Alex.h - Hmmm. I also have burned my mounted slide on a multiphoton. There isn’t much heat dissipation in glass and hardened mounting medium, this is the big issue. I’m sure you already tried the imaging tricks - keep power low, increase gain, do plenty of averaging … I wonder if wet-mount mediums might tolerate the localized IR heating a bit better…Have you tried imaging the slice first with multiphoton, then mount the slice for regular single photon? Remember also that mounting is reversible once its on the slide, so in theory you could mount and image, then reverse the mounting by incubating in a humid chamber, perhaps rinse the slice, then image with the A1RMP…(I’m brain storming).
Related, I’m wondering if your objective on the A1RMP is coverslip corrected - if not, you might get a better image with water (can therefore use less power to get the same signal), no glass. Also, a hint in general Genteal eye gel works very well for multiphoton microscopy, its thick doesn’t evaporate, and has a refractive index like water/tissue.