Sanding/Staining Before?

I’m laser engraving a logo on a piece of purpleheart for a client job. Should I sand and/or stain the wood prior to lasering? I don’t want to go through all the work of a nice laser engrave only to buff it out with sand paper afterwards.

I engrave on laser grade birch plywood. I would not consider it to be a particularly hard wood. After engraving, a bit of sanding does little damage to the work, but it’s easy enough to get carried away on the birch. Purpleheart is a good bit harder and may require higher power/slower speed to get a reasonable depth, but it will hold up for finishing sanding. Consider to test on a scrap. You won’t have to go more than a millimeter deep, I suspect.

The main reason for sanding after engraving is to get rid of the soot/scorching, so I either use clear packing tape and engrave trough that, or, if the engraving contains a lot of inside shapes that I would have to pick the tape out of, I put on a coat of the final finish before lasering, then the soot / scorch just wipes off with water. If I can do either for any reason, I increase the ingraving depth to about a millimetre then lightly sand off the scorch marks.
Hope that helps,