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The common methods of manufacturing the quartz wafer are grinding and finishing. These processes not only cause micron-scale flaws, but also limit the accuracy. In this paper, firstly, magnetorheological finishing (MRF) technology is applied as the follow-up treatment of traditional process to correct the defects on the surface of the wafer. Then ion beam figuring (IBF) technology is used to improve the surface figure accuracy to nanoscale. After MRF, micron-scale scratches and pit defects on the surface are effectively eliminated, and the Rq value of the surface roughness descends from 2.46 nm to less than 1 nm. Meanwhile, the RMS value of the surface accuracy descend from 35.60 nm to 5.06 nm through IBF. The experimental results show that MRF and IBF technology can improve the surface quality of the quartz wafer.

In recent years, monolithic multi-surface image systems are widely concerned with the deeply development of optoelectronic imaging system and the ultra precision machining technology, most of these systems consist of multiple mirrors, and these mirrors are machined on one substrate or grouping processing on two substrates. In this paper, we discuss the optical design of visible imaging system with a filed of view 2° based on common-axial folded optical system. This study described the optical design of visible all-reflective imaging systems based on the aviation aluminum material. It works in the 0.45~0.75μm wavelength bands. The visible imaging system includes two elements, the first one is a flat mirror, and the second one is an optical element with four concentric zone aspherical mirrors, each concentric zone aspherical surfaces are 12-th order, the beam is folded and reflected between concentric zone aspherical mirrors and flat mirror, and then focused on the image plane. The surface accuracy of submicron order and position accuracy of micron order, and the technology of single point diamond turning are used to ensure the coaxality accuracy of the concentric zone aspherical mirrors. According to the optical design results, the quality of imaging arrives at the diffraction-limitation. On this basis, we design the focusing mechanism and complete system manufacturing; assembly and imaging experiment. The final system has the advantages of compactness, convenient thermal management and simple installation. It can potentially be applied to the optical system of the unmanned aerial vehicle system.

All-reflective coaxial visible/infrared imaging systems based on monolithic multisurface optics have been a hot point of research in recent years. Since multiple surfaces share a single substrate, their relative positions are fundamentally guaranteed as fabricated without any alignment. In this paper, the coaxial system is designed with multifolded ideas. Both the visible subsystem and the infrared subsystem are comprised of two monolithic optical modules, which are machined by single-point diamond turning (SPDT). A novel method based on a computer-generated hologram (CGH) is then proposed to simultaneously measure the shape and position of monolithic multisurface optics. The effects of surface shape and position error on the wavefront aberration of the system are also discussed with the help of Zernike annular polynomials. Then the wavefront aberration of the system is measured, from which we subtract the contribution of surface shape and position error. The aberration induced by misalignment of the two monolithic modules is then estimated. It indicates that the concentricity is about 3 μm. Finally, two similar systems with different clear apertures are assembled as a coaxial visible/infrared imaging system. Coaxial visible and infrared images are captured and fused to show clearer details.

The primary problem of conventional wavefront interferometers is limited dynamic range. Unknown free-form surface figure error with large amplitude or slope is not measurable for too dense or invisible fringes. To troubleshoot this problem, we propose adaptive wavefront interferometry (AWI). AWI utilizes a wavefront sensor-less adaptive optics (AO) subsystem to intelligently speculate and compensate the unknown free-form surface figure error. In this subsystem, adaptive null optics is utilized to iteratively generate adaptive wavefronts to compensate the unknown severe surface figure error. The adaptive null optics is close-loop controlled (i.e., wavefront sensor-less optimization algorithms are utilized to control it by real time monitoring the compensation effects to guarantee convergence of the iteration). Ultimately, invisible fringes turn into resolvable ones, and null test is further realized. To demonstrate the feasibility of AWI, we designed one spatial light modulator (SLM) based AWI modality as an example. The system is based on a commercial interferometer and is easy to establish. No other elements are required besides the SLM. Principle, simulation, and experiments for the SLM based AWI are demonstrated.

The correction accuracy of a pint-sized unimorph deformable mirror (DM) is significantly influenced by the nonlinear hysteresis error of piezoelectric ceramics, especially in an open-loop state. Moreover, the control bandwidth is also reduced by the nonlinearity. In this paper, we fabricated a three-unit pint-sized unimorph DM with strain gauges integrated on the actuators as a feedback layer for the first time. An experimental platform was built and utilized to test each electrode’s strain signal. Testing results show that, under quasi-static condition, the hysteresis curve of the mirror’s central displacement is corrected and the hysteresis rate could be reduced from 11% to less than 2% by adopting the strain feedback signal. More specifically, the DM’s initial surface, Zernike defocus, together with spherical aberration can also be corrected by this method, and the correction accuracy is improved more than 20% compared to the open-loop state. By introducing a closed-loop control the gaps of the DMs under open loop are supplied. This demonstrates that adding a strain feedback layer is promising to enhance the performance of a unimorph DM.

Single layer piezoelectric driving deformable mirror (Unimorph DM) with large deformation, simple fabrication process and low cost has been widely applied for the adaptive optics system in recent years. In the past, the optimal design of deformable mirror is often used in analytic method, and made much simplified approximation in theory. This results in large error between theoretic and real system. In this paper, the influence laws between the fitting error and the effective aperture, and the spatial distribution are studied by the dynamic–electricity coupling simulation method. The relationship between the displacement and the thickness of the mirror, the diameter and thickness of the electrode and the width of the support ring are discussed. According to these rules, a scheme of optimizing the structure of deformable mirror has been proposed, and the key parameters are designed according to the requirements of the retinal imaging system. In the end, all the fitting errors of former Zernike items 3-30 are less than 0.4 with the rated voltage of 400V.