Are they good raspberries?
Do you really want to stop them? Why not enlarge your garden a bit?
Seriously, though, only way I can think of is to bury a solid barrier of some sort, and you may have to re-do your raised bed to accomplish that. I remember suggesting something similar before.... Ah here it is:
That being the case, what if you dig a trench all along the fence line, then put some kind of a barrier in it -- weed mat? line trench with weed mat and fill with gravel? corrugated roofing panels? sheet metal?
That was for [url=https://www.helpfulgardener.com/forum/viewtopic.php?p=110643&highlight=trench+fill+gravel#110643]bindweed[/url].
I think in your case, to completely stop the raspberries from getting in, I would re-design the area and put a path along the fence
. Put down cardboard and heavy mulch and keep it mulched, pulling any cane that tries to grow up there. Foot traffic and compaction should help. You could bring forward your raised bed and make it wider now that you can access it from both sides. This way, the raspberries won't be stealing all the rich goodness you put in your raised bed.