"Lense" is not a word recognised by any reputable UK English dictionary. I have found only one US dictionary that notes it as a variant, but even so does not use it. Just because it is a common error does not make it correct. No word-checker I have seen allows it. See
Lens or Lense ? Which is Correct? - Writing Explained, or several other similar sites.
Etymologically, it comes from the latin "lens" (for lentil), because of its shape. There is no etymological or historical justification for a trailing "e", or any need for it. This doesn't stop such mistakes working their way into standard English over time, the language is full of them, but I for one don't wish to encourage such pointless verbal bloat.
I also checked the English-Corpora: iWeb 14 Billion Word Web Corpus. It shows a word frequency of 635446 for "lens" and only 5343 (less than 1%) for "lense", consistent with it being a misspelling. We see it quite often on PF used by non-native English speakers, from whom I suspect most instances originate.
The reason for the mistaken "lense" is that it results from deleting the trailing s from the plural "lenses". By the same logic, the singular of "buses" should be "buse". Don't go there.
Last edited by Paul the Sunman; 07-02-2022 at 12:42 AM.