Diffraction Image Quality Research Articles

Single-Image Super-Resolution Improvement of X-ray Single-Particle Diffraction Images Using a Convolutional Neural Network.

Femtosecond X-ray pulse lasers are promising probes for the elucidation of the multiconformational states of biomolecules because they enable snapshots of single biomolecules to be observed as coherent diffraction images. Multi-image processing using an X-ray free-electron laser has proven to be a successful structural analysis method for viruses. However, the performance of single-particle analysis (SPA) for flexible biomolecules with sizes ≤100 nm remains difficult. Owing to the multiconformational states of biomolecules and noisy character of diffraction images, diffraction image improvement by multi-image processing is often ineffective for such molecules. Herein, a single-image super-resolution (SR) model was constructed using an SR convolutional neural network (SRCNN). Data preparation was performed in silico to consider the actual observation situation with unknown molecular orientations and the fluctuation of molecular structure and incident X-ray intensity. It was demonstrated that the trained SRCNN model improved the single-particle diffraction image quality, corresponding to an observed image with an incident X-ray intensity (approximately three to seven times higher than the original X-ray intensity), while retaining the individuality of the diffraction images. The feasibility of SPA for flexible biomolecules with sizes ≤100 nm was dramatically increased by introducing the SRCNN improvement at the beginning of the various structural analysis schemes.

Application features of optical polymers in optical systems design

Subject of Research.The paper considers analysis of mechanical and optical properties of modern optical polymer materials. We present the result of design and quality characteristics of small magnification telescopic glasses, made of modern optical polymers and intended for application in medicine, production of microelectronic circuits, and jewelry. Method. Calculation of telescopic glasses is carried out according to Galilei scheme on the basis of the automated method of aberration correction. The requirements are fulfilled concerning the necessity exception of additional accommodation of eyes at transition from observation with and without glasses, due to the object and image location in one plane. Main Results. The obtained optical system has diffraction image quality, and the mass of fully polymer glasses is two times lower than that of analogues made of glass. Practical Relevance. Modern optical polymers have advanced mechanical and optical properties, and create the perspective of glass component replacement with polymer ones and fabrication of fully polymeric optical systems with high quality characteristics. At the same time, manufacturing technologies of components made of optical polymers provides to obtain surfaces of complex shape (kinoforms, aspherics, and “freeforms”). Technical problems can be solved associated with the scaling of production, reducing of the assembly labor intensity, updating of the design, reducing of the mass and dimensional properties, and the cost of products.

МАЛОГАБАРИТНЫЕ ТЕПЛОВИЗИОННЫЕ ПРИБОРЫ СО СМЕННЫМИ ХАРАКТЕРИСТИКАМИ

The intensive development of thermal imaging device is accompanied by the expansion of its functional possibilities. One of them is the realization of changing magnifications and fields. The aim of the work is to justify the method of changing focal lengths and fields, ensuring the constancy of the relative aperture and axial length of the lenses when changing the field in thermal imaging devices using uncooled microbolometer infrared sensor arrays. A method of structural synthesis of a lens of three components is proposed. The method is characterized by the following: the optical power of the first component is equal to the optical power of the lens, the sum of the optical powers of the second and third components is zero. The aperture diaphragm is located on the third component. The internal component has two discrete positions. Relations between the parameters of components that are found provide the invariability of the back focal length and the relative aperture of the lens when changing the focal length. The capabilities of the method are confirmed by the development of four infrared lenses with two- and three-fold differences in focal lengths. Decreasing the length along the axis and the stability of the relative aperture of the lens with diffractive image qual-ity when changing the focal length in an optical scheme with a bi-aspheric design is achieved.

Quality assessment towards cell diffraction image based on multi-channel feature fusion

Image quality assessment towards cell diffraction image is significant for both the academic and medical domain. It plays an important role in medical detection and recognition, such as cell morphology and heterogeneity classification. However, cell diffraction image quality assessment is still a challenging task due to the high heterogeneity of cells and various appearance. To solve this problem, we propose a cell diffraction image quality assessment. More specifically, we first collect cell diffraction images including Jurkat and Ramos. To remove cell impurity and debris images, we leverage the K-means clustering algorithm and support vector machine (SVM) to eliminate these images. Subsequently, we calculate the Gray Level Co-occurrence Matrix (GLCM) of each image and extract deep representation by using DNN. Afterward, we fuse luminance, contrast, GLCM, and deep representation to calculate the feature similarity between the reference image and the test image. Extensive experiments conducted on Jurkat cells and Ramos cells datasets have shown the effectiveness of our proposed method.

Formation of Bainite in Advanced High-Strength Steels During Isothermal Transformation

Abstract The isothermal transformation of bainite in an advanced high-strength steel (AHSS) in the temperature range of 422°C to 482°C for transformation times of 10–6000 s has been examined using light optical microscopy (LOM), and orientation imaging microscopy (OIM). Thermodynamic calculations were done using equilibrium thermodynamic simulation software to produce a theoretical time-temperature-transformation (TTT) diagram, to which the experimental results of this study were compared. Advanced microstructural techniques, such as orientation-imaging-microscopy–electron-backscatter-diffraction (OIM-EBSD), image quality (IQ) phase identification, and polarized light microscopy, were used to observe and quantify the progress of the bainitic transformation during isothermal transformation. Orientation imaging microscopy using electron backscatter diffraction image quality (EBSD-IQ) was used with each sample to quantify the amount of bainite transformed. Results showed that the isothermal transformation at 422°C had 80.1 % bainite, whereas the isothermal transformation at 482°C had 85.5 % bainite transformed after 1200 s; while, after 6000 s, the amount of bainite increased to 90.1 % and 93.4 % respectively. As a result the chemical composition of the steel investigated and the microstructural characteristics of the bainite observed, it was not possible to discern the type of bainite formed at higher and lower temperatures because of the absence of carbides. The kinetics of transformation from the experimental results clearly indicated that the isothermal transformation is slower than that predicted by the theoretical thermodynamic program. The results of this study are presented and discussed.

Calculation and research of contact ophthalmic dual application lenses

Subject of research. Algorithm for calculation of contact ophthalmic lenses for dual application has been suggested based on unified approach for their calculation. The algorithm has been tested on the composition of Goldmann ophthalmic lenses and Panfundoscope lens optical systems. Method. The condition of mutual unambiguous orientation of patient’s eye and instruments is performed at the initial calculation step by face mounting and movement of coordinate table with optical head. Then such type of patient's eye optical system model is selected that the lens would be combined with the front surface of eye cornea optical system. Pupil of patient eye is under anesthesia. At the final calculation step we determine the functions of optical lens image quality and their values based on medical and technical requirements for the components of the complex system. Main results. The algorithm for ophthalmic lenses calculation has been suggested and its correctness has been proved practically on the example of two basic models in the group of such type lenses being applied in practice as a part of complex system with ophthalmic laser coagulators. Optical calculation of Goldmann ophthalmic contact lenses and Panfundoscope is presented. The method of neutralization is optimal for Goldmann lenses. The first component in Panfundoscope operates the position of object planes whereas the second component operates the position of complex system with ophthalmocoagulator's pupils. Computer modeling of complex system "Computer model of eye-ophthalmic lens" in ZEMAX confirmed the correctness of calculation algorithm in which the criteria of diffraction image quality has been used. Application possibility of simplified computer eye model called "Reduced eye" by Verbitskiy has been demonstrated. Practical relevance. The general scientific approach to the problem of synthesis, calculation and research of complex system with contact ophthalmic lenses for diagnostics and laser intervention on the eyeground has been found and confirmed. The results obtained have practical significance for the further development of optical calculation method and optical ophthalmologic instruments such as the fundus camera, wavefront analysers, opthalmoscopes and systems of vision optical correction.

Integrated evaluation of diffraction image quality in optical lithography using the rigorous diffraction solution for a slot

The method of integrated evaluation of quality of optical diffraction image is proposed. It uses several scalar parameters defined by integral comparison of two functions on the image surface. The first function represents real distribution of electric energy density on this surface, and can be simulated by the solution of corresponding exact or approximate diffraction problem of image formation. The second function describes required energy distribution on the given surface. The method is demonstrated by the example of evaluation of images formed by contactless printing from a mask in optical lithography, where the image function is computed by the known exact solution of plane wave diffraction by a slot in a conducting screen.

Precision imaging multilayer optics for soft X-rays and extreme ultraviolet bands

Optical methods that provide high diffraction image quality with a spatial resolution of several to tens of nanometers and are in demand in such areas as projection lithography, X-ray microscopy, astrophysics, and fundamental research on the interaction of matter (vacuum) with ultrahigh (– W cm) electromagnetic fields are reviewed in terms of fabrication and testing technologies and possible use in the – nm wavelength range. The current worldwide status of and recent achievements by the Institute for Physics of Microstructures of the Russian Academy of Sciences (RAS) in the field are discussed.

Selected techniques in diamond anvil cell crystallography: centring samples using X-ray transmission and rocking powder samples to improve X-ray diffraction image quality

The distinct X-ray transmission profile obtained by scanning a sample in a diamond anvil cell across a collimated X-ray beam is used to monitor sample displacement brought about by rotation. This measured displacement can in turn be used to calculate, and subsequently correct, the sample position with respect to a centre of rotation. This centring method differs from others also based on transmission in that it does not require a 180 degrees sample rotation, nor does it require prior positioning of the rotation axis in the path of the X-ray beam. After a full description of the method, an example is presented together with an extended record of use to evaluate the method in a practical setting. The practice and benefits of rocking polycrystalline samples during X-ray exposure have also been quantitatively examined. Changing the orientation of the sample grains with respect to the incident beam yields the expected result of a more homogeneous intensity distribution along Debye rings. Interestingly, by limiting the amount of time large grains assume a particular orientation, rocking brings about the added effect of significantly reducing detector saturation. Sample rocking yields more reliable relative intensities, a more appropriate line shape and narrower line width. Data are presented for a calibration standard at ambient pressure as well as a research sample at high pressure.

Optimization of a SCALPEL ® exposure tool using a diffractive image quality technique

Determining and maintaining the best exposure parameters, such as dose, focus, or illumination uniformity, is a primary concern in operating a modern day stepper or scanner. A commonly adopted means of obtaining lithographic image quality information relies on accurately measuring CD values across a wafer, die, or image field. Continually shrinking Linewidth have pushed this type of characterization into the realm of the CD-SEM; though greatly improved and automated in recent years, the accuracy required to reliably identify trends makes this a tedious and time consuming practice. We present here an alternative, flexible, and potentially rapid method for optimizing lithography conditions using a diffractive image quality (DIQ) technique, emphasizing its utility in a SCALPEL-based exposure system. A DIQ technique uses the fact that the maximum intensity of higher-order diffraction dispersions is a function of the (image) quality of the grating being illuminated so interrogation of gratings that have been exposed in resist can provide knowledge of how the aerial image quality can be varied for a given set of exposure conditions. We have evaluated grating diffraction efficiency using a probe beam (HeNe laser) introduced at a glancing angle. This arrangement has the advantage of looking at higher order intensity distributions while avoiding the zero order, as well as being fast since one is only collecting signal (eg. No feature recognition searches). Further, it enables the imaging optimization of a new system, such as SCALPEL, without tying up quantitative tools such as a CD-SEM. We have found that this metrology technique provides a quite sensitive and rapid identification of the best exposure conditions. Cross-correlation with a CD-SEM metrology tool has also been performed, in order to verify that the optimum imaging conditions identified through this DIQ technique correspond to the best CD conditions.

The Numerical Investigation of Diffraction Image Quality of Gradient-index Lenses

A method for the exact calculation of the light intensity distribution in the focal plane of a gradient-index lens is presented. A modification is proposed based on a method exploited in classical systems of small aperture. The results of an investigation performed on selected lenses are shown.

Diffraction image formation in optical systems with polarization aberrations II: Amplitude response matrices for rotationally symmetric systems

In the previous paper in this series (McGuire and Chipman, 1990), a formulation was established for the calculation and analysis of diffraction image quality in polarizing optical systems illuminated with partially polarized, partially coherent light. In the present paper, the effect of second- and fourth-order polarization aberrations on the image plane diffraction patterns are examined. The amplitude response matrix is calculated for optical systems with small numerical apertures. Numerical results are presented for optical systems with circular apertures for three of the aberration types.