Depending on whether you wanted the window to be openable when not lasering I’d either remove the window and replace it with an acrylic replacement with an exhaust fitting & flappy door in it (dryer vent type). But that would not allow the window to be used. It is what I did in my basement. You might want to mount the acrylic in a wooden frame you could attach to the current frame for security. If you use polycarbonate instead of acrylic you’ll want to cut it with a saw as it’s not good to laser but it would be unbreakable and offer a bit more security.
Or if you want to be able to use the window when not lasering, then just make a plywood or acrylic sheet with the dryer vent mount but size it so it fits into the inside frame. You would open the window, pop the insert in and laser away. When done, just remove the insert and the window is good. I’d use a strip of foam insulation all around the insert to keep from getting any blowback and I’d mount a handle in the center to make it easy to put in & pull out.
I have side opening casement windows in the living quarters so when I move the GF to the air conditioned space I’ll make something like the second approach for that room’s affected window (unless my filter comes first ).