doing a research on aberrations in order to

Septim

I need to derive the third order spherical aberration formula for a thin lens which consists of two refracting surfaces how can I do so? I am attaching an image file containing the formula at the bottom of the page. Thanks for your help.

Septim	I need to derive the third order spherical aberration formula for a thin lens which consists of two refracting surfaces how can I do so? I am attaching an image file containing the formula at the bottom of the page. Thanks for your help. Attached Thumbnails