Would it be possible ?

[Sigurthr]

That video uses a NdYAG pulsed laser, which is complete and stand-alone. The KTP shown is coated and the coatings form the doubler cavity mirrors. That is a case of using standalone optics instead of bundled optics. It is exactly what we were discussing above. Most pointers now use bundled optics though as it is easier to work with (half the alignment!).

 

[Cyparagon]

If what you guys say is true then how does this work without the mirrors and whatnot?...

"well enough" in this case looks like a few mW of green. :undecided: Regardless, Intra-cavity doubling works well enough if the power is very high. The video you linked was of a pulsed laser and pulsed lasers have very high powers.