Monitoring sidewall tilting of pixelated nanogratings in 3D display.

Sidewall tilting is an important parameter to describe the grating morphology and would affect the diffraction efficiency of three-dimensional (3D) display devices based on pixelated nanogratings. However, there is currently a lack of a non-destructive measurement method that can accurately measure the sidewall tilting of the pixelated nanogratings. This is mainly because the kind of nanograting is manufactured in a micron-scale pixel region and the grating lines generally have various directions to ensure that the display device can display images smoothly. In this work, we propose to use a home-made imaging Mueller matrix ellipsometer (IMME) to monitor sidewall tilting of pixelated nanogratings. Simulation and experiments were carried out to characterize the sidewall tilting angle. Through the combination of Mueller matrix elements, we can quickly and qualitatively identify the tilting angle for the purpose of on-line quality monitoring of the device. Through the inverse calculation of the Mueller matrix, we can accurately and quantitatively obtain the value of the tilting, so as to meet the demands of the device design. It is expected the proposed method can provide guidance for the identification and detection of tilting in 3D display elements based on pixelated gratings.

Pixelated volume holographic optical element for augmented reality 3D display.

Augmented reality (AR) three-dimensional (3D) display is the hardware entrance of metaverse and attracts great interest. The fusion of physical world with 3D virtual images is non-trivial. In this paper, we proposed an AR 3D display based on a pixelated volume holographic optical element (P-VHOE). The see-through combiner is prepared by spatial multiplexing. A prototype of AR 3D display with high diffraction efficiency (78.59%), high transmission (>80%) and non-repeating views is realized. Virtual 3D objects with high fidelity in depth is reconstructed by P-VHOE, with a complex wavelet structural similarity (CW-SSIM) value of 0.9882. The proposed prototype provides an efficient solution for a compact glasses-free AR 3D display. Potential applications include window display, exhibition, education, teleconference.

Characterization of pixelated nanogratings in 3D holographic display by an imaging Mueller matrix ellipsometry.

The diffraction grating, as an element that can control the direction of the emitted light, is the key component used in holographic sampling three-dimensional (3D) displays. The structural accuracy of nanogratings greatly affects the precision of light modulation, thus influencing the cross talk and resolution in 3D displays. It is of great significance for the nondestructive measurement of nanogratings. However, existing measurement methods have certain limitations such as destructiveness and low measurement efficiency in the face of measuring such pixelated nanogratings. In this work, aimed at the measurement requirements and challenges of pixelated nanogratings in 3D displays, we propose to use a self-designed imaging Mueller matrix ellipsometer (IMME) for grating characterization. A sample containing 6 periods and 10 orientations of pixelated gratings is investigated to verify the effectiveness of the method used. Through the measurement and fitting data, the measurement data obtained by using the IMME can be well matched with the theoretical results. At the same time, the extraction results of the structural parameters, periods, and orientations are also consistent with the measurement results from scanning electron microscopy. It is expected that the IMME will provide a guarantee for the accurate display of 3D holography.

An exploration of manure derived N in soils using 15N after the application of biochar, straw and a mix of both.

It is common practice to apply manure onto soil as an effective way to increase soil fertility. However, the impact of different carbon sources on the transformation and fate of manure derived nitrogen (N) remains poorly understood. This study investigated the mineralization and immobilization turnover (MIT) of various manure-N fractions using sequential extractions and 15N tracing techniques combined after soil amendment with biochar, straw and mixtures thereof. Soil N was fractionated into mineral nitrogen (NH4+ and NO3-), microbial biomass nitrogen (MBN), hot water extractable organic nitrogen (HWDON), hydrochloric acid extractable organic nitrogen (HCl-N), and residual nitrogen (RN). Results showed that biochar addition increased the 15NH4+ content by 45% during the early stage. However, the high pH and labile C absence of biochar inhibited the remineralization of microbial immobilization N during the mid-to-late stage. Straw addition enhanced 15NH4+ assimilation by 10% to form HCl-15N. After that, microbial cellular structures and secondary metabolites were remineralized to meet crop N requirements. Adding carbon source mixtures with the organic fertilizer manifested the relationship between biochar and straw. The labile C content of the carbon sources rather than the C/N ratio was the critical factor regulating the N-MIT process. Overall, these findings offer new insights into the N transformation approaches using the co-application technique of organic amendments.