Patent ID: 8517535

Claim:
A method of measuring a wavefront of an optical system including a multifocal element, the method comprising: providing a light beam to a lens, the lens being a refractive multifocal lens, a diffractive multifocal lens, or a diffractive monofocal lens, the lens configured to receive a light beam having a diameter greater than about 1.5 mm and comprising one or more aberrations; directing light from the lens to a phase diversity wavefront sensor, the phase diversity wavefront sensor comprising: a diffractive optical element the shape of which is defined by a filter function, the diffractive optical element being arranged to produce in conjunction with the optical system images of the light beam associated with at least two diffraction orders, the images corresponding to at least two or more sample planes, the one or more aberrations altering a size of the light beam between the sample planes; and a detector for detecting the images at a measurement plane and outputting image data corresponding to the detected images; wherein the optical system, lens, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam such that real images are formed at the sample planes and the measurement plane; and measuring the wavefront of the light from the lens using the image data output by the detector based on the images corresponding to the sample planes via a phase retrieval algorithm.