WISH: wavefront imaging sensor with high resolution

Wavefront sensing is the simultaneous measurement of the amplitude and phase of an incoming optical field. Traditional wavefront sensors such as Shack-Hartmann wavefront sensor (SHWFS) suffer from a fundamental tradeoff between spatial resolution and phase estimation and consequently can only achieve a resolution of a few thousand pixels. To break this tradeoff, we present a novel computational-imaging-based technique, namely, the Wavefront Imaging Sensor with High resolution (WISH). We replace the microlens array in SHWFS with a spatial light modulator (SLM) and use a computational phase-retrieval algorithm to recover the incident wavefront. This wavefront sensor can measure highly varying optical fields at more than 10-megapixel resolution with the fine phase estimation. To the best of our knowledge, this resolution is an order of magnitude higher than the current noninterferometric wavefront sensors. To demonstrate the capability of WISH, we present three applications, which cover a wide range of spatial scales. First, we produce the diffraction-limited reconstruction for long-distance imaging by combining WISH with a large-aperture, low-quality Fresnel lens. Second, we show the recovery of high-resolution images of objects that are obscured by scattering. Third, we show that WISH can be used as a microscope without an objective lens. Our study suggests that the designing principle of WISH, which combines optical modulators and computational algorithms to sense high-resolution optical fields, enables improved capabilities in many existing applications while revealing entirely new, hitherto unexplored application areas.Wavefront sensing: megapixel resolutionWavefront sensing with greatly improved spatial resolution is now possible thanks to a new approach. The scheme, invented by Yicheng Wu and coworkers at Rice University in the US uses a spatial light modulator (SLM), a CMOS image sensor and a computational phase-retrieval algorithm. The optical field to be analyzed is modulated by a series of random phase patterns generated by the SLM and a series of corresponding spatial intensity measurements are made on the CMOS sensor. The data is then processed by a phase-retrieval algorithm in order to generate the phase and amplitude information of the wavefront incident on the SLM. Importantly, the team says that the scheme can provide wavefront reconstruction with a ~10-megapixel resolution, several orders of magnitude better than commercial Shack-Hartmann sensors.