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Abstract The traditional manual analysis of microplastics has been criticized for its labor-intensive, inaccurate identification of small microplastics, and the lack of uniformity. There are already three automated analysis strategies for microplastics based on vibrational spectroscopy: laser direct infrared (LDIR)–based particle analysis, Raman-based particle analysis, and focal plane array-Fourier transform infrared (FPA-FTIR) imaging. We compared their performances in terms of quantification, detection limit, size measurement, and material identification accuracy and speed by analyzing the same standard and environmental samples. LDIR-based particle analysis provides the fastest analysis speed, but potentially questionable material identification and quantification results. The number of particles smaller than 60 μm recognized by LDIR-based particle analysis is much less than that recognized by Raman-based particle analysis. Misidentification could occur due to the narrow tuning range from 1800 to 975 cm−1 and dispersive artifact distortion of infrared spectra collected in reflection mode. Raman-based particle analysis has a submicrometer detection limit but should be cautiously used in the automated analysis of microplastics in environmental samples because of the strong fluorescence interference. FPA-FTIR imaging provides relatively reliable quantification and material identification for microplastics in environmental samples greater than 20 μm but might provide an imprecise description of the particle shapes. Optical photothermal infrared (O-PTIR) spectroscopy can detect submicron-sized environmental microplastics (0.5–5 μm) intermingled with a substantial amount of biological matrix; the resulting spectra are searchable in infrared databases without the influence of fluorescence interference, but the process would need to be fully automated.

In recent years, research on the interaction between orbital angular momentum (OAM) of light and matter has shown a continuous influx of investigations. OAM possesses distinct properties, such as a degree of freedom with multiple states, vortex characteristics, and topological properties, which expand its applications in optical communication, optical sensing, and optical manipulation. We have observed different phenomena in the chiral metal windmill structure under excitation of spin angular momentum (SAM)-OAM beam generated by Q-plate than under SAM excitation. Fourier back focal plane (FBP) imaging under SAM beam excitation easily identifies the chirality and geometric properties of the structure. When the SAM-OAM beam excites the structure, FBP not only identifies its chirality and geometric properties but also distinguishes different OAM topological charges and signs, as well as the degree of elliptic polarization. The Stokes parametric FBP imaging reveals asymmetric polarization distribution resulting from the interaction between a vortex beam and the chiral structure. Moreover, it clearly reflects the conversion process of SAM to OAM. The experimental results match well with simulation results. These findings hold valuable insights for the advancement of optical information storage and communication using OAM, opening up new possibilities for further exploration in this field.

The division of focal plane (DoFP) polarimeter is a vital tool for polarization imaging due to its compact structure and stable performance. However, its detection accuracy is significantly influenced by fabrication and integration errors of the micro-polarizer array (MPA). To address this, we establish a clear relationship between the accuracy of DoFP polarimeter and error sources, including the integration alignment, integration distance, integration angle, transmission axis angles, and extinction ratio of the MPA. Using a novel mathematical model based on the finite difference time domain method, we quantitatively analyze the impact of these errors on polarization detection accuracy. Our results demonstrate that as the detection accuracy improves from 10 − 1 to 10 − 2 and 10 − 3 , the required fabrication accuracy of MPA’s transmission axis angles and the integration accuracy both increase by approximately one order of magnitude. Additionally, to achieve same accuracy improvements, the extinction ratio of the MPA exhibits nonlinear growth, increasing by about 2.5 times and 20 times, respectively. These findings provide a critical foundation for error control and quantitative performance assessment in DoFP polarimeters, advancing their application in various fields.

This paper describes MUSTANG 2, a 338 element focal plane array that is being built for the Green Bank Telescope. Each element consists of a profiled feedhorn coupled to two transition edge sensor bolometers, one for each polarization. Initial deployment will be with 32 detectors, but once fully populated, MUSTANG 2 will be capable of mapping a 8 ′ × 8 ′ area to 23 μ Jy in 1 h with good image fidelity on angular scales from 9 ′ ′ to 6 ′ . As well as an instrument overview, the choice of bandpass and the design of the feeds, detectors and readout are given.

The complementary metal oxide semiconductor (CMOS) microbolometer technology provides a low-cost approach for the long-wave infrared (LWIR) imaging applications. The fabrication of the CMOS-compatible microbolometer infrared focal plane arrays (IRFPAs) is based on the combination of the standard CMOS process and simple post-CMOS micro-electro-mechanical system (MEMS) process. With the technological development, the performance of the commercialized CMOS-compatible microbolometers shows only a small gap with that of the mainstream ones. This paper reviews the basics and recent advances of the CMOS-compatible microbolometer IRFPAs in the aspects of the pixel structure, the read-out integrated circuit (ROIC), the focal plane array, and the vacuum packaging.

Robotics faces a long-standing obstacle in which the speed of the vision system’s scene understanding is insufficient, impeding the robot’s ability to perform agile tasks. Consequently, robots must often rely on interpolation and extrapolation of the vision data to accomplish tasks in a timely and effective manner. One of the primary reasons for these delays is the analog-to-digital conversion that occurs on a per-pixel basis across the image sensor, along with the transfer of pixel-intensity information to the host device. This results in significant delays and power consumption in modern visual processing pipelines. The SCAMP-5—a general-purpose Focal-plane Sensor-processor array (FPSP)—used in this research performs computations in the analog domain prior to analog-to-digital conversion. By extracting features from the image on the focal plane, the amount of data that needs to be digitised and transferred is reduced. This allows for a high frame rate and low energy consumption for the SCAMP-5. The focus of our work is on localising the camera within the scene, which is crucial for scene understanding and for any downstream robotics tasks. We present a localisation system that utilise the FPSP in two parts. First, a 6-DoF odometry system is introduced, which efficiently estimates its position against a known marker at over 400 FPS. Second, our work is extended to implement BIT-VO—6-DoF visual odometry system which operates under an unknown natural environment at 300 FPS.

Image-Based Overlay (IBO) equipment leverages optical reflection imaging principles, combined with focusing and alignment strategies to measure overlay marks. Among all measurement steps, the focal plane measurement of marks exerts the most critical impact on overlay accuracy, while the time consumed by focal plane detection directly determines the overall measurement throughput. To address the trade-off between accuracy and efficiency in advanced process nodes, this paper proposes an integrated optimization strategy encompassing optical hardware design and software algorithms. The hardware solution adopts a dual-wavelength, dual-detector architecture: optimal imaging wavelengths are selected independently for the previous-layer and current-layer marks, ensuring each layer achieves ideal imaging conditions without mutual interference. The software strategy employs a deep learning framework to simultaneously predict and adjust the horizontal position (alignment) and vertical defocus number of measured marks in real time with high precision, thereby securing the optimal imaging posture. By synergizing hardware-based optimal imaging conditions and software-based posture adjustment, this method effectively mitigates the impact of background noise and system aberrations, ultimately improving both the accuracy and efficiency of overlay measurement.

This study used polymeric micelles to improve quality by increasing drug solubility, extending mucosal drug retention time, enhancing mucoadhesiveness, and promoting drug permeation and deposition. Fluocinolone acetonide (FA) was loaded into polymeric micelles (FPM), which were composed of poloxamer 407 (P407), sodium polyacrylate (SPA), and polyethylene glycol 400, and their physicochemical properties were examined. Small-angle X-ray scattering (SAXS) revealed a hexagonal micellar structure at all temperatures, and the concentrations of P407 and SPA were shown to significantly affect the solubility, mucoadhesion, release, and permeation of FPMs. The proportion of P407 to PEG at a ratio of 7.5:15 with or without 0.1% w/v of SPA provided suitable FPM formulations. Moreover, the characteristics of FPMs revealed crystalline states inside the micelles, which was consistent with the morphology and nano-hexagonal structure. The results of ex vivo experiments using focal plane array (FPA)-based Fourier transform infrared (FTIR) imaging showed that the FPM with SPA penetrated quickly through the epithelium, lamina propria, and submucosa, and remained in all layers from 5–30 min following administration. In contrast, the FPM without SPA penetrated and passed through all layers. The FPM with extended mucoadhesion, improved drug–mucosal retention time, and increased FA permeation and deposition were successfully developed, and could be a promising innovation for increasing the efficiency of mouth rinses, as well as other topical pharmaceutical and dental applications.

Liquid-phase epitaxy (LPE) is a material growth technology used in the fabrication of mercury cadmium telluride (HgCdTe) infrared (IR) detectors, which is the highest-performing solution in the IR community. This paper presents the most successful LPE technology, “infinite-melt” vertical liquid-phase epitaxy (VLPE) from Hg-rich solutions. To fulfill requirements for large-format infrared focal-plane detectors, solutions were required to improve the uniformity, yield, and material properties of HgCdTe liquid-phase epitaxial (LPE) and cadmium zinc telluride (CdZnTe or CZT) bulk growth as well as substrate fabrication processing. Raytheon Vision Systems (RVS) produces CdZnTe substrates for epitaxial growth, and in this work, advancements in boule growth processes and metrology led to the identification and elimination of the infrared opaque extended defects within CdZnTe material. Boule growth advancements have also decreased the Cd precipitate defect diameter by a factor of 4. These improvements enabled large-format focal-plane arrays (FPAs) with uniform sensor response. Also, improvement in our polishing process has reduced substrate processing time and total thickness variation (TTV), improving downstream lithography and hybridization processes. Optimizing LPE growth chemistry dynamics resulted in the elimination of large defects, decreased density of epitaxial defects, and improved control of cut-on and thickness of resulting layers. Implementation of custom software allowed real-time prediction during layer growth which resulted in a higher process yield. The continuous improvement of VLPE results in better uniformity, reduced noise, and competitive die size, compared to other long-wave (LW) second-generation detector processes.

Augmented reality heads-up displays (AR-HUDs) have a much richer display than traditional heads-up displays. An ideal AR-HUD requires two or more focal planes to display basic and interactive driving information to the car driver separately. We present an off-axis reflective optical structure for dual-focal-plane displays using a single projection-type picture generation unit (PGU) and two freeform mirrors. The dual-focal-plane AR-HUD system designed in this paper can simultaneously generate high-quality far-field image (13° × 4°, 10 m) and near-field images (13° × 1.4°, 3.5 m) in a 130 mm × 60 mm eyebox. A fully automated analysis program is written to analyze the modulation transfer function (MTF) and distortion values of the optical system over the entire eyebox range. The analysis results show that the maximum distortion values of the far-field image and near-field image in the eyebox range are 3.15% and 3.58%, respectively. The MTF was greater than 0.3 at 7.2 lp/mm for both near-field images and far-field images. We also designed a projection lens for the projection-type PGU used in this system. The projection lens uses three plane mirrors to fold the image plane of the projection system into different positions to serve as the image source for the AR-HUD. This research provides a new solution for realizing the dual-focal-plane AR-HUD, which not only satisfies the need for simultaneous display of near-field basic information and far-field interactive information, but also has a larger display screen.