aspheric lens, how we know the index?

[cnet_baby]

how we know the index of lens, when it is aspheric lenses? by using what , how can it measure?

[hardbox_happy]

how we know the index of lens, when it is aspheric lenses? by using what , how can it measure?

using the lens measure to measure its radius then we know that

[QDO1]

dot the centre

measure the front aand rear curves at the center using a base curve clock, or sag gauge

measure the lens thickness using a caliper

measure power at OC

so long as the sag measured is for a area of the lens that is not too wide, a fairly accurate index can be worked out by pluging in all of the data into the re-arranged lensmaker and sag formulas

[Adachi Takehisa]

The front curve of a lens can be measured. (1 - 6D curve) - Rear surface curve of 凹power : Front curve +| power | - Rear surface curve of convex power: Front curve-| power |

spherical design = true circle
aspherical design= Ellipse

D=(n-1)/R
R=(n-1)/D

If there are compass and an acrylics board, it can make easily.

[Jim G]

Ask the optician/lab. Aspheric lenses cannot be measured in conventional ways using conventional instruments.