Build a grating stretcher and an autocorrelator

I did this a while ago.

with the autocorrelator’s rough construction. I still need to write the software for it, though.

Plus, I am in the process of building a stretcher for my green light, not the IR. I’ve got the optics down on the table, just need to align them. I will lose about 50% of my light, here…

Anyway, I found out that the pulse as it stands is about 10ps long out of the laser with the stretcher already in there. That’s a lot longer than I thought it was. I can even stretch it longer in the laser.

Hmmm. Not sure how to take all of this. At least I can build an autocorrelator.

I’ve now more or less built both the autocorrelator and the stretcher. I just need to align them and write the software and then I’m done.

Turns out that there’s a company which manufactures extremely good holographic gratings whose efficiencies are identical to those of ruled gratings—nice thing is that the grooves/mm are higher, so my stretcher will not need to be nearly as long as I thought it was.

There might be a longer lead time (the ruled ones would be ready to ship on the 17th of July, I’ve been told), but it would be totally worth it—it’s the difference between having to use up 20cm of table space or 2m of table space, and table space is at a premium right now…

I have to talk to the boss-man today and see what he says; the orders and everything need to be done by the end of the day or else we face a restocking fee!

I don’t have enough bandwidth for it to matter, and as my meeting with the Boss Man elucidated yesterday, what would I do even if I knew the chirp of the pulse? In fact, why would I even care? An autocorrelator is much cheaper, though it still costs about $5000 to assemble.

As far as the autocorrelator goes, I’ve almost received all of the parts. All of the orders have been made (save for the breadboard, which I will order after it has been assembled). I can’t wait to start building it!

I have a 1800grooves/mm grating blazed for somewhere in the visible that I can use to build a temporary stretcher while I wait for my IR-blazed grating to come in. It should also show me if this is the means by which to fix all these problems I am having damaging samples, and it will at least be educational as far as learning how these things are built.

Got all the part numbers figured out, as well as the required distances. I just need to get my boss’s approval on the purchasing (it will cost mucho dinero), then send in the orders and wait for the parts to start building!

Now that the laser is repaired, I’ll be able to really get the shear waves and DAC goals on the road, I think. But, both of them would profit by some means to increase the pulse duration, which is 3.5×10^-13 seconds long. If I can extend it to 2×10^-10 seconds, then I’ll probably stop frying my samples… and I REALLY don’t want to fry the diamonds of the DAC!

To build the grating stretcher, I should:

Compute the needed GVD with the 10nm of bandwidth I have.
Get the right grating with the right number of grooves/mm and a blaze for 1030nm light.
Build it in the folded geometry!

Now, a FROG (Frequency Resolved Optical Gating) is a means by which to characterize the pulse and make sure that I’ve done with it what I need to (i.e. to make it 200picoseconds long). In order to do this, I need to:

Get a spectrometer centered at 515nm or so
Get a computerized translation stage with the right amount of travel
Write the software
Get the optics (mounts, BBO crystal cut for 1030nm, etc)
Get a breadboard and build it

The autocorrelator would be the same thing as a FROG, just a photodiode instead of a spectrometer. So, maybe I’ll start with that…