A significant transformation of the crystalline structure at temperatures of 300°C and 400°C was responsible for the alterations in stability. The crystal structure's transition brings about a heightened degree of surface roughness, a greater measure of interdiffusion, and the generation of compounds.
Satellite imaging of the 140-180 nm auroral bands, originating from N2 Lyman-Birge-Hopfield emission lines, frequently demands the use of reflective mirrors. To achieve superior image quality, mirrors must exhibit outstanding out-of-band reflection suppression and high reflectivity at working wavelengths. Mirrors composed of non-periodic multilayer LaF3/MgF2, which were designed and fabricated by our team, exhibit operational wave bands of 140-160 nm and 160-180 nm, respectively. Fluorofurimazine purchase A deep search method and a match design method were combined in the multilayer design process. Our research has been applied in the development of China's new wide-field auroral imager, successfully decreasing the reliance on transmissive filters in the optical system of their space payload due to the high out-of-band suppression of the integrated notch mirrors. Our work, in addition, presents innovative paths for the design of reflective mirrors intended for the far ultraviolet region.
Ptychographic imaging's lensless systems offer a large field of view and high resolution, contrasted by their small size, portability, and lower cost compared to traditional lensed imaging. Lensless imaging, although advantageous in certain aspects, is nonetheless more prone to environmental noise and yields images of lower resolution than lens-based approaches, thus requiring an extended period to produce a clear image. This paper introduces an adaptive correction method to bolster convergence speed and noise resistance in lensless ptychographic imaging. The method modifies lensless ptychographic algorithms by incorporating adaptive error and noise correction terms, which results in faster convergence and enhanced suppression of Gaussian and Poisson noise. In our method, the Wirtinger flow and Nesterov algorithms are employed to mitigate computational complexity and enhance convergence speed. Simulation and experimentation confirmed the effectiveness of the method in phase reconstruction for lensless imaging applications. The method's application to other ptychographic iterative algorithms is uncomplicated.
The task of achieving high spectral and spatial resolution simultaneously in the areas of measurement and detection has long been a challenge. A compressive sensing-based single-pixel imaging measurement system is presented, demonstrating simultaneous excellent spectral and spatial resolution and providing data compression. The dual high spectral and spatial resolution possible with our method stands in stark contrast to the trade-offs that frequently occur in traditional imaging. Within the scope of our experimental work, 301 spectral channels were collected from the 420-780 nm band, boasting a spectral resolution of 12 nm and a spatial resolution of 111 milliradians. A 6464p image's 125% sampling rate, facilitated by compressive sensing, shortens measurement time, thereby enabling simultaneous high spectral and spatial resolution.
Continuing a pattern from the Optica Topical Meeting on Digital Holography and 3D Imaging (DH+3D), this feature issue is a direct result of the meeting's conclusions. Current research interests in digital holography and 3D imaging, mirroring the topics covered in Applied Optics and Journal of the Optical Society of America A, are the focus of this work.
Micro-pore optics (MPO) are integral to space x-ray telescopes that perform observations with a broad field-of-view. X-ray focal plane detectors with visible photon detection capabilities rely on the optical blocking filter (OBF) embedded in MPO devices to prevent any signal contamination resulting from visible photons. In this study, we developed a device meticulously calibrated to ascertain light transmission with exceptional precision. Evaluation of the transmittance of MPO plates shows compliance with the design specifications, which dictate a maximum transmittance value less than 510-4. By using the multilayer homogeneous film matrix approach, we ascertained suitable film thicknesses (incorporating alumina) exhibiting compatibility with the OBF design.
The surrounding metal mount and adjacent gemstones impede the process of identifying and assessing jewelry pieces. This study suggests the application of imaging-assisted Raman and photoluminescence spectroscopy for jewelry analysis, a crucial step towards maintaining transparency in the jewelry market. The image's alignment guides the system's automatic sequential measurement of multiple gemstones on a jewelry piece. The experimental prototype's non-invasive procedure successfully differentiates between natural diamonds and their laboratory-grown counterparts and their simulant mimics. Besides this, the image facilitates the process of evaluating gemstone color and estimating its weight.
The presence of fog, low-lying clouds, and other highly scattering environments can significantly hinder the performance of many commercial and national security sensing systems. Fluorofurimazine purchase Autonomous systems' navigation methods, employing optical sensors, are adversely affected by the presence of highly scattering environments. Our prior simulations indicated that light with polarization can pass through environments scattered by particles, for example, fog. Through our experiments, we have proven that circular polarization consistently maintains its initial polarization state across a large number of scattering instances and extended distances, in stark contrast to linearly polarized light. Fluorofurimazine purchase Other researchers have recently experimentally confirmed this. The active polarization imagers at short-wave infrared and visible wavelengths are presented in this work, including their design, construction, and testing procedures. We investigate various polarimetric configurations for imagers, particularly focusing on linear and circular polarization states. Sandia National Laboratories' Fog Chamber, under realistic fog conditions, served as the testing ground for the polarized imagers. Active circular polarization imagers demonstrate superior range and contrast enhancement in foggy conditions compared to linear polarization imagers. Circular polarization allows for a more effective imaging of road sign and safety retro-reflective films in varied fog conditions compared to linear polarization. Results show a marked improvement in contrast and penetration depth, exceeding the limitations of linear polarization by 15 to 25 meters. This enhancement is strongly associated with the interplay between the polarization state and the target materials.
Laser-induced breakdown spectroscopy (LIBS) is anticipated to be employed for real-time monitoring and closed-loop control of laser-based layered controlled paint removal (LLCPR) from aircraft surfaces. Despite the availability of other techniques, the LIBS spectrum necessitates rapid and accurate assessment, and the appropriate monitoring criteria must be established via machine learning algorithms. For paint removal process monitoring, this study fabricates a custom LIBS system, using a high-frequency (kilohertz-level) nanosecond infrared pulsed laser. Spectra from the LIBS system are collected while the top coating (TC), primer (PR), and aluminum substrate (AS) are being laser removed. After removing the continuous background from spectra and identifying crucial features, a three-class (TC, PR, and AS) classification model was developed using a random forest algorithm. This model and multiple LIBS spectra were used to establish and verify a real-time monitoring criterion, experimentally The results demonstrate a classification accuracy of 98.89%, and each spectrum's classification takes around 0.003 milliseconds. Monitoring results for the paint removal process concur with macroscopic and microscopic analysis of the samples. Through this research, core technical support is offered for real-time observation and closed-loop control of LLCPR originating from the aircraft's exterior surface.
Fringe patterns in experimentally acquired photoelasticity images exhibit variations due to the spectral interplay between the employed light source and sensor. High-quality fringe patterns can arise from such interaction, yet indistinct fringes and an inaccurate reconstruction of the stress field are also possible outcomes. We introduce an interaction assessment methodology based on four crafted descriptors: contrast, an image descriptor encompassing blur and noise, a Fourier-based descriptor quantifying image quality, and image entropy. Computational photoelasticity images, featuring selected descriptors, were used to validate the proposed strategy's utility. Evaluating the stress field from 240 spectral configurations with 24 light sources and 10 sensors confirmed the observed fringe orders. Significant findings demonstrated that elevated levels of the selected descriptors were linked to spectral configurations conducive to the better stress field reconstruction process. The collective results demonstrate that the chosen descriptors are useful indicators for identifying positive and negative spectral interactions, which can potentially contribute to the improvement of photoelasticity image acquisition protocols.
The petawatt laser complex PEARL now includes a newly developed front-end laser system with an optical synchronization feature for both chirped femtosecond and pump pulses. The new front-end system's significant contribution to the PEARL is a wider femtosecond pulse spectrum, coupled with temporal shaping of the pump pulse, which culminates in improved stability of the parametric amplification stages.
Atmospheric scattered radiance is a key factor in calculating daytime slant visibility. This paper scrutinizes the impact of atmospheric scattered radiance errors on the accuracy of slant visibility measurements. In light of the complexities involved in error synthesis of the radiative transfer equation, an error simulation scheme using the Monte Carlo method is developed.