[jamesbowman]

As I read that summary, feature sizes start at 22.5 µm and go down to 75 nm.

As they say, "significantly lower than the wavelength of visible light".

[cc439]

And how much of that 75nm feature is getting picked up by a diamond stylus? The stylii used in metrology grade surface roughness and contour analyzers can't pick up features even remotely close to that size and those are far finer and more sensitive that a turntables stylus.

[williadc]

Why does a laser have to work in the visible light spectrum? Lithography lasers have been drawing at 175nm for over a decade.