BACKGROUND: Solid surfaces possessing both superhydrophobic and superoleophilic properties have attracted great interest for fundamental research and potential application. However, fabrication of the reported surfaces is usually time-consuming and the wetability of the surfaces could not be achieved to the desired level in rugged environments.

The Gerchberg-Saxton (GS) algorithm is widely used to calculate the phase-only computer-generated hologram (CGH) for holographic three-dimensional (3D) display. However, speckle noise exists in the reconstruction of the CGH due to the uncontrolled phase distribution. In this paper, we propose a method to suppress the speckle noise by simultaneously reconstructing the desired amplitude and phase distribution. The phase-only CGH is calculated by using a double-constraint GS algorithm, in which both the desired amplitude and phase information are constrained in the image plane in each iteration. The calculated phase-only CGH can reconstruct the 3D object on multiple planes with a desired amplitude distribution and uniform phase distribution. Thus the speckle noise caused by the phase fluctuation between adjacent pixels is suppressed. Both simulations and experiments are presented to demonstrate the effective speckle noise suppression by our algorithm.

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The purpose of this study is to implement speckle reduced three-dimensional (3-D) holographic display by single phase-only spatial light modulator (SLM). The complex amplitude of hologram is transformed to pure phase value based on double-phase method. To suppress noises and higher order diffractions, we introduced a 4-f system with a filter at the frequency plane. A blazing grating is proposed to separate the complex amplitude on the frequency plane. Due to the complex modulation, the speckle noise is reduced. Both computer simulation and optical experiment have been conducted to verify the effectiveness of the method. The results indicate that this method can effectively reduce the speckle in the reconstruction in 3-D holographic display. Furthermore, the method is free of iteration which allows improving the image quality and the calculation speed at the same time.

Wearable sensors with water resistance and mechanical durability are of great value in dealing with long‐term movement and remote control in harsh environments. However, achieving high sensitivity with long‐term stability and real‐time remote control in a watery environment is still a challenge. Herein, the waterproof wearable sensors with good mechanical robustness composed of laser‐induced graphene and in situ‐coated protective silicone layers are reported. By being integrated with high‐capacitance ion‐gel dielectrics, the conformal sensors can detect multiple stimuli, including strain, temperature, and pressure. The long‐term water resistance of strain sensors is evaluated by continuously monitoring the resistance in underwater, sweat, and saline environment for up to 5.5 h. Underwater wireless remote control of a robotic hand is further demonstrated by mounting five sensor arrays. Moreover, different finger gestures are well recognized, making these sensor devices promising candidates for versatile waterproof wearable electronics and robotics technology.