Selective Couplers Based on Multiplexed Volume Holographic Gratings for Waveguide Displays

We report on the unique highly-configurable wavelength tuning and switching properties of a tunable external cavity laser based on multiplexed volume holographic gratings (VHGs) and a micromirror device. The ultra-compact laser has a 3 THz bandwidth and exhibits single mode operation in either single or multiple wavelengths with narrow linewidth (<7.5 MHz), and a switching rate of 0.66 kHz per wavelength. A prototype laser exhibited 40 mW of output power for wavelengths from 776 - 783 nm. The unique discrete-wavelength-switching features and low power consumption of this laser make it well suited as a source for continuous-wave (cw) terahertz signal generation in portable photomixing systems.

Augmented reality and portable devices to increase safety in container terminals: the testing of A4S project in the port of Genoa

Hand guidance of robots has proven to be a useful tool both for programming trajectories and in kinesthetic teaching. However hand guidance is usually relegated to robots possessing joint-torque sensors (JTS). Here we propose to extend hand guidance to robots lacking those sensors through the use of an Augmented Reality (AR) device, namely Microsoft's Hololens. Augmented reality devices have been envisioned as a helpful addition to ease both robot programming and increase situational awareness of humans working in close proximity to robots. We reference the robot by using a registration algorithm to match a robot model to the spatial mesh. The in-built hand tracking capabilities are then used to calculate the position of the hands relative to the robot. By decomposing the hand movements into orthogonal rotations we achieve a completely sensorless hand guidance without any need to build a dynamic model of the robot itself. We did the first tests our approach on a commonly used industrial manipulator, the KUKA KR-5.

In sheet and bulk forming, numerical simulation has become established over the last 20 years as an indispensable tool for research and industrial practice. The numerical calculation of forming processes supports a time- and cost-efficient development in the context of a virtual product evaluation. Currently, simulation and measurement results are mainly displayed on conventional screens. However, this approach has several disadvantages. On the one hand, only cut-outs can be displayed, especially in the case of large components. A visualisation of entire components in real size is often not possible. On the other hand, no direct comparison with the real components is possible. Augmented Reality is a promising approach to solve the challenges outlined above. As part of the contribution, an innovative approach for component validation based on Augmented Reality technology will be introduced. Thereby, the visualisation using different Augmented Reality devices and the feasibility of a measurement task with Augmented Reality devices will be presented.

A non-axial-scanning multi-plane microscopic system incorporating multiplexed volume holographic gratings and slit array detection to simultaneously acquire optically sectioned images from different depths is presented. The proposed microscopic system is configured such that multiplexed volume holographic gratings are utilized to selectively produce axial focal points in two or more planes inside the sample, and then to use confocal slit apertures to simultaneously image these multiple planes onto corresponding detection areas of a CCD. We describe the design, implementation, and experimental data demonstrating this microscopic system's ability to obtain optically sectioned multi-plane images of fluorescently labeled standard micro-spheres and tissue samples without scanning in axial directions.

The wavelength tuning properties of a tunable external cavity laser based on multiplexed volume holographic gratings and a commercial micromirror device are reported. The 3x3x3 cm(3) laser exhibits single mode operation in single or multi colors between 776 nm and 783 nm with less than 7.5 MHz linewidth, 37 mW output power, 50 μs rise/fall time constant and a maximum switching rate of 0.66 KHz per wavelength. The unique discrete-wavelength-switching features of this laser are also well suited as a source for continuous wave Terahertz generation and three-dimensional metrology.

Augmented and Virtual Reality for Inspection and Maintenance Processes in the Aviation Industry

Robotic surgery bedside assistants play an important role in robotic procedures by performing intra-corporeal tasks while accommodating the physical presence of the robot. We hypothesized that an augmented reality headset enabling 3D intra-corporeal vision while facing the surgical field could decrease time and improve accuracy of robotic bedside tasks. Bedside assistants (one physician assistant, one medical student, three surgical trainees, and two attending surgeons) performed validated tasks within a mock abdominal cavity with a surgical robot docked. Tasks were performed with a bedside monitor providing 2D or 3D vision, or an optical see-through head-mounted augmented reality device with 2D or 3D vision. The effect of augmented reality device resolution on performance was also evaluated. For the simplest task of touching a straw, performance was generally high, regardless of mode of visualization. With more complex tasks, including stapling and pulling a ring along a path, 3D augmented reality decreased time and number of errors per task. 3D augmented reality allowed the physician assistant to perform at the level of an attending surgeon using 3D augmented reality (p = 0.08). All participants had improved times for the ring path task with better resolution (lower resolution 23 ± 11s vs higher resolution 14 ± 4s, p = 0.002). 3D augmented reality vision with high resolution decreased time and improved accuracy of more complex tasks, enabling a less experienced robotic surgical bedside assistant to function similar to attending surgeons. These data warrant further study with additional complex tasks and bedside assistants at various levels of training.

Impairment of autonomous way-finding subsequent to a multitude of neurodegenerative and other diseases impedes independence of older persons and their everyday activities. It was the goal to use augmented reality to aid autonomous way-finding in a community setting. A spatial map and directional information were shown via head-up display to guide patients from the start zone on the hospital campus to a bakery in the nearby community. Hospital campus and nearby community. Patients with mild cognitive impairment (age 63 to 89). A head-up display was used to help patients find their way. Time needed to reach goal and number of assists needed. With use of augmented reality device, patients preceded along the correct path in 113 out of 120 intersections. Intermittent reassurance was needed for most patients. Patients affirmed willingness to use such an augmented reality device in everyday life if needed or even pay for it. Augmented reality guided navigation is a promising means to sustain autonomous way-finding as a prerequisite for autonomy of older persons in everyday activities. Thus, this study lays ground for a field trial in the community using assistive technology for older persons with cognitive impairment.

In recent years augmented reality has begun to be a presence in various industrial sectors. In augmented reality the operator's perception of reality is enriched through virtual information useful to help him in his working activity. Augmented reality can be generated through various technical solutions. A first classification can be made based on how the equipment is used: head mounted displays, handheld displays, and spatial displays. Maintenance can benefit from the introduction of augmented reality as it can help operators in activities characterized by variability and in the risky activities. This is because augmented reality allows to remember the steps of the procedures and highlight the dangers if present. However, the use of augmented reality devices can bring new dangers including ergonomic problems or visual fatigue or information overload. This chapter presents an index methodology for assessing the risks introduced by augmented reality devices.

Gratings are widely used as coupling parts in a waveguide display system for achieving a much lighter and more compact system, but their diffraction efficiency needs to be improved. Two combined gratings for integrating a subwavelength binary grating and volume holographic grating (VHG) are applied as incoupler and outcoupler of a holographic waveguide display system. Two basic design rules are put forward to guarantee the maximum diffraction energy guided into the waveguide and finally coupled out to enter into the user's eyes: one is the grating vector matching rule, the other is the refractive index matching rule on the interface of the binary grating and the VHG. The finite element method is used to simulate the couple-in parts and the whole waveguide display system. The combined grating with the metal binary grating is different from that with a dielectric binary grating for achieving higher diffraction efficiency and an additional second peak in the diffraction efficiency curve varied with the relative position between the binary grating and the VHG. The simulation results indicate that a VHG+Ag combined grating can obtain much higher diffraction efficiency compared to gold, aluminum, and other dielectric materials. In addition, several factors such as the Bragg wavelength, the index modulation of VHG, binary grating thickness, and the filling factor of the binary grating are discussed for the VHG+Ag combined grating. Moreover, a higher diffraction efficiency in the holographic waveguide system can be obtained by using VHG+Ag-VHG+Ag combined gratings as the incoupler and outcoupler.

Pedagogical Strategies for the Integration of Augmented Reality in ICT Teaching and Learning Processes

Displaying high-quality images on edge devices, such as augmented reality devices, is essential for enhancing the user experience. However, these devices often face power consumption and computing resource limitations, making it challenging to apply many deep learning-based image compression algorithms in this field. Implicit Neural Representation (INR) for image compression is an emerging technology that offers two key benefits compared to cutting-edge autoencoder models: low computational complexity and parameter-free decoding. It also outperforms many traditional and early neural compression methods in terms of quality. In this study, we introduce a new Mixed AutoRegressive Model (MARM) to significantly reduce the decoding time for the current INR codec, along with a new synthesis network to enhance reconstruction quality. MARM includes our proposed AutoRegressive Upsampler (ARU) blocks, which are highly computationally efficient, and ARM from previous work to balance decoding time and reconstruction quality. We also propose enhancing ARU's performance using a checkerboard two-stage decoding strategy. Moreover, the ratio of different modules can be adjusted to maintain a balance between quality and speed. Comprehensive experiments demonstrate that our method significantly improves computational efficiency while preserving image quality. With different parameter settings, our method can achieve over a magnitude acceleration in decoding time without industrial level optimization or achieve state-of-the-art reconstruction quality compared with other INR codecs. To the best of our knowledge, our method is the first INR-based codec comparable with Ballé et al. [1] in both decoding speed and quality while maintaining low complexity.

Brain-computer interfaces (BCI) have been shown as a powerful way to provide communication without motor actions. However, they are currently limited by their methodology and user aptitude. Motor imagery (MI) based BCIs require lenghthy training sessions to be effectively used, while steady state visual evoked potential (SSVEP) based BCIs are limited in number of classes by the refresh rate of the display monitor and visual space. By employing both MI and SSVEP-based BCIs in tandem with an augmented reality device, we designed a new asynchronous hybrid AR-BCI system for navigation of quadcopter flight. The use of hybrid BCI allowed us to reduce training time required for motor imagery based BCIs and increase number of total classes that can be used without need for extra visual clutter. This allows use of AR device to display SSVEP stimulus, which lets users to freely look around while maintaining mental control over the quadcopter.

Increasing attention in research in the field of networks and communication systems attracts the creation and development of communication networks of the fifth generation. An important role is given to new applications that determine the capabilities of these networks in the provision of services. Augmented Reality (AR) is one of the most promising applications. Requirements for the provision of Augmented Reality services are quite stringent, especially in terms of the circular delay, the permissible value of which is determined by the value of 5 ms. This requires the development of adequate solutions for the network structure, which in the fifth generation communications network are based on mobile edge computing technology. The article is devoted to the actual topic of using Augmented Reality technology and provides an investigation of the transmission of video data for Augmented Reality applications through a mesh network. The basis of the material presented is the solution of the problem of simulation modeling of the use of Augmented Reality in a mesh network, made using the COOJA simulator.