Jpintn.. wrote that lense was a perfectly acceptable spelling.

Hate to burst your bubble sir but you are WRONG!!!

Despite that fact that you might find it in an obscure dictionary somewhere it is still the wrong way to spell it and just because you find it somewhere does not make it correct, nor acceptable.

Since you wanted to be so precise I ask you to read this please: A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element. A compound lens is an array of simple lenses (elements) with a common axis; the use of multiple elements allows more optical aberrations to be corrected than is possible with a single element.

Lenses are typically made of glass or transparent plastic. Elements which refract electromagnetic radiation outside the visual spectrum are also called lenses: for instance, a microwave lens can be made from paraffin wax.

The variant spelling "lense" is sometimes seen. While it is listed as an alternative spelling in some dictionaries, most mainstream dictionaries do not list it as acceptable, nor as a correct way to spell the word "lens". I rest my case.