I also kind of get that the DPSS lasers are made by either frequency doubling or sum frequency generation. 532nm is made by frequency doubling 1064nm. 473nm is made by frequency doubling 946nm. 589nm and 593.5 use sum frequency generation I believe.

So I guess what I'm asking is if in theory can the principle that gives us yellow DPSS lasers be used to create a non-spectral color like Magenta? I get yellow is in the spectrum and magenta isn't but a DPSS yellow is made by adding two beams together so in that sense it isn't pure either...couldn't you achieve non spectral colors by adding two beams together?