Prismatic Research Articles

Nonreciprocal transmission based on coupled resonance of two magnetic cavities

Nonreciprocal transmission is achieved through an optical prism coupling system composed of magneto-optical (MO) media. The transmission properties of the system are studied through the developed transfer matrix method for magnetic materials. The unusual result is that a tunable nonreciprocal resonance tunneling occurs if two MO cavities have reversal magnetization. The results are verified through an electromagnetic field simulation based on the finite element solver.

Apparatus for testing deflection due to thin prisms

An instrument for testing deflection due to thin prisms, which has been designed and fabricated at IRDE, Dehradun is described in this paper.

Superconducting magnetic Wollaston prism for neutron spin encoding.

A magnetic Wollaston prism can spatially split a polarized neutron beam into two beams with different neutron spin states, in a manner analogous to an optical Wollaston prism. Such a Wollaston prism can be used to encode the trajectory of neutrons into the Larmor phase associated with their spin degree of freedom. This encoding can be used for neutron phase-contrast radiography and in spin echo scattering angle measurement (SESAME). In this paper, we show that magnetic Wollaston prisms with highly uniform magnetic fields and low Larmor phase aberration can be constructed to preserve neutron polarization using high temperature superconducting (HTS) materials. The Meissner effect of HTS films is used to confine magnetic fields produced electromagnetically by current-carrying HTS tape wound on suitably shaped soft iron pole pieces. The device is cooled to ~30 K by a closed cycle refrigerator, eliminating the need to replenish liquid cryogens and greatly simplifying operation and maintenance. A HTS film ensures that the magnetic field transition within the prism is sharp, well-defined, and planar due to the Meissner effect. The spin transport efficiency across the device was measured to be ~98.5% independent of neutron wavelength and energizing current. The position-dependent Larmor phase of neutron spins was measured at the NIST Center for Neutron Research facility and found to agree well with detailed simulations. The phase varies linearly with horizontal position, as required, and the neutron beam shows little depolarization. Consequently, the device has advantages over existing devices with similar functionality and provides the capability for a large neutron beam (20 mm × 30 mm) and an increase in length scales accessible to SESAME to beyond 10 μm. With further improvements of the external coupling guide field in the prototype device, a larger neutron beam could be employed.

Comparison of Injection Molding Technologies for the Production of Micro-optical Devices

Injection molding is a complex process regulated by many factors (injection speed, injection pressure, melt temperature, mold temperature, and others). Despite, process control and parameter optimization, it is often difficult to replicate thermoplastic components with adequate dimensional accuracy, especially in the case of geometries with high aspect ratios. For these reason, there is a need for innovative moulding technologies such asInjection Compression Molding – ICMor Vacuum Injection Moulding – VIM. In this paper conventional injection molding – IM is compared to ICM and VIM for the replication of optical thermoplastic microscale prism patterns typical of Fresnel lenses. A full Design of Experiments was performed including several micro structured prism geometries, injection molding technologies and specific process parameters for a total of 288 tests. Data analysis evidenced the greater quality of workpieces obtained by ICM, whereas VIM was a minor process improvement.

Severe gallbladder hydrops (mucocel) following obstructive cholangioma (biliary adenoma) in a cattle.

This article describes a case of obstructive cholangioma (biliary adenoma) followed by  severe hydrops (mucocelle of the gallbladder) in an adult bovine. The animal, a six year old female, crossbred cattle, was presented to the necropsy following an acute episode of postpartum septicemia. At necropsy the cholecyst was overdistended, with thick walls and field with 2 liters of  clear-mucous content. Proximal to the emergence of the common bile duct, a well-circumscribed,  sessile, caulii¬‚ower-shaped  tumoral mass messuring  4/6 cm, obstruction to bile flow was identified. Cholangioma (cholangiocellular adenoma, biliary adenoma) was histologically diagnosticated bassed on the well-differentiated gland-like structures of the tumor, containing papillary projections covered by cuboidal and prismatic epithelium immunohistochemically positive at cytokeratin 19. In the rest of the gallbladder wall mucinous hyperplasia and discreet mononuclear inflammation was noticed. In this study we described, from our knowledge for the first time in cattle, a case of gallbladder mucocel due to obstructive cholangioma.

Optical Measurement for Solid- and Liquid-Phase Sb2Te3 around Its Melting Point

We have developed a system for measuring the complex refractive index of liquid- and solid-phase chalcogenide around their melting points. The system consists of a spectroscopic ellipsometer, an infrared heating system, and prism optics. As a container for the chalcogenide, we use a customized quartz cell, evacuated to several pascal level to avoid sample degradation. We adopted a measurement configuration that uses access from the bottom side, because a mirror-like surface which is necessary for optical measurement was naturally and easily created at the container bottom by gravity. We succeeded in observing the remarkable difference on the indices between liquid- and solid-phase Sb2Te3.

Partial rectus muscle transposition for strabismus with lateral rectus muscles paralysis

To investigate surgical approach for paralytic strabismus with lateral rectus muscles paralysis and evaluate its clinical effects. Design retrospective, observational case series. 28 patients (31 eyes) who underwent augmented partial rectus muscle transposition (APRMT) in the treatment of paralytic strabismus with lateral rectus muscles paralysis from May 2009 to May 2011 at Eye & ENT Hospital of Fudan University were included in this study. The following data were analyzed: (1) The procedure that was performed, (2) The angle of deviation of primary position, (3) The presence of compensatory head posture, (4) The presence of diploma in the primary position, (5) The binocular single visual fields, (6) The motility of the affected eye. According to the results of rectus muscle forced traction test and examination before and after operation, among 31 eyes in 28 patients, 8 eyes were treated with APRMT, 10 eyes were treated with recession of antagonistic muscle of paralytic rectus muscle combined with APRMT, 7 eyes were treated with APRMT and recession of yoke muscle, 6 eyes were treated with APRMT and recession of yoke muscle combined with recession of antagonistic muscle. 17 among 28 patients were orthotopicin the primary position while others were in mild under correction with deviation no more than 10 prism degrees during 5 months (range: 3-8 months) follow-up in average. The diploma and abnormal head posture were eliminated in 26 patients except one patient who was appeared with 10 prism degrees under correction postoperatively and was resolved by wearing prisms thereafter. Binocular single visual fields were extended from 27.0° ± 6.4 ° preoperatively to 40.5° ± 4.8 ° postoperatively (t = -34.692, P < 0.001). Ocular movement was improved from -4.9 ± 0.4 to -2.9 ± 0.9 postoperatively (t = -13.418, P < 0.001). APRMT can safely and effectively correct the primary position in paralytic strabismus with lateral rectus muscles paralysis, eliminate the presence of diploma in primary position and abnormal head posture, and improve the ability of the ocular movement, furthermore, significantly expand the scope of binocular single visual fields. The results also demonstrate that rectus muscle forced traction test is a key measurement to determine the surgical procedure.

Effect of placing GaAs solar cells on the optical rod prism of a concentrated photovoltaic

In a concentrated photovoltaic (CPV) solar cell system, placing an additional solar cell on an optical rod prism with parallel connection to the original cell generated more than 12.1 mA output current and 15.6% output power under the same illumination conditions. This mechanism provided a simple method to enhance the utility rate of CPV solar cells. Such a concept can be further applied to the aerospace industry and to the development of CPV solar energy.

Homonymous hemianopia and related visual defects: Restoration of vision after a stroke.

The term homonymous hemianopia refers to visual impairment due to a post-chiasmatic brain lesion. Mammalian neurons of the central nervous system do not have the ability to regenerate. However, the cerebral cortex shows plasticity in certain cases. Motor or speech disorders due to frontal lobe brain damage can be improved with well-directed rehabilitation techniques. If such plasticity is possible, it raises the question whether specialized training could improve a cortical visual disorder. There is need for simple visual training which could be used in rehabilitation. A few different approaches have been developed to treat patients with hemianopia: (1) substitution including special devices, such as optical prisms; (2) compensation using intact residual abilities - especially training of eye movements; (3) restitution which is based on stimulating the blind hemifield. The third method of rehabilitation is the most controversial; however, it has the largest potential. To support concepts of the targeted rehabilitation outlined here, first: further development of the theory of plasticity in visual pathways is required and second: the efficacy of the rehabilitation procedures has to be demonstrated by clinical evidence. We review methods and approaches of hemianopia rehabilitation and treatment. We also review results of contemporary clinical studies and meta-studies.

재귀반사체를 이용한 지하시설물 위치측정 타깃의 정확도 분석에 관한 연구

최근 도심기반 지하시설물 정보에 대한 체계적인 관리를 위해 현장시공 시 되메우기 전에 시설물에 대한 3차원 측량을 권장하고 있다. 시설물에 대한 정확한 위치측정 요구 증가와 함께 보다 신속하고 정확하게 각종 지하시설물의 DB 구축을 위해서는 타깃을 포함한 측량방법의 간소화로 비용의 절감 및 데이터 구축의 일관성을 유지할 필요성이 있다. 본 연구에서는 지하시설물 DB 구축을 위한 시설물 위치측정 방법으로 현재 측량에 이용되는 광학프리즘의 재귀반사 원리를 이용하여 최적의 반사체 타깃을 제작(삼각형, 사각형 및 반구형)하여 현장에서 측량자에 의해 되메우기 전에 위치측정을 수행할 수 있는 새로운 유형의 측량타깃을 개발하는데 목적이 있다. 새로운 측량타깃은 지하시설물 측량이 가능하고 데이터의 신뢰성 및 정확도 확보를 위해 유형별로 토털스테이션 측량좌표와의 정량적 비교를 통하여 위치 측정의 정확도를 비교하여 보았다. 연구결과 시설물 위치측정을 위한 반사체 타깃의 유용성을 입증 하였으며 새로운 타깃의 사용으로 보다 신속하고 정확하게 측량자에 의해 지하시설물 DB 구축을 위한 3차원 위치를 획득할 수 있는 기반을 마련하였다. Recently 3D surveying is recommended to manage underground facilities systematically before refilling of site operation. As the demand of realtime localization increases, cost reduction and consistent data construction which are realizable by using one man surveying method with unmanned target, are necessary for constructing DB of all sorts of the underground facilities with more speediness and correctness. This study sets a goal to develop a new type of surveying target which allows realtime localization to be performed by one man, through making an optimum reflector(triangle, quadrangle, and semispherical shape) by using the retro-reflection principle of optical prism which is being used for surveying currently. The new surveying target makes realtime surveying possible. To check reliability of its data, the accuracy is compared with surveying coordination of total station for each type in a quantitative method. In the result, the usefulness of the reflector for Underground Facilities localization is proved. Thus the foundation for underground DB construction conducted by one man is established for acquisition of 3D location information in more efficient way through using unmanned target.

Robust Hybrid Complex Motion Control Using Fuzzy Logic, Inverse Dynamic and PID-Q Controllers

A simple prototypical hybrid dynamic system, namely the bouncing ball system, is used to illustrate modeling and control of a hybrid dynamic system. This standard system is extended to include a complex inelastic bounce surface and actuation. A nonlinear one-axis prismatic actuator applies a bounce force to the ball to regulate the bounce height. Several controllers are compared with each other in simulations; linear and nonlinear PID, inverse dynamic, and fuzzy logic. Robustness against unmodeled dynamics, parameter variations and external disturbances are shown. SimMechanics is used to model the bounce actuator, bouncing ball system and surface. Simulation results show that the fuzzy logic controller fairs better on average on a complex surface.

Optofluidic solar concentrators using electrowetting tracking: Concept, design, and characterization

We introduce a novel optofluidic solar concentration system based on electrowetting tracking. With two immiscible fluids in a transparent cell, we can actively control the orientation of fluid–fluid interface via electrowetting. The naturally-formed meniscus between the two liquids can function as a dynamic optical prism for solar tracking and sunlight steering. An integrated optofluidic solar concentrator can be constructed from the liquid prism tracker in combination with a fixed and static optical condenser (Fresnel lens). Therefore, the liquid prisms can adaptively focus sunlight on a concentrating photovoltaic (CPV) cell sitting on the focus of the Fresnel lens as the sun moves. Because of the unique design, electrowetting tracking allows the concentrator to adaptively track both the daily and seasonal changes of the sun’s orbit (dual-axis tracking) without bulky, expensive and inefficient mechanical moving parts. This approach can potentially reduce capital costs for CPV and increases operational efficiency by eliminating the power consumption of mechanical tracking. Importantly, the elimination of bulky tracking hardware and quiet operation will allow extensive residential deployment of concentrated solar power. In comparison with traditional silicon-based photovoltaic (PV) solar cells, the electrowetting-based self-tracking technology will generate ∼70% more green energy with a 50% cost reduction.

Pharmacognostical study on flowers and fruits of Apamarga (Achyranthes aspera Linn.)

Background: Medicinal plants occupied a distinct place in human life right from the primitive period to until date. It is seen from the literature that Achyranthes aspera Linn. of Amaranthaceae family is an important plant for its medicinal uses in the treatment of heart diseases, haemorrhoids, etc., Until date different extracts of this plant has been evaluated for its activities such as spermicidal, anti‑allergic, nephroprotective, antiparasitic, hypoglycemic, analgesic and antipyretic etc., Though it is an important plant, until date no pharmacognostical work is found on its parts such as flowers and fruits. Aim: Present study was carried out to evaluate pharmacognostical characters of fruit and flower of A.aspera Linn. Materials and Methods: Macroscopic and microscopic pharmacognostical characters of flowers and fruits were noted. Results: Pharmacognostical evaluation of both the parts shows the presence of rosette crystals, prismatic crystals, polyhedral pollen grains and oil globules. Conclusion: The current work appears to be the first of its kind and can be considered as reference standards for future studies. Key words: Androecium, Apamarga, flower, fruit, pollen grains

Pharmacognostic and phytochemical investigation of root of Solanum nigrum Linn.: An ethnomedicinally important herb

Background: Roots of Solanum nigrum Linn. (Solanaceae), commonly known as black night shade (Kakamachi), is traditionally used in the treatment of worms and abdominal pain. Until date no scientific evaluation has been reported on its roots. Aim: The present study deals with the microscopical, histochemical, physicochemical, fluorescence analysis, preliminary phytochemical and chromatographic study of roots of S. nigrum L. Materials and Methods: Thin sections of fresh root were used for the microscopical and histochemical evaluation. Root powder was used for physicochemical and fluorescence analysis. For preliminary phytochemical study water, methanol and ether soluble extractives were used. Chromatographic study was carried out on methanol soluble extractive. Results: Diagnostic features of the roots are presence of prismatic crystals, border pitted vessels, and tannin content. Physico‑chemical analysis of root powder shows ash value 3.99% w/w, 13.04% w/w and 11.85% w/w of water and alcohol soluble extractive values respectively. Phytochemical investigations of root shows presence of alkaloids, tannins and saponins along with other phytoconstituents in different extracts. In chromatographic study, alcoholic extract of root shows 10, 7 and 8 number of spots at 256 nm, 366 nm wavelengths and after spray of vanillin sulphuric acid, respectively. Conclusion: The information generated in this study will be helpful for the proper identification and authentication of roots of this herb. Key words: Kakamachi, pharmacognosy, phytochemistry, Solanun nigrum Linn

Mid-Infrared Pulsed Laser Lithotripsy with a Tunable Laser Using Difference-Frequency Generation

A novel technique of lithotripsy was investigated with a mid-infrared tunable pulsed laser using difference-frequency generation (DFG). Human gallstone samples obtained from 24 patients were analyzed with their infrared absorption spectra. It was found that the principal components of the gallstones were different for the different patients and that the gallstone samples used in this research could be classified into four groups, i.e., mixed stones, calcium bilirubinate stones, cholesterol stones, and calcium carbonate stones. In addition, some gallstone samples had different compositions within the single stone. The mid-infrared laser tunable within a wavelength range of 5.5 - 10 μm was irradiated to the cholesterol stones at two different wavelengths of 6.83 and 6.03 μm, where the cholesterol stones had relatively strong and weak absorption peaks, respectively. As the result, the cholesterol stones were more efficiently ablated at the wavelength of 6.83 μm with the strong absorption peak. Therefore, it is suggested that the gallstones could be efficiently ablated by tuning the wavelength of the laser to the strong absorption peak of the gallstones. The higher efficiency of the ablation using the characteristic absorption peaks should lead to the safer treatment without damage to the surrounding normal tissues. In order to identify the composition of the gallstones in the patients, endoscopic and spectroscopic diagnosis using the DFG laser and an optical fiber probe made with two hollow optical fibers and a diamond attenuation total reflection prism should be useful. The absorption spectrum of the gallstones in the patients could be measured by measuring the energy of the DFG laser transmitted through the optical fiber probe and by scanning the wavelength of the DFG laser.

Exploring the effects of ecological activities during exposure to optical prisms in healthy individuals

Prism adaptation improves a wide range of manifestations of left spatial neglect in right-brain-damaged patients. The typical paradigm consists in repeated pointing movements to visual targets, while patients wear prism goggles that displace the visual scene rightwards. Recently, we demonstrated the efficacy of a novel adaptation procedure, involving a variety of every-day visuo-motor activities. This “ecological” procedure proved to be as effective as the repetitive pointing adaptation task in ameliorating symptoms of spatial neglect, and was better tolerated by patients. However, the absence of adaptation and aftereffects measures for the ecological treatment did not allow for a full comparison of the two procedures. This is important in the light of recent findings showing that the magnitude of prism-induced aftereffects may predict recovery from spatial neglect. Here, we investigated prism-induced adaptation and aftereffects after ecological and pointing adaptation procedures. Forty-eight neurologically healthy participants (young and aged groups) were exposed to rightward shifting prisms while they performed the ecological or the pointing procedures, in separate days. Before and after prism exposure, participants performed proprioceptive, visual, and visual-proprioceptive tasks to assess prism-induced aftereffects. Participants adapted to the prisms during both procedures. Importantly, the ecological procedure induced greater aftereffects in the proprioceptive task (for both the young and the aged groups) and in the visual-proprioceptive task (young group). A similar trend was found for the visual task in both groups. Finally, participants rated the ecological procedure as more pleasant, less monotonous, and more sustainable than the pointing procedure. These results qualify ecological visuo-motor activities as an effective prism-adaptation procedure, suitable for the rehabilitation of spatial neglect.

Liquid prism for beam tracking and steering

We propose a liquid prism based on electrowetting for wide-angle beam tracking and steering. Two transparent cubic cells which are filled with two immiscible liquids are stacked together to form the device. The two cubic cells function as two optical prisms. Via eletrowetting, we successfully control the liquid–liquid interface by changing the applied voltage on the opposite sidewalls. The device is capable of wide-angle beam tracking and steering. The experiment shows that the device can deflect and steer the light through an angle of ∼19.9 deg (+10.4 deg to −9.5 deg), and the total response time is ∼202 ms. The proposed liquid prism has a potential application such as free-space optical communications and laser detection electrowetting solar cells.

Reliability-based calibration of vision and proprioception following exposure to in-depth prismatic distortion

The former (336 mm2) was significantly larger than the latter (54 mm2; p < 0.0001). On average, the relative adaptation for vision (0.88) approximated the inverse of its relative reliability (0.81; p = 0.4).

Investigations into the accuracy of angle calibration

Abstract Technical possibilities to create equipment for the calibration of flat angles are discussed in the article. The angular standard measure, the radian, has not been realised as a standard unit until now. Nevertheless, the unit of angular measure in degrees is used as the geometric measure of length in geodesy, machine engineering and other branches of industry – by multiangular prisms – polygons with an autocollimator, rotary tables, circular scales, etc. It should be noted that these angle measures are calibrated against the upper level measures (etalons) only at the several intervals depending on the number of sides (angles) of the polygon or the other standard measure. The methods of calibration of constant angle value in full circle are used as well. At the same time geodetic instruments, rotary tables of metal cutting tools and instruments, rotary encoders have a great number of discrete values. These values between the calibrated points remain unknown during calibration. The information rece...

Development of 3D city model applying cadastral information

Abstract Problems of development of 3D city models are analysed. To develop such kind of model a great amount of information has to be computed. Collecting and matching the initial data is the most time and labour consuming job. Therefore first of all we have tried to investigate such a data source that would comprise the biggest part of needed data. We also have been looking for the data source that enabled us to constantly refresh and present the data describing the real or true to life situation. We have analysed the possibilities of city cadastral information system and here we state that it is suitable for that purpose. This article presents the idea how 3D city model consisting of prismatic building block models could be developed with the help of available cadastral information.