This PDF file contains the front matter associated with SPIE Proceedings Volume 12684, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Photopolymers are considered to be the most potential holographic storage materials due to their advantages of high resolution, real-time recording and low-cost preparation. Thereinto, Phenanthraquinone-doped polymethyl methacrylate (PQ/PMMA) photopolymers have excellent properties such as easy to prepare, controllable thickness, negligible photoinduced volume shrinkage, and long life-time for holographic data storage. Nevertheless, the current holographic properties such as diffraction efficiency and photosensitivity of PQ/PMMA photopolymers cannot meet the requirements of the information writing-speed. It is well known that the holographic properties of materials can be improved by optimizing preparation conditions and doping nanoparticles. The concentration of PQ can increased to 1.0 wt.% using 60 °C as the prepolymerization temperature in our previous report. Herein, via introducing a new monomer pentaerythritol-tetrakis-3-mercaptopropionate (PETMP) into PQ/PMMA, the photosensitizer concentration of PQ could be increased to 2.0 wt.% compared with PQ/PMMA. And under the same production process conditions, both of the photosensitivity and diffraction efficiency of PETMP-PQ/PMMA increased ~20 times (from ∼0.27 cm/J to ∼5.61 cm/J) and more than 25% (from ~50% to ∼75%). Finally, by the use of the PETMP−PMMA/PQ in a collinear holography system, it appeared to be promising for a fast but low bit error rate(BER) in holographic information storage. The current study shows that, PETMP-PQ/PMMA material has the excellent potential for holographic data storage. Keywords: Photopolymer, PQ concentration, photosensitivity, co-monomer

In the past, we used hand-made holographic data storage materials for research and storage, but these materials have many problems, such as the experiment has a certain degree of non-repeatability, and the data storage system performance is unstable. This work uses an automated chamber to prepare photopolymers without manual operation. The automation room will complete all material fabrication processes except the initial weighing and pouring. Compared with hand-made materials, the automatically made materials have no bubbles due to the special mold design. The overall production process is carried out under the condition of constant temperature and humidity.

Holographic data storage (HDS), a three-dimensional volume storage technology, is becoming a strong candidate for huge data storage due to its advantages of higher storage density, faster data transfer rate, and longer life. In this paper, we use phenanthraquinone doped polymethyl methacrylate (PQ/PMMA) photopolymer to record the phase data page, and use deep learning to recover the phase. The experimental setup used 532 nm laser wavelength. The phase data page uploaded on the SLM are made up of 4-gray level random phase coded (π/6,2π/3, π,3π/2). Every pixel pitch of SLM is 20 μm. Every phase data is described by some oversampling display such as 8*8 pixels on the SLM. And, the CMOS captured phase data pages using PQ/PMMA photopolymers. We input 4439 randomly generated phase data pages into the experimental system. 4439 phase data pages after rotating 90°, rotating 180°, rotating 270°, upside down, flipped left to right, expanded to 6 times, a total of 26634 phase data pages. Among them, 90 % is used as the training set to optimize the network, 10 % is used as the testing set to verify the generalization ability of the trained neural network. We trained the U-net 50 epoch, and when we got the predicted phase data. And the bit error rate (BER) of the reconstructed image using PQ/PMMA photopolymers were measured, and we found that, different numbers experimental images has different BER. So, deep learning can effectively reduce BER of phase data page by using PQ/PMMA photopolymers.

Laser Induced Refractive Index Change (LIRIC) uses femtosecond laser pulses to locally modify a material’s refractive index below material damage thresholds. This technique has been successfully applied to create refractive correctors in wet ophthalmic materials such as hydrated contact lenses. However, applying LIRIC in wet contact lens materials to mass produce refractive correctors would require drastic changes to the current manufacturing infrastructure. To integrate LIRIC in the production line in a cost-effective manner, applying this technique in a dry contact lens is necessary. Therefore, this study seeks to understand how the absence of water affects LIRIC writing mechanisms. Our experiments have shown that LIRIC writing using 400nm laser light produced rough, non-uniform regions of index change in dehydrated Hydroxyethyl Methyl Acrylate based hydrogels. However, in dehydrated silicone hydrogels, LIRIC successfully induced greater index changes than when the materials are in hydrated state.

Heat-assisted magnetic recording (HAMR) is a promising technology to increase the recording density of hard disk drives. A near-field transducer (NFT), which forms a small light spot on the recording medium, is necessary in HAMR. We previously proposed a device for HAMR, in which a metal nano-antenna as an NFT is attached to a semiconductor ring resonator as a light source. There are even and odd modes in this device. Because the near-field light is generated at the nano-antenna tip only in the even mode, how to excite the even mode selectively is an important issue. For this purpose, we introduced a split-ring-resonator-type device and investigated its effectiveness through a numerical simulation considering gain. When a narrow gap was placed at the nano-antenna bottom (Type 1) or at the opposite side to the nano-antenna bottom (Type 2) in the ring resonator, the gain for the even mode became higher than that for the odd mode. When the gap width increased, the gain difference became maximum at a certain width and then gradually decreased. The energy density at the nano-antenna tip for Type 1 was higher than that for Type 2. As the gap width increased, the energy density for Type 1 increased. Moreover, in Type 1, when the nano-antenna position was varied from outside to inside the ring resonator, the gain difference gradually decreased and the energy density increased. Therefore, the gap width and nano-antenna position should be designed considering the trade-off relationship between the gain difference and energy density.

Deflectometry is a versatile optical testing tool used in various fields, from astronomy to industrial applications, due to its non-null testing capability which facilitates precise measurement despite challenging optical surfaces and system layout constraints. In this manuscript, we present novel variational advancements to traditional deflectometry, towards universal functionality and system friendliness. Traditional dark-field illumination is an inspection technique that is sometimes used to detect particles on a specular surface. Problems arise in its repeatability, as an intensity-based measurement is vulnerably dependent on the testing conditions of time, limiting its ability to be used in automated fashion. The first advancement leverages phase algorithms commonly seen in deflectometry; by adding a secondary light source (normal to the surface) and modulating each source's intensity with a time-varying sinusoid. The phase-based information has a higher sensitivity to the light scattered from a defect producing a more robust computational image process method that is now insensitive to the environment. The second advancement is an alignment method to obtain lower-order shape. While deflectometry proves effective in measuring mid-to-high frequency surface shape, it faces challenges when assessing low-order shape measurements like power, astigmatism, and coma due to relative position and alignment error between the unit under test (UUT) and the deflectometry system. To avert the necessity of additional instruments like a coordinate measuring machine, laser trackers, or interferometers, we leveraged computational fiducials and sensitivity matrices to identify and address misalignments effectively. With enhanced capabilities and system-friendly features, our advanced deflectometry techniques provide powerful options in optical testing. By addressing the challenges in low-order shape measurements and incorporating dark field testing, our approaches extend the potential of deflectometry as a valuable tool in optical metrology across a broad spectrum of industries and scientific endeavors.

The increasing demands in industry, for example for products in the consumer electronics sector or for assistance systems in cars, and the continuous development in semiconductor are leading to significant miniaturization in electronic components. These requirements are inevitably also transferred to ultra-precise manufacturing and thus ask for monitored production steps. In the context of Industry 4.0 and other developments in the context of modern production sensors to supervise production steps are crucial. An essential component here is non-destructive testing (NDT) and specifically optical metrology and overall end of line qualification. The FlyingSpotScanner (FSS) provides OCT measurements for thickness and topography based on a breakthrough, unique technology that enables high-speed, non-contact inspection for quality assurance across a wide range of materials and surfaces. The FSS310 Version has changed the semiconductor market. Thanks to its huge scan area of 310mm, a 12 inches diameter wafer can be fully checked for TTV, bow and warp in just 10 seconds. Due to the movable mirror system, long paths of linear axes are replaced by short rotary movements, resulting in an extreme reduction of the measuring time. The FLYING SPOT SENSOR FSS310 was awarded with the SPIE Prism Award in 2023.

Recently, aerial display technologies have fascinated people. Dynamic projection mapping on drones is one way to achieve such aerial displays. In this presentation, methods to achieve dynamic projection mapping on a flying screen by drones using a high-speed optical gaze controller are introduced. The high-speed gaze controller is a combination of two or three automatically controlled rotating mirrors that optically control the camera’s imaging direction or the projector’s projection direction at high speed. The results of the demonstration of the proposed aerial display by using high-speed image processing to project images while tracking a flying screen will also be presented.

Tackling the ever-increasing demands on the electromagnetic spectrum from a proliferation of connected devices while enabling the supportive communication infrastructure for new technology is crucial to continuing technological advancement in the 21st century. There is a critical need for intelligent transportation systems (ITS), not only to enable autonomy, but to improve the safety and efficiency of vehicles on roadways. Visible light communication (VLC) offers an attractive and relatively untapped solution to complement or replace radio frequency communications in vehicles and connected devices. This work explores a low power, low complexity, flicker-free VLC system operating outdoors in full daylight from 5 m to 550 m using a digital polarization modulation scheme. A delaminated LCD computer monitor and an Android smartphone with monoscope were employed as low-cost representative components, successfully transmitting frames at varying ranges from 5 m out to 550 m outdoors at midday in Monterey, California. Received signal performance with 26 cd of transmitted optical power ranged from 36 dB to 9 dB SNR at 5 m out to 550 m, respectively, providing throughput at greater ranges than seen in other outdoor VLC literature. These tests demonstrate the successful implementation of a VLC polarization modulation imperceptible to human vision that remains robust to solar noise at 550 m using very low transmitted power. Such a system could enable dual utilization of vehicle lights both for illumination and communication in an ITS, and is extendable as a low-cost, high-efficiency physical layer encoding for many other connected devices.

Due to its advantages and potential, Hyperspectral Imaging (HSI) has been widely used in many fields, including the food industry, astronomy, archeology, forensic medicine, and medical diagnosis. In this work, we report the performance of a spectrum-simulating light source named the Chromatiq Spectral Engine (CSE) to highlight its advantages in the application of hyperspectral imaging. The CSE is powered by a high-brightness Laser-Driven Light Source (LDLS) and high-throughput spectrally programmable light engine. Key parameters examined for the HSI applications include wavelength tunable range, spectral resolution, out-of-band suppression, and the flexibility in spectral manipulation. A comparison between the CSE and popular solutions in HSI applications, including liquid crystal tunable filters (LCTF), is presented regarding key features and specs along with a discussion of application-dependent design for an efficient HSI system. Also discussed is system control for the CSE, which features an easy-to-use interface for system configuration, output characterization, creation and matching of test spectra, and storage of matched spectra to the instrument. An embedded controller is incorporated into the CSE deploying application firmware which allows for easy integration with the camera system for HSI studies.

Fourier-based frequency sweeping interferometry (FSI) is an interferometric technique, which offers absolute distance measurement based on the detection of interference beat frequencies of reflected signals. Through the multiple beat frequencies detected, Fourier-based FSI performs robust and simultaneous measurements of absolute distances to multiple targets. This measurement technique is less sensitive to the variations in reflected optical signal intensity because frequency peaks in the Fourier spectrum are easily retrievable for weak interference signals without any significant degradation of the measurement accuracy. Moreover, the tolerance for variations in the reflected light intensity makes Fourier-based FSI useful for distance measurements using various reflector types, even those with low reflectance materials. The drawback of Fourier FSI method is the need to use complex and time-consuming computations, consisting of fast Fourier transform, laser sweep speed estimation and data resampling, to correct the non-uniform sweep speed of the laser. The complexity of the computations and the quality of the measurement results are also strongly dependent on the setup of the FSI components. In addition, the detected beat frequencies are highly impacted by the target retroreflector movements or vibrations, which introduce Doppler shifts to the detected frequencies that causes drift effects. This paper describes the distance measurement error sources of Fourier-based FSI interferometer components and assesses their impact on the measurement uncertainty. All analyses are based on a CERN FSI interferometer setup, operating in Cband optical sweep frequency range, with a sweep speed of 2000 nm/s, equipped with a hydrogen cyanide gas cell for frequency tracking purposes.

An interferometer with off-axis and phase-shifting methods is developed to quantitatively measure complex amplitude distributions of fabricated metasurfaces. The developed interferometer switches between the off-axis and phase-shifting methods depending on the maximum spatial frequency components of a specimen metasurface. The off-axis method allows complex amplitude measurements from a single interference pattern and is robust to environmental vibrations, whereas the phase-shifting method can achieve high spatial resolutions via sequential recording of multiple interference patterns. We measured the complex amplitude distribution of fabricated metasurfaces using the developed interferometer. This interferometer would be useful for reducing design and fabrication errors and optimizing metasurface structures.

Bending losses in optical fiber result in additional propagation losses when light is coupled from core modes to cladding modes as the fiber is bent. This effect becomes significant once a certain critical radius of curvature is reached, and its value increases considerably at longer wavelengths as the modes become less confined to the nucleus. In this way, flexion sensors have had a wide range of applications, including structural monitoring, motion detection in devices for biomedical purposes, and robotic configurations, among others. This article studies the bend-loss in two single-mode fiber embedded in two different silicones and arranged in a circular shape. The experiment is carried out in two parts by vertically inserting pressure with a C-clamp into a bent optical fiber silicone-filled mold while holding the initial condition constant to induce bend-loss in a four-turn fiber. In both sensors, optical fiber was coiled a total number of 4 times with a diameter of 4.8 cm and 5.0 cm. Each mold has different characteristics, e.g., density, 1050.92 mg/cm3 and 878.33 mg/cm3. It is found that both sensors are suitable for measuring pressure, but the difference comes in the range of measurements, the denser sensor can measure 2.12 dB per lap, while the less dense sensor can measure 0.70 dB per lap. Also, an Arduino program connected to a web analyzer is used to access the data on a computer in real time.

In-line fiber Mach-Zehnder interferometers have become more popular than traditional electric sensors because of their small size, low cost, easy fabrication, resistance to electromagnetic interference, durability against extreme environments, and ease of use. This paper discusses the development, characteristics, and properties of a curvature-based Mach-Zehnder interferometer (MZI). The MZI comprises a filter made by splicing core-offset sections of a special mode fiber (SSMF) with a cladding diameter of 70 μm in an SMF-SSMF-SMF-SSMF-SMF (1m/25mm/30mm/25mm/1m) configuration. The SSMF splices act as the arms of the MZI, while the mismatch diameter sections serve as optical fiber couplers. The MZI was characterized by measuring the optical spectrum response when a broadband source of 1537.5 to 1600 nm was launched with a power of 10 dBm to transmit light through the arrangement. The optical spectrum analyzer (OSA) detects the transmitted light and analyzes its optical transmission characteristics, showing 5 notches of modal interferences into the longitude region. As a result of the experimental arrangement, the displacement and curvature sensitivities are 0.003 nm/μm and 0.509 nm/μm^-1, respectively. The proposed sensor has potential advantages for measuring refractive index, pH, torsion, curvature, and temperature.

Augmented Reality (AR) is emerging as an innovative frontier in medical applications. The ability to provide preoperative training, thorough explanation and demonstration of procedures to patients, and intra-operative information and navigation are among many valuable use cases. Head mounted display (HMD) based AR devices are particularly promising for use in medical settings due to their hands-free capabilities. HMD AR devices have shown immense promise in the effort to produce better trained surgeons and to pioneer new risk-reduced surgical protocols to advance modern medicine. Current studies on the benefit of HMD AR in medical applications have been limited to off-the-shelf devices which are not specifically tailored for their use cases. Most FDA approved devices for AR in medical applications are off-the-shelf as well. However, specific use case tailoring may potentially improve HMD AR device use further for medical settings. This study proposes a HMD AR device tailored for use in medical applications. This proposed design shall contain the expected hallmarks of a user-friendly HMD AR device such as lightweight design and high see-through transmittance, with particular attention paid to facets that affect medical applications: battery longevity (for continued use during surgery) and display brightness (for use in bright operating room environments).