This paper reports a polymer nano-composite with enhanced electro-mechanical performance by mixing TiO 2 nano-particles into polydimethylsiloxane (PDMS) matrix. The nano-composites with TiO 2 concentration up to 30 wt% were synthesized by in-situ polymerization. High energy ball milling and surfactant polyethylene glycol was used to reduce the agglomeration and ensure a stable dispersion. The properties of nano-composites, i.e. transmittance, elastic modulus, response time and dielectric constant, can be tuned by controlling the TiO 2 concentration. The nano-composites were applied in tunable gratings and showed reduced driving voltage and response time, comparing with traditional electroactive polymers (EAPs).

An array of diffraction gratings and a Random Phase Plate (RPP) are used to suppress laser speckle effect. Dynamic diffraction spots are generated on the surface of the RPP, after which the scattering lights are perceived by a detector. Speckle Contrast Ratio (CR) and Number of Independent Speckle Patterns (NISP) with different gratings rotation orientations (θ), gratings frequencies (grooves per millimeter: f), diameters of laser beam (D), and distances between the array of diffraction gratings and the RPP (Z) are calculated based on ZEMAX simulations, and an optimized model is proposed.

This paper reports a novel idea of using a tandem grating modulator for speckle reduction in laser displays. The modulator was designed based on finite-element method simulations, fabricated using micromachining technology, and characterized for speckle reduction. Two types of modulator were fabricated with different shape of gratings. Experiments showed that these modulators reduced the speckle contrast to 0.57 and 0.37, respectively. The results agreed with theoretical analysis. With some modification of this modulator, the speckle noise can be reduced to 0.07 according to the theory. The despeckle modulator is flexible for system implementation and can be a promising component in display system with coherent light source to restrain the speckle noise.

Carbon fibers (CFs) cannot be directly used for the preparation of CF paper because of their chemically inert nature. Herein, the surface of CF was modified via the spontaneous oxidative self-polymerization of dopamine. By taking full advantage of the spontaneous oxidation and self-polymerization properties of PD to maintain the maximum strength of CFs, a polydopamine-modified CF paper (PDA-CFP) with excellent performance was prepared using PD-modified CFs (PDA-CFs), which increased the proportion of hydrophilic functional groups on the surface of carbon fibers, increased the O/C ratio on the CF surface by 6 times, and improved the bond strength between the modified CF and the adhesive by making full use of the interaction force between polydopamine and PVA fibers. In this way, the primary properties of the CF paper was improved. Overall, the results showed that the dispersion of CF was considerably improved by the dopamine modification. In addition, the primary physical properties of PDA-CFP were better than those of virgin CF paper (CFP-0). PDA-CFP exhibited a maximum tensile strength of 2.04 kN/m2, a minimum resistivity of 0.06055 Ω·cm and a minimum porosity of 72.4%. The tightness could be increased by up to 12.1%.

We report a polymer based multiple diffraction modulator, in which PDMS (polydimethylsiloxane) is utilized as the actuation material, for speckle reduction. The properties of the PDMS are characterized based on its response time and deformability, which are the key properties concerned in this work. The structure dependent properties of PDMS are discussed. Using the described technique, the PDMS satisfy the system demand.The modulator is used to create real-time diffraction patterns by dynamic gratings formed by flexible PDMS. The diffracted light passes through a diffuser, which is placed after the modulator, and induces speckle patterns on the screen. Speckle-reduction is achieved by adding the time-varying speckle patterns in the integration time of the detector. It is observed that using the modulator which has two gratings, the speckle contrast ratio reaches to 50%, which shows fair agreement with the simulation.