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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - THz Near- Field Imaging and Spectroscopy with Nanoscale Resolution
摘要： Scattering-type near-field microscopy can overcome the limits in spatial resolution present in conventional THz imaging and spectroscopy techniques. This talk shows how THz near-field imaging and THz-TDS with a spatial resolution <20 nm can be realized with our neaSNOM microscope and some of the possible applications.
关键词： THz-TDS,nanoscale resolution,neaSNOM microscope,THz near-field imaging
更新于2025-09-04 15:30:14
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Designing an anisotropic noise filter for measuring critical dimension and line edge roughness from scanning electron microscope images
摘要： The scanning electron microscope (SEM) is often employed in inspecting patterns transferred through a lithographic process. A typical inspection is to measure the critical dimension (CD) and line edge roughness (LER) of each feature in a transferred pattern. Such inspection may be done by utilizing image processing techniques to detect the boundaries of a feature. Since SEM images tend to include a substantial level of noise, a proper reduction of noise is essential before the subsequent process of edge detection. In a previous study, a method of designing an isotropic Gaussian filter adaptive to the noise level was developed. However, its performance for relatively small features was not so good as for large features, especially in the case of LER. The main objective of this study is to improve the design method such that the accuracy of the measured CD and LER is not deteriorated substantially as the feature size decreases. The new design method allows a Gaussian filter to be anisotropic for the better adaptability to the signal and noise, both of which show a substantial level of directional correlation. The cutoff frequency for the direction normal to features is determined to include most of the signal components, and the cutoff frequency in the other direction is set to balance the signal and noise components to be included. This procedure enables a systematic and easy design of the filter. Also, the method of estimating the noise has been modified for higher accuracy. The performance of the new design method has been thoroughly analyzed using the reference images for which feature boundaries are known. It has been shown that the anisotropic filter designed by the proposed method performs better than the isotropic filter from the viewpoint of CD, LER, and power spectral density accuracy.
关键词： critical dimension,image processing,anisotropic noise filter,scanning electron microscope,line edge roughness
更新于2025-09-04 15:30:14
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Ergonomic Microscope: Need of the Hour
摘要： Background: Prolonged use of conventional microscope develops musculo-skeletal injuries like chronic pain syndrome, including shoulder, neck, back aches & fatigue. Since the problems go unnoticed, the injuries can lead to some serious permanent damages. This further leads to a compromise in the health and welfare of the person and the institute. Hence, an understanding about the ergonomics is the need of the hour in this postmodern era. Inspite of few studies and surveys about ergonomics, there is still a steep rise in the musculoskeletal disorders. Aim of the Study: The aim of our study was to gauge the general awareness of pathologists, microbiologists and oral pathologists towards ergonomics in their profession. Materials and Methods: A cross-sectional survey based study was de signed, which included a questionnaire. The questionnaire four alternatives. included multiple choice questions with Professionals (pathologists, microbiologists and oral pathologists) were included in the survey. Teaching faculty (Professors, Associate Professors and Lecturers) and Post graduate students formed the study group. results and Observations: The response to the questionnaire was 100%. Less than 50% of oral pathologists were aware of the importance of ergonomics in their profession. The most common site affected was neck and back. One of the drastic observations was that, Oral Pathologists suffered from a combination of problems affecting neck, back, eyes, headache, shoulders, arms and wrists. conclusion: Increase in our understanding regarding ergonomic- ally designed microscopes can increase our efficiency and in turn improve our general well-being. With improvements in ergonomics, professionals would be able to modify and optimize their working conditions. Certain guidelines need to be followed by the profes- sionals to reduce chances of musculoskeletal disorders.
关键词： Occupational injury,Neutral spine,OSHA,Conventional microscope,Work-related musculoskeletal disorder,CDC guidelines
更新于2025-09-04 15:30:14
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Robust nonlinear control of atomic force microscope via immersion and invariance
摘要： This paper reports an immersion and invariance (I&I)–based robust nonlinear controller for atomic force microscope (AFM) applications. The AFM dynamics is prone to chaos, which, in practice, leads to performance degradation and inaccurate measurements. Therefore, we design a nonlinear tracking controller that stabilizes the AFM dynamics around a desired periodic orbit. To this end, in the tracking error state space, we define a target invariant manifold, on which the system dynamics fulfills the control objective. First, considering a nominal case with full state measurement and no modeling uncertainty, we design an I&I controller to render the target manifold exponentially attractive. Next, we consider an uncertain AFM dynamics, in which only the displacement of the probe cantilever is measured. In the framework of the I&I method, we recast the robust output feedback control problem as the immersion of the output feedback closed-loop system into the nominal full state one. For this purpose, we define another target invariant manifold that recovers the performance of the nominal control system. Moreover, to handle large uncertainty/disturbances, we incorporate the method of active disturbance rejection into the I&I output feedback control. Through Lyapunov-based analysis of the closed-loop stability and robustness, we show the semiglobal practical stability and convergence of the tracking error dynamics. Finally, we present a set of detailed, comparative software simulations to assess the effectiveness of the control method.
关键词： output feedback control,chaos,immersion and invariance,disturbance rejection control,atomic force microscope
更新于2025-09-04 15:30:14
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Inverse photonic design of functional elements that focus Bloch surface waves
摘要： Bloch surface waves (BSWs) are sustained at the interface of a suitably designed one-dimensional (1D) dielectric photonic crystal and an ambient material. The elements that control the propagation of BSWs are defined by a spatially structured device layer on top of the 1D photonic crystal that locally changes the effective index of the BSW. An example of such an element is a focusing device that squeezes an incident BSW into a tiny space. However, the ability to focus BSWs is limited since the index contrast achievable with the device layer is usually only on the order of Δn≈0.1 for practical reasons. Conventional elements, e.g., discs or triangles, which rely on a photonic nanojet to focus BSWs, operate insufficiently at such a low index contrast. To solve this problem, we utilize an inverse photonic design strategy to attain functional elements that focus BSWs efficiently into spatial domains slightly smaller than half the wavelength. Selected examples of such functional elements are fabricated. Their ability to focus BSWs is experimentally verified by measuring the field distributions with a scanning near-field optical microscope. Our focusing elements are promising ingredients for a future generation of integrated photonic devices that rely on BSWs, e.g., to carry information, or lab-on-chip devices for specific sensing applications.
关键词： focusing elements,scanning near-field optical microscope,integrated photonic devices,Bloch surface waves,photonic design
更新于2025-09-04 15:30:14
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Scanning frequency comb microscopy—A new method in scanning probe microscopy
摘要： A method for superimposing a microwave frequency comb (MFC) on the DC tunneling current in a scanning tunneling microscope (STM) is described in which a mode-locked laser is focused on the tunneling junction. The MFC is caused by optical rectification of the regular sequence of laser pulses due to the nonlinear current-voltage characteristics of the tunneling junction. Hundreds of harmonics, at integer multiples of the laser pulse-repetition frequency, are generated with a metal tip and sample. However, the harmonics have less power with a resistive sample due to the loss in its spreading resistance. The microwave power is greatest at a tip-sample distance that is unique for each sample resistivity. This distance may be set by using different pairs of the applied DC bias and the set-point for the DC tunneling current. However, the laser, and not the applied DC bias or the DC tunneling current, is the source of energy for the MFC so they are not required. Feedback control of the tip-sample distance may be based on maximizing the attowatt-level microwave power of the harmonics, which have a signal-to-noise ratio of 20 dB. This method shows promise for nondestructive carrier profiling of semiconductors with true sub-nanometer resolution which is essential in the continued progress below the 40-nm technology node. It may enable carrier profiling with 2-D materials such as graphene, and it also shows promise for finer resolution in images of biological materials or other resistive samples.
关键词： optical rectification,microwave frequency comb,resistive sample,feedback control,scanning tunneling microscope
更新于2025-09-04 15:30:14
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3D Printing and Ophthalmology for the Community
摘要： People may have heard of three dimensional (3D) printed firearms, which carries bad publicity for 3D printing, yet amazing things have been achieved with simple desktop 3D printers within the medical field. 3D printing was almost unheard of until the last 5 years; as key additive-manufacturing patents expire, affordable desktop 3D printers mushroomed globally. The technology of 3D printing is not new. Actually, the idea can be traced back to as early as the 1890s when Blanther suggested a layered method for making a mould for topographical relief maps. However, it was not until 1987 when the first additive manufacturing machine emerged. In simpler terms, 3D printing is in fact 2D printing but over and over again, layered together. As patents expire, innovation took over the stage and people started building affordable, user-friendly 3D printers that are now widely available. Fused deposition modelling (FDM) printers are the most common consumer oriented printers and brands such as MakerBot and Ultimaker currently dominate the consumer market. These are low end 3D printers that have made the biggest impacts and allowed innovative leaps in the medical field. Recently, an interventional radiologist managed to save a patient’s spleen with 3D printing technology. The patient was diagnosed with a number of complicated tortuous splenic aneurysms and conventionally, she would have been treated with splenectomy. However, the interventional radiologist managed to spare her spleen by coiling the aneurysms instead. The success was not by luck or co-incidence; it was through countless practices on a 3D printed replica of the patient’s splenic aneurysms. 3D printing in ophthalmology is an exciting field. There are a variety of uses ranging from optics industry printing spectacles to scientist printing ocular tissues such as sclera and cornea. 3D printing has the advantage of low-cost yet high-level customization, making it cost-effective for making one of a kind devices or prostheses. Combined with 3D scanning technology, a patient could have his or her customized prosthetic eye 3D printed in a matter of days instead of weeks.
关键词： Smartphone retinal camera,Smartphone slit lamp microscope,3D printing in ophthalmology,Smartphone in teleophthalmology
更新于2025-09-04 15:30:14