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Is it possible to use a laser with built-in pre-chirp instead of using the external, custom prism-based pre-chirp?

At 970nm, we found that >35,000 fs2 of negative GDD was necessary to fully compensate for the GDD of the whole microscope system.  As far as we know, this far exceeds the amount that any commercial pre-chirp can provide, whether it's a stand-alone device or internal to a laser, which is why we implemented our own custom prism-based prechirp that can have a very large (~8ft) separation between prism passes.  A system that can only provide half of that negative GDD (-17500 fs^2 @ 970nm) would result in 100fs pulses being stretched to ~500fs at the brain, dramatically lowering signal level.

It is possible to sequentially add pre-chirps, so it might be possible to achieve the necessary GDD by combining a laser-internal pre-chirp with a commercially available external pre-chirp.

One must be careful when looking at negative GDD specs, as they are highly wavelength specific.  Pre-chirps can provide much more negative GDD at bluer wavelengths than red.

What is the smallest air table that can be used with the 2p-RAM?

All tables must be at least 4 ft wide to accommodate the 2p-RAM cage.

4'x9': This is the size of the table used for the 2p-RAM workshop.  It provides a comfortable amount of room.  In addition to a Chameleon or Mai-Tai-type Ti:Sapph laser and the prism-based pulse pre-chirp, a Fidelity fiber laser and also a few, small lasers for fiber-coupled photostimulation can fit onto it without much effort.

4'x8': This is still pretty comfortable, as long as the Fidelity laser isn't needed.  Smaller lasers can definitely go inside the 2p-RAM cage.  It's probably possible to add the Fidelity inside the cage as well, but there might be an issue with its height.

4'x7': It would be tough to fit the Ti:sapph laser and prism-based pulse pre-chirp.  The Ti:Sapph probably needs to go outside the cage due to it's size, so the pre-chirp would have to go inside (might require some modifications), or it would have to go vertical somehow.

4'x6': This is just enough room to put the 2p-RAM cage on.

Should I order all items on the Jenoptik quote?

No. Only order items 1-5. Note in addition that pupil relays 1 & 2 are identical (but you need 2), so it's only 4 distinct parts. 

We decided to order items 6-8 from another vendor to save some $$.


After Jenoptik and Thorlabs Gantry, what is the longest lead-time item?

Cambridge Technologies scan mirrors. These can take 3 months, so order them as soon as you can.


Should I order everything on 2p-RAM Parts List (072616).xlsx?

No. Follow instructions. 

There is a mismatch in the numbers in the quotes and in '2p_RAM Parts List (072616)'?

This is because we asked vendors to quote quantities of 5 & 10 in cases where discounts are possible.

Please order the number of units specified in 2p-RAM Parts List (072616).xlsx
Refer to the quotes supplied in the table.

What about the list '2p-RAM Accessory Optics Parts List'?

This pertains to the auxillary light path (not two-photon). It is a collection of parts, mostly off-the-shelf, that provide very useful functions.
These will allow optogenetics with laser scanning photostimulation, wide-field imaging, and alignment of the coverglass to be normal to the beam axis.


For the Schneeberger item, please reach out to Lance Cobb ( for a quote and pricing.  The previously referenced quote HHMI-20-160321-0 is WRONG.  The part needed is "NDN-2 30.20".  The quote Schneeberger_JHHMI-20-150220-01.pdf can be referenced.  It is correct.

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