Sorry, my PC cannot type chinese now, crazy. bRb+3au_x
Ij}k>qO/2
I saw some Japanese engineers use "primary differential and second differential" to define the extended freeform optical surface tolerance. K^fH:pV
I guess it define some vatied range for each coefficients but I don't know Japanese words. k| Ye[GM*
Still cannot know how to do that.