A process for shaping high-precision optical components for ground- and space-based electrooptic systems

ÖZ: Bu araştırmanın amacı, çok boyutluluğun eş zamanlı ve ayrı kalibrasyon yapılarak elde edilen eşitlenmiş puanlara etkisini incelemektir.Araştırma simülasyon verileri kullanılarak yürütülmüştür.Araştırma kapsamında [5 (boyutluluk düzeyi: 0.90, 0.75, 0.50, 0.25 ve 0.00) x 2 (kalibrasyon yöntemi: eş zamanlı ve ayrı kalibrasyon) x 2 (ölçek dönüştürme yöntemi: Stocking-Lord ve Haebara) x 2 (test eşitleme yöntemi: Madde Tepki Kuramı gerçek puan eşitleme ve gözlenen puan eşitleme) ] olmak üzere toplam 40 koşul incelenmiştir.Çok boyutluluk testlerin Ɵ 1 ve Ɵ 2 olmak üzere farklı iki yeteneği ölçtüğü varsayılarak oluşturulmuştur.İki yetenek arasındaki korelasyonun değeri düştükçe çok boyutluluğun derecesi artmaktadır.İki yetenek arasındaki korelasyonun 0.90 olduğu koşul çok boyutluluğun derecesinin en düşük, iki yetenek arasındaki korelasyonun 0.00 olduğu koşul çok boyutluluğun derecesinin en yüksek olduğu koşulu temsil etmektedir.Eşdeğer olmayan gruplar ortak test deseni altında testler birbirine eşitlenmiştir.Elde edilen eşitlenmiş puanlar yanlılık, standart sapma ve RMSE ölçütleri kullanılarak değerlendirilmiştir.Araştırma bulguları, tüm koşullarda eş zamanlı kalibrasyon yapılarak elde edilen eşitleme sonuçlarının ayrı kalibrasyon ile elde edilenlere göre genel olarak daha yanlı ve daha fazla eşitleme hatasına sahip olduğunu göstermiştir.Standart sapma ölçütüne göre ise çok boyutluluğun derecesinin düşük olduğu koşullarda eş

The purpose of this study is to investigate the reliability of an essay test when the scores are reduced into several rating categories. The165essays by high school students were evaluated holistically and given the marks between0to100points. The marks were then classified into the2to5rating categories according to the two criteria: the percentiles and the standard deviation of each rater's original mark distribution. The reliability coefficients were calculated based on the values of information functions which were obtained through applying the graded response models. It was found that the reliability of the5-category scores(standard deviation criterion)was almost as high as the original100-point marks, which indicates validity of the categorical rating. The characteristics of some of the raters were also described using their information functions.

The distribution of groundwater inflows in a stream reach plays a major role in controlling the stream temperature, a vital component shaping the riverine ecosystem. In this study, the Distributed Temperature Sensing (DTS) system was installed in a small Danish lowland stream, Elverdamsåen, to assess the seasonal dynamics of groundwater inflow zones using high spatial (1 m) and temporal (3 minutes) resolution of water temperature measurements. Four simple criteria consisting of 30 min average temperature at 16:00, mean and standard deviation of diurnal temperatures, and the day–night temperature difference were applied to three DTS datasets representing stream temperature responses to the variable meteorological and hydrological conditions prevailing in summer, winter and spring. The standard deviation criterion was useful to identify groundwater discharge zones in summer and spring conditions, while the mean temperature criterion was better for the winter conditions. In total, 20 interactions were identified from the DTS datasets representing summer, 16 in winter and 19 in spring, albeit with only two interactions contributing in all three seasons. Higher baseflow to streamflow ratio, antecedent precipitation and presence of fractured clayey till in the stream reach were deemed as the vital factors causing apparent seasonal variation in the locations of upwelling zones, prompting use of DTS not only in preconceived scenarios of large diurnal temperature change but rather a long-term deployment covering variable meteorological and hydrological scenarios. Copyright © 2012 John Wiley & Sons, Ltd.

A single crystal sapphire component has been widely used in various high-tech fields because of its significant advantages such as high hardness, high stability, and excellent optical and mechanical properties, and has put forward high requirements for surface accuracy and quality. The existing sapphire polishing technology has problems such as low polishing efficiency, difficult control of polishing accuracy, and difficulty in removing surface defects and subsurface damage introduced by the front grinding process. Therefore, for the polishing and damage removal stage of sapphire optical components, the surface shape accuracy should be strictly controlled, especially for the surface shape accuracy after ultra-precision grinding. It is of great significance to study the uniform removal technology of grinding damage based on not destroying the surface shape. This study focuses on the mechanical polishing of sapphire. Firstly, the characteristics of the sapphire removal function of the elastic polishing tool are analyzed and the stability of the polishing tool is verified. Secondly, by establishing the relationship between the amount of workpiece material removal and the radius of rotation, the feed rate is planned to achieve the effect of uniform spiral removal. By optimizing the center feed speed of the tilting axis small-size polishing tool, the center feature of the polishing surface is controlled to be sharp. Finally, based on the sub-aperture polishing figuring theory, the influence of the center feature on the surface profile is reduced by using the spiral grating processing method. This study provides an efficient and stable strategy for the uniform removal and polishing of rotationally symmetric optical elements (such as aspheric surfaces) of high-hardness material sapphire and is expected to play a role in scenes that are particularly difficult to process, difficult to detect full aperture, difficult to calculate removal function and dwell time, such as higher steep aspheric surfaces and Gaussian aspheric surfaces.

The paper is devoted to the fundamental problems of manufacturing and testing substrates with fine precision for multilayer mirrors which surface shape, as a rule, is an aspherical one and that should be made with a sub-nanometer precision, to characterizing multilayer covers deposited onto these substrates and also to measuring with the subnanometer accuracy the wave-front aberrations of high-aperture optical projective objectives. A particular attention has been given to interferometers with a diffraction reference wave. Last experimental results on aberrations of the reference spherical wave of a source based on a single mode tipped fiber with a sub-wave exit aperture are presented. The application of this interferometer for characterizing aspherical convex optical surfaces and wave-front aberrations of optical systems is illustrated. Resent results on correcting the optical element surfaces are presented. Some peculiarities of the deposition technology as applied to the mirrors with ultra-high precision surface shape are discussed.

High-accuracy aspherical mirrors and lenses with large dimensions are widely used in large telescopes and other industry fields. However, the measurement methods for large aspherical optical surfaces are not well established. Scanning deflectometry is used for measuring optical signals near flat surfaces with uncertainties on subnanometer scales. A critical issue regarding scanning deflectometry is that high-accuracy autocollimators (AC) have narrow angular measuring ranges and are not suitable for measuring surfaces with large slopes and angular changes. The goal of our study is to measure the profile of large aspherical optical surfaces with an accuracy of approximately 10 nm. We have proposed a new method to measure optical surfaces with large aspherical dimensions and large angular changes by using a scanning deflectometry method. A rotating AC was used to increase the allowable measuring range. Error analysis showed that the rotating AC reduces the accuracy of the measurements. In this study, we developed a new AC with complementary metal-oxide semiconductor (CMOS) as a light-receiving element (CMOS-type AC). The CMOS-type AC can measure wider ranges of angular changes, with a maximum range of 21 500 µrad (4500 arcsec) and a stability (standard deviation) of 0.1 µrad (0.02 arcsec). We conducted an experiment to verify the effectivity of the wide measuring range AC by the measurement of a spherical mirror with a curvature radius of 500 mm. Furthermore, we conducted an experiment to measure an aspherical optical surface (an off-axis parabolic mirror) and found an angular change of 0.07 rad (4 arcdegrees). The repeatability (average standard deviation) for ten measurements of the off-axis parabolic mirror was less than 4 nm.

Aspherical optics have superior performance in many applications. However, precision metrology for an aspherical surface is a key stage in its manufacture. Subaperture stitching interferometry (SSI) is one of the mainstream testing methods for aspherical metrology. In many cases, Annular Stitching Subaperture Interferometry (ASSI) is more suitable for components having rotational symmetry because, compared to SSI, the number of motion directions that need to be adjusted is less. Although motion only along the optical axis is of concern in ASSI, inaccurate localization for subapertures may also occur due to the machining error at the optical center of the optics under test and errors in Cat's eye location, thereby leading to measurement errors. To overcome these problems, an accurate localization method for subaperture stitching is proposed. It is based on the maximum asphericity information between the reference spherical wavefront and the test aspherical surface. First, by using the test aspherical formula and theoretical spherical wavefront, we can calculate the minimum peak-to-valley (PV) value of maximum asphericity. The theoretical location of an optimal reference sphere, which corresponds to this value, can be obtained. Then, we perform a practical test, which starts at the initial zero position, and find an actual minimum PV value near its theoretical location. The difference between the theoretical location and the actual one is the compensation quantity. Finally, we execute ASSI measurement to aspherical optics. The location coordinate of each subaperture is compensated with the acquired quantity. Through the experiments, it can be concluded that the proposed method can improve the measurement accuracy of ASSI in terms of error elimination. The results produced by the new method are more desirable than those of the conventional one.

Many complex optical and electro-optical systems are currently operating in the space environment, and other more sophisticated systems are being planned for future development and operation. Assurance of the survivability of these systems is typically provided by ground-based testing, simulating those aspects of the space environment considered most serious. Such testing, however, has not prevented occasional anomalous behavior and unexplained failures from occurring. To properly explain the degradation mechanisms affecting these systems and to obtain the engineering and testing data necessary for the development of improved systems requires that in situ testing in the space environment be accomplished. The Long Duration Exposure Facility (LDEF) can provide this capability. Several of the experiments being developed for the first LDEF mission will seek to determine the effects of the space environment on components which will form the key elements of future electro-optical systems, and a considerable number of related experiments have been proposed. The engineering and scientific community is encouraged to become aware of this activity and to participate in the planning and experiment development for future LDEF missions.

Functional dyspepsia (FD) is a common disorder with multi-factorial pathophysiology. It has two sub-types, post-prandial distress syndrome (PDS) and epigastric pain syndrome (EPS), which frequently overlap. Emerging evidence suggests that low-grade inflammation, particularly duodenal eosinophilia (DE), may play a pathogenic role in FD. However, Indian data on this subject remains scarce. This study aimed at evaluating the prevalence and clinical correlates of DE in patients with refractory FD. In this prospective, cross-sectional study, Rome- IV defined FD patients with refractory symptoms and normal esophagogastroduodenoscopy (EGD) were enrolled. Age and sex-matched non-dyspeptic controls with normal EGD were also recruited. Standardized duodenal biopsies from cases and controls were independently assessed by two blinded histopathologists for eosinophil counts and degranulation. Symptom profiles and health-related quality of life (HRQoL) were evaluated using validated questionnaires. Of 274 patients with refractory dyspepsia screened, 189 patients with normal EGD (mean age 41.4 ± 15.2years; 54.5% males) were enrolled, along with 96 controls. The mean duodenal eosinophil count in controls was 8.2 ± 1.5 per high-power field (HPF). Applying the mean + 3 standard deviation criteria, DE was defined as ≥ 13 eosinophils/HPF. DE was identified in 65.3% (123/189) of refractory FD patients (65.7% in EPS, 52.5% in PDS and 69.1% in the overlap group, p > 0.05). Duodenal eosinophil counts correlated positively with PDS symptom severity (r = 0.376; p < 0.0001), overlap symptom severity (r = 0.3; p = 0.031) and worse HRQoL (r = 0.21; p = 0.010). Furthermore, patients with eosinophilic degranulation (24.3%) had significantly higher PDS scores and worse HRQoL scores, compared to those without degranulation. Up to two-thirds of the refractory FD patients exhibited duodenal eosinophilia, which was associated with increased symptom severity in PDS and overlap sub-types and poorer HRQoL. These findings support the incorporation of duodenal mucosal assessment in the diagnostic algorithm for refractory FD.

Callitrichids are small monkeys with high metabolic rates who appear to be susceptible to spontaneous diseases and possibly to environmental changes creating challenges in maintaining them in captivity. This study investigates whether life events (i.e. medical, social and housing changes) can influence weight. In previous research, body mass has been shown to be correlated with periods of illness, group composition changes and stress. Weights of 56 individual callitrichid monkeys (20 marmosets, 26 tamarins and 11 lion tamarins) at the WCS's Bronx Zoo were examined over approximately 2½ years. Weight fluctuations were scored based on 5%, 10% and 1 standard deviation criteria during periods of medical (illness and injury), social (introductions and separations), housing (movement within or between buildings) events and during periods when no-events occurred. Additionally, weights were examined for 3 months before and after periods of illness to look for trends in weight changes for 47 medical events (14 marmosets, 21 tamarins and 12 lion tamarins). Moreover, in five alloparenting males (four tamarins and one lion tamarin), weights were examined to determine if weight loss occurred after births as observed in earlier studies. The results show that a 5% and 1SD criterion may be too sensitive a criterion. We therefore deemed that a 10% weight loss may be the best criterion. For marmosets, a 10% weight loss occurred in association with all events. For tamarins, weight loss occurred with housing events. In lion tamarins, weight loss was observed with medical events. No significant weight loss was observed in alloparenting males.

On the correlation between ionospheric perturbations as detected by subionospheric VLF/LF signals and earthquakes as characterized by seismic intensity

Purpose A contributing reason for the common problem of missing middle anchors on behaviorally anchored rating scales (BARS) is the standard deviation (SD) criterion used in scaling phase. An alternative BARS scaling process is proposed based on the awg(1) index of interrater agreement.

The initial result of using a single 2-D checkerboard phase-grating Talbot interferometer as a feed-back loop sensor element of an adaptive x-ray mirror system is reported. The test was performed by measuring the surface profile of a deformable Pt coated Silicon mirror at five different actuation states. The reflected beam was detected at the fractional Talbot distance of a π/2 phase grating. The measured interferograms were de-convolved using the spatial harmonic imaging technique to extract the phase and amplitude of the reflected wavefront. The wavefront was then propagated to the mirror center to retrieve the surface profile of the mirror. The activation of a single actuator was easily detected from the reconstructed surface profile of the mirror. The presented results indicate that the single phase-grating x-ray Talbot interferometer is capable of sensing nano-meter scale profile changes of an adaptive mirror.

The shape of an aspherical surface can optically be measured by focusing a small light spot on its surface. Scanning in a line across the surface and going through the apex of the surface, one can interferometrically detect its shape. This paper describes the performance and limitations of such a scanning-spot interferometer. Special attention is paid to the ability to measure very steep aspherical surfaces.

An adaptive secondary mirror (ASM) with novel actuator technology is being designed and built for the UH88 telescope as a demonstration of a new generation of ASMs that might be deployed at ground based observatories such as Keck, Subaru, and TMT. Before putting the ASM on the telescope, a set of calibrations and characterizations need to be made in the lab. The crucial lab characterizations of the ASM are to measure its influence functions, and its surface shape when powered and unpowered. To measure these, we develop a novel and inexpensive optical metrology approach using phase measuring deflectometry. This paper describes the simulations we wrote to model the deflectometry method, our data acquisition/analysis pipeline, and a lab prototype system we built that demonstrates its feasibility on a microelectromechanical systems (MEMS) deformable mirror. Based on the information gained through the deflectometry simulation and the setup prototype, we conclude that phase measuring deflectometry is a reasonable method for obtaining the influence functions but that the absolute surface shape of the ASM will be limited by our knowledge of the placement of components within the deflectometry setup itself. We discuss challenges with extending this approach to larger convex adaptive secondary mirrors.