Longer GRIN lens

[Honi]

Hello,
We are trying to get the imaging working in rats.  One issue is that the 0.25 pitch lenses are too short.  Are there any ~2mm diameter relay lenses?  Are there 0.75 pitch GRIN lenses? 

[Daniel Aharoni]

Hi Honi,
You can try stacking 3 0.25 pitch lenses together to achieve a 0.75 lens. We have tried this and it works well but you have to start out with lenses that are already very close to 0.25 pitch. We used a 2mm ID stainless steel tube a little shorter than the length of the 3 lenses. Placed the lenses in the tube with some optical glue around the outer edges of the top and bottom lens. Your other options would be to see what sort of relay lenses Inscopix will sell you.

[Honi]

Sounds like a plan! I don't quite understand the mechanics though.  Is the glue adhesive between the lenses or between the lens and the tube?

[Daniel Aharoni]

I would suggest only gluing the top and bottom GRIN lens to the tube and just make sure that each GRIN surface is in contact with its neighboring GRIN lens surface.