Extreme Ultraviolet (EUV) Lithography mask defects were examined on the actinic mask imaging system, SHARP, at Lawrence Berkeley National Laboratory. A quantitative phase retrieval algorithm based on the Weak Object Transfer Function was applied to the measured through-focus aerial images to examine the amplitude and phase of the defects. The accuracy of the algorithm was demonstrated by comparing the results of measurements using a phase contrast zone plate and a standard zone plate. Using partially coherent illumination to measure frequencies that would otherwise fall outside the numerical aperture (NA), it was shown that some defects are smaller than the conventional resolution of the microscope. Programmed defects of various sizes were measured and shown to have both an amplitude and a phase component that the algorithm is able to recover.
Night vision equipment is crucial in order to accomplish supremacy and safety of the troops on the battlefield. Evidently, system integrators, MODs and end-users need access to reliable quantitative characterization of the expected field performance when using night vision equipment. The Image Intensifier tube is one of the most important engines driving the performance for night vision equipment. As a major tube manufacturer, PHOTONIS has investigated the link between its products physical design parameters and the actual end-user field performance. The developments include 1) an end-to-end performance measurement method and test facility, 2) an image-based night vision simulation and 3) a range estimation model. The purpose is twofold: i) being able to support the need of the integrators and end users, and ii) further systematic improvement of night vision equipment design. For the end-to-end test, PHOTONIS and TNO cooperated in the implementation of the TOD (Triangle Orientation Discrimination) test for night vision equipment. This test provides a clear and rigorous ranking of the products with respect to their target acquisition performance level. With respect to the image-based simulation, PHOTONIS performs physical and performance comparisons between artificial and real imagery, promising exciting further development of a model based on the merging of the different approaches of night vision evaluation and modelling. In this paper, we present the PHOTONIS night vision test laboratory, provide TOD results for a set of night vision devices and show range prediction examples.
A simple fabrication technique for a silica suspended-core holey fiber design is presented that features a higher air-filling fraction than most holey fibers, making it ideal for evanescent-field-sensing applications. The holes in the fiber are defined through mechanical drilling of the preform, which is a significantly quicker and more straightforward approach to the customary stacking method. During the draw, the shape of the holes are manipulated so that the final fiber design approximates that of an air-suspended rod with three fine struts supporting the core. Modeling reveals that the modal overlap is greater than at for a core diameter of , which is significantly higher than any previously reported index-guiding structure used for sensing. A basic gas sensor is demonstrated using acetylene as the sensing medium and the results are reported.
A novel binary level set method for boundary-based image segmentation is proposed, which is extended from region-based binary level set methods. The proposed binary level set method is based on the geometric active contour framework, which is a traditional level set method applied in boundary-based image segmentation. However, being different from the geometric active contour, the proposed binary level set method replaces the traditional level set function with a binary level set function to reduce the expensive computational cost of redistancing the traditional level set function. The experiments and complexity analysis show that the proposed binary level set method is more efficient than the geometric active contour for image segmentation while giving similar results to the geometric active contour.
An object tracking algorithm using an adaptive Kalman filter (KF) combined with mean shift (MS) is proposed. First, the system model of KF is constructed, then the center of the object predicted by KF is used as the initial value of the MS algorithm. The searching result of MS is fed back as the measurement of the adaptive KF, and the estimate parameters of KF are adjusted by the Bhattacharyya coefficient adaptively. The proposed method has the robust ability to track a moving object in consecutive frames under certain real-world complex situations, such as a moving object disappearing partially or totally due to occlusion, fast moving objects, and sudden changes in velocity of a moving object. The experimental results demonstrate that the proposed tracking algorithm is robust and practical.
A dual-parameter optical sensor is demonstrated by connecting together a fiber Bragg grating and a no-core fiber. The hybrid configuration permits the detection of the temperature and the external refractive index.
We experimentally demonstrate the fabrication of silicon optical fibers by using the powder-in-tube technique. The fibers are drawn from a preform utilizing a custom-made fiber drawing system. Silicon optical fibers having cladding diameters in the range of , core diameters in the range of , and an approximate overall length of have been fabricated. The powder-in-tube technique is versatile and can be utilized to fabricate fibers with different dimensions and core/cladding materials.
A compact slot waveguide polarization splitter based on the silicon (Si) material system is proposed and analyzed. The slot waveguide structure introduces significant beat-length differences for transverse electric and transverse magnetic polarizations at operation wavelength of . The special self-imaging design with limited modes and weak second-mode excitation shortens the device length to , while still delivering good performance. The polarization extinction ratio is , and the excess loss is only . The splitter also has a relaxed length tolerance of . These attributes make it an excellent candidate for polarization diversity circuits and compact electronic-photonic integrated circuits.
A new intraprediction method is proposed to decrease coding complexity as well as improve coding efficiency of H.264/AVC. Whether the predicted values of different prediction modes are similar is determined according to the proposed rules. When the predicted values are similar, the average of such values is used to predict the current block without invoking the rate-distortion optimization process. Experimental results show that by integrating the proposed method in the H.264/AVC codec, 39.25 coding time can be saved; meanwhile, the average bit-rate reduction is 2.62 under the same peak signal-to-noise ratio of reconstructed videos.
A fast directional discrete cosine transform (FDDCT) is proposed for efficient representation of anisotropic edges in images. The transform is performed on the predefined direction lines similar to the intraprediction mode in H.264. Comparing to the directional discrete cosine transform (DDCT) now available, no interpolation is needed in FDDCT; thus, the amount of computation decreases by 80 . Simulation results indicate that the peak signal-to-noise ratios of images compressed using FDDCT are higher than those using DDCT.
We propose a new system of quantum key distribution via optical wireless communication links, where the required information, especially telephone conversation, can be secured by using a quantum code/decode (CODEC) technique incorporated in the networks. The entangled photons can be encoded into the classical information and then the decoded signal can also be retrieved. The proposed system consists of quantum key generation and uplink and downlink parts that can be implemented in the mobile telephone handset and networks. Such a system and technique show the feasibility of use for a perfectly security telephone networks.
We propose a motion vector memory reduction scheme for the H.264 spatial scalable motion estimation. The spatial scalable prediction of H.264 scalable video coding requires a significant amount of motion vector bits from the previous layer motion prediction. This motion vector causes the Internal memory size to increase, which may result in increasing hardware cost and power consumption. To reduce the memory size of the motion vector, we propose a motion vector bit-compression scheme of the interlayer motion estimation. The proposed compression scheme uses the difference value of current motion vector and previous motion vector to get a probability for entropy coding. In addition, the proposed scheme modifies a variable length coding table of the H.264 system as a simple entropy coding table. The proposed scheme reduces the motion vector-storing bit by with less changes in hardware size.
We present an adaptive quarter-pel (Qpel) motion estimation (ME) method for H.264/AVC. Instead of applying Qpel ME to all macroblocks (MBs), the proposed method selectively performs Qpel ME in an MB level. In order to reduce the bit rate, we also propose a motion vector (MV) encoding technique that adaptively selects a different variable length coding (VLC) table according to the accuracy of the MV. Experimental results show that the proposed method can achieve about 3 average bit rate reduction.
The optical wavelength-division-multiplex filter for bidirectional optical subassembly (BOSA) is embedded to the fiber core, which results in simplicity of the BOSA module. The fiber cladding is angle polished to receive a downstream signal. The core is etched by a femtosecond laser to have a normal core facet and to transmit an upstream signal. The downstream signal, which is core mode, is coupled to the cladding mode by the long-period fiber grating and then detected by a photodiode by means of the total internal reflection effect at the angle polished cladding facet. The measured transmitted and received coupling efficiencies are 27.3 and 43.8 , respectively.
We have developed and demonstrated a high-duty-cycle asynchronous InGaAsP-based photon counting detector system with near-ideal Poisson response, room-temperature operation, and nanosecond timing resolution for near-infrared applications. The detector is based on an array of Geiger-mode avalanche photodiodes coupled to a custom integrated circuit that provides for lossless readout via an asynchronous, nongated architecture. We present results showing Poisson response for incident photon flux rates up to 10 million photons per second and multiple photons per timing bin.
We optimize the layout of each light plane in a dual-view multistripe measurement system by employing spatial geometry analysis to avoid ambiguity. The imaging regions of every light plane can be labeled uniquely on two image planes within a certain measurement depth. Moreover, the flexible density of fringe patterns corresponding to the different measurement depths is immediately projected without the conventional coding procedure. Some experiments verify the effectiveness of the proposed method applied in high-resolution 3-D measurements.
We report the first demonstration of silica waveguide optical passive ring resonator gyro (OPRG) based on the phase modulation spectroscopy technique. The ring resonator is composed of a -long silica waveguide. Observed from the resonance curve, the free spectral range (FSR) of the resonator, the full width at half maximum (FWHM) of the resonance curve, the finesse of the resonator, and the resonance depth are , , 54.8, and 70 , respectively. The detection sensitivity of this OPRG will be . In the experiments, there is an acoustic-optical modulator (AOM) in each light loop. We lock the lasing frequency at the resonance frequency of the silica waveguide ring resonator for counterclockwise (CCW) lightwave; the frequency difference between the driving frequencies of the two AOMs is equivalent to the Sagnac frequency difference caused by gyro rotation. Thus, the gyro output is observed.
We propose a new multimodal biometric recognition based on the fusion of finger vein and finger geometry. This research shows three novelties compared to previous works. First, this is the first approach to combine the finger vein and finger geometry information at the same time. Second, the proposed method includes a new finger geometry recognition based on the sequential deviation values of finger thickness extracted from a single finger. Third, we integrate finger vein and finger geometry by a score-level fusion method based on a support vector machine. Results show that recognition accuracy is significantly enhanced using the proposed method.
We recorded a hologram in a photorefractive crystal with a two-color recording technique in transmission geometry. The holographic recording involves a light with wavelength for interference, and a light with wavelength for exciting. The short wavelength light excites more charges so that the holographic recording is affected, and the storage capacity ( -number) and the sensitivity vary accordingly. We found that the optimized intensity ratio of the interference lights and the exciting light is between 50 and 60. In the optimized conditions, the number and the sensitivity are enhanced by 43 and 35 , respectively. Because the crystal we used is a typical iron-doped crystal and the short wavelength exciting light source is inexpensive now, the proposed method is easy to be achieved in most holographic systems.