Dispersed fringe sensors are a promising approach for sensing the large-scale physical step between adjacent segments with acceptable accuracy. However, the nature of dispersion in a dispersed fringe sensor leads to the ideal dispersed fringe pattern becoming vulnerable to noise, particularly at low light levels. A reliable merit-function-based algorithm with an active actuation is introduced here. The feasibility of our algorithm is numerically demonstrated, and Monte Carlo experiments for different signal-to-noise ratios are conducted to assess its robustness. The results show that the method is valid even when the signal-to-noise ratio is as low as 1.

The precise alignment of a high-performance telescope is a key factor to ensure the imaging quality. However, for telescopes with a wide field of view, the images are sometimes under-sampled. To study the effects of under-sampled images on the precision of telescope alignment, numerical simulations are implemented with the stochastic parallel gradient descent algorithm. The results show that the alignment program can converge stably and quickly. However, with the reduction of the full width at half-maximum of images, the relative residual errors increase from 9.5% to 19.5%, and the wavefront errors raise from 0.0972λ to 0.1074λ, indicating that the accuracy of the alignment decreases.

In this Letter, a 116-actuator deformable mirror (DM) was used to correct the wavefront distortion in a 10.7 J, 10 Hz neodymium-doped yttrium aluminum garnet (Nd:YAG) slab amplifier. By applying a pump-light homogenizer to transform the 3 × 1 near-field beam array into an integrated beam, the beam quality was greatly improved from 5.54 times diffraction limit (TDL) to 1.57 TDL after being corrected by the DM. To the best of our knowledge, this is the first investigation on beam quality control of an arrayed near-field beam in high-energy diode-pumped solid-state lasers.

An objective visual performance evaluation with visual evoked potential (VEP) measurements was first integrated into an adaptive optics (AO) system. The optical and neural limits to vision can be bypassed through this system. Visual performance can be measured electrophysiologically with VEP, which reflects the objective function from the retina to the primary visual cortex. The VEP measurements without and with AO correction were preliminarily carried out using this system, demonstrating the great potential of this system in the objective visual performance evaluation. The new system will provide the necessary technique and equipment support for the further study of human visual function.

We propose the active metasurface using phase-change material Ge2Sb2Te5 (GST), which has two distinct phases so called amorphous and crystalline phases, for an ultrathin light path switching device. By arranging multiple anisotropic GST nanorods, the gradient metasurface, which has opposite directions of phase gradients at the two distinct phases of GST, is demonstrated theoretically and numerically. As a result, in the case of normal incidence of circularly polarized light at the wavelength of 1650 nm, the cross-polarized light deflects to 55.6° at the amorphous phase and +55.6° at the crystalline phase with the signal-to-noise ratio above 10 dB.

A bimorph deformable mirror (DM) with a large stroke of more than 30 μm using 35 actuators is presented and characterized for an adaptive optics (AO) confocal scanning laser ophthalmoscope application. Facilitated with a Shack–Hartmann wavefront sensor, the bimorph DM-based AO operates closed-loop AO corrections for human eyes and reduces wavefront aberrations in most eyes to below 0.1 μm rms. Results from living eyes, including one exhibiting ～5D of myopia and ～2D of astigmatism along with notable high-order aberrations, reveal a practical efficient aberration correction and demonstrate a great benefit for retina imaging, including improving resolution, increasing brightness, and enhancing the contrast of images.

A zonal decoupling algorithm used to control a dual deformable mirror (DM) is proposed. One of the two DMs is characterized with a large stroke (woofer), while the other one is characterized by a high spatial frequency (tweeter). A numerical model is used to compare the zonal decoupling algorithm with some traditional zonal decoupling algorithms. The simulation results indicate that the algorithm presented in this Letter improves the performance in suppressing the coupling error. An experimental system is built to prove the effectiveness of this algorithm. The experiments demonstrate that the phase aberrations could be effectively compensated and that the coupling error could also be suppressed.

An improved model-based wavefront sensorless adaptive optics algorithm is proposed for laser beam cleanup. Deformable mirror (DM) eigenmodes are used to replace traditional Lukosz modes in order to avoid DM fitting errors. The traditional method is based on a sophisticated calibration process and solving linear equations. In our method, coefficients of DM eigenmodes are estimated by adding bidirectional modal biases into the system and then solving parabolic equations. The calibration process is omitted in our method, which makes it more feasible. From simulation and experimental results, the corrective accuracy of the improved method is higher than the traditional one.

We present a hybrid adaptive optics system for a kW-class solid-state slab master oscillator power amplifier laser that consists of both a low-order aberration corrector and a 59-actuator deformable mirror. In this system large defocus and astigmatism of the beam are first corrected by the low-order aberration corrector and then the remaining components are compensated by the deformable mirror. With this sequential procedure it is practical to correct the phase distortions of the beam (peak to valley up to 100 μm) and the beam quality β is successfully improved to 1.9 at full power.

A prototype of a solar ground-layer adaptive optics (GLAO) system, which consists of a multi-direction correlating Shack–Hartmann wavefront sensor with 30 effective subapertures and about a 1 arcmin field of view (FoV) in each subaperture, a deformable mirror with 151 actuators conjugated to the telescope entrance pupil, and a custom-built real-time controller based on field-programmable gate array and multi-core digital signal processor (DSP), is implemented at the 1 m New Vacuum Solar Telescope at Fuxian Solar Observatory and saw its first light on January 12th, 2016. The on-sky observational results show that the solar image is apparently improved in the whole FoV over 1 arcmin with the GLAO correction.