Holography has immense potential for near-eye displays in virtual and augmented reality (VR/AR), providing natural 3D depth cues through wavefront reconstruction. However, balancing the field of view (FOV) with the eyebox remains challenging, constrained by the étendue limitation. Additionally, holographic image quality is often compromised due to differences between actual wave propagation and simulation models. This study addresses these by expanding the eyebox via multi-angle illumination, and enhancing image quality with end-to-end pupil-aware hologram optimization. Further, energy efficiency is improved by incorporating higher-order diffractions and pupil constraints. We explore a Pupil-HOGD algorithm for multi-angle illumination and validate it with a dual-angle holographic display prototype. Integrated with camera calibration and tracked eye position, the developed Pupil-HOGD algorithm improves image quality and expands the eyebox by 50% horizontally. We envision this approach extends the space-bandwidth product (SBP) of holographic displays, enabling broader applications in immersive, high-quality visual computing.

3GPP has completed the standardization of 5G NR positioning in Release 16 (Rel-16) and Rel-17, and the Rel-18 study on expanded and improved positioning was finished in November, 2022. The standard solutions enable several positioning techniques in efforts to improve accuracy and power efficiency, and to decrease the latency. RAT-independent positioning techniques have also been standardized to support user equipment positioning via satellites and sensors. This article provides the latest progress on 3GPP 5G positioning including requirements, use cases, and the newly supported positioning techniques in Release-17 and Release-18. Finally, future challenges are discussed.

In this paper, we propose an effective target localization strategy for Internet of Things (IoT) scenarios, where positioning is performed by resource-constrained devices. Target-anchor links may be impaired by Non-Line-Of-Sight (NLOS) communication conditions. In order to derive a feasible IoT-oriented positioning strategy, we rely on the acquisition, at the target, of a sequence of consecutive measurements of the Received Signal Strength Indicator (RSSI) of the wireless signals transmitted by the anchors. We then consider a pragmatic approach according to which the NLOS channels are pre-mitigated and “transformed” into equivalent Line-Of-Sight (LOS) channels to estimate more accurately each target-anchor distance. The estimated distances feed “agnostic” localization algorithms, operating as if all links were LOS. We experimentally assess the performance of our approach in indoor (IEEE 802.11-based) and outdoor (Long Term Evolution, LTE-based) scenarios, considering both geometric and Particle Swarm Optimization (PSO)-based localization algorithms. Even if NLOS mitigation per single communication link is very effective, our results show that, in a given environment, it is possible to derive an “average” NLOS mitigation strategy regardless of the specific position of the target in the given environment. This is crucial to limit the computational complexity at IoT nodes performing localization, yet guaranteeing a relatively high (for IoT scenarios) localization accuracy, especially in an IEEE 802.11-based indoor case (with six anchors). The obtained performance compares favorably (in relative terms) with that obtained with more sophisticated wireless technologies (e.g., Ultra-WideBand, UWB).

Digital holography is a nondestructive testing technology with high precision and sensitivity. This paper presents a vibration parameter detection method based on digital holography. The vibration process of cylindrical aluminum excited by ultrasonic wave was simulated by finite element method. Then, the vibration parameters were recorded and reconstructed based on digital holography, and the analysis results verified the feasibility of the method.

Aiming at the influence of refraction, an underwater vision measurement method based on segmented synchronous rotational scanning is proposed in this paper. First, the underwater measurement refraction model is established. When the optical axis of the projector is perpendicular to the refraction plane and the light plane passes through the projection optical axis, the calibration can be done in the air, which simplifies the calibration process. Then the structure projection mode is designed to realize the segmented synchronous rotational scanning of the underwater area. Finally, we perform 3D measurements of underwater flat objects. The experimental results show that the measurement method proposed in this paper can achieve a measurement accuracy of 1.19mm when the measurement distance is within 1000mm.

This paper proposes a real-time measurement technology of digital speckle deformation based on Fourier transform by slightly improving the existing out-of-plane deformation measurement technology of planar objects. The speckle image collected by the CCD is subjected to carrier elimination, inverse Fourier transform and other methods to obtain the speckle interference fringes with low noise and high contrast. The experimental results of the out-of-plane deformation measurement of the aluminum plate show that the technology can measure the real-time deformation of the tested piece.

3GPP is paving the way to enhance the 5G NR positioning for general use cases as well as vertical industry scenarios, which attracts wide research from industry and academy. Among the varied requirements the most important one is to reduce the power consumption of the positioning device while keeping high accuracy in order to dominate the increasing market of positioning. In this paper, we propose a LPHAP solution under the 3GPP NR standard framework. For reduced power consumption, a new category or capability for positioning device is defined where RRC_INACTIVE state positioning with user-centric positioning area. For accuracy enhancement, we propose to improve TOA measurement by stitching the SRSs in multiple bands and analyze the Cramer-Rao Bound of TOA estimation. Uplink time difference of arrival (UL-TDOA) with expected angle-of-arrival is investigated to enhance TDOA measurements. Performance evaluations show that the device can reach the accuracy of 0.3m @90 % and the device battery life can be extended 20 times compared to Rel-17 UE.

The positioning algorithm currently in wireless networks is a separate estimation problem. The first step is to estimate the delay of each link to obtain the time-of-arrival (TOA) information. The second step is to pass the TOA into the positioning algorithm to get position estimation. However, the transmission of the signal between the user equipment (UE) and the base station (BS) is inevitably affected by non-line-of-sight (NLOS) transmission. At this time, the estimation of delay may not be the true TOA, resulting in the positioning performance is greatly reduced. To solve this problem, this paper proposes a Joint Approximate Maximum Likelihood (JAML) positioning algorithm, which combines delay estimation and position estimation, in 5G New Radio (NR) Systems. When the delay estimation is inaccurate, JAML reselects the correct delay estimation as TOA information for position estimation. We use a channel model of 5G NR in the simulation, and simulation results show that the JAML positioning algorithm improves the positioning performance.

We report a simple setup for two-step quadrature phase-shifting holography that could be useful and suitable for industrial applications. Only two on-axis holograms are captured with the system and a complex hologram is formed from the two holograms. Autocorrelation is used to quantify the quality of all the reconstructed images from the holograms. We have tested a transparent sample as well as a reflective sample to validate this simple setup.