High-resolution Projection Research Articles

High resolution imaging and optical control of Bose-Einstein condensates in an atom chip magnetic trap

A high-resolution projection and imaging system for ultracold atoms is implemented using a compound silicon and glass atom chip. The atom chip is metalized to enable magnetic trapping while glass regions enable high numerical aperture optical access to atoms residing in the magnetic trap about 100 μm below the chip surface. The atom chip serves as a wall of the vacuum system, which enables the use of commercial microscope components for projection and imaging. Holographically generated light patterns are used to optically slice a cigar-shaped magnetic trap into separate regions; this has been used to simultaneously generate up to four Bose-condensates. Using fluorescence techniques, we have demonstrated in-trap imaging resolution down to 2.5 μm.

High-Resolution Multi-View Projection Display With a Quantized-Diffusion-Angle Screen

In this paper, we have devised a novel projection screen using a double-sided lenticular lens with a diffusion angle range quantized by the incident light angle and a constant diffusion light intensity, independent of the angle of the incident light. We developed high-resolution multi-view projection display using a novel projection screen and multiple projectors. Our display system has the advantage of making it easy to align multiple projectors, and the capability of simultaneously projecting multiple different images at different viewing angles at any distance from the projection screen.

Changes in climate classification and extreme climate indices from a high-resolution future projection in Korea

We investigate the future changes in the climate zone and six extreme temperature indices in Korea, using the 20-km high-resolution atmospheric general circulation model (MRI-AGCM3.1S). The Trewartha and Koppen climate classification schemes are applied, and four summer-based extreme temperature indices (i.e., summer days, tropical nights, growing degree days, and cooling degree days (CDD) and two winter-based indices (frost days and heating degree days (HDD) are analyzed. To represent significantly the change in threshold indices, the monthly mean bias is corrected in model. The model result reasonably captures the temporal and spatial distribution of the present-day extreme temperatures associated with topography. It was found that in the future climate, the area of the subtropical climate zone in Korea expands northward and increases by 21% under the Trewartha classification scheme and by 35% under the Koppen classification scheme. The spatial change in extreme climate indices is significantly modulated by geographical characteristics in relation to land-ocean thermal inertia and topographical effects. The change is manifested more in coastal regions than in inland regions, except for that in summer days and HDD. Regions with higher indices in the present climate tend to reveal a larger increase in the future climate. The summer-based indices display an increasing trend, while the winter-based indices show a decreasing trend. The most significant increase is in tropical nights (+452%), whereas the most significant decrease is in HDD (−25%). As an important indicator of energy-saving applications, the changes in HDD and CDD are compared in terms of the frequency and intensity. The future changes in CDD reveal a higher frequency but a lower temperature than those in HDD. The more frequent changes in CDD may be due to a higher and less dispersed occurrence probability of extreme temperatures during the warm season. The greater increase in extreme temperature events during the summer season remains an important implication of projecting future changes in extreme climate events.

High resolution dual detector volume‐of‐interest cone beam breast CT––Demonstration with a bench top system

In this study, we used a small field high resolution detector in conjunction with a full field flat panel detector to implement and investigate the dual detector volume-of-interest (VOI) cone beam breast computed tomography (CBCT) technique on a bench-top system. The potential of using this technique to image small calcifications without increasing the overall dose to the breast was demonstrated. Significant reduction of scatter components in the high resolution projection image data of the VOI was also shown. With the regular flat panel based CBCT technique, exposures were made at 80 kVp to generate an air kerma of 6 mGys at the isocenter. With the dual detector VOI CBCT technique, a high resolution small field CMOS detector was used to scan a cylindrical VOI (2.5 cm in diameter and height, 4.5 cm off-center) with collimated x-rays at four times of regular exposure level. A flat panel detector was used for full field scan with low x-ray exposures at half of the regular exposure level. The low exposure full field image data were used to fill in the truncated space in the VOI scan data and generate a complete projection image set. The Feldkamp-Davis-Kress (FDK) filtered backprojection algorithm was used to reconstruct high resolution images for the VOI. Two scanning techniques, one breast centered and the other VOI centered, were implemented and investigated. Paraffin cylinders with embedded thin aluminum (Al) wires were imaged and used in conjunction with optically stimulated luminescence (OSL) dose measurements to demonstrate the ability of this technique to image small calcifications without increasing the mean glandular dose (MGD). Using exposures that produce an air kerma of 6 mGys at the isocenter, the regular CBCT technique was able to resolve the cross-sections of Al wires as thin as 254 μm in diameter in the phantom. For the specific VOI studied, by increasing the exposure level by a factor of 4 for the VOI scan and reducing the exposure level by a factor of 2 for the full filed scan, the dual-detector CBCT technique was able to resolve the cross-sections of Al wires as thin as 152 μm in diameter. The CNR evaluated for the entire Al wire cross-section was found to be improved from 5.5 in regular CBCT to 14.4 and 16.8 with the breast centered and VOI centered scanning techniques, respectively. Even inside VOI center, the VOI scan resulted in significant dose saving with the dose reduced by a factor of 1.6 at the VOI center. Dose saving outside the VOI was substantial with the dose reduced by a factor of 7.3 and 7.8 at the breast center for the breast centered and VOI centered scans, respectively, when compared to full field scan at the same exposure level. The differences between the two dual detector techniques in terms of dose saving and scatter reduction were small with VOI scan at 4× exposure level and full field scan at 0.5 × exposure level. The MGDs were only 94% of that from the regular CBCT scan. For the specific VOI studied, the dual detector VOI CBCT technique has the potential to provide high quality images inside the VOI with MGD similar to or even lower than that of full field breast CBCT. It was also found that our results were compromised by the use of inadequate detectors for the VOI scan. An appropriately selected detector would better optimize the image quality improvement that can be achieved with the VOI CBCT technique.

Digital High Resolution Small Pixel LCOS Technology

The progress in digital high resolution, small pixel liquid crystal on silicon (LCOS) microdisplays will be discussed and how it will lead to HD displays in very small form factors. The first generation of this technology is enabling very small yet high resolution projection engines devices that can be embedded in cell phones, cameras, head-mount displays, and set-top boxes and the next generation will bring HD resolution. As lasers become more affordable we see this LCOS display technology fundamentally changing the power consumption, cost, and size of pico-projectors and other display devices. One of the most interesting conclusions is that by using LCOS technology in combination with lasers, it should soon be possible to build an “ultra-green” television that would consume less than 1/8th the power of equivalent size LCD flat panel TV.

Structured-light 3D surface imaging: a tutorial

We provide a review of recent advances in 3D surface imaging technologies. We focus particularly on noncontact 3D surface measurement techniques based on structured illumination. The high-speed and high-resolution pattern projection capability offered by the digital light projection technology, together with the recent advances in imaging sensor technologies, may enable new generation systems for 3D surface measurement applications that will provide much better functionality and performance than existing ones in terms of speed, accuracy, resolution, modularization, and ease of use. Performance indexes of 3D imaging system are discussed, and various 3D surface imaging schemes are categorized, illustrated, and compared. Calibration techniques are also discussed, since they play critical roles in achieving the required precision. Numerous applications of 3D surface imaging technologies are discussed with several examples.

The role of the simulation setup in a long-term high-resolution climate change projection for the southern African region

High-resolution regional climate change simulations have proven to offer an added value compared to available global climate model simulations. However, over many regions of the globe, long-term high-resolution climate change projections are rather sparse. We present a transient high-resolution climate change projection with the regional climate model with the regional climate model REMO over the southern African region, following the SRES A1B emission scenario. The simulation was conducted at 18 km grid spacing for the period from 1960 to 2100, making it to the longest available climate change projection at such a high resolution for the region. In the first part of the study, we focus on the impact of the model setup on the simulated rainfall over the southern African region. In the standard setup, we used the output of the global climate model ECHAM5/MPIOM directly to force REMO. This setup led to a very strong wet bias over the region. Changing it to the double-nesting setup significantly reduced this bias, but a substantial wet bias still persists. The remaining bias could partly be attributed to a warm bias in the SST forcing over the southern Atlantic Ocean. Thus, we applied an SST correction based on the anomaly approach to the data, which led to a further improvement of the rainfall simulation. As the SST bias in the southern Atlantic is a common feature of all global climate models assessed by the IPCC, we recommend the chosen model setup, including the SST correction, as general procedure for dynamical downscaling studies over the southern African region. In the second part, we present the projected spatial and temporal changes of temperature and precipitation, including several rainfall characteristics, over the southern African region. Herby we compare the projections of the high-resolution REMO simulation to those of the forcing regional and global models. We generally find that for temperature the magnitude of the projected changes of the regional model only slightly differs from the GCM projection; however, the spatial patterns are much better resolved in the RCM projections. For precipitation, REMO shows a more intense drying toward the end of the twenty-first century than it is simulated by the global model. This can have a major influence when investigating the impacts of future climate change on a regional or even local scale. In combination with the improved spatial patterns, the application of high-resolution climate change information could therefore improve the results of such applications.

High-resolution NMR spectroscopy in unstable and inhomogeneous fields via stroboscopic acquisition

In this paper, we demonstrated that despite the insensitivity of intermolecular zero-quantum coherences (iZQCs) to B 0 variations, the influence of unstable fields on the observable single-quantum coherence signals causes strong t 1 noises in the high-resolution iZQC projection spectra. Stroboscopic acquisition was then proposed for noise suppression. The feasibility of the modified sequences with the proposed acquisition scheme was verified by computer simulations and experiments in different unstable fields generated by the Z0 and Z1 coil current oscillations, which mimic the unstable fields of NMR using externally powered magnets and MRS in the presence of physiological motions, respectively.

高分辨率投影光刻机光瞳整形技术

高分辨率投影光刻机光瞳整形技术

High-resolution projection image reconstruction of thick objects by hard x-ray diffraction microscopy

Hard x-ray diffraction microscopy enables us to observe thick objects at high spatial resolution. The resolution of this method is limited, in principle, by only the x-ray wavelength and the largest scattering angle recorded. As the resolution approaches the wavelength, the thickness effect of objects plays a significant role in x-ray diffraction microscopy. In this paper, we report high-resolution hard x-ray diffraction microscopy for thick objects. We used highly focused coherent x rays with a wavelength of $\ensuremath{\sim}0.1\text{ }\text{nm}$ as an incident beam and measured the diffraction patterns of a $\ensuremath{\sim}150\text{-nm}$-thick silver nanocube at the scattering angle of $\ensuremath{\sim}3\ifmmode^\circ\else\textdegree\fi{}$. We observed a characteristic contrast of the coherent diffraction pattern due to only the thickness effect and collected the diffraction patterns at nine incident angles so as to obtain information on a cross section of Fourier space. We reconstructed a pure projection image by the iterative phasing method from the patched diffraction pattern. The edge resolution of the reconstructed image was $\ensuremath{\sim}2\text{ }\text{nm}$, which was the highest resolution so far achieved by x-ray microscopy. The present study provides us with a method for quantitatively observing thick samples at high resolution by hard x-ray diffraction microscopy.

X-pinch source of subnanosecond soft X-ray pulses based on small-sized low-inductance current generator

For the first time, the regime of a micrometer-size hot spot formation is impemented for an X-pinch in a plasma, which is fed from a current generator based on low-inductance capacitors and rapid current switches. The configurations of X-pinches, which can be used effectively as point sources of soft X-rays with this type of current generator, are determined. A prototype of a small-size radiation source for high-resolution point projection X-ray radiography has been constructed. The main parameters of X-pinch as a radiation source are analyzed and compared with X-pinch parameters in high-voltage setups with shaping lines. An analysis of the data on the operation of X-pinches in generators with different parameters has led to simple relations that can be used to select optimal initial X-pinch parameters.

University of Massachusetts Medical School

University of Massachusetts Medical School

Analysis of image of objective for formation of nanostructures by computer isophotometry method

The possibilities of using the computer isophotometry method to estimate the image quality of high-resolution projection objectives are considered. An experimental setup for measuring the point spread function is developed. A two-mirror objective of the Schwarzschild type with a numerical aperture of 0.36 designed for the use in an experimental nanolithographer is studied. Control measurements by the computer isophotometry method show that, at a wavelength of 13.4 nm, this objective is capable of resolving image features with a size of no larger than 50 nm.

Laser-produced MeV electrons and hard X-ray spectroscopic diagnostics

A new spectroscopic technique for the measurement of the sizes of hard X-ray sources produced by the irradiation of solid-density targets by intense laser radiation is discussed. The technique is based on the source broadening of K shell spectral lines from targets irradiated by intense picosecond laser pulses. The spectra are recorded by a modified Cauchois type spectrometer, where the detector is placed far behind the Rowland circle where source broadening dominates instrumental resolution. The laser irradiation with focused intensity greater than 10 18 W/cm 2 produces relativistic electrons that propagate from the focal spot into the surrounding target material with mm range. The energetic electrons produce 1 s electron ionization and K shell radiation with picosecond duration that can be utilized for transient radiography of dense objects including evolving dense plasmas. However, the hard X-ray source has mm lateral size when extended targets are utilized while a much smaller source size (of order 10 μm) is necessary for high-resolution point projection radiography. The lateral source size can be greatly reduced by using targets with limited aspect to the radiography object such as thin foils and wires, but the brightness of these sources is greatly reduced compared to thick planar targets. Studies indicate that the electron range and source size can also be reduced by utilizing an electrically resistive target material such as teflon. In this case the electron propagation from the focal spot is inhibited by a weak return current and incomplete space–charge neutralization. These experimental results are important not only for producing a small hard X-ray source for picosecond radiography but also for reducing the lateral propagation of energetic electrons that can be detrimental to fast-ignition fusion.

3D microfabricated bioreactor with capillaries

We present in this paper the implementation of an innovative three dimensional (3D) microfabrication technology coupled with numerical simulation to enhance the mass transport in 3D cell culture. The core of this microfabrication technology is a high-resolution projection micro stereolithography (PmicroSL) using a spatial light modulator as a dynamic mask which enables a parallel fabrication of highly complex 3D microstructures. In this work, a set of poly (ethylene glycol) microfabricated bioreactors are demonstrated with PmicroSL technology. We observed both experimentally and numerically the regulation of metabolism and the growth of yeast cells by controlling the density of micro-capillaries. Further development of these 3D microfabricated bioreactors is expected to provide artificially constructed tissues for clinical applications.

High resolution projection X-ray microscope equipped with fluorescent X-ray analyzer and its applications

We have newly developed an open type fine-focus X-ray tube "TX-510" to realize a spatial resolution of 50nm and to radiate low energy characteristic X-rays for giving high absorption contrast to images of microscopic organisms. The "TX-510" employs a ZrO/W(100) Schottky emitter and an "In-Lens Field Emission Gun". The key points of the improvements are (1) reduced spherical aberration coefficient of magnetic objective lens, (2) easy and accurate focusing, (3) newly designed astigmatism compensator, (4) segmented thin film target for interchanging the target materials by electron beam shift and (5) fluorescent X-ray analysis system.

Dual resolution cone beam breast CT: A feasibility study

In this study, the authors investigated the feasibility of a dual resolution volume-of-interest (VOI) cone beam breast CT technique and compared two implementation approaches in terms of dose saving and scatter reduction. With this technique, a lead VOI mask with an opening is inserted between the x-ray source and the breast to deliver x-ray exposure to the VOI while blocking x rays outside the VOI. A CCD detector is used to collect the high resolution projection data of the VOI. Low resolution cone beam CT (CBCT) images of the entire breast, acquired with a flat panel (FP) detector, were used to calculate the projection data outside the VOI with the ray-tracing reprojection method. The Feldkamp-Davis-Kress filtered backprojection algorithm was used to reconstruct the dual resolution 3D images. Breast phantoms with 180 microm and smaller microcalcifications (MCs) were imaged with both FP and FP-CCD dual resolution CBCT systems, respectively. Two approaches of implementing the dual resolution technique, breast-centered approach and VOI-centered approach, were investigated and evaluated for dose saving and scatter reduction with Monte Carlo simulation using a GEANT4 package. The results showed that the breast-centered approach saved more breast absorbed dose than did VOI-centered approach with similar scatter reduction. The MCs in fatty breast phantom, which were invisible with FP CBCT scan, became visible with the FP-CCD dual resolution CBCT scan. These results indicate potential improvement of the image quality inside the VOI with reduced breast dose both inside and outside the VOI.

Prospects for the development of optical systems for nanolithography

This paper discusses the principles under which high-resolution projection photolithographic objectives are created and the requirements on the optical materials used for them. It is shown that fluorite is one of the most promising materials for creating objectives for photolithography at wavelengths 248 and 193nm. A discussion is given of the prospects for developing lens-based projection objectives with high numerical aperture, the modern state of the production technology, and also methods for certifying the main optical parameters of photolithographic-quality fluorite. Fluorite crystals up to 300mm in diameter and 50mm thick have been fabricated and certified. The crystals grown using this technology have high transmittance (99.92-99.96% at λ=193nm), good optical homogeneity [Δn=(1-4)×10−6], and low birefringence (δ=0.5-2.0nm/cm). The crystals have virtually no luminescence. Proposals are given for the development of photolithographic optics.

Active Region Cascading for Improved Performance in InAs–GaSb Superlattice LEDs

Cascading of active regions in InAs-GaSb superlattice light-emitting diodes (LEDs) grown by molecular beam epitaxy is demonstrated as an effective means of increasing optical emission. Devices were fabricated into 120 x 120 mum2 mesas to demonstrate suitability for high resolution projection systems. Devices with 1, 4, 8, and 16 stages were designed for midwave infrared emission at 3.8 mum operating at 77 K, and quasi-continuous-wave output powers in excess of 900 muW from a 16-stage LED have been demonstrated. External quantum efficiency is shown to improve substantially with cascading, approaching 10% for a 16-stage device.

Realistic CT simulation using the 4D XCAT phantom

The authors develop a unique CT simulation tool based on the 4D extended cardiac-torso (XCAT) phantom, a whole-body computer model of the human anatomy and physiology based on NURBS surfaces. Unlike current phantoms in CT based on simple mathematical primitives, the 4D XCAT provides an accurate representation of the complex human anatomy and has the advantage, due to its design, that its organ shapes can be changed to realistically model anatomical variations and patient motion. A disadvantage to the NURBS basis of the XCAT, however, is that the mathematical complexity of the surfaces makes the calculation of line integrals through the phantom difficult. They have to be calculated using iterative procedures; therefore, the calculation of CT projections is much slower than for simpler mathematical phantoms. To overcome this limitation, the authors used efficient ray tracing techniques from computer graphics, to develop a fast analytic projection algorithm to accurately calculate CT projections directly from the surface definition of the XCAT phantom given parameters defining the CT scanner and geometry. Using this tool, realistic high-resolution 3D and 4D projection images can be simulated and reconstructed from the XCAT within a reasonable amount of time. In comparison with other simulators with geometrically defined organs, the XCAT-based algorithm was found to be only three times slower in generating a projection data set of the same anatomical structures using a single 3.2 GHz processor. To overcome this decrease in speed would, therefore, only require running the projection algorithm in parallel over three processors. With the ever decreasing cost of computers and the rise of faster processors and multi-processor systems and clusters, this slowdown is basically inconsequential, especially given the vast improvement the XCAT offers in terms of realism and the ability to generate 3D and 4D data from anatomically diverse patients. As such, the authors conclude that the efficient XCAT-based CT simulator developed in this work will have applications in a broad range of CT imaging research.