OPG, and the beam optics are not
> arranged as a 1:1 telescope (they have to go through vacuum cells to
> avoid air breakdown near focus).  Thus any angular error turns into
> position error.
>
> Since none of you is standing at my elbow looking at this thing, I'm not
> expecting terribly detailed help, but a sanity check would be very
> useful--is it normal for a pulsed laser to need this amount of
> babysitting?
>
> Thanks,
>
> Phil Hobbs