Showlaser backstage

The laser projects:

The 532nM Laser:

Some of the faithfull readers of alt.lasers may remember my project a few years ago, trying to double a Lightwave Electronics model 221 laser from 1064nm operation to 532nm visible green.. Some of the project homepage i made back then is still available on Sam's laser FAQ at http://repairfaq.ece.drexel.edu/sam/lwe221/

I gave up that project before it really got going, because a lot of people told me it would be way to hard for a hobbyist like me to figure out how to double a laser like that, and because i got an offer on the old lightwave laser and the extra bits i had bought for it..

Anyway, the idea of building my own high power DPSS laser in the "up to 10 Watts" region has not been given up, and for the last couple of years i have been planning how to do it, and building support equipment for it, and not least been waiting for the components i need for it..

For the 532nm laser, the setup will be a V-fold, using a thin disk Nd:YVO4 crystal as the lasing medium. The thin disk will have a broadband HR coating on the back side, and will have that side soldered directly to a copper heat spreader, that is soldered to a TEC, that is mounted on a heatsink.
The Thin disk will be pumped by a fiber coupled 808nm diode bar. The light from the fiber will be collimated and focused on the thin disk. The pump light that is not absorbed by the nd:yvo4 crystal will be reflected off the back side of the thin disk crystal, and out of the thin disk, where it will be re-collimated, reflected and focused back onto the thin disk for another pass, to get the highest level of efficiency..

The temperature of the thin disk will be controlled by a Wavelength Electronics MPT1000 PID temperature controller:
(I dont have pictures of the thin disks yet, as i have not recieved them)

The thin disk will serve as one of the HR's in the V-fold setup. For the OC i have a choice of a flat and a 50cm cc optic (HR @ 1064, AR @ 532), and the other HR, i havent figured out yet.

The doubling from 1064 to 532 will be done by this KTP crystal:
mounted in this adjustable mount:
I still need to figure out how to make an insert for the mount, that will hold the KTP, and provide temperature control by means of a TEC.
The KTP is made by Litton airtron and should be very high quality..

For pumpuing this thin disk, i am looking at using either one or two of the laser modules being tested in the following pictures, or one of the two outputs from a Spectra physics J80 laser.
The laser module in these pictures is an Optopower (now spectra physics, no Newport, its hard to keep up :-)) diode module. It is capable of about 20W out of the fiber, but the one i have is calibrated for a maximum of 15W out of the fiber..

The laser will be build up inside this aluminum box. It is made from a 30mm thick plate at the bottom and the sides and top is made from 10mm thick aluminum.
The overall size is 50 by 30 by 20 cm. The laser(s) themselves are supposed to be build up inside the box, and the beams will shoot up vertical through two holes in the top plate, and the top plate will then serve as my laser show beam table, with the aoms, galvos, and stuff on it..

I am going to cut out two holes in the back wall of the box, and mount a couple of heatsinks outside these holes, for holding the thin disks.
The whole box will be packed in 2cm thick foam on every side and bottom for shoch protection, and mounted at the top of a mobile 19" rack, with the pump diodes and control electronics in rack enclosures below it..

(i am probably going to build another rack than this one, but it will be something like this)

For holding most of the optics in the lasers, i am going to use kinematic holders like the 3 in the middle of this picture. I am going to machine some aluminium mounts for the optics for focusing the pump light onto the thin disks, and some aluminum blocks to mount the optic holders on, so all the optics are at the same hight from the baseplate.

Well, this is where it gets really interesting..

The 635nM Laser:

When the green laser is up and running properly, the next project will be to build a 635nm dpss laser, that will also fit into the enclosure, together with the 532nm laser.
I will have an extra thin disk ND:YVO4 module, so this is going to be the basis of this red laser system. It is going to be pumped either by one more of the Optopower modules, or by the other output of a Spectra Physics J80 or similar laser.

The fundamental laser will consist only of the thin disk and a 1064nM OC mirror (Flat, 60% R).

To get 635nm out of that, i am going to use this little beauty:

This is a small crystal oven, and inside it is a 50 by 10 by 0,5 mm PPLN crystal. The crystal is an OPO and a doubling crystal in one, and it makes 635nm light from 1064nm light without even being inside the cavity. It should be capable of 3-4W output in this setup, but it does have one disadvantage; it suffers from something called "reversible photo induced ion migration", wich roughly translated means that when the laser has been on for some hours, the output fades to a very low level, untill you turn the laser off for a while, and then the power will come back up..

The crystal has to be heated to about 180 deg C. and comes with its own little temperature controller. (and before anyone starts bombarding me with emails: 1. I bought it from that special place. 2. It costs around the same as a house in the country, and 3. They dont have any more of them, and i dont want to sell mine.)

However the optical setup for this crystal is rather tricky. The 1064nm input to the crystal has to be attenuated when focusing the 1064nm onto the PPLN crystal, to avoid burning it, and this cant be done just by setting the pump diodes at lower power, because this will apparantly cause the beam to move a tiny bit, so in stead a polarizing beam splitter and a 1/4 waveplate has to be placed in the 1064nm beam, before it hits the PPLN.
Also, the 1540nm light that the PPLN produces has to be shot through the PPLN crystal several times, so this requires a somewhat tricky optical setup, that looks a bit like a ring laser.

So in the end, the complete optical setup inside the "black box" should look something like this:

This is still a sketch, and not excactly to scale, and a few things is probably going to be changed. But the general setup will be something like this..

Any help, suggestions or questions are more than welcome and i can be reached at hackmann@hackmann.dk

I hope you have enjoyed reading about my project. I will try to update this page as the project progresses, untill then you can have a look at some of the supporting equipment i have also buld, in the pictures below..

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Rebuilding a couple of Martin Mac250 moving head lighting fixtures, to be fiber fed laser projectors: