Weixing Yu

A novel curved focal plane extreme ultraviolet (EUV) detector array designed for a moon-based EUV camera is demonstrated. The curved focal plane detector array operating in a pulse-counting mode consists of a curved microchannel plate (MCP) stack and an induced charge wedge-strip anode (WSA). The curved MCP is fabricated by firstly thermally slumping of the MCPs, and then followed by optical polishing and core glass etching. By using this technology, curved MCPs with a length-to-diameter (L/D) ratio of 80:1 and a radius of curvature of 150 mm have been successfully achieved. The performance of the curved MCP detector is fully characterized in terms of the background noise, pulse height distribution, gain, image linearity and spatial resolution. It is measured that a spatial resolution of 7.13 lp/mm can be achieved with a background noise of less than 0.3 counts/cm²⋅s. The characterization results indicate that the curved focal plane detector can fulfill the requirements of the moon-based EUV camera.

In this work, a hierarchic reflow method is demonstrated for the monolithic micro-fabrication of biomimetic compound eye arrays.

In this paper, a light absorbing model based on the hierarchic structure with randomly distributed nanospheres is proposed for strong absorption over 400-900 nm. The effect of different parameters including the size range, the particle number and the hierarchic height of the nanospheres on the light absorption is systematically analyzed. It is found that this structure can absorb light efficiently with an average absorptivity of 91% at the 400-900 nm waveband. The great enhancement of light absorption can be attributed to the localized surface plasmon resonant of the random metallic nanospheres as well as the strong light scattering of the metallic nanospheres embedded in the dielectric film.

In this paper, we demonstrate a novel thermal reflow method with an additional near ultraviolet (UV) flood exposure and upside-down reflow configuration for the fabrication of microlenses with an ultrahigh focal number. By using this method, microlenses with a focal number (F^#) as high as 9.7 have been successfully obtained, which is about four fold higher than that can be fabricated with a conventional reflow method. The final profile of the microlenses can be flexibly and accurately tuned by controlling the flood exposure dosage and adopting the appropriate reflow configuration, which enables fabrication not only of spherical microlenses but also of more complex aspheric lenses. The fabricated microlens is characterized by measuring the point spread function (PSF) and the measurement result indicates that the diffraction limited optical performance of the microlens can be achieved. The method developed in this work can be used for the mass and cost-effective fabrication of high performance microlenses with ultrahigh focal numbers, which can find applications such as in accurate optical testing, integration imaging, and laser beam collimating.

We present a beam shaping technique in controlling the complex amplitude of an optical beam. The constraint on the amplitude of the output beam in the Gerchberg-Saxton algorithm is replaced with constraints both on the amplitude and phase of the output beam in the proposed method. The total areas of the constrained regions and free regions on the complex amplitude of the output beam in the proposed method are maintained. An output beam with arbitrary complex amplitude can be realized with the proposed method. The computing result from the proposed method is a phase-only distribution, which can be fabricated as diffractive optical element for higher diffraction efficiency. Both simulations and experiments are present and the effectiveness of the proposed method is verified.

A simple hydrothermal method is developed to directly grow TiO₂ nanosheets on a bare glass substrate.