3,153 research outputs found

    LiDAR-derived digital holograms for automotive head-up displays.

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    A holographic automotive head-up display was developed to project 2D and 3D ultra-high definition (UHD) images using LiDAR data in the driver's field of view. The LiDAR data was collected with a 3D terrestrial laser scanner and was converted to computer-generated holograms (CGHs). The reconstructions were obtained with a HeNe laser and a UHD spatial light modulator with a panel resolution of 3840Γ—2160 px for replay field projections. By decreasing the focal distance of the CGHs, the zero-order spot was diffused into the holographic replay field image. 3D holograms were observed floating as a ghost image at a variable focal distance with a digital Fresnel lens into the CGH and a concave lens.This project was funded by the EPSRC Centre for Doctoral Training in Connected Electronic and Photonic Systems (CEPS) (EP/S022139/1), Project Reference: 2249444

    Waveguide Holography: Towards True 3D Holographic Glasses

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    We present a novel near-eye display concept which consists of a waveguide combiner, a spatial light modulator, and a laser light source. The proposed system can display true 3D holographic images through see-through pupil-replicating waveguide combiner as well as providing a large eye-box. By modeling the coherent light interaction inside of the waveguide combiner, we demonstrate that the output wavefront from the waveguide can be controlled by modulating the wavefront of input light using a spatial light modulator. This new possibility allows combining a holographic display, which is considered as the ultimate 3D display technology, with the state-of-the-art pupil replicating waveguides, enabling the path towards true 3D holographic augmented reality glasses

    높은 곡간 λŒ€μ—­ν­μ„ μœ„ν•œ λ³΅μ†Œ 진폭 이미징 및 λ””μŠ€ν”Œλ ˆμ΄ μ‹œμŠ€ν…œ

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    ν•™μœ„λ…Όλ¬Έ (박사) -- μ„œμšΈλŒ€ν•™κ΅ λŒ€ν•™μ› : κ³΅κ³ΌλŒ€ν•™ 전기·정보곡학뢀, 2021. 2. μ΄λ³‘ν˜Έ.빛을 νŒŒλ™μœΌλ‘œ μ΄ν•΄ν•˜λ©΄ κ°„μ„­κ³Ό νšŒμ ˆμ„ ν¬ν•¨ν•œ λ‹€μ–‘ν•œ κ΄‘ν•™ ν˜„μƒμ„ 해석 ν•  수 μžˆλ‹€. 미래 기술이라 λΆˆλ¦¬λŠ” ν™€λ‘œκ·Έλž¨, 3차원 이미징 및 3차원 λ””μŠ€ν”Œλ ˆμ΄ μ‹œμŠ€ν…œλ“€μ€ νŒŒλ™μ˜ λ³΅μ†Œμ§„ν­μ„ μ΄ν•΄ν•˜κ³  λ³€μ‘°ν•¨μœΌλ‘œμ¨ κ΅¬ν˜„λ  수 μžˆλ‹€. ν˜„μ‘΄ν•˜λŠ” 광곡학 μž₯치λ₯Ό λ„˜μ–΄μ„œλŠ” νŒŒλ™ 광학에 κΈ°λ°˜ν•œ 광곡학 μž₯μΉ˜λ“€μ„ μƒμš©ν™” 및 λ°œμ „μ‹œν‚€κΈ° μœ„ν•΄ λ§Žμ€ 연ꡬ가 μ§„ν–‰λ˜μ–΄μ™”μ§€λ§Œ, μ§€κΈˆκ» κ΅¬ν˜„λœ μž₯μΉ˜λ“€μ€ 곡간 λŒ€μ—­ν­ (space-bandwidth product)의 μ œν•œμœΌλ‘œ 인해 κ·Έ μ„±λŠ₯이 λŒ€μ€‘μ˜ κΈ°λŒ€μ— λΆ€ν•©ν•˜κΈ° 어렀움을 κ²ͺκ³ μžˆλ‹€. λ³Έ 논문은 λ³΅μ†Œ 진폭 이미징 및 λ””μŠ€ν”Œλ ˆμ΄ μ‹œμŠ€ν…œμ—μ„œ 곡간 λŒ€μ—­ν­μ„ ν–₯상 μ‹œν‚€λŠ” 방법을 μ œμ•ˆν•œλ‹€. λ³΅μ†Œ 진폭 λ³€μ‘° μ‹œμŠ€ν…œμ˜ μ„±λŠ₯은 κ΄‘ν•™ μ‹œμŠ€ν…œμ˜ μ •λ³΄λŸ‰μ„ λ‚˜νƒ€λ‚΄λŠ” 곡간 λŒ€μ—­ν­μ— μ˜ν•΄ μ œν•œλœλ‹€. 이 곡간 λŒ€μ—­ν­μ„ ν–₯μƒμ‹œν‚€κΈ° μœ„ν•˜μ—¬ μ €μžλŠ” λ‹€μ–‘ν•œ 닀쀑화 κΈ°μˆ μ„ μ μš©ν•˜λ©°, λ™μ‹œμ— λ‹€μ€‘ν™”λœ 정보λ₯Ό λΆ„λ¦¬ν•˜λŠ” μ•Œκ³ λ¦¬μ¦˜κ³Ό μž₯치λ₯Ό κ³ μ•ˆν•œλ‹€. 첫번째둜 디지털 ν™€λ‘œκ·Έλž˜ν”Ό κΈ°μˆ μ— 곡간 주파수λ₯Ό 닀쀑화해 λŒ€μ—­ν­μ„ 효율적으둜 ν™œμš©ν•˜λŠ” 방법을 κ³ μ•ˆν•˜μ—¬ νšλ“λœ ν™€λ‘œκ·Έλž¨μ˜ 촬영 μ˜μ—­μ„ μ¦κ°€μ‹œν‚¨λ‹€. λ‘λ²ˆμ§Έλ‘œ, 단일 촬영 푸리에 νƒ€μ΄μ½”κ·Έλž˜ν”Ό (single-shot Fourier ptychography) κΈ°μˆ μ—μ„œλŠ” κ΄‘ 쑰사 닀쀑화λ₯Ό μ‚¬μš©ν•˜μ—¬ 이미지 μ„Όμ„œμ— κΈ°λ‘λ˜λŠ” μ •λ³΄μ˜ 양을 ν™•μž₯μ‹œν‚¨λ‹€. 닀쀑화 된 정보λ₯Ό λΆ„ν•΄ν•˜κ³  λ³΅μ†Œ 진폭을 νšλ“ν•˜κΈ° μœ„ν•˜μ—¬ μƒˆλ‘œμš΄ κ΄‘ν•™ μ‹œμŠ€ν…œκ³Ό μ „μ‚° μ•Œκ³ λ¦¬μ¦˜μ„ κ³ μ•ˆν•˜μ—¬ 해상도가 ν–₯μƒλœ λ³΅μ†Œ 진폭을 νšλ“ν•œλ‹€. μ„Έλ²ˆμ§Έλ‘œ, μ €μžλŠ” ν™€λ‘œκ·Έλž¨ λ””μŠ€ν”Œλ ˆμ΄μ— μ‘°λͺ… 닀쀑화 및 μ‹œλΆ„ν•  κΈ°μˆ μ„ μ μš©ν•œλ‹€. 닀쀑화 된 μ •λ³΄λŠ” μΈκ°„μ˜ 인지적 μ‹œκ°„ λŒ€μ—­ν­κ³Ό μ œμ•ˆλœ μ‹œμŠ€ν…œμ˜ 곡간 ν•„ν„°λ§μ˜ κ²°ν•©μœΌλ‘œ λΆ„ν•΄λœλ‹€. κ΅¬ν˜„λœ ν™€λ‘œκ·Έλž˜ν”½ λ””μŠ€ν”Œλ ˆμ΄λŠ” 곡간 λŒ€μ—­ν­μ΄ ν™•μž₯λ˜μ–΄ 더 넓은 μ‹œμ•Όκ°μ— 삼차원 ν™€λ‘œκ·Έλž¨μ„ μ œκ³΅ν•œλ‹€. λ³Έ 논문은 μž‘μ€ κ³΅κ°„λŒ€μ—­ν­μ΄λΌλŠ” κ³΅ν†΅λœ 문제λ₯Ό κ³΅μœ ν•˜λŠ” 이미징 및 λ””μŠ€ν”Œλ ˆμ΄ λΆ„μ•Όμ˜ λ°œμ „μ— κΈ°μ—¬ν•  κ²ƒμœΌλ‘œ κΈ°λŒ€λœλ‹€. μ €μžλŠ” λ³Έ μ—°κ΅¬μ—μ„œ μ œμ•ˆλœ 방법이 λ‹€μ–‘ν•œ λ³΅μ†Œ 진폭 λ³€μ‘° μ‹œμŠ€ν…œμ˜ μ„±λŠ₯ ν–₯상에 μ˜κ°μ„ μ£Όλ©°, λ‚˜μ•„κ°€ 삼차원 계츑, ν™€λ‘œκ·Έλž˜ν”Ό, 가상 및 μ¦κ°•ν˜„μ‹€μ„ ν¬ν•¨ν•œ λ‹€μ–‘ν•œ 미래 산업에 λ°œμ „μ— κΈ°μ—¬ν•  수 있기λ₯Ό κΈ°λŒ€ν•œλ‹€.Understanding light as a wave makes it possible to interpret a variety of phenomena, including interference and diffraction. By modulating the complex amplitude of the wave, hologram, three-dimensional imaging, and three-dimensional display system, called future technologies, can be implemented that surpass the currently commercialized optical engineering devices. Although a lot of research has been conducted to develop and commercialize the wave optical system, state-of-the-art devices are still far from the performance expected by the public due to the limited space-bandwidth product (SBP). This dissertation presents the studies on high SBP for complex amplitude imaging and display systems. The performance of a complex amplitude modulating system is limited by the SBP, which represents the amount of information in the optical system. To improve the SBP of the complex amplitude in a limited amount of information, the author applies various multiplexing techniques suitable for the implemented system. In practice, the spatial frequency multiplexed digital holography is devised by efficiently allocating frequency bandwidth with dual-wavelength light sources. The author also applies illumination multiplexing to the single-shot Fourier ptychography to expand the amount of information recorded in the image sensor. Computational reconstruction algorithm combined with novel optical design allows the acquired multiplexed information to be decomposed in the imaging system, leading to improvement of size of the image or resolution. Furthermore, the author applied illumination multiplexing and temporal multiplexing techniques to holographic displays. The multiplexed information is decomposed by a combination of human perceptual temporal bandwidth and spatial filtering. The SBP enhanced holographic display is implemented, providing a more wide viewing angle. It is expected that this thesis will contribute to the development of the imaging and display fields, which share a common problem of small SBP. The author hopes that the proposed methods will inspire various researchers to approach the implementation of complex amplitude modulating systems, and various future industries, including 3-D inspection, holography, virtual reality, and augmented reality will be realized with high-performance.Abstract i Contents iii List of Tables vi List of Figures vii 1 Introduction 1 1.1 Complex Amplitude of Wave 1 1.2 Complex Amplitude Optical System 3 1.3 Motivation and Purpose of the Dissertation 5 1.4 Scope and Organization 8 2 Space-Bandwidth Product 10 2.1 Overview of Space-Bandwidth Product 10 2.2 Space-Bandwidth Product of Complex Amplitude Imaging Systems 11 2.3 Space-Bandwidth Product of Complex Amplitude Display Systems 13 3 Double Size Complex Amplitude Imaging via Digital Holography 15 3.1 Introduction 15 3.1.1 Digital Holography 16 3.1.2 Frequency Multiplexed Digital Holography 22 3.1.3 Adaptation of Diffractive Grating for Simple Interferometer 24 3.2 Principle 26 3.2.1 Single Diffraction Grating Off-Axis Digital Holography 26 3.2.2 Double Size Implementation with Multiplexed Illumination 29 3.3 Implementation 32 3.4 Experimental Results 34 3.4.1 Resolution Assessment 34 3.4.2 Imaging Result 36 3.4.3 Quantitative 3-D Measurement 38 3.5 Conclusion 42 4 High-Resolution Complex Amplitude Imaging via Fourier Ptychographic Microscopy 43 4.1 Introduction 43 4.1.1 Phase Retrieval 45 4.1.2 Fourier Ptychographic Microscopy 47 4.2 Principle 52 4.2.1 Imaging System for Single-Shot Fourier Ptychographic Microscopy 52 4.2.2 Multiplexed Illumination 55 4.2.3 Reconstruction Algorithm 58 4.3 Implementation 60 4.3.1 Numerical Simulation 60 4.3.2 System Design 64 4.4 Results and Assessment 65 4.4.1 Resolution 65 4.4.2 Phase Retrieval of Biological Specimen 68 4.5 Discussion 71 4.6 Conclusion 73 5 Viewing Angle Enhancement for Holographic Display 74 5.1 Introduction 74 5.1.1 Complex Amplitude Representation 76 5.1.2 DMD Holographic Displays 79 5.2 Principle 81 5.2.1 Structured Illumination 81 5.2.2 TM with Array System 83 5.2.3 Time Domain Design 84 5.3 Implementation 85 5.3.1 Hardware Design 85 5.3.2 Frequency Domain Design 85 5.3.3 Aberration Correction 87 5.4 Results 88 5.5 Discussion 92 5.5.1 Speckle 92 5.5.2 Applications for Near-eye Displays 94 5.6 Conclusion 99 6 Conclusion 100 Appendix 116 Abstract (In Korean) 117Docto

    ν™€λ‘œκ·Έλž˜ν”½ ν”„λ¦°ν„°λ₯Ό μ΄μš©ν•œ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄μ˜ λ§žμΆ€ν˜• ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμž μ œμž‘

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    ν•™μœ„λ…Όλ¬Έ (박사) -- μ„œμšΈλŒ€ν•™κ΅ λŒ€ν•™μ› : κ³΅κ³ΌλŒ€ν•™ 전기·정보곡학뢀, 2020. 8. μ΄λ³‘ν˜Έ.This dissertation presents the studies on the design and fabrication method of a holographic optical element (HOE) for augmented reality (AR) near-eye display (NED) by using a holographic printing technique. The studies enable us to manufacture HOEs based on the digitalized design process and allow more freedom to design HOEs, beyond the conventional HOE manufacturing process. The manufactured HOE can play the role of the image combiner of the AR NED and can be designed precisely according to each users distinctive characteristics. The prototype of the HOE printer is presented and the structure is analyzed. The HOE printer can record a hogel with 1900 Γ— 1900 pixels in 1 mm2 and can give complex wavefront information via using an amplitude SLM and sideband filtering technique. The author adopts an index-matching frame with a passive optical isolator, which consists of quarter waveplates and linear polarizers, to eliminate the internal reflection noise. With the HOE printer, a lens HOE with field of view (FOV) 50Β° is manufactured, and a holographic AR NED is implemented with the lens HOE. The experimental result shows the lens HOE and the HOE printer work properly as our purpose. Using the prototype HOE printer, the author proposes two types of novel AR NEDs. First, the author suggests a customized HOE for an eye-box extended holographic AR NED. The limitation of the conventional holographic AR NED is that the eye-box becomes very narrow when large FOV is implemented due to the limited spatial bandwidth product. By using the proposed HOE printer, the eye-box can be extended along with both horizontal and vertical directions without any mechanical scanning devices. Also, the position of the extended eye-box can be designed to fit with the movement of the eye pupil. This prevents the vignetting effect due to the eye-box mismatch. Second, the author presents a freeform mirror array (FMA) HOE and implement a retinal projection AR NED with the HOE. By using the FMA HOE, the holographic mirrors no longer block the sight of the observer. Also, the freeform phase function allows the FMA HOE to float the display to the desired location without any additional optics, such as a lens. In this way, a wide depth of field and extended eye-box retinal projection AR NED with a compact form factor is implemented. It is expected that this dissertation can help to develop a customized AR NED based on the customers needs. Furthermore, it is believed that this work can show new possibilities for research on the design and fabrication of HOEs.λ³Έ λ°•μ‚¬ν•™μœ„ λ…Όλ¬Έμ—μ„œλŠ” κ·Όμ•ˆ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄μ˜ ν™€λ‘œκ·Έλž˜ν”½ μ˜μƒ κ²°ν•© μ†Œμžλ₯Ό ν™€λ‘œκ·Έλž˜ν”½ ν”„λ¦°νŒ… κΈ°μˆ μ„ μ΄μš©ν•˜μ—¬ 섀계 및 μ œμž‘ν•˜λŠ” 방법에 λŒ€ν•˜μ—¬ λ…Όν•œλ‹€. 이λ₯Ό ν†΅ν•˜μ—¬ 기쑴의 μ•„λ‚ λ‘œκ·Έ 방법에 μ˜μ‘΄ν•œ ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμž μ œμž‘ 기법을 디지털화 ν•  수 μžˆλ‹€. λ˜ν•œ ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμžμ˜ 섀계 μžμœ λ„κ°€ μ¦κ°€ν•˜μ—¬ μ‚¬μš©μž νŠΉμ§•μ— λ”°λ₯Έ κ·Όμ•ˆ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄μ˜ λ§žμΆ€ν˜• μ˜μƒ κ²°ν•© μ†Œμžλ₯Ό μ œμž‘ν•  수 μžˆλ‹€. 이 λ°•μ‚¬ν•™μœ„ λ…Όλ¬Έμ—μ„œλŠ” ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμž ν”„λ¦°ν„°μ˜ ν”„λ‘œν† νƒ€μž…μ„ μ œμž‘ 및 μ†Œκ°œν•œλ‹€. ν•΄λ‹Ή ν”„λ‘œν† νƒ€μž…μ€ 1 mm2의 면적 μ•ˆμ— 1900 Γ— 1900 λ³΅μ†Œ κ΄‘νŒŒ 정보λ₯Ό ν‘œν˜„ ν•  수 μžˆλ‹€. κ΄‘νŒŒμ˜ λ³΅μ†Œ λ³€μ‘°λ₯Ό μœ„ν•˜μ—¬ 진폭 λ³€μ‘° 곡간광변쑰λ₯Ό μ΄μš©ν•œ sideband filtering 기법이 μ‚¬μš©λœλ‹€. λ˜ν•œ ꡴절λ₯ μ΄ λ³΄μƒλœ ν”„λ ˆμž„μ— 1/4 파μž₯판 및 μ„ ν˜• νŽΈκ΄‘μžλ₯Ό μ΄μš©ν•œ μˆ˜λ™ κ΄‘λΆ„λ¦¬μ†Œμžλ₯Ό μ μš©ν•˜μ—¬ ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμžλ₯Ό 기둝 ν•  λ•Œ λ°œμƒν•˜λŠ” λ‚΄λΆ€ λ°˜μ‚¬ λ…Έμ΄μ¦ˆλ₯Ό 효과적으둜 μ œκ±°ν•  수 μžˆλ‹€. 이와 같은 ν™€λ‘œκ·Έλž˜ν”½ ν”„λ¦°ν„°μ˜ ν”„λ‘œν† νƒ€μž…μ΄ μ˜λ„ν•œ λŒ€λ‘œ μ œμž‘λ˜μ—ˆμŒμ„ κ²€μ¦ν•˜κΈ° μœ„ν•˜μ—¬ ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμž 렌즈λ₯Ό μ œμž‘ 및, ν•΄λ‹Ή ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμž λ Œμ¦ˆκ°€ κ·Όμ•ˆ ν™€λ‘œκ·Έλž˜ν”½ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄μ˜ μ˜μƒ κ²°ν•© μ†Œμžλ‘œ μ‚¬μš©λ  수 μžˆμŒμ„ 보인닀. μ œμž‘λœ ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμž ν”„λ¦°ν„°λ₯Ό μ΄μš©ν•˜μ—¬ 두 κ°€μ§€μ˜ μƒˆλ‘œμš΄ κ·Όμ•ˆ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄λ₯Ό μ œμ•ˆν•œλ‹€. 첫 λ²ˆμ§ΈλŠ” μ‹œμ²­μ˜μ—­μ΄ μ¦κ°€ν•œ κ·Όμ•ˆ ν™€λ‘œκ·Έλž˜ν”½ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄λ‘œ, κ³΅κ°„λŒ€μ—­ν­μ— μ˜ν•˜μ—¬ μ œν•œλœ μ‹œμ²­ μ˜μ—­μ„ 수직 및 μˆ˜ν‰ λ°©ν–₯으둜 λ™μ‹œμ— ν™•μž₯ν•  수 μžˆλ‹€. λ˜ν•œ ν™•μž₯된 μ‹œμ²­ μ˜μ—­μ€ μ‚¬μš©μžμ˜ μ•ˆκ΅¬ 길이 및 νšŒμ „ 각도에 맞좰 μ„€κ³„λ˜μ–΄ μ‹œμ²­μ˜μ—­ 뢈일치둜 μΈν•œ λΉ„λ„€νŒ… λ“±μ˜ 이미지 μ™œκ³‘μ„ μ΅œμ†Œν™”ν•œλ‹€. λ§ˆμ§€λ§‰μœΌλ‘œ λ§λ§‰νˆ¬μ‚¬ ν˜•νƒœμ˜ κ·Όμ•ˆ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄μ— μ‚¬μš©λ  수 μžˆλŠ” 프리폼 거울 μ–΄λ ˆμ΄ ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμžλ₯Ό μ œμ•ˆν•œλ‹€. 이λ₯Ό μ΄μš©ν•˜μ—¬, κΈ°μ‘΄ 거울 μ–΄λ ˆμ΄ 기반의 λ§λ§‰νˆ¬μ‚¬ λ””μŠ€ν”Œλ ˆμ΄μ˜ 문제점 쀑 ν•˜λ‚˜μΈ 거울이 μ‹œμ•Όλ₯Ό κ°€λ¦¬λŠ” 문제λ₯Ό ν•΄κ²°ν•œλ‹€. λ˜ν•œ ν™€λ‘œκ·Έλž˜ν”½ 거울 배열에 μœ„μƒ λ³€μ‘° νŒ¨ν„΄μ„ κΈ°λ‘ν•˜μ—¬ 좔가적인 렌즈 λ“±μ˜ 광학계 없이 μ›ν•˜λŠ” κΉŠμ΄μ— λ””μŠ€ν”Œλ ˆμ΄ 평면을 λ„μšΈ 수 있게 λœλ‹€. 이λ₯Ό μ΄μš©ν•˜μ—¬ μž‘μ€ νΌνŒ©ν„°μ˜ 넓은 깊이 ν‘œν˜„ λ²”μœ„λ₯Ό μ§€λ‹ˆλŠ” λ§λ§‰νˆ¬μ‚¬ν˜• κ·Όμ•ˆ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄λ₯Ό κ΅¬ν˜„ν•œλ‹€. λ³Έ λ°•μ‚¬ν•™μœ„ λ…Όλ¬Έμ˜ κ²°κ³ΌλŠ” μ‚¬μš©μžμ˜ ν•„μš”μ— κΈ°λ°˜ν•œ λ§žμΆ€ν˜• κ·Όμ•ˆ μ¦κ°•ν˜„μ‹€ λ””μŠ€ν”Œλ ˆμ΄μ˜ κ°œλ°œμ— 도움이 될 κ²ƒμœΌλ‘œ κΈ°λŒ€λœλ‹€. λ‚˜μ•„κ°€, λ³Έ μ—°κ΅¬λŠ” ν™€λ‘œκ·Έλž˜ν”½ κ΄‘ν•™ μ†Œμžμ˜ 섀계와 μ œμž‘μ— κ΄€ν•œ μ—°κ΅¬μ˜ μƒˆλ‘œμš΄ κ°€λŠ₯성을 보여쀄 κ²ƒμœΌλ‘œ κΈ°λŒ€λœλ‹€.1 Introduction 1 1.1 Image combiners of augmented reality near-eye display 1 1.2 Motivation and purpose of this dissertation 8 1.3 Scope and organization 10 2 Holographic optical element printer 12 2.1 Introduction 12 2.2 Overview of the prototype of holographic optical element printer 16 2.3 Analysis of the signal path 21 2.4 Considerations in designing an HOE 27 2.5 Removal of the internal reflection noise using passive optical isolator 32 2.6 Manufacturing customized lens holographic optical element 37 2.7 Discussion 41 2.7.1 HOE printer to modulate both signal and reference beams 41 2.7.2 The term "hogel" used in this dissertation 41 2.8 Summary 44 3 Holographically customized optical combiner for eye-box extended near-eye display 45 3.1 Introduction 45 3.2 Proposed method and its implementation 51 3.3 Implemented prototype 57 3.4 Experiments and results 61 3.5 Discussion 63 3.5.1 Vignetting effect from mismatched pupil position along axial direction 63 3.5.2 Diffraction efficiency simulation according to incident angle 65 3.6 Summary 67 4 Holographically printed freeform mirror array for augmented reality near-eye display 68 4.1 Introduction 68 4.2 Retinal projection NED based on small aperture array 70 4.3 Proposed method 72 4.4 Design method of FMA HOE 75 4.4.1 Depth of field analysis 75 4.4.2 The size of the mirror 77 4.4.3 The distance between the mirrors 79 4.5 Experiments and results 82 4.6 Discussion 86 4.6.1 Eye-box of the system via the angular selectivity of the HOE 86 4.7 Summary 89 5 Conclusion 90 Appendix 104 Abstract (In Korean) 105Docto

    Large-scale Huygens metasurfaces for holographic 3D near-eye displays

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    Novel display technologies aim at providing the users with increasingly immersive experiences. In this regard, it is a long-sought dream to generate three-dimensional (3D) scenes with high resolution and continuous depth, which can be overlaid with the real world. Current attempts to do so, however, fail in providing either truly 3D information, or a large viewing area and angle, strongly limiting the user immersion. Here, we report a proof-of-concept solution for this problem, and realize a compact holographic 3D near-eye display with a large exit pupil of 10mm x 8.66mm. The 3D image is generated from a highly transparent Huygens metasurface hologram with large (>10^8) pixel count and subwavelength pixels, fabricated via deep-ultraviolet immersion photolithography on 300 mm glass wafers. We experimentally demonstrate high quality virtual 3D scenes with ~50k active data points and continuous depth ranging from 0.5m to 2m, overlaid with the real world and easily viewed by naked eye. To do so, we introduce a new design method for holographic near-eye displays that, inherently, is able to provide both parallax and accommodation cues, fundamentally solving the vergence-accommodation conflict that exists in current commercial 3D displays.Comment: 21 pages, 9 figure

    Multiplexed Holographic Combiner with Extended Eye Box Fabricated by Wave Front Printing

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    We present an array-based volume holographic optical element (vHOE) recorded as an optical combiner for novel display applications such as smart glasses. The vHOE performs multiple, complex optical functions in the form of large off-axis to on-axis wave front transformations and an extended eye box implemented in the form of two distinct vertex points with red and green chromatic functions. The holographic combiner is fabricated by our extended immersion-based wave front printing setup, which provides extensive prototyping capabilities due to independent wave front modulation and large possible off-axis recording angles, enabling vHOEs in reflection with a wide range of different recording configurations. The presented vHOE is build up as an array of sub-holograms, where each element is recorded with individual optical functions. We introduce a design and fabrication method to combine two angular and two spectral functions in the volume grating of individual sub-holograms, demonstrating complex holographic elements with four multiplexed optical functions comprised in a single layer of photopolymer film. The introduced design and fabrication process allows the precise tuning of the vHOE’s diffractive properties to achieve well-balanced diffraction efficiencies and angular distributions between individual multiplexed functions

    Accommodation-Free Head Mounted Display with Comfortable 3D Perception and an Enlarged Eye-box.

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    An accommodation-free displays, also known as Maxwellian displays, keep the displayed image sharp regardless of the viewer's focal distance. However, they typically suffer from a small eye-box and limited effective field of view (FOV) which requires careful alignment before a viewer can see the image. This paper presents a high-quality accommodation-free head mounted display (aHMD) based on pixel beam scanning for direct image forming on retina. It has an enlarged eye-box and FOV for easy viewing by replicating the viewing points with an array of beam splitters. A prototype aHMD is built using this concept, which shows high definition, low colour aberration 3D augmented reality (AR) images with an FOV of 36Β°. The advantage of the proposed design over other head mounted display (HMD) architectures is that, due to the narrow, collimated pixel beams, the high image quality is unaffected by changes in eye accommodation, and the approach to enlarge the eye-box is scalable. Most importantly, such an aHMD can deliver realistic three-dimensional (3D) viewing perception with no vergence-accommodation conflict (VAC). It is found that viewing the accommodation-free 3D images with the aHMD presented in this work is comfortable for viewers and does not cause the nausea or eyestrain side effects commonly associated with conventional stereoscopic 3D or HMD displays, even for all day use

    Neural \'{E}tendue Expander for Ultra-Wide-Angle High-Fidelity Holographic Display

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    Holographic displays can generate light fields by dynamically modulating the wavefront of a coherent beam of light using a spatial light modulator, promising rich virtual and augmented reality applications. However, the limited spatial resolution of existing dynamic spatial light modulators imposes a tight bound on the diffraction angle. As a result, modern holographic displays possess low \'{e}tendue, which is the product of the display area and the maximum solid angle of diffracted light. The low \'{e}tendue forces a sacrifice of either the field-of-view (FOV) or the display size. In this work, we lift this limitation by presenting neural \'{e}tendue expanders. This new breed of optical elements, which is learned from a natural image dataset, enables higher diffraction angles for ultra-wide FOV while maintaining both a compact form factor and the fidelity of displayed contents to human viewers. With neural \'{e}tendue expanders, we experimentally achieve 64Γ—\times \'{e}tendue expansion of natural images in full color, expanding the FOV by an order of magnitude horizontally and vertically, with high-fidelity reconstruction quality (measured in PSNR) over 29 dB on retinal-resolution images
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