Goniometer System Research Articles

A goniometric measurement system for reflection, diffusion, and transmission characterization in the VUV range

The characterization in the Vacuum Ultraviolet (VUV) range of reflection, diffusion and transmission of mechanical components plays a crucial role in understanding and optimizing the performance of particle detectors exploiting the scintillation light coming from liquefied noble gases. To this purpose a goniometric measurement system has been realized. In this presentation, the main technical characteristics and performances of the system are shown together with results coming from preliminary tests on different materials. © 2001 Elsevier Science. All rights reserved.

Full wireless goniometer design with activity recognition for upper and lower limb

People must move using their lower and upper extremities to complete their work. Depending on these extremities' using frequency or different effects such as age, genetics, and body weight, the extremities' ability may decrease. The joints' range of motion(ROM) is measured to evaluate this decrease. Different systems, such as conventional goniometers, mobile phone applications, and sensor-based systems, can measure the ROM value. Still, it can be challenging to measure this parameter in different situations, such as training, moving activities, etc. The partial wireless goniometer and a companion 3D visualization and control GUI were developed in our previous study. However, it was difficult to mount it on the limbs at a distance, or it was impossible to use it for both legs to measure the hip angles. Therefore, this study presents a full wireless goniometer system that can simultaneously measure in real-time and show joint movements in a 3D model for the upper and lower extremities. The angle values required for the ROM were measured with two IMU sensors. Two ESP32s were used as microcontrollers in the system, and a fully wireless system was enabled by transferring data via ESP-NOW and Bluetooth. Thanks to ESP-NOW, the system has less latency compared to other protocols and can transmit data over longer distances. The developed system can also perform activity recognition which is not available in other goniometers. The measurements of the system were compared with a conventional goniometer, and their results were found to be completely correlated (ρc=1).

Optical characteristics of thin film-based InGaN micro-LED arrays: a study on size effect and far field behavior

Micro-light emitting diodes (µ-LEDs) are considered the key enabler for various high-resolution micro-display applications such as augmented reality, smartphones or head-up displays. Within this study we fabricated nitride-based µ-LED arrays in a thin film chip architecture with lateral pixel sizes down to 1 µm. A metal mirror on the p-side enhances the light outcoupling via the n-side after removal of the epitaxial growth substrate. Mounted devices with pixel sizes ranging from 1×1 to 8×8 µm2 were electro-optically characterized within an integrating sphere and in a goniometer system. We measure increased external quantum efficiencies on smaller devices due to a higher light extraction efficiency (LEE) as predicted by wave optical simulations. Besides this size dependence of the LEE, also the far field properties show a substantial change with pixel size. In addition, we compared µ-LEDs with 40 nm and 80 nm thick aluminium oxide around the pixel mesa. Considerably different far field patterns were observed which indicate the sensitivity of optical properties to any design changes for tiny µ-LEDs. The experimentally obtained radiation behavior could be reasonably predicted by finite-difference time-domain simulations. This clearly reveals the importance of understanding and modeling wave optical effects inside µ-LED devices and the resulting impact on their optical performance.

A modified algebraic method of mathematical signal processing in radar problems

A new method for approximate solution of ill-posed inverse problems of reconstructing images of objects with angular resolution exceeding the Rayleigh criterion is proposed and justified, i.e. with super resolution. Angular super-resolution allows you to obtain images of objects with increased clarity and distinguish previously invisible details of images of complex objects. In addition, on this basis, the probability of correct solutions to problems of object recognition and identification increases. Mathematically, the problem is reduced to solving the linear Fredholm integral equation of the first kind of convolution type. Solutions are sought with additional conditions in the form of restrictions on the location and size of the desired radiation source, which makes it possible to regularize the problem. The method is a development of one of the parameterization methods the algebraic method. The solution is sought in the form of a representation of the desired function in the area where the source is located in the form of a series expansion over the input sequence of orthogonal functions with unknown coefficients. Thus, the inverse problem is parameterized and reduced to searching for expansion coefficients. The presented method is based on the use of a priori information about the localization area of the radiation source, or on an estimate of the location and size of this area obtained by scanning the viewing sector with a goniometer system. Using zero values of the function describing the source outside this region, for systems based on antenna arrays it is possible to find tens and even hundreds of expansion coefficients of the desired function in a Fourier series. The solution is constructed in the form of an iterative process with a consistent increase in the number of functions used in the expansion until the solution remains stable. The adequacy and stability of the solutions was verified during numerical experiments using a mathematical model. The results of numerical studies show that the presented methods of digital processing of received signals make it possible to achieve an effective angular resolution 3–10 times higher than the Rayleigh criterion. The proposed method makes it possible to miniaturize the antenna system without degrading its characteristics. Compared to known ones, it is relatively simple, which allows it to be used by systems in real time.

Validity and Reliability of Inertial Measurement Units in Active Range of Motion Assessment in the Hip Joint.

Measuring joint range of motion has traditionally occurred with a universal goniometer, inclinometer, or expensive laboratory systems. The popularity of the inertial measurement unit (IMU) is growing, enabling the small and even single portable device to measure the range of motion. Until now, they were not used to assess hip joint range of motion. Our study aimed to check the validity of IMUs in assessing hip range of motion and compare them to other measurement devices-universal goniometer and inclinometer. Twenty participants completed three hip movements (flexion in standing and prone internal and external rotation) on both hips. Two testers independently assessed each movement with a goniometer, digital inclinometer, and IMU at different time points. To assess the agreement of active hip ROM between devices, Intraclass Correlation Coefficient (ICC) and Bland-Altman analysis were used. Furthermore, inter-rater and intra-rater reliability were also assessed by using ICC and Bland-Altman analysis. Limits of agreement (LOA) were calculated using Bland-Altman plots. The IMU demonstrated good to excellent validity (ICC: 0.87-0.99) compared to the goniometer and digital inclinometer, with LOAs < 9°, across all tested movements. Intra-rater reliability was excellent for all devices (ICC: 0.87-0.99) with LOAs < 7°. However, inter-rater reliability was moderate for flexion (ICC: 0.58-0.59, LOAs < 22.4) and poor for rotations (ICC: -0.33-0.04, LOAs < 7.8°). The present study shows that a single inertial measurement unit (RSQ Motion, RSQ Technologies, Poznan, Poland) could be successfully used to assess the active hip range of motion in healthy subjects, comparable to other methods accuracy.

High Accuracy Solar Diffuser BRDF Measurement for On-Board Calibration in the Solar Reflective Band

In the solar reflective band, an on-board calibration method based on a solar diffuser (SD) can realize full aperture, full field of view, and end-to-end absolute radiometric calibration of optical remote sensors. The SD’s bidirectional reflectance distribution function (BRDF) is a key parameter that affects the accuracy of the on-board calibration. High-accuracy measurement of the SD BRDF is required in the laboratory before launch. Due to the uncertainty of the goniometer system, polarization effects, and other factors, the measurement uncertainty of the SD BRDF at large incident angles is much higher than that at a 0° incident zenith angle and 45° reflection zenith angle. In this paper, an absolute BRDF measurement facility is reported. The goniometric system consists of a high-brightness integrating sphere as a radiation source, a six-axis robot arm, and a large rotation stage. The measurement wavelength range was from 350 nm to 2400 nm. An improved data processing method based on the reciprocity theorem was proposed to reduce the measurement uncertainty of the SD BRDF at large incident angles. At an incident zenith angle of 75°, the improved data processing method reduced the measurement uncertainty of the SD BRDF by 52% at 410 nm to 480 nm, by 70% at 480 nm to 1000 nm, and by 20% at other bands compared to the absolute measurement method. The influence of the radiation source, goniometer system, detection system, and other factors on the measurement uncertainty are analyzed in this paper. The results show that the measurement uncertainty (coverage factor k = 2) of the SD BRDF was better than 1.04% at 350 nm to 410 nm, 0.60% at 410 nm to 480 nm, 0.43% at 480 nm to 1000 nm, and 0.86% at 1000 nm to 2400 nm.

Modified prism methods for measuring the refractive index of solid and liquid substances

Methods for measuring the refractive index of optically transparent dielectric materials are considered. Modified methods based on the methods of minimum deviation and constant deviation are proposed and allow determining the refractive index of triangular prisms with unknown apex angles. In the proposed methods, the angles of light deviation on three faces of the prism are measured, and the refractive index of the material and the prism angles are determined from the solution of a system of equations. To implement the proposed methods, a goniometric system is used. That system was designed to measure angles between the flat surfaces of objects in manual and automated modes. Reference prism samples made of N-SF 1 optical glass, and a hollow prism filled with distilled water are studied. The proposed methods are compared and the measurement error is estimated. It is shown that the modified methods can be used for high-precision measurements of the refractive index in cases where the angles of the prism are unknown, or their measurement is associated with technical difficulties.

Proximal to distal sequencing impacts on maximum shoulder joint angles and the risk of impingement in baseball pitching involving a scapular independent thoracohumeral model.

Hyperangulation of the scapulohumeral joint due to poor coordination of the scapula during throwing motion is claimed to be a major cause of internal impingement in baseball pitchers. However, evidence of injurious scapular kinematics is lacking, particularly regarding how hyperangularion actually occurs in full-effort pitching. The purpose of this study was to describe sequential scapular motions involved in attaining maximum joint angles during pitching and the implications for internal impingement in elite baseball pitchers. An electromagnetic goniometer system computed kinematics for pelvis, thorax, scapulae, arms, and forearms during baseball pitching in 72 pitchers. Internal impingement risk was assessed based on kinematic characteristics of internal impingement quantified in a cadaveric study. The pelvis, thorax, and scapula rotated in the proximal-to-distal sequence. Large forearm layback observed near the end of the cocking phase (182 ± 27°) was achieved with a submaximal scapulohumeral external rotation (98 ± 14°). In the next 0.027 ± 0.007 s, forward thoracic rotation and then scapular rotation caused increased scapulohumeral external rotation to a maximum of 113 ± 14°. Here, humeral horizontal adduction and scapula protraction occurred simultaneously preventing the humerus from lagging further behind the scapula. Only one participant reached critical hyperangulation beyond which internal impingement was reported to occur. Most elite pitchers safely attained the fully cocked position, yet off-timed recoiling of scapular protraction caused hyperangulation in full-effort pitching. Therefore, proximal-distal sequencing between the scapula and humerus should be evaluated to lessen the risk of internal impingement in baseball pitchers.

Measurement of the refractive index using a goniometric system in an automated mode

Subject of study. A method for the measurement of the refractive index using an automated autocollimating goniometric system is proposed. Aim of study. The study facilitates the precise measurement of the refractive indices of transparent solid and liquid optical materials. Method. Goniometric methods based on the measurement of angles of light refraction caused by a substance are often used to measure the refractive indices of trihedral prisms. A method to determine the refractive index via measuring the light deviation angle caused by a prism after reflection from the internal facet in the automated mode is proposed. Main results. The refractive indices of two trihedral prisms composed of different glass types, namely, N-BK7 and SF-1, measured using the proposed method and autocollimating goniometric system are presented. The measurement error did not exceed 1.5×10−4 when compared with the nominal value for these prisms at the wavelength of the radiation source of the autocollimator, thus confirming the prospect of application of this method in high-precision refractive index measurements. Practical significance. The method proposed in this study can be used to measure the refractive indices of trihedral prisms made of optically transparent materials with different apex angles using the goniometric system in an automated mode. The method can also be applied to optically transparent liquid materials located in a hollow trihedral prism.

Blood-repellent and anti-corrosive surface by spin-coated SWCNT layer on intravascular stent materials.

Despite intravascular bare metallic stents (BMS) being indispensable products in cardiovascular surgery, they face in-stent restenosis (ISR), resulting in stent failure or secondary surgical operation necessity. Accumulation or corrosion processes are key factors that promote ISR development in a vascular pathway, including an intravascular stent. The ISR can be inhibited by increasing the blood-repellency, and electrochemical corrosion resistance features using surface modification techniques on intravascular stent materials. In this study, Single-Walled Carbon Nanotube (SWCNT) structures were deposited using the spin-coating method on stent specimens made of 316L, 316LVM, CoCr-alloy, and Ti-alloy. Hydrophobicity and blood-repellency functions of coated and uncoated specimens were analysed by the Contact Angle (CA) values for distilled water (DIW), glycerol, blood plasma, and total-blood droplets using a computer-controlled goniometer system. Using a potentiostat, the electrochemical corrosion resistance features were analysed from obtained Electrochemical Impedance Spectroscopy (EIS) and Tafel curves in 37 °CSimulated Body Fluid (SBF) mimicking the human blood plasma. Due to the CA values below 90°, the repellency limit for hydrophobicity and blood-repellency, bare specimens performed hydrophilic and blood-philic features. However, SWCNT coating increased the repellency functions to 95°for DIW and 96°for total blood. The electrochemical corrosion resistance analysis showed that 1.433 kΩ cm2 polarization resistance and 1.07 kΩ cm2 electrochemical impedance of bare specimens increased to 142.8 kΩ cm2 and 141.3 kΩ cm2 by SWCNT coating. These corrosion resistance enhancements led to ratios of 78.13% inhibition in the corrosion rate and mass loss rate per year for SWCNT-coated 316LVM specimens. The maximum inhibition efficiency was observed for SWCNT-coated 316LVM specimens with a ratio of 87.92%. Obtained results indicate that SWCNT coating of the intravascular stents can inhibit the ISR risks of the BMS group.

MEDICAL REHABILITATION GONIOMETRICAL SYSTEM

Physiological rehabilitation is applied in medical practice to restore a person's functional ability after musculoskeletal injuries. Movements in the joints are the main functional indicator of the activity of the organs of support and movement. The paper considers a resistive goniometric sensor in the form of a ball joint. Based on such a sensor, a medical rehabilitation goniometric system is developed. It includes also a data collection device (autonomous data recorder) and a portable modem. That is why the system works autonomously in real-time and transmits data over a distance. This allows the system to be mobile and control joint mobility without the direct involvement of a doctor.

Calibration of BRDF Based on the Field Goniometer System Using a UAV Multispectral Camera.

The bidirectional reflectance distribution function (BRDF) is important for estimating the physical properties of a surface in remote sensing. In the laboratory, the BRDF can be estimated quickly and accurately using a goniometer, but it is very difficult to operate in the field. The purpose of this study was to evaluate whether estimating the BRDF with reasonable accuracy using an unmanned aerial vehicle (UAV) with a multispectral camera is possible in the field. Hemispherical reflectance was created from images taken using an UAV multispectral camera. The ground targets were four calibrated reference tarps (CRTs) of different reflectance, and the UAV was operated five times. Down-welling irradiance for reflectance calculation was measured in two ways: a sunlight sensor was mounted on a UAV, and a spectroradiometer with a remote cosine receptor (RCR) was installed on the ground. The BRDF was assessed through the anisotropy factor (ANIF) of the CRT reflectance derived from the collected data. As a result, the irradiance data for the reflectance calculation were more effective from the spectroradiometer with RCR on the ground than from the sunlight sensor mounted on an UAV. Furthermore, the high reflectance CRTs, ANIF, and BRDF had similar results. Therefore, when analyzing the BRDF, the effectiveness can be guaranteed when the reflectance of the target is over 21~46%, because a low reflectance tendency differs due to the adjacency effect. In addition, weather affects irradiance, so it is more effective to conduct fieldwork in clear weather.

Parameterization of user functions in digital signal processing for obtaining angular superresolution

Objectives. One of the most important tasks in the development of goniometric systems is improving resolution in terms of angular coordinates. This can be achieved in two ways: firstly, by increasing the aperture, which is very expensive and often technically challenging to implement; secondly, with the help of digital signal processing methods. If the recorded signal sources are located close to each other and not resolved by the Rayleigh criterion, it can be impossible to determine their number, location and reflection characteristics. The aim of the present work is to develop a digital signal processing algorithm for obtaining angular superresolution.Methods. Mathematical methods for solving inverse problems are used to overcome the Rayleigh criterion, i.e., obtain angular superresolution. These problems are unstable, since there is an infinite number of approximate solutions and false targets may occur. The search for the optimal solution is carried out by minimizing the standard deviation.Results. A description of a mathematical model for a goniometric system is presented. A signal processing algorithm is developed based on existing methods according to the principle of parameterization of user functions. Results of numerical experiments for achieving superresolution by algebraic methods are given along with an estimation of solution stability. The accuracy and correspondence of the amplitude of the obtained objects to the initial parameters are measured. The degree of excess of the Rayleigh criterion by the obtained solution is estimated.Conclusions. Algebraic methods can be used to obtain stable solutions with angular superresolution. The results obtained correctly reflect the location of objects with a minor error. Errors in the distribution of the signal amplitude are small, appearing false targets have negligible amplitude.

Methods of mutual high-precision navigation based the use of relative modes of anglemeasuring receivers of global navigation satellite systems signals

The article presents the results of experimental studies of mutual high-precision navigation methods for unmanned and specialized transport systems. The proposed methods are based on the application of the relative operating modes of two or more angle-measuring receivers of global navigation satellite systems signals. To conduct research, a software and hardware complex has been developed, consisting of two angle-measuring receivers of global navigation satellite systems signals, a turntable and a computer model of the navigation system of unmanned and specialized transport systems. It provides the positioning error of the antenna system in angular coordinates less than 1 arc minute, which allows it to be used as a reference when measuring the angular displacements of the receiver of global navigation satellite systems signals antenna system. The results of measurements of planar and angular coordinates both in autonomous and relative phase modes of operation of goniometric receivers global navigation satellite systems signals are presented and analyzed. It has been established that the root-mean-square error of measuring relative coordinates was 0,019 meter. A further increase in the relative position measurement accuracy is possible by taking measures to reduce the multipath reception error, which is the most significant uncorrelated position measurement error by two sets of receivers of global navigation satellite systems signals. Thus, the methods of mutual high-precision navigation using angle-measuring receivers of global navigation satellite systems signals have high accuracy without the use of external information about differential corrections. This will allow the operation of unmanned or special transport systems in hard-toreach and northern regions, in conditions of lack of communication and other adverse factors.

Biocompatible Chemically Fueled Transient Polymer Nanoparticles for Temporally Programmable in Vivo Imaging

Biocompatible Chemically Fueled Transient Polymer Nanoparticles for Temporally Programmable in Vivo Imaging

Effects of rotation errors on goniometric measurements

Goniometric measurements are essential for the determination of many optical quantities, and quantifying the effects of errors in the rotation axes on these quantities is a complex task. In this paper, we show how a measurement model for a four-axis goniometric system can be developed to allow the effects of alignment and rotation errors to be included in the uncertainty of the measurement. We use three different computational methods to propagate the uncertainties due to several error sources through the model to the rotation angles and then to the measurement of bidirectional reflectance and integrated diffuse reflectance, a task that would otherwise be intractable. While all three methods give the same result, the GTC Python package is the simplest and intrinsically provides a full uncertainty budget, including all correlations between measurement parameters. We then demonstrate how the development of a measurement model and the use of GTC has improved our understanding of the system. As a consequence, taking advantage of negative correlations between measurements in different geometries allows us to minimise the total uncertainty in integrated diffuse reflectance, lowering the standard uncertainty from 0.0029 to 0.0015.

Измерение показателя преломления с помощью гониометрической системы

The article proposes a method for measuring the refractive index using a goniometric system that does not require measuring the prism angle, which simplifies the measurement process compared to the widely used methods of minimum deviation and autocollimation. This method can be used to measure the refractive index of samples in the form of triangular prisms in the visible, ultraviolet and infrared ranges. To implement the method, a goniometric system was used. To obtain the reflection of the refracted beam, a fixed mirror was used, and the refractive index of the prism material was calculated from the solution of a system of equations. The results of an experimental study of a triangular prism made of optical glass N-BK7 using the proposed method and their comparison with the data obtained on the State Primary Standard of the Refractive Index Unit GET 138-2021 are presented.

Measurement of the refractive index using a goniometric system

The article proposes a method for measuring the refractive index using a goniometric system that does not require measuring the prism angle, which simplifies the measurement process compared to the widely used methods of minimum deviation and autocollimation. This method can be used to measure the refractive index of samples in the form of triangular prisms in the visible, ultraviolet and infrared ranges. To implement the method, a goniometric system was used. To obtain the reflection of the refracted beam, a fixed mirror was used, and the refractive index of the prism material was calculated from the solution of a system of equations. The results of an experimental study of a triangular prism made of optical glass N-BK7 using the proposed method and their comparison with the data obtained on the State Primary Standard of the Refractive Index Unit GET 138-2021 are presented. Keywords: goniometer, refractive index, prism method.

Variants of the gradient method of trajectory control of observation in goniometric two-position air-based systems

Variants of the gradient method of trajectory control of observation in goniometric two-position air-based systems

Temperature dependent radiative properties of semi-transparent fiberglass-epoxy composite materials from 20 °C to 200 °C

The radiative properties of polymer-reinforced composite materials such as laminates may change according to the temperature. The knowledge of the relationship between radiative properties and temperature becomes crucial when designing structural components subjected to thermal stresses, induced for example by a laser irradiation. This study deals with the analysis of the absorption and scattering properties of fiberglass-epoxy composites from room temperature to 200 °C. From the point of view of thermal radiation, the two-phase system (polymer matrix and fibers reinforcements) is treated as an equivalent homogeneous medium characterized by volumetric radiative properties, namely the absorption coefficient, the scattering coefficient, and the scattering phase function. The light interaction with the rough boundaries of the sample is modeled by boundary scattering coefficients. The aim is to determine these volumetric and boundary scattering properties as function of the temperature. We use a robust inverse method based on a Gauss-Newton algorithm to solve the nonlinear least squares problem. It minimizes the sum of the squared difference between the theoretical and experimental data of bidirectional and normal-hemispherical reflectances and transmittances. Scattering measurements are carried out using a visible and near-infrared spectrometer (400 to 2500 nm spectral range) equipped with a goniometric system and a heated sample holder. Theoretical results are retrieved by employing the Monte Carlo method for solving the Radiative Transfer Equation (RTE). We report that reflectance are insensitive to the temperature rise below 150 °C, and increase above this temperature up to 200 °C. Transmittances increase with temperature, reach a maximum around 105–125 °C near the glass transition temperature of the resin (assessed by a differential scanning calorimetry analysis), and decrease until 200 °C. Upon others, this study reveals that radiative properties are strongly temperature-dependent above 100 °C, first because of the dependence of the resin refractive index to the temperature, but also due to the onset of the polymer chemical degradation. The mismatch between the glass fibers and the polymer refractive indexes is at its lowest near the glass transition temperature of the resin, and explains the peak of transmittances and the trough on the extinction coefficient and the scattering albedo. The onset of the resin chemical degradation above 150 °C increases the absorption coefficient. The asymmetry parameter of the Henyey Greenstein phase function decrease notably from 0.94 to 0.3 above 150 °C, due to the enhancement of backscattered light within the sample.