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The work aims to explore a microscopic observation system of paper surface and achieve high-precision stereoscopic observation with detail characterization of paper surface morphology. Based on the DT-400E precision program-controlled three-dimensional translation stage and KEYENCE LJV-7200 two-dimensional laser scanner, the hardware parts of our own system are developed to scan and transmit point cloud data of paper surface morphology to the computer. The corresponding system software will automatically process the point cloud data acquired from the laser scanner and generate the corresponding vivid 3D model and height histogram. This system scans and characterizes four different types of paper samples, allowing the human eye to visually distinguish the differences in surface morphology as well as automatically calculate the numerical differences in paper surface morphology parameters. The results of the applicability test show that the system is highly efficient in acquiring, observing, and evaluating the topography of the paper surface. The system can not only predict the paper surface quality of printed paper, but can also be extended to the evaluation of 3D printed surfaces.

Abstract Tissue paper softness relies on two major factors, the bulk softness, which can be indicated by the elasticity of the sheet, and surface softness. Measurement of surface softness is complicated and often requires a multi-step process. A key parameter defining surface softness is the topography of the surface, particularly the crepe structure and its periodicity. Herein, we present a novel approach to measure and quantify the tissue paper surface crepe structure and periodicity based on the detection of waviness along the sample using laser scanning confocal microscopy (LSM) and X-ray tomography (XRT). In addition, field emission scanning electron microscope (FESEM) was used to characterize the tissue paper surface. We demonstrate that surface topography is directly correlated to the erosion of the doctor blade, which is used to remove the dry tissue paper from the Yankee cylinder. Because of its accuracy and simplicity, the laser confocal microscopy method has the potential to be used directly on the production line to monitor the production process of the tissue paper. XRT revealed more structural details of the tissue paper structure in 3D, and it allowed for the reconstruction of the surface and the internal structure of the tissue paper. Graphic abstract

This paper utilizes a hybrid Debye model to accurately simulate the relaxation response process of the oil‐paper insulation of a transformer to explore the application of frequency domain dielectric spectroscopy (FDS) in nondestructive diagnosis of the aging condition of oil‐paper insulation. Via FDS test data, the model parameters can be identified, and the influence laws of FDS can be obtained through the variation of model parameters. To explore the effects of insulating paper moisture content, insulating paper layers, and test temperature on FDS characteristics, an FDS experimental platform is established. The results show that the hybrid Debye model can effectively reflect the relaxation response process of oil‐paper insulation under different conditions, as well as that a physical relationship between the model parameters and oil‐paper dielectric polarization exists. In addition, the parameters of the hybrid Debye model can be used as the characteristic quantities for the non‐destructive evaluation of the oil‐paper insulation state, providing new ideas for the non‐destructive evaluation of the oil‐paper insulation state.

The printing effect of paper packaging has an impact on the circulation effect of products. Only when the printing effect is good can it attract consumers’ purchasing desire. In this study, based on color management technology, the printing of the designed Bazhong specialty paper packaging was studied. Firstly, the content and process of color management were analyzed, and equipment correction and characterization were introduced. Then, the printing process of Bazhong specialty paper packaging was explored, and the printing equipment and the establishment of the profile file were analyzed. The application of color management achieves a high-quality printing effect, which provides a theoretical reference for its further application in the printing industry.

Laser-cut paper patterns which are suitable for focusing terahertz radiation are presented. Such designs provide an extremely low-cost route for the prototyping and production of terahertz optical components. Diffractive binary Fresnel lenses have been explored using a multilayer paper stack and a liquid absorption method in order to phase shift THz radiation through paper by the optimum 180° The conventional Fresnel lens design has been extended to produce multiple focal spots and explore alternative shapes (e.g. hexagonal).

Applications of digital micromirror device for lidar are overviewed. A large Lagrange invariant value makes DMD as one of the attractive beam steering transmitter and receiver solutions for a time-of-flight lidar, especially with its an extended angular throw by synchronized pulsed laser illumination.

BACKGROUND/AIM The aim of the study was to investigate the dosimetric characteristics of electron beams with a tungsten functional paper (TFP) surface collimator. MATERIALS AND METHODS The circular field of 6.0 cm diameter was created with the TFP collimator put on the phantom. Depth and lateral dose profiles for 4 and 6 MeV electron beams were obtained. The characteristics of lateral dose profile, treatment diameter as width over 90% of the dose, and penumbra as width of the off-axis positions from 80% to 20% dose levels were evaluated. RESULTS Compared to the lead collimator, the TFP collimator generated higher surface doses, the treatment diameters were increased from 42.8 to 48.6 mm and from 40.0 to 41.4 mm, and the penumbras were reduced from 15.0 to 9.6 mm and from 16.4 to 13.0 mm for 4 and 6 MeV electron beams, respectively. CONCLUSION The TFP surface collimator can provide an excellent dose distribution compared to the conventional lead collimator.

Airborne particulate matter has become an emerging issue globally due to environmental degradation and the health risk it causes. Volatilization of weakly adsorbed particles onto quartz filter paper (QFP) limits its performance. The adsorption of particulate matter ( P M 10 ) onto QFP coated with different concentrations of graphene oxide (GO) was investigated to enhance the adsorption potential. Hummer’s method was adopted to synthesize GO. QFPs were coated with different concentrations of GO using a spin coating technique to optimize the result. The morphology and microstructure of GO-QFP were characterized by various experimental techniques, like XRD, FTIR, EDX, and SEM. GO showed considerable affinity to aerosol particles for GO-QFP weighing 5 mg/ml, whereas adsorption of the coated samples before and after was significantly reduced. The high affinity to aerosol particles was due to dominated π - π interactions and the grooved regions formed on the GO layer. It was considered that the high surface to volume ratio of GO-QFP improves the adsorptive property of the QF and consequently enhances the performance of the filter paper.

The inherent advantages of reflective e-paper displays (EPD) — wide viewing direction range and excellent readability even under bright sunlight — can be extended into low-light conditions by the addition of an integrated lighting unit (ILU) such as a front light. A methodology for predicting the viewing direction dependence of ambient contrast and color from display measurements and illumination models is here applied to reflective EPD where the ILU is switched on. First results show that an ILU improves the indoor performance of EPD, and enables their usage in environments with illumination otherwise inadequate for reading.

Sizing (ahar) has been used extensively in Turkish-Islamic handwritten documents. In this study, we present comparative experimental results including femtosecond (fs) and nanosecond (ns) pulsed laser cleaning of model paper samples with various types of sizing. The samples were artificially soiled with graphite and graphite-kaolinite mixture. For aging, the samples were exposed to air at 90 C temperature and 50% relative humidity during 16 days. Thickness variations of corn starch sizing were determined, and absorbance and transmittance values of corn, wheat and alum-egg sizing types at UV, VIS and IR wavelengths were measured for comparison. Two different methods and lasers were used for cleaning. In the first method, Yb:Glass fs laser beam (1030 nm wavelength) was focused on the paper surface by using a cylindrical lens (25 mm focal length). Square regions were cleaned through scanning the samples under laser light. Laser fluence was varied in the range of 0.39 - 0.78 J/cm(2). In the second method, a Q-switched Nd:YAG ns laser was operated at fundamental (1064 nm) and second harmonic (532 nm) wavelengths. Laser fluence was varied from 0.24 to 1.24 J/cm(2). Samples were cleaned by means of 1 and 10 laser shots for each fluence. The effectiveness of cleaning was investigated through measurements of color variations, visual and microscopic observations.

International audience; This paper presents a parallel-plate waveguide lens for wide-angle mechanical beam steering. A previously developed ray-tracing procedure is used for designing the quasi-optical system. The feed system is based on gap waveguide technology enabling a simple and rapid mechanical actuation. Validation of the proposed concept is given by numerical results for a Ka-band lens design. A high scanning performance over an angular range of ± 50° with a worst-case scan loss of about 3 dB is achieved. The simulated return loss is greater than 15dB in the 27.5-31 GHz band. The proposed lens beamformer is an attractive ground-segment solution for future Satcom applications. © 2021 EurAAP.

The inherent advantages of reflective e-paper displays (EPD) – wide viewing direction range and excellent readability even under bright sunlight – can be extended into low-light conditions by the addition of an integrated lighting unit (ILU) such as a front light. A methodology for predicting the viewing direction dependence of ambient contrast and color from display measurements and illumination models is here applied to reflective EPD where the ILU is switched on. The predictions can be used to optimize task lighting. The ILU improves the indoor performance of EPD without compromising their superior daylight performance.

Paper making and converting industry in Europe is suffering from transfer of basic manufacturing to fast-growing economies, such as China and Brazil. Pulp and paper production volume in Finland, Sweden and France was the same in 2011 as it was in 2000. Meanwhile China has tripled its volume and Brazil doubled. This is a situation where innovative solutions for papermaking and converting industry are needed. Laser can be solution for this, as it is fast, flexible, accurate and reliable. Before industrial application, characteristics of laser beam and paper material interaction has to be understood. When this fundamental knowledge is known, new innovations can be created. Fulfilling the lack of information on interaction phenomena can assist in the way of lasers for wider use of technology in paper making and converting industry. This study was executed by treating dried kraft pulp (grammage 67 g m-2) with different laser power levels, focal point settings and interaction time. Laser equipment was TRUMPF TLF HQ2700 CO2 laser (wavelength 10.6 μm). Interaction between laser beam and dried kraft pulp was detected with multi-monitoring system (MMS), which consisted of spectrometer, pyrometer and active illumination imaging system. There is two different dominating mechanisms in interaction between laser beam and paper material. Furthermore, it was noticed that there is different interaction phases within these two interaction mechanisms. These interaction phases appear as function of time and as function of peak intensity of laser beam. Limit peak intensity divides interaction mechanism from one-phase interaction into dual-phase interaction.

The WALOP-South instrument will be mounted on the 1 m SAAO telescope in South Africa as part of the PASIPHAE program to carry out a linear imaging polarization survey of the Galactic polar regions in the optical band. Designed to achieve polarimetric sensitivity of $0.05~\%$ across a $35\times35$ arcminute field of view, it will be capable of measuring the Stokes parameters I, q and u in a single exposure in the SDSS-r broadband and narrowband filters between $0.5~{\mu}m - 0.7~{\mu}m$. For each measurement, four images of the full field corresponding to linear polarization angles of 0 deg, 45 deg, 90 deg and 135 deg in the instrument coordinate system will be created on four detectors from which the Stokes parameters can be found using differential photometry. In designing the optical system, major challenges included correcting for the dispersion introduced by large split angle Wollaston Prisms used as analysers as well as other aberrations from the entire field to obtain imaging quality PSF at the detector. We present the optical design of the WALOP-South instrument which overcomes these challenges and delivers near seeing limited PSFs for the entire field of view., Comment: 31 pages, 18 Figures and 8 Tables. Accepted in the Journal of Astronomical Telescopes, Instruments, and Systems

Summary Surface textures of a large collection of photographic papers dating from 1896 to the present were measured using a laser scanning confocal microscope (LSCM) with four different objective lenses. Roughness characterization parameters were calculated from the texture measurements and were compared with gloss measurements. Characterization by the area-scale fractal dimension (Das) and the area-scale fractal complexity (Asfc) provided the strongest correlations between gloss reflectance and surface texture. The measurements with the 5× and 10× objectives, which contained many large-scale, spiky measurement artifacts that distorted the measurement, resulted in the strongest correlations (R2 > 0.8) compared to the 20× and 50× (R2

The design and technology of tunable liquid crystal based lenses is discussed. Specific attention is paid to lenses with small diameters and high f‐number and it is demonstrated that in that case a segmented Fresnel lens approach can be most favorable in terms of both ease of manufacturing and optical performance.

Surface-enhanced Raman scattering (SERS) is highly promising for ultra-sensitive detection in a series of applications. Although extensive advances have been achieved in SERS technologies, the preparation of highly efficient SERS substrates still suffers from several limitations, including complex preparation procedures, high cost, and instability for long time storage. To address these problems, we report a novel, to the best of our knowledge, SERS platform that combines graphene oxide (GO) and cellulose composite paper with colloidal silver nanoparticle (Ag NP) ink. As an efficient substrate, the GO and cellulose composite paper that features hierarchical micro-nanostructures and improved interaction with target molecules can be fabricated on a large scale, and the Ag NP ink can be well stored, avoiding being oxidized in ambient conditions. In this way, our SERS platform not only reduces the cost, but also improved the stability. The sensitivity, reproducibility, and tunable SERS detection performance were evaluated using rhodamine 6G as probing molecules. To demonstrate the capability of our SERS platform in practical analysis, the SERS spectra of two monosodium salt solutions of different concentrations have been collected. The SERS platform has revealed great potential for practical application of SERS technologies.

Since Leith and Upatnieks demonstrated the first optical hologram in 1964, hologram technology has attracted a great deal of interest in a wide range of optical fields owing to its potential use in future optical applications such as holographic imaging and optical data storage. Although there have been considerable efforts to develop holographic technologies using conventional optics, critical issues still hinder future development. Recently, metasurfaces composed of artificially fabricated subwavelength structures have been considered as novel holographic devices that show an unprecedented ability to control electromagnetic waves. In this review, we outline the recent progress in metasurface holography. A general introduction to several types of metasurface holography categorized based on their physics and application is provided. Then, our personal perspective on the future of this field is discussed.

Colorimetric properties of fluorescent materials depend on the SPD of the illumination. That is why most standards for evaluating them specify the illuminations, which are often hard-to-realize daylight illuminants. The presented method using commercially available LEDs enables accurate enough colorimetric measurements of FWA-treated papers or prints on them illuminated by the specified illuminant. The total spectral radiance factor of a fluorescent specimen, from which most colorimetric values are derived, consists of the luminescent spectral radiance factor and the spectral reflectance factor. This method separately estimates those of FWA-treated paper to add up to the total spectral radiance factor. The luminescent spectral radiance factor is obtained by estimating the SPD of luminescence excited by the specified illuminant as the weighted sum of the multiple SPDs of luminescence excited by the respective narrow band LED emissions at different wavelengths. The LEDs and their weights are determined optimally for generally used papers. The spectral reflectance factor is derived from the estimated SPD of the radiation with fluorescence excluded from the paper illuminated by visible illumination. The method was applied with five different illumination systems each using two or three narrow band LEDs in the excitation range. They were evaluated by measuring the total spectral radiance factors by D50 of seven FWA-treated papers and CMYK prints on four papers. The derived colorimetric values were compared to the respective references by the ideal D50.

Simulating the reflectance of electronic paper (e-paper) using cholesteric liquid crystals, we found that the e-paper's black color was tinged red with the light reflected on the electrode. To make the black color achromatic, we optimized the interfacial reflectance of electrodes by changing their thickness. Finally, we developed some new e-paper improved black color.

The Uplink Wavefront Corrector System (UWCS) is a pathfinder instrument to demonstrate the uplink correction by Adaptive Optics techniques; this novel application can be directly usable in two fields: Free-Space Optical Communications and the generation of Laser Guide Stars. A Rayleigh LGS is propagated to the sky while the atmospheric wavefront aberrations are measured by a Shack-Hartmann WFS with 12 x 12 sub-apertures using a Natural Guide Star as a reference. The laser upwards propagation path is then pre-compensated by a 97-actuator deformable mirror. A scoring camera is attached to the finder telescope, next to the main aperture, in order to show the overall result, which is assessed in terms of beam power concentration. Present paper described the design process of the UWCS and its integration and testing in the Optical Ground Station telescope, at Teide Observatory (Spain).