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A millimeter wave synthetic aperture radar imaging radar system is built, which is used to research on shallow surface imaging technology. The principle of near-field millimeter-wave imaging is analyzed. By detecting the hidden target under different complex materials, the imaging performance and penetration performance of the millimeter wave imaging system are studied and verified. Measured results show that millimeter-wave has its unique advantages in shallow surface imaging, such as higher range resolution and azimuth resolution, and the equipment is more miniaturized and safer.

Traditional synthetic aperture radar (SAR) ocean surface simulation is based on uniform sampling in azimuth assuming the pulse repetition frequency (PRF) is constant. However, to achieve High-Resolution Wide-Swath (HRWS) imaging, the variable PRF mode will be applied in the next-generation spaceborne SAR systems such as Tandem-L and NISAR. To study the impact of nonuniform sampling in azimuth on ocean remote sensing, a PRF varying HRWS SAR ocean surface imaging simulator is presented in this paper. Based on the ocean wave spectrum and backscatter model, the PRF-varying radar echo signal from the sea surface is simulated. Then, the raw signal samples are reconstructed and resampled to a uniform grid which will be focused by frequency-domain algorithm. The effectiveness of the proposed simulator is verified by simulation results.

In the last decade there was enormous progress in integrated mm-wave integrated circuit design, targeting primarily mobility applications like automated driving [1], [2]. It is shown in this paper how this progress, paired with advanced signal processing and the enormous increase of available processing power, enables successful implementation of completely different, yet spectacular, applications. The evolution of designs of massive multiple-input multiple-output imaging radars in combination with the associated real-time signal processing and in-line autocalibration for analyzing the burden surface in blast furnaces, the BLASTDAR system, is presented. BLASTDAR systems now operate in all five voestalpine blast furnaces for several years.

We report a high resolution 3D imaging using variable structured illumination via Lissajous scanning MEMS mirror module. The Lissajous scanning MEMS mirror was operated at pseudo-resonant frequencies within the bandwidth. The structured illumination pattern density was controlled by selecting the greatest common divisor (GCD) of two scanning frequencies. Scanning frequency selection with high GCD provides a coarse illumination pattern. The constant pattern was obtained by modulating a laser beam at the least common multiple (LCM) of the two selected scanning frequencies. A low-Q inner mirror provides wide frequency tuning range as well as enables variable structured illumination. 3D stereoscopic image has been successfully obtained by using a variable structured illumination and stereoscopic camera. Structured illumination effectively enhances 3D imaging resolution. This structured illumination module can provide a new breakthrough for 3D MEMS imaging applications.

Emittance is an important figure of merit for electron beams which, coupled with overall current, determines a beam's utility in vacuum electronic devices (VEDs)1. As VEDs push into higher frequency and higher power regimes, low emittance, high current beams become critical2. Much theoretical work on understanding and predicting emittance has been presented, but little to no experimental results are available1,3,4, We report here the measurement of 2D emittance maps for a series of field emission fiber cathodes and their correlation to surface features, imaged using a field emission electron microscope and scanning electron microscope. This work serves to further inform theoretical investigations into emittance and aid in the a priori selection of suitable cathodes for specific uses.

The corrosion of reinforced concrete sewer pipes in aging infrastructure is a serious ongoing issue and as such, research into technologies that allow for autonomous site assessments are of major priority to wastewater managing utilities. The use of Ground Penetrating Radar (GPR) is being investigated for providing sub-surface images of sewer crowns. Due to the nature of GPRs, the analysis of a radargram for identifying sub-surface features is non-intuitive and usually require the use of an expert. Traditional methods to help ease analysis involve the use of Synthetic Aperture Radar (SAR) and migration techniques. These techniques refocus dipping and point reflectors to be closer to their true shape but require an accurate velocity model to be effective. This is not always readily available and difficult to estimate especially in regards to sewer conditions. We instead provide an alternative and present a deep learning framework for transforming ground penetrating radargrams into sub-surface permittivity maps. An evaluation of various state-of-the-art deep learning architectures is also conducted, comparing the performance of different objective functions and identifying current limitations. This work provides the base for further exploration of the application of deep learning for use in infrastructure monitoring.

Microwave mammography is promising alternative from X-ray based imaging modality, in terms of compactness, low cost and cell-friendly exposure. The most important part of this modality is a suppression of surface reflection clutters, which can be enhanced by combining accurate surface shape estimation. The coupling effect between antenna and breast surface degrades accuracy in the shape estimation, which is caused by a mismatch between reference and observed waveform. To solve this problem, this paper incorporates the Envelope-based shape estimation and FDTD-based waveform correction with a fractional derivative adjustment. Numerical simulation based on realistic breast phantom derived from MRI show that our proposed method significantly enhance the accuracy for breast surface imaging and the SCR (signal to clutter ratio) by suppressing a skin reflection.

This research developed an alternative to grayscale Phase Shifting Interferometry for 3D surface measurement by utilizing three channels color fringe. As it has been known, grayscale PSI has limitation on dynamic object measurement due to its multi-frame term. By utilizing digital color image, it merely needs a single fringe projection making it possible to obtain faster data acquisition. However, each channel of the recorded image has different intensity range due to optical system's non-linearity that would significantly affect the quality of the reconstruction. Therefore, normalization is urgently needed before performing phase computation. In this study, the normalization was performed using Isotropic N-Dimensional Fringe Normalization (INFPN) based on Hilbert Transformation, while the phase processing includes extraction using 3-step PSI and global phase unwrapping. Experiments are conducted to evaluate RGB fringe performance compared to the grayscale 3-step PSI and grayscale single frame Fourier Transform Profilometry (FTP). The results show that RGB fringe can produce a fairly good reconstruction with the measurement error of less than 6% compared to the grayscale 3-step PSI on static evaluation. It also gives far better quality of reconstruction than the grayscale single frame FTP.

A novel microwave sub-surface imaging scheme based on a scattered-field calibration technique is proposed in this paper. In this framework, the scattering parameters of the test object using the standard RF measurement system is first transformed into the electric field data. The transformation is based on measuring the scattering parameters of a known specimen under the same test environment, and then comparing the scattering parameters of this specimen with that of the test object under the assumption that electric field of the known specimen is computed in advance. The RF measurement system comprises of a transmitter-receiver array wherein the region under observation is illuminated sequentially. The solution of the inverse scattering problem is based on iterative distorted Born approximation. The performance of the proposed method is evaluated by means of numerical simulations and their inversion results.

In this paper the potential advantages of imaging outdoor environments in the low Terahertz (low-THz) range of frequencies (0.1 THz-1 THz) are discussed, in terms of the device parameters available at these frequencies and also in terms of the scattering expected by THz waves propagating in real-world environments. The results presented confirm that imaging surfaces with surface characteristics similar to those found in outdoor environments, with low-THz devices, aids in the interpretation of the obtained image whilst keeping the image processing complexity low.

The goal of carrying out sub-surface imaging from space or aircraft has so far remained elusive. In response, a description is offered here of a novel new imaging technique. Virtual-bandwidth SAR (VB-SAR) promises to deliver a previously unachievable high-resolution sub-surface imaging capability from large stand-off distances applicable to airborne and spaceborne platforms. This is in sharp contrast to current techniques, where discrimination relies on close-proximity measurement of the scene, usually with a ground-based system using large bandwidths. The scheme for separation of surface and sub-surface features is based on their differing DInSAR phase histories. Whereas the latter experience phase delays in sympathy to variations in soil moisture, these are absent from the phase history of surface features. Because the technique works on phase it is essentially independent of distance, and so applicable to large stand-off distances applicable to aircraft and satellite platforms.

Novel electromagnetic (EM) techniques for sub-surface high resolution imaging in layered lossy media are presented in this talk.

OsteoArthritis is a debilitating disease throughout the developed world, causing significant loss of quality of life to individuals and damaging economies, the imaging system described in this paper has the potential to provide an objective means of measuring and reporting lesion dimensions and providing a machine readable data archive for future study. Existing imaging methodologies have been reviewed and contrasted and despite certain limitations the optical method proposed has the potential to address the issues highlighted to date. The preliminary depth measurement results with an accuracy of 200 µm±6% suggests a potential system for the objective reporting of tissue degradation. It is also envisaged that the bio tribological performance may be inferred from the tissue surface condition as image by the proposed system.

Microfluidically controlled metalized plates are proposed for the first time as a low-cost interrogation mechanism for high resolution surface imaging arrays. The pixels of the envisioned imaging system are formed as a dense array of sub-wavelength size slot spiral resonators etched at the ground plane of a microwave substrate. The resonance frequencies of these resonators shift based on the dielectric properties of the material sample within their close proximity. Interrogation of the resonance frequency of each resonator is done by utilizing metalized plates as RF shorts between read-out microstrip lines and resonators. The metalized plates can be repositioned within the microfluidic channels by use of a single micropump unit to sequentially interrogate resonance frequencies of all pixels to extract an image. The concept is introduced through simulations and experiments carried over a 1D material sample. An example 2D imaging system is also presented (through computational simulations) for imaging of tumorous excised breast tissue. The proposed technique alleviates the needs for expensive/complex RF switch based interrogation circuitries or bulky/slow mechanical raster scans.

This paper outlines applications of terahertz spectrometry, terahertz reflectometry and sub-surface imaging for effective characterization of various aspects of semiconductor wafer testing. Exemplary results of scanning a wafer have been analyzed for defect determination. Additionally, terahertz reflectometry for controlling wafer polishing for planarization has been exemplified via high precision thickness monitoring. Application of terahertz spectrometry for identifying self-assembled monolayer (SAM) on a wafer is also outlined with example. The technique may be extended to other substrates transparent to terahertz radiation. Characterizing different SAM coated silicon wafers for identifying two different SAM species has been discussed. The Fourier transform absorbance spectra of both SAM specimens reveals several distinguishable absorbance peaks that may be used as signatures of the respective SAMs. The SAM having 18 carbon chain exhibits higher absorbance than that of the SAM comprised of 8 carbon chain. This is consistent with the higher molecular weight of the former.

In this paper, 2-D MIMO antenna arrays suitable for high resolution burden surface imaging radar operating in frequency band 24-26GHz are proposed. In order to eliminate the cross-range resolution degradation when the antenna beam radiates to the burden surface in nonperpendicular angle, MIMO antenna arrays with elliptical cross-section beam are specially designed. To suppress the high side lobe level of these designed MIMO arrays, two MIMO array sparse methods by symmetrically sparse the arrays with denser elements in the centre and sparse elements around are presented and analyzed. Patterns of the designed MIMO arrays are simulated, which verified the effectiveness of the MIMO arrays for burden surface imaging.

Sub-surface imaging system using a solid immersion lens (SIL) is introduced. Aberration caused by cover layer of Blue ray disk is minimized with truncated SIL and diffractive optical element (DOE). Sub-surface imaging simulation is achieved by using rigorous coupled wave technique, partial coherence and vector diffraction.

In medical applications, 3D information of ulcer wounds are very crucial in measuring the volume of the ulcer cavity. Volume measurement is the most significant criterion in ulcer wound assessment as reduction in wound volume is an indicator of wound healing. Treatment efficacy can be improved and healing period can be shorten if changes in wound parameters are being observed regularly and accurately. 3D skin surface imaging technique is used to replace the conventional measuring method which is qualitative and subjective. Optical and laser scanners are used to obtain the surface scanned of the ulcer wound. Two algorithms for solid reconstruction and volume computation are being proposed, namely midpoint projection and convex hull approximation. Seventeen ulcer models with different wound attributes have been used to assess the suitability and reliability of the algorithms. Using ulcer models with known volume, it is found that midpoint projection is suitable for all the wound type whereas convex hull is suitable for all types of wounds except wounds with elevated base.

A sub-surface imaging method for detecting invisible and buried micro-flaws under fine metallic surface is described. This system, which has a laser source, a CCD camera, and an eddy current exciting device is developed for this work. A pulse generator supplies an intermittent square pulse to induce the exciting coil, which can intensify eddy currents yet reduce the working temperature of the exciting coil and specimens. The magnetic field variation produced by the imbedded defect causes a rotation of the polarization plane of the reflected beam, therefore the reflected beam carries an image of the defect, which is received by a CCD camera. Now the imperceptible flaws in subsurface of mental product are visually tested. Image edge processing approaches are designed to enhance the imaging effect. The method presented is proved to be feasible by the experiment results.

This paper reports on development of AFM-like active CMOS-MEMS conductive probes and arrays. The active probes are aimed for scanning tunneling microscopy (STM) imaging and field-emission (FE) assisted nanostructure formation. Two kinds of STM tip approaches compatible with CMOS-MEMS process — Electron-Induced Beam Deposition (EBID) and Spindt tip method — are presented, and their functionality is examined. Atomic-level resolution is achieved using tips in an ultra-high vacuum (UHV) STM. The MEMS probe working in ambient STM is also demonstrated. The active probe is equipped with a transimpedance amplifier (TIA) for tip FE current measurement around a nominal value of 1 nA.

This paper reports an electromagnetic shielded cantilever-tip microwave-probe for conductive-property imaging at micro/nano surface-area. Equipped with an ultra-sharp tip apex (

In an attempt to improve the resolution of optical microscopy of semiconductor devices, it is possible to use a Weierstrass solid immersion lens (SIL). A suitable SIL eliminates spherical aberration due to the refractive-index mismatch at the silicomair interface and increases the numerical aperture (NA) of the system, decreasing the focal spot size. An increase in the spatial sampling frequency also results because physical translations of the SIL and sample result in a smaller movement of the focused spot. It is known that in the lateral direction the reduction factor equals the square of the refractive index, 12.1 in silicon. In the axial direction the scaling factor is around 75. We report here 2D imaging with an improved resolution of 166nm and 3D sub-surface imaging with approximately 100nm resolution.

The 2-step negative resist image by dry etching (2-step NERIME) focused ion beam (FIB) top surface imaging (TSI) process has been previously reported as an excellent technique for patterning nanometer scale features in DNQ/novolak based photoresists on silicon substrates. In this paper we demonstrate that the 2-step NERIME process can be used to pattern nanometer scale resist features on different substrate materials and topography substrates.

Measuring changes in ulcer during treatment can indicate the effectiveness of a treatment regime. Identifying appropriate treatment regime will reduce healing time. Current methods for measuring wound size are subjective and require manual contact with the wound. With the availability of techniques which can provide accurate depth measurement and surface profile, computer programs that can construct solids out of the wounds and quantitatively compute volume are indispensable. The development of volume estimation algorithms from 3D skin surface images to monitor wounds progress throughout treatment is discussed. The performance of midpoint projection and convex hull approximation (Delaunay tetrahedralization) methods, for solid reconstruction and volume computation, is detailed. Results of calculating wound models volume indicate that convex hull reconstruction preceded by surface division outperforms midpoint projection in case of regular boundary models. The error ranged from (0–2.8%) for convex hull reconstruction, while midpoint projection error range was from (0–6.5%).