Evaluation challenges for the application of extended reality devices in medicine

Augmented and virtual reality devices are being actively investigated and implemented for a wide range of medical uses. However, significant gaps in the evaluation of these medical devices and applications hinder their regulatory evaluation. Addressing these gaps is critical to demonstrating the devices\u27 safety and effectiveness. We outline the key technical and clinical evaluation challenges discussed during the US Food and Drug Administration\u27s public workshop, Medical Extended Reality: Toward Best Evaluation Practices for Virtual and Augmented Reality in Medicine and future directions for evaluation method development. Evaluation challenges were categorized into several key technical and clinical areas. Finally, we highlight current efforts in the standards communities and illustrate connections between the evaluation challenges and the intended uses of the medical extended reality (MXR) devices. Participants concluded that additional research is needed to assess the safety and effectiveness of MXR devices across the use cases

Transverse Chromatic Aberrations in Virtual Reality Devices

We demonstrate a method for measuring the transverse chromatic aberration (TCA) in a virtual reality head-mounted display (VR HMD). This procedure was used to characterize the optical performance of the Oculus Go VR HMD. Results show a measurable TCA for angles larger than approximately 6◦ from the center of the field of view. TCA can be thought of as a wavelength dependent magnification, and as a result, the relative size of objects vary based on the rendering color. In addition, this leads to color changes in the image due to mixing with neighboring pixels, which impacts image quality. The test results for the Oculus Go show promise for characterizing TCA across different HMDs

Tip-enhanced Raman scattering of graphene

This article reviews the mechanism of tip-enhanced Raman spectroscopy (TERS) and its importance for characterizing graphene. The theoretical foundation of TERS and experimental implementation are discussed. Conventionally, Raman scattering is treated as a spatially incoherent process where the total signal is proportional to the scattering volume. However, in the near-field regime, the scattered fields can add coherently because the TERS interaction volume is on the same length scale as the phonon correlation length. These coherence effects are significant for two-dimensional materials as will be discussed theoretically and experimentally. Therefore, TERS provides an optical method to probe phonon correlations at the nanoscale. In addition, this article will review the TERS applications for characterizing defects, edges, and nanoscale strain in graphene. Finally, the outlook and future applications are discussed