Pyramid wavefront sensor

A pyramid wavefront sensor measures the optical aberrations of an optical wavefront . It was shown that it has the potential for applications in astronomy and ophthalmology . This wavefront sensor uses a pyramidal prism with a large apex angle (~ 179°) to split the beam into multiple parts at the geometric focus of a lens. A four-faceted prism, with its tip centered at the peak of the point spread function, will generate four identical pupil images in the absence of aberrations. In the presence of aberrations, the intensity distribution among the pupils will change. The local wavefront gradients can be obtained by recording the distribution of intensity in the pupil images. The wavefront aberrations can be evaluated from the estimated wavefront gradients. The prism is often modulated (mechanically moved in a circle/square) for averaging. Recently, it has been shown that the need for mechanically moving parts can be overcome in a digital pyramid wavefront sensor .