The connection between the Bessel discrete variable basis expansion and a speci…c form of an orthogonal set of Jacobi polynomials is demonstrated. These so-called Zernike polynomials provide alternative series expansions of suitable functions over the unit interval. Expressing a Bessel function in a Zernike expansion provides a straightforward method of generating series identities. Furthermore, the Zernike polynomials may also be used to e¢ ciently evaluate the Hankel transform for rapidly decaying functions or functions with …nite support.