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• A method of promoting the axial feature size of PPI-DLW is proposed. • A 3D hollow focus was generated using one beam without light field superposition. • Two-focus parallel scanning using 3D hollow focus was realized without hardware updating based on a classic method. • The isotropic 30 nm feature size was realized. • This work will improve the ability of PPI-DLW to fabricate arbitrary 3D structures. Peripheral-photoinhibition (PPI)-based direct laser writing (DLW) inspired by simulated emission depletion (STED) microscopy has improved the fabrication resolution of three-dimensional (3D) structures on the nano-scale. However, most previous studies have focused on the lateral feature size, neglecting axial-feature-size enhancement. This article proposes a novel method to simultaneously reduce the axial and lateral feature sizes of PPI-DLW. By employing a pseudo 3D hollow focus, a suspended nanowire with an isotropic 30-nm feature size was realized. Such an isotropic 3D hollow focus for photoinhibition is generated using a single beam instead of two-beam superposition, thus it does not increase the system complexity of a PPI-DIW system. Owing to the reduced feature size in all three dimensions and the low systematic complexity, the proposed method improves the capabilities of PPI-DLW for fabricating arbitrary 3D structures. [ABSTRACT FROM AUTHOR]

An active beam stabilization system with high-precision correction and fast response with a small size is developed. By completely separating the correction of positional (x, y) and angular (α , β) deviations, this system avoids the coupling effect which increases the errors caused by the nonlinear, hysteresis, and creep characteristics of the piezoelectric actuators in conventional dual fast steering mirrors (FSMs) control system. And a combination of lenses is designed to achieve a large focal length in a small space, which is advantageous for high-precision and strong anti-interference ability. The experimental results show that the peak and valley (PV) values of the positional and angular deviations over 60 min are smaller than 0. 58 μ m and 1.07 μ rad which are less than 8% of the deviations without control, the standard deviation (STD) values are smaller than 0. 07 μ m and 0.09 μ rad. The regulating time is reduced to 38 ms. Moreover, the results from a series of experiments show that the STD values of the deviations over 10 h are smaller than 0. 09 μ m and 0.13 μ rad. Thus, the proposed system is effective for many laser applications, especially those involving high-precision optical systems. [ABSTRACT FROM AUTHOR]