Edge smoothing optimization method in DMD digital lithography system based on dynamic blur matching pixel overlap technique.

Due to digital micromirrors device (DMD) digital lithography limited by non-integer pixel errors, the edge smoothness of the exposed image is low and the sawtooth defects are obvious. To improve the image edge smoothness, an optimized pixel overlay method was proposed, which called the DMD digital lithography based on dynamic blur effect matching pixel overlay technology. The core of this method is that motion blur effect is cleverly introduced in the process of pixel overlap to carry out the lithography optimization experiment. The simulation and experimental results showed that the sawtooth edge was reduced from 1.666 µm to 0.27 µm by adopting the 1/2 dynamic blur effect to match pixel displacement superposition, which is far less than half of the sawtooth edge before optimization. The results indicated that the proposed method can efficiently improve the edge smoothness of lithographic patterns. We believe that the proposed optimization method can provide great help for high fidelity and efficient DMD digital lithography microfabrication.

Mechanism Study of Ultrasonic Vibration-Assisted Microgroove Forming of Precise Hot-Pressed Optical Glass.

Microgroove structures with helical pitches in a wavelength level are increasingly required in optical areas. However, conventional manufacturing techniques generate relatively high stresses during pressing, resulting in poor precision when forming microgrooves. This paper reports on the mechanism of the ultrasonic vibration-assisted microgroove forming of precise hot-pressed optical glass. A finite element (FE) thermocompression model of the viscoelastic material was developed and the entire forming process was numerically simulated using coupled thermal-structural analysis. The analysis of several process parameters was carried out using orthogonal experiments, from which the optimum combination of parameters was selected. The glass thermoforming process is also assisted by ultrasonic vibration. The thermal and mechanical effects of vibration improved material flow and optimized forming results. The average maximum stress in the glass during the forming process was only 3.04 × 10-3 Mpa, while the maximum stress in the hot-pressing stage without ultrasound was 1.648 Mpa. The stress results showed that the material-forming stress is significantly reduced.

MoOx-Decorated Co-Based Catalysts toward the Hydrodeoxygenation Reaction of Biomass-Derived Platform Molecules.

Catalytic conversion of a biomass derivative (levulinic acid, LA) to a high value-added product (γ-valerolactone, GVL) has attracted much attention, in which the control of catalytic selectivity plays an important role. Herein, a stepwise method was developed to prepare Co-MoOx catalysts via topological transformation (calcination reduction) from layered double hydroxide (Mo/CoAl-LDH) precursors. X-ray diffraction, high-resolution transmission electron microscopy, and hydrogen temperature-programmed reduction demonstrate the formation of MoOx-decorated Co structures of Co-MoOx samples. Remarkably, the sample that is reduced at 500 °C is featured with the most abundant interfacial Coδ+ (denoted as Co-MoOx-500), which exhibits an excellent catalytic performance toward the hydrodeoxygenation (HDO) reaction of several biomass-derived platform molecules (furfural, FAL; succinic acid, SA; 5-hydroxymethyl-furfural, HMF; and levulinic acid, LA). Especially, this optimal catalyst displays a high yield (99%) toward the HDO reaction of LA to GVL, which stands at the highest level among non-noble metal catalysts. The combination of in situ FT-IR characterization and theoretical calculation further confirms that interfacial Coδ+ sites in Co-MoOx-500 act as adsorption active sites for the polarization of a C═O bond in an LA molecule, which simultaneously promotes C═O hydrogenation and C-O cleavage. Moreover, the MoOx overlayer suppresses the formation of byproducts by covering the Co0 sites. This work offers a cost-effective and efficient catalyst, which can be potentially applied in catalytic conversion of biomass-derived platform molecules.