That's right Marie B. has found Fresnel's grave in Division 14 of Pere Lachaise. I recall looking for him probably a dozen times -- and eventually involving Marie and, I think even Philippe in the search for his grave.
Who is Fresnel and why should we care? For an answer to the first half of that question, check out what Wikipedia says.
As for the second half, well I suppose it's because of his work in developing the lens used in virtually every lighthouse in the world!