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Iris extraction is a crucial step in iris recognition technology. However, it is easily interfered with by eyelashes. In the process of iris recognition, the detection of eyelashes is very significant when taking iris images. But the precision of the existing iris detection algorithm is not high. This paper proposes an eyelash segmentation method based on the adaptive threshold. Firstly, a specific area in the picture is selected as the region of interest according to the position of the eyelashes. Then the gray range of the area is defined according to the iris gray information. Finally, under the above two constraints, the optimal threshold of gray-scale image segmentation is calculated using the algorithm of maximizing variance between classes. The method improves the subjective accuracy of eyelash segmentation in the iris image and lays the foundation for the next step of iris recognition.

Aiming at the bad performances of existing traditional local stereo matching methods in ill-posed regions, an improved AD-Census algorithm based on two-phase adaptive optimization and gradient fusion is proposed. During the cross arm construction phase, an adaptive nonlinear constraint of intensity difference between pixels is adopted to get the optimal arm length. In the cost computation phase, the absolute difference(AD) cost and Census transform(CT) cost of each pixel are weighted summed firstly. Then the result is fused with the gradient cost by adaptive weight, which is determined by the exponential function with the shortest arm length as the independent variable. Finally, the disparity map is obtained by cost aggregation, disparity selection and disparity refinement. The experimental results indicate that the average disparity error of all regions on Middlebury 2014 datasets is reduced by 31% compared with the original AD-Census algorithm, and the average disparity error of non-occlusion regions is reduced by 40%. The proposed algorithm performs better in textureless regions and disparity discontinuity regions, and it shows enough robustness for radiometric changes and noise.

The detection of corona discharge is an effective way for early fault diagnosis of power equipment. UV–Visible dual-band imaging can detect and locate corona discharge spot at all-weather condition. In this study, we introduce an image registration protocol for this dual-band imaging system. The protocol consists of UV image denoising and affine transformation model establishment. We report the algorithm details of UV image preprocessing, affine transformation model establishment and relevant experiments for verification of their feasibility. The denoising algorithm was based on a correlation operation between raw UV images, a continuous mask and the transformation model was established by using corner feature and a statistical method. Finally, an image fusion test was carried out to verify the accuracy of affine transformation model. It has proved the average position displacement error between corona discharge and equipment fault at different distances in a 2.5m-20 m range are 1.34 mm and 1.92 mm in the horizontal and vertical directions, respectively, which are precise enough for most industrial applications. The resultant protocol is not only expected to improve the efficiency and accuracy of such imaging system for locating corona discharge spot, but also supposed to provide a more generalized reference for the calibration of various dual-band imaging systems in practice.

Cu dual-damascene interconnects with an amorphous Ru–Mo–C (labeled as RuMoC) seedless barrier layer were successfully fabricated and its feasibility for advanced Cu dual-damascene interconnects were investigated. The results show that the RuMoC II films obtained with sputtering rates (Ru:MoC) of 100:50 demonstrated the best performance, exhibiting an amorphous structure, low residual oxygen content, low resistivity at temperatures up to 500 °C. A Cu plug of good quality was successfully electroplated on the RuMoC II barrier layer with 4-nm-thick without seed layer in a damascene structure. The ultra-thin RuMoC II barrier effectively blocked the diffusion of Cu and O atom after being annealed up to 500 °C. The damascene structure showed much lower leakage current and via resistance compared to the damascene structures with traditional Ta barrier, suggesting that RuMoC II film has sufficient barrier properties. Moreover, the via resistance of the damascene structures with RuMoC II barrier were quite low and met the requirement of different technology nodes for the future semiconductor industry, indicating great prospects for advanced seedless Cu metallization applications.

Ultrathin graded ZrN x self-assembled diffusion barriers with controllable stoichiometry was prepared in Cu/p-SiOC:H interfaces by plasma immersion ion implantation (PIII) with dynamic regulation of implantation fluence. The fundamental relationship between the implantation fluence of N + and the stoichiometry and thereby the electrical properties of the ZrN x barrier was established. The optimized fluence of a graded ZrN thin film with gradually decreased Zr valence was obtained with the best electrical performance as well. The Cu/p-SiOC:H integration is thermally stable up to 500 °C due to the synergistic effect of Cu 3 Ge and ZrN x layers. Accordingly, the PIII process was verified in a 100-nm-thick Cu dual-damascene interconnect, in which the ZrN x diffusion barrier of 1 nm thick was successfully self-assembled on the sidewall without barrier layer on the via bottom. In this case, the via resistance was reduced by approximately 50% in comparison with Ta/TaN barrier. Considering the results in this study, ultrathin ZrN x conformal diffusion barrier can be adopted in the sub–14 nm technology node.

As one of the most reliable biometric identification techniques, iris recognition has focused on the differences in iris textures without considering the similarities. In this work, we investigate the correlation between the left and right irises of an individual using a VGG16 convolutional neural network. Experimental results with two independent iris datasets show that a remarkably high classification accuracy of larger than 94% can be achieved when identifying if two irises (left and right) are from the same or different individuals. This exciting finding suggests that the similarities between genetically identical irises that are indistinguishable using traditional Daugman&rsquo, s approaches can be detected by deep learning. We expect this work will shed light on further studies on the correlation between irises and/or other biometric identifiers of genetically identical or related individuals, which would find potential applications in criminal investigations.

We numerically investigate the thermal effects in a cornea illuminated by terahertz radiation. By modifying the bioheat and Arrhenius equations, we studied the heat-transfer and temperature distributions in the corneal tissue, and evaluated the potential thermal damage. The influence of the beam radius and power density are discussed. We also estimated the effective cornea-collagen shrinkage region, and evaluated the degree of thermal damage in the cornea. We expect this work to open up a novel effective and safe thermal-treatment approach based on THz radiation for cornea reshaping in the field of ophthalmology.

We present a study aimed at developing a terahertz time domain spectroscopy (THz-TDS) system for detection of the optical properties of ex vivo rabbit corneal tissues with different water content at terahertz frequencies (0.1–0.3 THz). The refractive index decreased with frequency while the absorption coefficient increased with frequency. Our experimental results matched the theoretical calculation very well revealing that both the absorption coefficient and the refractive index of a hydrated cornea were much larger than that of a dehydrated cornea and the terahertz properties depended on the hydrate conditions of the biosamples.

We show that ultrasensitive THz sensors can be achieved based on corrugated hyperbolic metamaterials. For the proposed sensor the sensitivity of the proposed sensor reaches 1 THz/RIU (9.3 × 103nmlRIU), which is orders of magnitude larger than those based on metasurfaces.

A series of 60 keV He + implantations was conducted on Cu/W(Re, 5.9 at.%) multilayered structures with ion doses from 5 × 10 19 to 5 × 10 21 m 2 under different temperature. Three distinct, temperature-dependent He release mechanisms were found by subsequent X-ray diffraction (XRD) and scanning electron microscope (SEM) investigations. Firstly, with implantation at 300 K (about T / T m (Cu) = 0.22), a certain degree of blistering was observed with a critical dose higher than 5 × 10 21 m −2 . But, at higher temperature irradiation (about T / T m (Cu) = 0.35), samples implanted were characterized by extensive blisters at the dose of 2 × 10 21 m −2 . Finally, at 673 K (about T / T m (Cu) = 0.5), the specimen flaked and a rough, porous surface formed when the dose was higher than 1 × 10 21 m −2 . The mechanisms involved have been analyzed based on the detailed characterization studies.

Ultrathin RuMoC amorphous films prepared by magnetron co-sputtering with Ru and MoC targets in a sandwiched scheme Si/p-SiOC:H/RuMoC/Cu were investigated as barrier in copper metallization. The evolution of final microstructure of RuMoC alloy films show sensitive correlation with the content of doped Mo and C elements and can be easily controlled by adjusting the sputtering power of the MoC target. There was no signal of interdiffusion between the Cu and SiOC:H layer in the sample of Cu/RuMoC/p-SiOC:H/Si, even annealing up to 500 °C. Very weak signal of oxygen have been confirmed in the RuMoC barrier layer both as-deposited and after being annealed, and a good performance on preventing oxygen diffusion has been proved. Leakage current and resistivity evaluations also reveal the excellent thermal reliability of this Si/p-SiOC:H/RuMoC/Cu film stack at the temperatures up to 500 °C, indicating its potential application in the advanced barrierless Cu metallization.

Conventional Photometric Stereo (PS) techniques are usually based on the assumption that the light sources are assumed sufficiently far from the object that all incoming light can be modeled using parallel rays. Meanwhile, for near-field lighting conditions the light sources are close to the object so the parallel ray model cannot be used. To determine the surface normal for each point on the object more accurately, the incoming light direction should be calculated individually for each point. In this work, based on a simple PS setup consisting of LED lamps and one camera, we present a practical method for calibrating lighting directions. First, an optical model of an LED was introduced in the calibration procedure to represent the surface irradiance and image irradiance more accurately. A reference sphere was used for the calibration so that the LED optical axis could be estimated by extracting the specular points from the reference sphere. By introducing the LED emitting model, distance between the LED and the specular point along the optical axis can be calculated. Thus, the incident lighting directions for various image points can be estimated individually. To improve the estimation robustness, a non-linear fitting approach was also applied. Experiments were conducted using objects and the results are compared with traditional methods to demonstrate its feasibility and improvement.

Viewing an airborne scene from a totally submerged camera will suffer severe refractive distortions due to the water surface random fluctuation. One way to reduce this distortion is to use a wave sensor to image a known guide star, through which the water wave surface is measured and reconstructed. In the wave reconstruction, a wave equivalent plane is needed to determine the positions of the wave normal vector samples. The equivalent plane is determined by measuring the under water depth of the wave sensor using a pressure-based gauge. This way can't reveal the overall wave distribution and the reading is usually haphazard. In this paper, a novel wave equivalent plane estimation method based on the incident rays parallelism is presented. Computer simulation results show that the derived plane with the minimum reconstructed sampling position error (PMPE) is the ideal equivalent plane, and the estimated plane based on the incident rays parallelism is in agreement with PMPE. Experiment results are also presented.

We propose and demonstrate an interferometric sensor based on visibility modulation. In the interferometric sensor, a section of polarization maintain (PM) fiber is spliced into one arm as the sensing head. Due to the interference between the two beams in the two arms, respectively, an interferometric fringe can be obtained. The birefringence of the PM fiber splits the beam in the sensing arm, yielding a visibility envelop in the interferometric fringe. Strain applied on the PM fiber can be demodulated by measuring the visibility change in a given wavelength. Experimental result shows that the sensor can achieve resolution of up to 28 nano-strain. This demodulation scheme is immunity to the wavelength shift and power fluctuation of OSA, thus improving the accuracy of the sensor. This type of sensor can be improved by using a wavelength-swept laser or a mode-locked fiber laser.

The diffusion barrier properties of Zr–Ge–N thin films are reported, focusing on issues relevant to their application as diffusion barriers for Cu interconnections in Si devices. The Zr–Ge–N films were prepared by reactive r.f. magnetron sputtering with different bias voltage. The analyses of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) indicate that the final structure and composition of Zr–Ge–N film are very sensitive to the sputtering bias voltage. The N content in Zr–Ge–N film changes very little, and only decreases from 51.6 to 48.4 at.% when sputtering bias voltage increases from 0 V to − 150 V. However, the correlation between bias voltage change and the atomic ratio of Zr and Ge is very remarkable. These results clearly show that the Ge atoms are preferentially resputtered with increasing substrate bias voltage. The high sputtering bias appears to be in favor of the growth of ZrN grains. The copper diffusion barrier properties of Zr–Ge–N on Si have been examined and compared to ZrN. XRD and four-point probe method (FPP) both showed the onset of formation of copper silicide crystallites for ZrN barriers annealed at 650 °C. In contrast, TEM on a Zr–Ge–N barriers annealed even at high annealing temperatures of 800 °C revealed sharp interfaces and the energy dispersive X-ray spectroscopy (EDS) line scan showed no Cu diffusion through the barrier into Si substrate. The results suggest that Zr–Ge–N is superior to ZrN as a copper diffusion barrier on Si.

Laser scanners are critical components in material processing systems, such as welding, cutting, and drilling. To achieve high-accuracy processing, the laser spot size should be small and uniform in the entire objective flat field. However, traditional static focusing method using F-theta objective lens is limited by the narrow flat field. To overcome these limitations, a dynamic focusing unit consisting of two lenses is presented in this paper. The dual-lens system has a movable plano-concave lens and a fixed convex lens. As the location of the movable optical elements is changed, the focal length is shifted to keep a small focus spot in a broad flat processing filed. The optical parameters of the two elements are theoretical analyzed. The spot size is calculated to obtain the relationship between the moving length of first lens and the shift focus length of the system. Also, the Zemax model of the optical system is built up to verify the theoretical design and optimize the optical parameter. The proposed lenses are manufactured and a test system is built up to investigate their performances. The experimental results show the spot size is smaller than 450um in all the 500*500mm~2 filed with CO2 laser. Compared with the other dynamic focusing units, this design has fewer lenses and no focusing spot in the optical path. In addition, the focal length minimal changes with the shit of incident laser beam.

A bi-spectral camera for visible and solar-blind UV (240nm-280nm) was developed for detecting the corona discharge. Due to the UV light generated by corona discharge is very weak, so an optical system by careful calculation was designed for the UV band. The UV optical system was schemed with the focal length of 200mm, relative aperture of 1:2.77 and the FOV of ±2°. The assembly of UV optical system also introduced in paper. A new method used to solve the problem of corona point not calibration in non-central of FOV in fusion image. After calibrating, the position of corona discharge can be observed accurately by overlaying UV image of the corona on a visible light image of the background. The bi-spectral optical system was accomplished and tested in the lab. Results showed that the FOVs of visible light and solar-blind UV optical systems were matched well.

Piezoelectric actuators are widely deployed in many precise positioning applications. However, all piezoelectric systems feature hysteresis effect to limit their linearity. To solve this problem, feedforward compensation is the most common technique. Many models have been proposed and applied, but their expressions are complex and parameters are difficult to identify. In this paper, a simple model for a piezoelectric laser scanner is proposed. The principle of the mode is to obtain the data of smaller hysteresis loop from the bigger one by multiplying a scaling factor. Simulation results show that the error of the model is less than + 0.8%. Based on the model, a feedforward open-loop controller is detailed. Experimental results show the nonlinearity reduces from + 7% to + 1% after compensation.

This paper proposed a solution about low cost multi-channels Gallium Arsenide (GaAs) absorption-based fiber optic temperature sensing system, which can get specific channel temperature information at pre-set time slots by combining time division multiplexing technology and fiber optic multiplexing module. Established an seven channels fiber optic temperature sensing system using only one spectrum analysis unit and achieved -/+ 1°C temperature resolution, 2Hz measuring frequency at temperature range from 0°C to 150°C.

100 nm thick RuMoC films and 5 nm thick RuMoC films with Cu capping have been deposited on Si(111) by magnetron co-sputtering with Ru and MoC confocal targets. The samples were subsequently annealed at temperatures ranging from 450 to 650 °C in vacuum at a pressure of 3 × 10−4 Pa to study the annealing effects on the microstructures and properties of RuMoC films for advanced seedless Cu metallization applications. The sheet resistances, residual oxygen contents, and microstructures of the RuMoC films have close correlation with the doping contents of Mo and C, which can be easily controlled by the deposition power ratio of MoC versus Ru targets (DPR). When DPR was 0.5, amorphous RuMoC film (marked as RuMoC II) with low sheet resistances and residual oxygen contents was obtained. The fundamental relationship between the annealing temperatures with the microstructures and properties of the RuMoC films was investigated, and a critical temperature point was revealed at about 550 °C where the components and microstructures of the RuMoC II films changed obviously. Results indicated that below 550 °C, the RuMoC II films remained amorphous due to the well-preserved C-Ru and C-Mo bonds. However, above 550 °C, the microstructures of RuMoC II films transformed from amorphous to nano-composite structure due to the breakage of Ru-C bonds, while the supersaturated solid solution MoC segregated out along the grain boundaries of Ru, thus hindering the diffusion of Cu and O atoms. This is the main mechanism of the excellent thermal stability of the RuMoC films after annealing at high temperatures. The results indicated great prospects of amorphous RuMoC films in advanced seedless Cu metallization applications.

Spectroscopic measurements and terahertz imaging of the cornea are carried out by using a rapid scanning terahertz time domain spectroscopy (THz-TDS) system. A voice coil motor stage based optical delay line (VCM-ODL) is developed to provide a rather simple and robust structure with both the high scanning speed and the large delay length. The developed system is used for THz spectroscopic measurements and imaging of the corneal tissue with different amounts of water content, and the measurement results show the consistence with the reported results, in which the measurement time using VCM-ODL is a factor of 360 shorter than the traditional motorized optical delay line (MDL). With reducing the water content a monotonic decrease of the complex permittivity of the cornea is observed. The two-term Debye relaxation model is employed to explain our experimental results, revealing that the fast relaxation time of a dehydrated cornea is much larger than that of a hydrated cornea and its dielectric behavior can be affected by the presence of the biological macromolecules. These results demonstrate that our THz spectrometer may be a promising candidate for tissue hydration sensing and practical application of THz technology.