In this Letter we aim to bring an understanding to the apparition of multiple spots when using a Shack–Hartmann (SH) wavefront sensor behind diffractive lenses. In contrast to previous work, this phenomenon is described in terms of diffractive orders. It is illustrated with Zemax simulations, where three kinds of diffractive lenses (monofocal, bifocal, and trifocal) are set behind a microlens array. The presence of multiple spots is related to the phase jump of the diffractive profile and also to the number of steps seen through the microlens pupil. The possibility of assessing the optical quality of such lenses using SH measurements is discussed, in particular within the field of ophthalmology, where the need for precautions is underlined.
© 2011 Optical Society of America
Diffraction and Gratings
Original Manuscript: February 22, 2011
Manuscript Accepted: February 23, 2011
Published: April 13, 2011
Vol. 6, Iss. 5 Virtual Journal for Biomedical Optics
F. Castignoles, T. Lepine, P. Chavel, and G. Cohen, "Shack–Hartmann multiple spots with diffractive lenses," Opt. Lett. 36, 1422-1424 (2011)