Asymmetric Hydrophosphonylation of Imines to Construct Highly Stable Covalent Organic Frameworks with Efficient Intrinsic Proton Conductivity.

Imine-linked covalent organic frameworks (COFs) have received widespread attention because of their structure features such as high crystallinity and tunable pores. However, the intrinsic reversibility of the imine bond leads to the poor stability of imine-linked COFs under strong acid conditions. Also, their thermal stability is significantly lower than that of many other COFs.

Three-Dimensional hybrid structure loader type flexible supercapacitor based on Polyvinyl alcohol gel and Acetylene black.

In order to overcome the structural drawbacks of layered electrodes in flexible supercapacitors, the construction of an electrode frame with high adaptability for the loading of different active materials makes the production of flexible supercapacitors simpler and more accurate. Herein, a novel loader type flexible supercapacitor with three-dimensional hybrid structure is built. In our design, the acetylene black and active material are enriched in the polyvinyl alcohol matrix, and the three-dimensional conductive network that can load different active material is formed.

Kinetics control over the Schiff base formation reaction for fabrication of hierarchical porous carbon materials with tunable morphology for high-performance supercapacitors.

Schiff base formation reaction is highly dynamic, and the microstructure of Schiff base polymers is greatly affected by reaction kinetics. Herein, a series of Schiff base cross-linked polymers (SPs) with different morphologies are synthesized through adjusting the species and amount of catalysts. Nitrogen/oxygen co-doped hierarchical porous carbon nanoparticles (HPCNs), with tunable morphology, specific surface area (SSA) and porosity, are obtained after one-step carbonization.

Methods for the performance enhancement and the error characterization of large diameter ground-based diffractive telescopes.

This paper is devoted to the improvement of ground-based telescopes based on diffractive primary lenses, which provide larger aperture and relaxed surface tolerance compared to non-diffractive telescopes. We performed two different studies devised to thoroughly characterize and improve the performance of ground-based diffractive telescopes. On the one hand, we experimentally validated the suitability of the stitching error theory, useful to characterize the error performance of subaperture diffractive telescopes.

Error analysis of large-diameter subaperture stitching Fresnel diffractive elements.

Image quality is dramatically influenced by the stitching errors in a large-diameter stitching Fresnel lens. In this paper, we studied three kinds of errors that can cover all stitching errors in a Cornwell deployed Fresnel lens. In particular, a 300-mm-diameter, three-belt deployed Fresnel diffractive lens was simulated to investigate the stitching error.

[Analysis and Correction of Spectral Curvature in Hadamard Transform Spectrometer with DMD].

Due to the advantages of its low cost and high utilization rate of light energy and no moving parts, Hadamard transform spectrometer with DMD has become a focus in the research of spectrometer. In order to solve the reduction of spectral resolution caused by the spectral curvature of Hadamard transform spectrometer with DMD (Digital Micro-mirror Device), the spectral aliasing in the spectrometer was investigated. Firstly, the mathematical relationship of spectral aliasing to radius of spectral curvature was deduced.

Computation of the diffracted field of a toothed occulter by the semi-infinite rectangle method.

To observe the solar corona, stray light in the coronagraph, arising primarily from an external occulter and diaphragm illuminated directly by the Sun, should be strongly suppressed. A toothed occulter and diaphragm can be used to suppress stray light because they diffract much less light in the central area than a circular disk. This study develops a method of computing the light diffracted by a toothed occulter and diaphragm, obtaining the optimum shape using this method.

Design of secondary optics for IRED in active night vision systems.

An effective optical design method is proposed to solve the problem of adjustable view angle for infrared illuminator in active night vision systems. A novel total internal reflection (TIR) lens with three segments of the side surface is designed as the secondary optics of infrared emitting diode (IRED). It can provide three modes with different view angles to achieve a complete coverage of the monitored area.

Third-order aberration fields of pupil decentered optical systems.

By introducing a transformed pupil vector into the aberration expansions of an axially symmetric optical system, the aberration coefficients through third order of a pupil decentered off-axis optical system are obtained. Nodal aberration characteristics are revealed only by means of the pupil decentration vector and the aberration coefficients of the axially symmetric system, which shows great convenience since parameters of individual surface such as radius of curvature, decenter as well as the shifted center of the aberration field are not used in the analysis.

The Talbot effect of plasmonic nanolenses.

The Talbot effect of an Ag nanolens with five periodic concentric rings that are illuminated by the radially polarized light was numerically studied by means of rigorous finite-difference and time-domain (FDTD) algorithm. It was found that the Talbot effect occurs only when the incident wavelength is at the scale of less than half of period of the grating structures of the nanolenses. Specifically, in this work, the nanolenses with a 500 nm period grating structures has five focal points due to Talbot effect for the incident wavelength of λ = 248 nm.

Automated optimization of an aspheric light-emitting diode lens for uniform illumination.

In this paper, an automated optimization method in the sequential mode of ZEMAX is proposed in the design of an aspheric lens with uniform illuminance for an LED source. A feedback modification is introduced in the design for the LED extended source. The user-defined merit function is written out by using ZEMAX programming language macros language and, as an example, optimum parameters of an aspheric lens are obtained via running an optimization.

Lithographic fabrication of diffractive optical elements in hybrid sol-gel glass on 3-D curved surfaces.

We demonstrate the lithographic fabrication of diffractive optical elements (DOEs) in hybrid SiO2/TiO2 sol-gel glass on 3-D curved surfaces. The concentric circular gratings with periods of 20 μm, 10 μm and 5 μm have been fabricated in sol-gel glass on concave lens by laser direct writing successfully. Continuous 3-Dimensional surface relief with a height of 435 nm, 110 nm and 50 nm has been obtained for the period of 20 μm, 10 μm and 5 μm respectively.

Fabrication of diffractive optical elements on 3-D curved surfaces by capillary force lithography.

We demonstrate the fabrication of diffractive optical elements (DOEs) on 3-Dimensional curved surfaces by capillary force lithography (CFL). Curved gratings with a period of 20mum and 820nm have been successfully fabricated in polymer on concave surfaces by CFL. The experiment results indicate that the capillary force lithography is an effective method to replicate DOEs on curved surfaces with a very high fidelity and a relatively fast speed.

Design of multiplexed phase diffractive optical elements for focal depth extension.

A more computationally tractable method to design a multiplexed phase diffractive optical element with optical design software to extend the depth of focus is proposed, through which the intensity distribution of the output beams can also be controlled with great flexibility. The design principle is explained in detail. And the feasibility of this design method is illustrated through a design example followed by computer simulation verification.

The characteristics of compound diffractive telescope.

Compound diffractive telescope is a new type of space optical system. It applies the structure of compound eyes into diffractive telescopes. With the help of diffractive optical element, the optical system could become lighter in weight, lower in cost, and looser in sensitivity to manufacturing tolerance.

Modified phase function model for kinoform lenses.

A more computationally tractable model of the kinoform lenses in hybrid refractive-diffractive systems is proposed by taking into consideration the actual phase function of the kinoform lenses for every wavelength. The principle and outline of this modified model are explained. We compare the results of this approach with the more conventional single order calculation and with the standard diffraction-order expansion by using a practical hybrid optical system example.

Design of a novel hologram for full measurement of large and deep convex aspheric surfaces.

We proposed a valid method with a novel computer-generated hologram (CGH) to test large-aperture convex aspheric. The CGH consisted of two zones with different amounts of power: the central zone has a larger amount of power than the marginal zone. Compared with other CGHs used for convex aspheric testing [SPIE.

Single step fabrication of microlens arrays with hybrid HfO2-SiO2 sol-gel glass on conventional lens surface.

We demonstrate a novel method for fabricating glass microlens (arrays) with single step on conventional lens surface. In this method, the glass microlens can be achieved by only one step with sol gel glass material. The microlens aperture and focus length can be controlled easily and uniformly.

Redistribution of output weighting coefficients for complex multiplexed phase-diffractive elements.

The formation of multiplexed phase-only holograms with more weighted phase functions creates spurious cross terms and nonlinear scaling. We extend previously reported work [Appl. Opt.

Using curved hologram to test large-aperture convex surface.

A valid optical system with a computer-generated hologram fabricated on a concave lens surface, for measuring large-aperture convex surface, is demonstrated experimentally. The CGH employed in this system has been constructed using a new technology that combines laser direct writing and lithography. This technology allows precise alignment, superior linear profile and high resolution of the gratings that compose the CGH.

Lithographic fabrication of large curved hologram by laser writer.

We fabricated a large curved computer-generated hologram pattern on the concave substrate with diameter of 110mm and radius of curvature of 504mm. The line width of the hologram varied form 39um to 810um. We adopt the single pass and the screw-lines to fabricate this curved hologram precisely and efficiently.

Fabrication of large diffractive optical elements in thick film on a concave lens surface.

We demonstrate experimentally the technique of fabricating large diffractive optical elements (DOEs) in thick film on a concave lens surface (mirrors) with precise alignment by using the strategy of double exposure. We adopt the method of double exposure to overcome the difficulty of processing thick photoresist on a large curved substrate. A uniform thick film with arbitrary thickness on a concave lens can be obtained with this technique.

Method for correcting the joint error of a laser writer.

We present what we believe to be a new method for correcting the joint error of a laser writer without reduction of throughput. By digitization, we optimize the intensity data of the incident beam at the vicinity of the start point and the end point. The joint error will not be sensitive to lengthening of the start or end point by optimization.

Lithographic fabrication of large diffractive optical elements on a concave lens surface.

We demonstrate experimentally the lithography technique to fabricate a large computer-generated diffractive optical element (DOE) pattern on a concave lens surface with precise alignment by using a laser direct writer. We obtained photoresist film with uniform thickness on the large concave substrate by selecting proper spin-coating parameters, which mainly involve spin rate, spin acceleration, and viscosity of the photoresist. We obtained a square line profile on the concave lens surface.