Crossed-sine wavefront sensor for adaptive optics, metrology and ophthalmology applications

Wavefront Sensors (WFS) have now become core components in the fields of adaptive optics for astronomy, biomedical optics, or metrology of optical systems. However, none of the designs used or proposed so far seems to achieve simultaneously a high spatial resolution at the pupil of the tested optics and absolute measurement accuracy comparable to that attained by laser-interferometers. This paper presents a new WFS concept susceptible to achieving both previous goals. This device is named crossed-sine wavefront sensor and is based on a gradient transmission filter located near the image plane of the tested system. The theoretical principle of the sensor is fully described in a Fourier optics framework. Numerical simulations confirm that the achievable measurement accuracy can reach lambda/80 RMS, which is significantly higher than achieved by other types of WFS. The crossed-sine WFS also offers the advantages of being quasi-achromatic and working on slightly extended, natural or artificial light sources.