Wow! Not much optical path length in that crystal!

I think your plan with the UV cure adhesive sounds fine. We more often use a thermally cured epoxy like Ablebond or Minbond, but we’ve had good luck with UV cured adhesive in less challenging uses.

There are just a couple things to consider. It doesn’t stick until the UV light hits it, so you’ll want perform the mounting in an orientation where gravity helps keep it in place until you cure the glue. A similar point: it doesn’t stick unless UV light gets to it. It doesn’t look like an issue here: it’s just a thin plate and BBO is transparent to the curing light. But, the point is, you want to be sure the curing light gets to the glue.

The one think that concerns me: why did it debond in the first place? Glued at the corners, there is little thermal conductivity. Do you think there might have been enough absorption in the BBO to cause any differential thermal expansion? This looks like a simple arrangement where that isn’t an issue, and SHG in BBO generally doesn’t deposit much heat. Nevertheless, it might have come unglued for a reason.

Mike Albert

Dear Mike,

Thanks a lot for the answer!

I have found that the minimum transmittance wavelength of BBO crystals can reach 185 nm. UV curing adhesive uses 365 nm UV light for curing, which sounds feasible. I'm actually not quite sure why it debonded from the holder, I guess it might be due to the aging of the adhesive.