Feature issue introduction: applications of adaptive optics

Pupil calibration for pyramid wavefront sensors based on a wavefront corrector

The pyramid wavefront sensor (PWS) presents numerous advantages, such as high energy utilization, exceptional spatial resolution, and adjustability. Precise calibration of the pupil's position and size in advance is essential for accurately extracting wavefront slope information from the captured pupil image by the PWS. What we believe to be a novel calibration method is proposed using a wavefront corrector to enhance the sharpness of the pupil images in the PWS. An experimental setup using a crystal spatial light modulator (SLM) is established to validate this method. Both physical experiments and simulated results demonstrate that our proposed method can achieve accurate calibration of the pupil image with an error within 4 pixels for pupil size and not exceeding 3 pixels for position, meeting practical application requirements. The proposed PWS calibration method exhibits excellent repeatability and robustness, making it directly applicable in astronomical adaptive optics systems.

Ghost imaging lidar system for remote imaging

Research towards practical applications of ghost imaging lidar system especially in longer sensing distance has been urgent in recent years. In this paper we develop a ghost imaging lidar system to boost an extension of remote imaging, where the transmission distance of the collimated pseudo-thermal beam can be improved hugely over long range and just shifting the adjustable lens assembly generates wide field of view suiting for short-range imaging. Based on the proposed lidar system, the changing tendency of illuminating field of view, energy density, and reconstructed images is analyzed and verified experimentally. Some considerations on the improvement of this lidar system are also discussed.

Steady optical beam propagating through turbulent environment

A steady optical beam (SOB) propagating stably in a disorder medium is constructed by using a specially designed aspherical lens. Our theoretical and experimental results show that the generated SOB exhibits much better propagation features with small divergence and long Rayleigh length, as well as weak deformation through turbulent environment as compared with a conventional Gaussian beam. The beam parameter product of the SOB reaches 49.40% of the Gaussian beam by multiple measurements within a certain distance range. The SOB may find applications in optical communications and optical detection in turbulent transmission conditions.