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A tubular skylight (TS) is an effective system for transporting natural sunlight into the building interiors. However, the passive nature of the system may not account for the changing orientation of the sun and the conventional daylight collector designs like transparent dome are less effective under low altitude sun. This paper focuses on the performance evaluation of specifically designed TS having rectilinear parabolic-profile reflectors integrated with plane surface reflectors and wedge-shaped prism for daylight collection. The designed configuration redirects the low altitude incident rays efficiently into a vertical mirror light pipe having a rectangular cross-section and aims at giving desired levels of lighting throughout the sunny day. Numerical analysis of the same was carried out for various sky conditions. Experimental results for the proposed TS design show improved lighting levels during the low-altitude sun and reduced but consistent lighting during the mid-day. Average illuminance of ~ 400 lx was observed on the floor of the experiment room for the most part of the day. Along with capturing beam sunlight a significant amount of diffuse daylight capturing ability under clear sky conditions is observed using the proposed TS. The average illuminance value obtained on the work plane during winter solstice through the most optimized configured TS was more than twice the lighting value achieved by a conventional daylight-collecting transparent dome and almost twice the lighting value achieved by a TS with a prismatic dome collector. Under overcast sky conditions, the performance of the proposed configuration of TS is at par.

I present a new aiming adjustment mechanism for riflescopes featuring partially-rotatable wedge prisms. The optical adjustment mechanism introduced in this paper does not require any laterally-moving components, off- axis optical components or turrets. Furthermore, the wedge prisms used in the system have no optical axis which makes the proposed solution immune to many types of mounting misalignments or decentering errors caused by shock and vibrations.

A polarized laser beam steering system using multiply cascaded rotating polarization gratings (PGs) is presented. The rotating PGs steer incident circularly polarized beams with high optical throughput because the theoretical limitation of the PG diffraction efficiency is 100%. The system also offers more rapid rotation when compared with wedge prism pairs because of the weight of the PGs. The beam steering performance was analyzed theoretically for schemes using two and four rotating PGs. The system’s feasibility was demonstrated experimentally by projecting Lissajous and raster patterns using PGs fabricated from photocrosslinkable polymer liquid crystal films via a photo-alignment technique. The steered beam’s diffraction efficiency and ellipticity were maintained at 83 ∼ 89 % and 96 ∼ 99 % , respectively, during PG rotation. This beam steering system will be applicable to light detection and ranging, optical imaging, and laser displays.

Prismatic adaptation (PA) with wedge prisms is a non-invasive technique used in the rehabilitation of patients suffering from spatial neglect. Unfortunately, as for many behavioural intervention techniques, it is nearly impossible to achieve adequate blinding using wedge prisms, and the potential benefit of PA in the rehabilitation of neglect remains controversial. In order to study an alternative to wedge prism, we examine whether virtual PA at different degrees of deviation may alleviate signs of neglect in a double-blind design. Fifteen neglect patients participated in three adaptation sessions, which differed by the degree of deviation (0°, 15°, or 30°). Performance in line bisection and item cancellation tasks was measured in virtual reality immediately before and after adaptation. Session allocation was concealed from patients and the examiner. Despite the presence of robust, dose-dependent effects of virtual PA on Open-Loop Pointing (OLP), no transfer to line bisection and item cancellation tests were observed. None of the patients were aware of differences between sessions. Virtual PA did not result in visuo-motor transfer effects despite inducing significant adaptation effects in OLP. Together with recent negative findings of randomized-controlled trials, these findings cast doubt on the general efficacy of PA as a rehabilitation method of spatial neglect.

During infrastructure construction and resource exploitation, the stability analysis of the working face and the determination of the limit support pressure are important. Herein, an improved wedge-prism model is proposed with consideration of three aspects. The inter-slice vertical force expression at any depth in the prism is derived using the slice method, and the vertical force acting on the wedge is determined. Equilibrium equations of the wedge in the limit state are formulated, and the limit support pressure of the working face is derived. A set of semi-analytical methods for calculating the limit support pressure is developed. The proposed method is verified via comparison with existing approaches. Finally, case studies are conducted to analyse the factors affecting the limit support pressure, and the following conclusions are drawn. (1) The limit support pressure increases with the tunnel depth and tunnel diameter. Compared with the tunnel depth, the tunnel diameter has a greater effect on the limit support pressure. (2) The shear-strength indices of the crossed layer have significantly greater effects on the limit support pressure than those of the covering layer. (3) The limit support pressure increases linearly with the increasing groundwater level. The research results provide guidance for infrastructure construction and mineral resource development and can be used to ensure the safety of construction and mining.

The study of accelerating Airy-family beams has made significant progress, not only in terms of numerical and experimental investigations but also in conjunction with many potential applications. However, the curvature of such beams (and hence their acceleration) is usually greater than the wavelength. Relatively recently, a new type of localized wave beam with subwavelength curvature, called the photonic hook (PH), was discovered. This photonic hook is a curved high-intensity focus by, for example, a wavelength-scaled dielectric cuboid topped with a wedge prism (Janus particle) illuminated by a plane wave – an interesting situation combines diffraction with prism refraction, which adds a newfound degree of simplicity. The difference between the phase velocity and the interference of the waves inside the particle causes the phenomenon of focus bending. It is important that in the PH, there is an inflexion where the curved beam changes its propagating direction. This property is not possessed by Airy-like beams family. Amazingly, the mesoscale dielectric Janus particle, with broken shape or refractive index symmetry or broken symmetry of illuminating wave, is used to generate the photonic hook – emerging from its shadow-side surface. Moreover – PH has unique features – the radius of curvature is less than the wavelength; this is the smallest curvature radius of electromagnetic waves ever reported today. Although the curved profile evokes a similarity with Airy beams, in contrast to Airy beams there are no curved sidelobes. In this chapter, we discussed the key properties of PH based on full-wave simulations confirmed by experimental research of a scale model. The principal possibility of exotic looped shape of localized field and photonic trajectories is also briefly discussed. Using the photonic hook, the resolution of optical scanning systems can be improved to develop optomechanical tweezers for moving nanoparticles, cells, bacteria, and viruses along curved paths and around transparent obstacles. These unique properties of photonic jets and hooks combine to afford important applications for low-loss waveguiding, subdiffraction-resolution nanopatterning, and nanolithography.

Using a see-through optical viewer with a prism combiner is an affordable solution for head mounted devices. Free-form surfaces are a general way to correct off-axis aberrations generated by combiners. A glass high index wedge prism is used as a combiner to keep the wedge angle small while maintaining total internal reflection and the combiner becomes thinner. Free-form surfaces, on the other hand, are used in relay lenses to correct off-axis aberrations. The diagonal FOV is 44° and the exit pupil diameter is 4.8 mm. After two optical design using XY and Zernike polynomial, we confirm which free-form expression is superior in aberration correction for the viewer.

The Sagnac interference imaging spectrometer with a variable optical path difference (OPD) is proposed in this paper, which employs two wedge prisms coupled with a modified Sagnac interferometer, and produces a variable OPD through the moving wedge prism. Compared with the conventional imaging spectrometer, the Sagnac interference imaging spectrometer shows its advantages of miniaturization and insensitive to the non-uniform variation of the moving speed and the environment vibration. The exact expression of the OPD as a function of different parameters is derived, and the influences of the moving displacement, wedge angle and acute angles on the OPD are analyzed and discussed within the scope of engineering design. This study provides an important theoretical and practical guidance for the engineering of the Sagnac interference imaging spectrometer.

This paper describes a novel optical system that can be integrated to the image port of an existing brightfield microscope in order to enhance the microscope with the features of digital holographic microscopy. The proposed system is modular and portable. It is relatively inexpensive and robust to vibrations due to its compact design. An additional benefit is that the system does not need to undergo path-length realignment if the sample is changed, unlike several other architectures. The module is based on a square in-line Mach–Zender architecture but achieves the off-axis condition using two sets of wedge prism pairs. This design offers a significant advantage over competing Mach–Zender nearly common-path modules in terms of path length matching of object and reference wavefields for the case of low-temporal coherence sources, which are preferable for low noise phase imaging. An additional advantage that the proposed system has when compared with similar modules is the facility to continuously vary the tilt angles of the object and reference wavefields that are incident on the sensor, which enables the module to be readily adapted to any given microscope and camera. We provide a detailed overview of the module design and construction. Experimental results are demonstrated on a micro-lens array as well as buccal epithelial cells. We also provide a detailed discussion on the relationship between the proposed self-reference module and related common-path and nearly common-path holographic modules that have previously been proposed in the literature.

Over the past decade, boresight angle calibration of airborne laser scanning (ALS) systems has evolved from ad hoc methods often based on qualitative assessments of point cloud fidelity to rigorous self-calibration algorithms that optimize multiple sensor parameters by minimizing the spatial discrepancies between common features. Although the calibration of linear-mode ALS systems employing oscillating or rotating mirrors has been well developed, little work has addressed the calibration of emergent single-photon lidar (SPL) sensors with circular scan patterns. We adapt a least-squares algorithm employing planar-surface matching to accommodate a spinning wedge prism, employ a synthetic dynamic wedge angle by way of a trigonometric polynomial (TP) to model imperfections in the circular scanning mechanism, and address unique characteristics of SPL data within the stochastic model. Planar fit residuals are reduced by 40% with a boresight and wedge angle adjustment and a further 40% with the introduction of the synthetic wedge angle TP. The addition of the TP also improves the median vertical discrepancy between point clouds generated from fore and aft look angles by over 75%.

A novel Sagnac imaging polarization spectrometer based on a modified Sagnac interferometer (MSI) with a moving wedge prism is proposed in this paper, and it is a framing instrument with the advantages of miniaturization, variable optical path difference (OPD) and large field of view. The construction and split-beam principle of the system are described detailedly, and the exact expressions of the OPD and lateral displacement changing with different parameters are obtained. The variations of the OPD and lateral displacement as a function of the wedge angle and moving displacement are simulated, and the influences of the wedge angle on the OPD and lateral displacement are very small, while most effects come from the moving displacement. In order to obtain a larger OPD and lateral displacement, the wedge angle is controlled in a range of [ 45 ° , 50 ° ] . In addition, the influences of the dispersion effect of the glass plate on the OPD and lateral displacement are analyzed and discussed, and the suitable material choice for the MSI can reduce the influence of the dispersion effect on the OPD, which also allows the system construction spanning the spectral range of [480 nm, 960 nm]. In comparison with the conventional Sagnac interferometer with a large optical path difference (LOPDSI), the spectral resolution of the MSI can be made much higher if choosing suitable parameters. This study provides a theoretical and practical guidance for the design and engineering of the Sagnac imaging polarization spectrometer.

Multichannel (multicolor) imaging has become a powerful technique in biology research for performing in vivo neuronal calcium imaging, colocalization of fluorescent labels, non-invasive pH measurement, and other procedures. We describe a novel add-on approach for simultaneous multichannel optical microscopy based on simple wedge prisms. Our device requires no alignment and is simple, robust, user-friendly, and less expensive than current commercial instruments based on switchable filters or dual-view strategies. Point spread function measurements and simulations in Zemax indicate a reduction in resolution in the direction orthogonal to the wedge interface and in the axial direction, without introducing aberration. These effects depend on the objective utilized and are most significant near the periphery of the field of view. We tested a two-channel device on C. elegans neurons in vivo and demonstrated comparable signals to a conventional dual-view instrument. We also tested a four-channel device on fixed chick embryo Brainbow samples and identified individual neurons by their spectra without extensive image postprocessing. Therefore, we believe that this technology has the potential for broad use in microscopy.

We propose an ultrasonic-assisted point-one-shot mid-infrared Fourier spectroscopy device involving an ultrasonic liquid-cell and point-one-shot Fourier spectroscopy (diameter: 6 mm, thickness: 5 mm) for ear clip type non-invasive blood glucose sensors, at a low cost (approximately 1,000 EUR). As the prevalence of diabetes increases over time, methods for non-invasive monitoring of blood glucose concentration in daily life are increasingly important for diabetes control and prevention. However, there are currently no sensors for non-invasively detecting biological components in daily environments. In the current study, we propose a point-one-shot Fourier spectroscopy method comprising one objective lens and a camera. The objective lens is a spherical lens at the front side and a dual-axis wedge prism inclined along the horizontal and vertical axes. An objective beam is collimated by the objective lens, with a difference in optical path length caused by the wedge prism. This device can be used to obtain two-dimensional spatial fringe patterns. Conventional one-shot Fourier spectroscopy produces one-dimensional fringe patterns in the horizontal direction of the array device. Thus, the maximum optical path length is limited by the number of pixels in only the horizontal line of the array device. However, our proposed point-one-shot Fourier spectroscopy device can produce an interferogram with longer maximum optical path lengths compared with conventional devices because horizontal lines at difference rows are connected by the same phase pixel. Thus, spectroscopic imaging devices can be produced at a low cost because low-resolution cameras (e.g., 80 × 80 pixels) can be used for spectroscopy.

As manufacturing capabilities have developed, the potential to create complex geometries for optical elements of a variety of materials has become a reality. Under these conditions, freeform optical components have become more prevalent in the industry, and have allowed a new class of optical systems to be engineered. In the past, freeforms have commonly been described parametrically for optimization, which in some cases limits their flexibility and utility. In this paper we demonstrate a novel freeform design methodology which uses a grid-based sag definition to serve as an alternative to polynomial coefficient optimization. The OpticStudio TrueFreeForm model allows direct optimization of sag values at grid points across the surface to enable spatially-selective surface sag optimization. Here, a case study is presented on the effectiveness of TrueFreeForm optimization in the design of freeform optical surfaces for use in modern augmented reality/virtual reality (AR/VR) optical systems. We demonstrate the flexibility and advantages of grid sag optimization and discuss key implementation considerations in the context of a freeform wedge prism system as might be found in an AR headset. In particular we demonstrate, via sub-aperture grid sag optimization, the integration of an eye-tracking subsystem into the AR wedge prism. An average MTF of 0.446 at 40 lp/mm is achieved in the user pupil imaging portion of the eye-tracking system, while introducing no degradation in the nominal performance of the AR visual display system.

In order to improve excitation signal of temperature sensor calibration system based on laser, an approach to laser homogenization is established. The homogenization principle, laser attenuation measurement, temperature change in the laser spot, and its uniformity of excitation signal in the system are studied and analyzed. The experimental results show that the laser can be effectively homogenized by use of imaging micro lens array, and the uniformity deviation is about 9.3%. The laser can be attenuated via wedge prism to 0.51% of its power with approximately same distribution. It is verified that uniformity of excitation temperature signal in the system can be improved.

A double-wedge prism device has been used in various imaging detection applications due to its high precision and strong anti-disturbance capability. In this paper, a self-adaptation double-wedge prism boresight adjustment principle suitable for both far-field and near-field target tracking is proposed. In order to realize this application, an adaptive variable boresight imaging tracking device is designed specifically. Then a tracking error model is established, and dynamic simulation, error evaluation, and sensitivity analysis are carried out according to the design objective. The experimental results show that the pitch angle deviation and azimuth angle deviation of the device are less than 6', and the blind zone can be eliminated by adding a third wedge prism, thus achieving high-precision boresight adjustment and tracking.

We propose the point one-shot mid-infrared Fourier spectroscopic imager, which is composed of only a single Ge lens (diameter: 6 mm; thickness: 5 mm) and a two-dimensional array device. The lens is a nonspherical lens on the front side and a dual-axis inclined wedge prism at the rear side. The objective beams, which have different optical path lengths because of the effects of the prism, are imaged using the array device and we obtain a two-dimensional spatial fringe pattern. We can improve the wavelength resolution analytically by connecting the same optical path difference (OPD) pixels of the horizontal lines at different rows, even though we use low-resolution cameras.

Mass sensing offering both a broad detection range and a high resolving power is essential for quantitative precision content analysis and high-yield mass production of various kinds of materials. Here, we propose and successfully demonstrate a novel type of simple low-cost optomechanical mass sensing employing an optical displacement detector that consists of a free-space Fabry-Perot optical cavity and an intra-cavity wedge prism pair, which provides an enhanced resolution and an extended capacity simultaneously. By implementing the null-method-based scheme of mass measurement, we achieve a resolution higher than 5000:1 (mass range from 1 kg) and an excellent linearity of R2>0.99998 in the prototype demonstration.

The conventional ray deviation formula and analytical inverse solution for Risley prisms are traditionally derived by the first-order paraxial method, which is simplified and does not provide sufficient accuracy. When a light ray enters the wedge prism, the component that is perpendicular to the base side is deviated by the wedge prism and the component parallel to the base side is uninfluenced. In this study, the problem is presented and analyzed from the scalar form of Snell’s law, and 2D vector algebra is used to solve the problem. The rotation and refracting angles of a single wedge prism are obtained by analyzing the propagation through the prism of incident rays from different directions, and ray deviation formulas are derived. Four configurations are described with ray deviation formulas and analytical inverse solutions deduced from the corresponding formulas for a single wedge prism. In the final section, two examples are considered for the four configurations. The numeric results demonstrate the accuracy of the inverse solution provided by the proposed method.

Adoption of quantitative phase imaging for biomicroscopy applications has been limited due to the technical knowledge requirements or the cost of commercial systems. Here, a wedge prism based simple approach is introduced to acquire quantitative phase images on a standard microscope. The proposed approach minimizes the alignment requirements and the cost. Acquired quantitative phase images reflect the sample morphology and the refractive index. Hence, it enables quantitative microscopy without the need for labeling. Optimization parameters are explored for the physical constraints of the cameras and microscope objectives. Experimental quantitative phase images are provided for the USAF-1951 test target, epithelial cell samples, and microsphere samples. Cell imaging results demonstrate the qualitative performance in an exemplary scenario. Quantitative phase imaging of microsphere samples provides experimental proof for the preservation of the resolving power. Istanbul Development Agency (ISTKA), Innovative and Creative Istanbul Financial Support Program 2016

The increasing interest in small-scale problems demands novel experimental protocols providing dense sets of 3D deformation data of complex shaped microstructures. Obtaining such information is particularly significant for the study of natural and engineered cellular solids for which experimental data collected at macro scale and describing the global mechanical response provide only limited information on their function/structure relationship. Cellular solids, in fact, due their superior mechanical performances to a unique arrangement of the bulk material properties (i.e. anisotropy and heterogeneity) and cell structural features (i.e. pores shape, size and distribution) at the micro- and nano-scales. To address the need for full-field experimental data down to the cell level, this paper proposes a single-camera stereo-Digital Image Correlation (DIC) system that makes use of a wedge prism in series to a telecentric lens for performing surface shape and deformation measurements on microstructures in three dimensions. Although the system possesses a limited measurement volume (FOV~2.8×4.3mm(2), error-free DOF ~1mm), large surface areas of cellular samples can be accurately covered by employing a sequential image capturing scheme followed by an optimization-based mosaicing procedure. The basic principles of the proposed method together with the results of the benchmarking of its metrological performances and error analysis are here reported and discussed in detail. Finally, the potential utility of this method is illustrated with micro-resolution three-dimensional measurements on a 3D printed honeycomb and on a block sample of a Luffa sponge under compression.

Different processes are involved during visuomotor learning, including an error-based procedural and a strategy based cognitive mechanism. Our objective was to analyze if the changes in the adaptation or the aftereffect components of visuomotor learning measured across development, reflected different maturation rates of the aforementioned mechanisms. Ninety-five healthy children aged 4-12years and a group of young adults participated in a wedge prism and a dove prism throwing task, which laterally displace or horizontally reverse the visual field respectively. The results show that despite the age-related differences in motor control, all children groups adapted in the error-based wedge prisms condition. However, when removing the prism, small children showed a slower aftereffects extinction rate. On the strategy-based visual reversing task only the older children group reached adult-like levels. These results are consistent with the idea of different mechanisms with asynchronous maturation rates participating during visuomotor learning.

Earth dam with impervious element in the form of asphaltic concrete core is currently the most promising type of earth dams (due to simple construction technology and universal service properties of asphaltic concrete) and is widely used in the world. However, experience in the construction and operation of high dams (above 160 m) is not available, and their work is scarcely explored. In this regard, the paper discusses the results of computational prediction of the stress-strain state and stability of a high earth dam (256 m high) with the core. The authors considered asphaltic concrete containing 7 % of bitumen as the material of the core. Gravel was considered as the material of resistant prisms. Design characteristics of the rolled asphaltic concrete and gravel were obtained from the processing of the results of triaxial tests. The calculations were performed using finite element method in elastoplastic formulation and basing on the phased construction of the dam and reservoir filling. The research shows, that the work of embankment dam with vertical core during filling of the reservoir is characterized by horizontal displacement of the lower resistant prism in the tailrace and the formation of a hard wedge prism descending along the core in the upper resistant prism. The key issue of the safety assessment is to determine the safety factor of the overall stability of the dam, for calculation of which the destruction of the earth dam is necessary, which can be done by reducing the strength properties of the dam materials. As a results of the calculations, the destruction of the dam occurs with a decrease in the strength characteristics of the materials of the dam by 2.5 times. The dam stability depends on the stability of the lower resistant prism. The destruction of its slope occurs on the classical circular-cylindrical surface. The presence of a potential collapse surface in the upper resistant prism (on the edges of the descending wedge) does not affect the overall stability of the dam.

We present a three-dimensional (3D) computational imaging architecture based on the imaging principle of a dynamic virtual camera, which enables the spatial reconstruction using a single camera and a compact wedge prism device. By rotating the prism for camera boresight adjustment, the proposed system can capture an object from different viewpoints. Each captured image appears to be recorded directly with one virtual camera moving in a certain path, facilitating the computational process for stereo matching and profile reconstruction. The experimental results have demonstrated that our architecture allows a compact and flexible system to achieve 3D imaging performance competitive to conventional stereovision.

A novel, to the best of our knowledge, method for circular-polarization imaging with white light is presented. The vital optical elements of the proposed system are two polarization gratings (PGs) and a wedge prism. The chromatic dispersion of the PG diffraction angle is compensated by the difference of the grating period for the two PGs. In addition, the distance between the diffracted lights on the imaging plane is controlled by using a wedge prism. As a result, S 3 of the Stokes parameter, including the wavelength dependence of a scarab beetle, was observed at a time, and the S 3 contribution to each color was determined by using the color filter of the light-receiving element. Because the white-light polarization image includes a lot of information about the illuminated structure, the proposed method should be applied to biomedical sensing and remote sensing.

We present a practical wide-field optical design for a 60 m aperture submillimeter telescope, which is currently under conceptual design study in China. The telescope is specified to operate over a wavelength range of 0.65–3 mm and provide a wide field of view (FOV) of 1° in diameter. We designed an F/6 Ritchey Chrétien (RC) system with a quasi-planar tertiary corrector, which cancels all spherical, coma, and astigmatism aberrations. It also achieves a good balance among the mirror sizes, central obscuration, and focal-plane curvature. The problems of focal surface curvature and nontelecentricity are treated in the subfield instrumental design, which employs a simple silicon wedge prism to obtain flat and telecentric focal planes for each subfield instrument module. Our studies show that by such a design, more than 10 5 detector pixels can be efficiently and uniformly fed at the shortest wavelength band with Strehl ratios above 0.85 across the entire 1° FOV. Several practical issues related to the telescope optics are also discussed.

The double-wedge Sagnac lateral shearing interferometer was put forward as a novel device for the upper atmospheric wind field measurement, and its shearing principle was presented. Using the geometrical optics, the exact expression of the optical path difference (OPD) within the range of the whole field was calculated when the incident ray with arbitrary directions arrived at the incoming plane. In order to analyze and discuss the influences of different parameters on the OPD, the computer simulations were performed for two moveable directions (the hypotenuse and right angle side) of the moving wedge prism. The OPD of the double-wedge Sagnac lateral shearing interferometer was changed by the moving wedge prism, which could enlarge the field of view be as much as possible for a specific OPD. These works provided an important theoretical guidance for improving the detecting precision of the upper atmospheric wind field, and had great practical value for the development of the double-wedge Sagnac lateral shearing interferometer apparatus.

The increase of atmospheric concentration of anthropogenic greenhouse gases(GHGs), primarily carbon dioxide(CO2) and methane(CH4), is concerned as a main cause of the global climate change. From the previous experiences in GHG detecting, satellite imaging spectral remote sensing provides the unique potentials in accuracy, precision, coverage, temporal sampling and spectral resolution, having been developing as an effective and efficient means for monitoring GHGs’ accumulation and emission in the atmosphere. This paper reports a promising optical design of very high spectral resolution imaging spectrometer on LEO satellite with a swath of over 100 km and a spatial resolution of less than 3 km. Its specification satisfies with the requirement of high column concentration retrieval precision of 1ppm for CO2 and 9ppb for CH4 within four absorption bands (755-765nm, 1595-1625nm, 2040-2080nm and 2275-2325nm). Above all, up to 23000 spectral resolving power hints us the superiorities of immersed grating in increasing resolution but decreasing volume. A holographic flat plane grating is directly etched on a wedge prism, operating in reflective near-Littrow condition, having optimized diffraction efficiency of over 85%. Additional prisms are introduced to correct the smile distortion of the slit image produced by the grism. This method is crucial for the fidelity of the instrument spectral response function (ISRF) and data processing. Moreover, to desensitize the instrument to the polarization state of the income radiation, four polarization scramblers are adopted after the shared fore-optics, specially designed for each bands. Thanks to the scramblers, the predicted polarization sensitivity is lower than 1% at worst.

An infrared imaging spectrometer based on a variable gap interferometer is introduced, which is working in 7.7μm~14μm, and often used in spectral measurement, camouflage target detection and gas component identification. In this paper, the wedge prism shapes processed by grinding and diamond knife turning is compared, which affects the phase distribution near zero phase of the interferogram, and results in the difference of spectrum in the result. Finally, the turning process with less damage to the sharp edges was selected. An adjusting device and monitoring software are designed to ensure the symmetry of the wedge angle of the interference cavity with variable gap, so that two sides of the interferogram are sampled at equal intervals. The working mode is designed as the interferometer’s linear translation scan inside the imaging spectrometer. This working mode can reduce the volume of the system, and decrease the noise caused by the nonuniformity of the FPA response, improving signal-to-noise ratio. Stepper motor, rail and slide block are used to realize uniform reciprocating scanning. Finally, some measurement results using this infrared imaging spectrometer are presented.

We proposed the measurement system of the six degree of motion errors which is based on distance measurement by the laser interferometer. The system has six parallel laser beams and six ball lenses as the retroreflectors on the linear stage, which reflect the corresponding laser beams. In the proposed system, the error of axial direction is measured with the ordinary distance measurement method by laser interferometer. The vertical errors to the axial direction and the roll errors around the optical axis are measured by tilted beams using the wedge prism. The pitch and yaw errors in the vertical plane to the optical axis are measured by the difference between distance of two ball lenses. The former system can measure the displacement and the error angle in one-direction. The propose system are expanded and bi-directional displacement and error angle can be measured. In this paper, it is shown how to expand the measurement system. As a result, the maximum displacement errors in x, y and z directions are 242nm, 179nm and 90nm. The maximum rotational errors around x, y, z axes are 1.75 arcsec, 2.35 arcsec and 1.67 arcsec.

Objective. To evaluate the effect of age-related cognitive changes in a visuomotor learning task that depends on strategic control and contrast it with the effect in a task principally depending on visuomotor recalibration.Methods. Participants performed a ball throwing task while donning either a reversing dove prism or a displacement wedge prism, which mainly depend on strategic control or visuomotor recalibration, respectively. Visuomotor performance was then analysed in relation to rule acquisition and reversal, recognition memory, visual memory, spatial planning, and spatial working memory with tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB).Results. The results confirmed previous works showing a detrimental effect of age on visuomotor learning. The analyses of the cognitive changes observed across age showed that both strategic control and visuomotor recalibration had significant negative correlations only with the number of errors in the spatial working memory task. However, when the effect of aging was controlled, the only significant correlation remaining was between the reversal adaptation magnitude and spatial working memory.Discussion. These results suggest that spatial working memory decline across aging could contribute to age-dependent deterioration in both visuomotor learning processes. However, spatial working memory integrity seems to affect strategic learning decline even after controlling for aging.

This study sought to determine whether symmetrical compared to asymmetrical horizontal prisms (base-out or base-in) evoked different rates of phoria adaptation. Sixteen young adults with normal binocular vision participated in a symmetrical phoria adaptation experiment using a 3Δ base-out or 3Δ base-in binocular prism flipper and an asymmetrical phoria adaptation experiment using a 6Δ base-out or 6Δ base-in monocular wedge prism. The experiments were randomized and counterbalanced to reduce the influence of the prism stimulation order. Asymmetrical base-out prism adaptation was significantly faster than symmetrical prism adaptation for subjects with normal binocular vision. Asymmetrical phoria adaptation with base-in prism was not significantly different from symmetrical phoria adaptation implying that there are directional asymmetries (convergent versus divergent eye movements) in the slow fusional component of vergence. Data suggest that a potential interaction between the version system and the slow fusional vergence system may exist. Results have clinical relevance because patients with convergence or divergence insufficiency / excess may potentially show more pronounced differences between symmetrical and asymmetrical phoria adaptation compared to binocularly normal controls. These differences might also be relevant to clinical measurements such as vergence fusional range, which can be measured symmetrically (with Risley prisms in a phoroptor) or asymmetrically (with prism bar).

A method for high resolution roll angle measurement of linear displacement stages is developed theoretically and tested experimentally. The new optical configuration is based on a special differential plane mirror interferometer, a wedge prism assembly, and a wedge mirror assembly. The wedge prisms assembly is used as a roll angle sensor, which converts roll angle to the changes of optical path. The special interferometer, composed a polarization splitter plane, a half wave plate, a beam splitter, a retro-reflector and a quarter wave plate, is designed for high resolution measurement of the changes of the optical path. The interferometric beams are a completely common path for the adoption of the centrosymmetrical measurement structure, and the cross talk of the straightness, yaw, and pitch errors is avoided. The angle measurement resolution of the proposed method is 3.5 μrad in theoretical with a phase meter which has a resolution of 2π/512. The experimental result also shows the great stability and accuracy of the present roll angle measurement system.

This paper presents an enhanced differential plane mirror interferometer with high resolution for measuring straightness. Two sets of space symmetrical beams are used to travel through the measurement and reference arms of the straightness interferometer, which contains three specific optical devices: a Koster prism, a wedge prism assembly, and a wedge mirror assembly. Changes in the optical path in the interferometer arms caused by straightness are differential and converted into phase shift through a particular interferometer system. The interferometric beams have a completely common path and space symmetrical measurement structure. The crosstalk of the Abbe error caused by pitch, yaw, and roll angle is avoided. The dead path error is minimized, which greatly enhances the stability and accuracy of the measurement. A measurement resolution of 17.5 nm is achieved. The experimental results fit well with the theoretical analysis.

Sufficient support pressure is required for tunneling by the shield machine to prevent the face collapse. It is found that the failure mechanism and soil aching effect have great influence on the accurate evaluation of the required support pressure by using the limit equilibrium methods, especially in cohesionless soils. In this paper, an improved 3D wedge-prism model which considers the height of the prism and the effect of soil arching was proposed for the analysis of tunnel face stability. In this model, the height of the prism is thought to be min{C, 2L} (where C is the cover depth and L is the width of the prism) by summarizing the results of previous researchers. The effects of soil arching are mainly embodied in the lateral stress ratio between the prism and the adjoining soils. An analytical formula for the lateral stress ratio K s between the prism and the adjoining soils which reflects soil arching effects was also proposed. Comparing the results (i.e., the limit support pressure) from theoretical models and typical model tests (i.e., centrifuge model test and 1 g model test), the accuracy of the improved wedge-prism model was verified. A design chart was finally proposed for determining the limit support pressure during tunneling in the cohesionless ground.

Recently, an axially distributed sensing system (ADS) was proposed for three-dimensional imaging and visualization. In ADS system, the 3D information cannot be collected when the coordinates of the object are close to the optical axis. In this paper, we present a wedge-prism based axially distributed sensing for improving the visual quality of 3D reconstructed images. In the proposed method, a wedge prism is placed in front of a camera and the parallax information is collected through the wedge prism by translating the wedge prism and the image sensor together along the optical axis. Accordingly, the 3D object is recorded as the improved multiple 2D perspective images within the full area of the image sensor. The volumetric images are generated from the recorded elemental images using a computational reconstruction algorithm based on ray back-projection. The proposed method is applied to partially occluded 3D object visualization. Preliminary experiments are performed to verify the approach.

The prism (minimum deviation) method of measurement of refractive indices in solids has a couple of disadvantages including problems associated with manufacturing of a good prism itself. Besides this method is unsuitable to be used in piezo- and electro-optical experiments when one needs to achieve so-called homogeneous distribution of an interaction (electric field, stress, strain) within the sample. Besides, worked out with a large expenditure of energy and cost, the prism is usually useless in other applications (destructive method). Therefore, an “elder” method of measurement of refractive indices by measuring shift of the refracted beam of light in a plane-parallel plate has been reconsidered in this paper. The sample itself may be a cuboid (if one wishes to measure all of three principal refractive indices in optically biaxial crystal), or just a crystalline boule in which one is cutting off the conical and tail parts and by suitable mechanical treatment (lapping and polishing) reveals a pair of plane parallel surfaces properly oriented to crystallographic (or principal axes of the optical indicatrix) directions. In such case, however, one can only measure one (isotropic crystals) or two (optically uniaxial crystals) refractive indices. However, in case of this method as opposed to the prism method one can repeat the measurement a couple of times, e.g. after a series of consecutive annealing, when this is either impossible or undesirable to cut the boule into smaller pieces prior to the final annealing (nondestructive method). The error depends on the angle of incidence and on sample (boule) thickness and is usually of the order of 0.001. However, in the future it is expected that the error can be reduced by implementing an electronic readout of the beam shift below 1 μm. Working of the method has been illustrated with a couple of examples in GdCOB (biaxial), LiNbO3 (uniaxial) and YAG:Cr,Mg (isotropic) crystals.

Due to the possession of advantages of passivity working mode, good disguise, and easy observation, infrared systems are used in a wide variety of applications. This paper using 640×480 uncooled detector designed a long-wave scan optical system with large field and large aperture working at 8.0μm～12μm, the Pixel Dimensions of the detector is 30μm. The F number of this system is 1.4 and focal length is 17mm, FOV is 63.6°, which extended to 143° by adopting dual-wedge prism rotating, the paper also given the extended field theory by the dual-wedge prism. Because there are a limited number of lens materials used in LWIR spectral bands, Germanium material and three aspheric surfaces were adopted to balance sphere aberrations and chromatic aberration. All above mentioned are intending to ensure the system has good imaging quality. The results show that the optical performance approximates to the diffraction limit and the design has better achromatic performance. The modulation transfer function (MTF) is above 0.5 at spatial frequency of 20lp/mm, energy concentration ratio is greater than 70% within the sensing element of the detector and Root Mean Square (RMS) value of spot diameter is smaller than the Pixel Dimensions. The system has advantages of simple structure, large aperture, high image quality etc.

In order to reduce the adverse effects of the roof prism on the imaging quality of the system, the intensity distribution function in the diffraction pattern which is used to analyze the relationship between the characteristic of the zero order diffraction splitting spot and the structural parameters in one roof prism is obtained by methods of polarization ray tracing and far field diffraction integral. The methods are determined by given the general structure parameters of the roof prism, the prism refractive index and the entering azimuth angle if illuminated with linearly polarized light. Based on that, structure parameters and reflection shift on roof surfaces of the roof prisms are analyzed. The result shows that: (1) within the allowable structure angle, the splitting effect decreases with the increase of the structural angle; (2) at a certain wavelength, the optimum condition to eliminate the splitting phenomenon is that the reflection phase shift of the roof surfaces equal to π.