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Re: [Phys-l] optical center : real-life physics

WallMart obviously doesn't have this:

When I worked for a IOL company we had a device that used four collimated pencils that gave the power of a lens including cylinder and prism. It also found the "centre". I've since seen it at ophthalmologists' offices.
Before the LASER a common method was the place the lens in a rotating jig and look at a target off centre. When it the image of the target doesn't move it's centred. After the edge is then ground it may be mechanically centred by using two collinear tubes. The lens centres when squeezed between.
I'm rather certain the principal axis intersects the centres of the lenses in a system, therefore, one may think of the centre of the system as the same as the intersection of the PA w/ any lens or just the PA.

bc, knows less, but has a library.

BTW, What the h .. was s/he doing in Wal*Mart?

John Denker wrote:

On 06/11/2007 05:24 PM, alex brown wrote:

What principles did you use to find the optical centre of the lens