Conventional head-up displays (HUDs) suffer from a limited exit pupil and a lack of compactness mainly due to the use of bulky optics. HUDs need a high-quality image with a large field of view (FOV) in small packaging to gain commercial acceptability. Holographic HUDs are phase-only devices that allow vision correction and focus adjustment while having a wide FOV. However, the limited bandwidth of a spatial light modulator (SLM) imposes a trade-off between the FOV and eye-box size. Combining a holographic system with an image-replicating element eliminates such a tradeoff. For image replication, we designed and fabricated a compact 2D diffractive beam splitter formed from two perpendicular volume gratings operating in the Raman-Nath regime. The gratings were recorded holographically in photo-thermo-refractive (PTR) glass, with optimized index modulation, thickness, and period to provide uniform intensity distribution across all desired orders for the fundamental red, green and blue (RGB) colors. We demonstrated a full-color holographic projection with an eye-box expanded by the designed 2D diffractive beam splitters.
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http://dx.doi.org/10.1364/OE.478532 | DOI Listing |
Sci Rep
January 2025
Department of Physics, University of Trieste, 34127, Trieste, Italy.
Phase-contrast micro-tomography ([Formula: see text]CT) with synchrotron radiation can aid in the differentiation of subtle density variations in weakly absorbing soft tissue specimens. Modulation-based imaging (MBI) extracts phase information from the distortion of reference patterns, generated by periodic or randomly structured wavefront markers (e.g.
View Article and Find Full Text PDFUltrasonics
January 2025
School of Biological Science and Medical Engineering, Beihang University, Beijing, China. Electronic address:
Transcranial focused ultrasound (tFUS) has been gaining increased attention as a non-invasive modality for treating brain diseases. However, accurately focusing on brain structures remains a challenge as the ultrasound is severely distorted by the presence of the skull. In this article, we propose a promising distortion correction method based on spherical wave expansions.
View Article and Find Full Text PDFNanophotonics
September 2024
State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China.
Two-dimensional (2D) layered materials without centrosymmetry, such as GaSe, have emerged as promising novel optical materials due to large second-order nonlinear susceptibilities. However, their nonlinear responses are severely limited by the short interaction between the 2D materials and light, which should be improved by coupling them with photonic structures with strong field confinement. Here, we theoretically design photonic crystal circular Bragg gratings (CBG) based on hole gratings with a quality factor as high as = 8 × 10, a mode volume as small as = 1.
View Article and Find Full Text PDFAdv Mater
December 2024
Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA.
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