Search

Vertical Cylinder Tank is used as a storage area or as a measuring tool. Liquids are used in the form of Fuel oil, Liquid Natural Gas, vegetable liquids, and other chemical liquids. The tank calibration results are in the form of a volume per height table that is used as a reference by Automatic Tank Gauging. There are two tank calibration methods, namely: the strapping method and the optical method. The process of measuring the inside or outside diameter of the tank becomes very important in the tank calibration process—the measurement of tank diameter by the strapping method using steel meters manually. At the same time, the optical method uses theodolite or total station. For tank diameters ≤ 5 m, the strapping method has smaller diameter measurement results with a difference of 0.7% compared to the optical method. In further research, a prototype can be developed that can accelerate the calibration process using the strapping method (for example, a vertical track measuring robot) or a low-cost prototype theodolite

The selection of the nozzle shape of inner diameter pneumatic probe, the number of nozzles and the amount of nozzle sinking design have a great effect on the uncertainty of the inner hole diameter measurement. According to the structural characteristic of tested part, the scientific design of the machining technology and the application requirements is to ensure the key to measurement accuracy of the inner diameter; In addition, how to use the inner diameter pneumatic meter correctly in the production process, how to change the pneumatic probe correctly, how to reduce the influence of inner hole surface roughness on the measurement results is also an important measure to ensure the accuracy of the inner diameter measurement; one to one reply is given in this paper, to design inner diameter pneumatic probe and to use in the site has certain guidance significance.

Aiming at the difficulty in judging the quality of potting in the process of encapsulating transparent adhesive for micro-rectangular electrical connectors, the bubble diameter measurement technology based on image processing was studied. Through the image acquisition of the sampled samples, the diameter and quantity information of the bubble particles are obtained. By calculating the standard circle of the micrometer, the error of the algorithm is about 5%. By setting up the test platform for the transparent potting, the three stages of mixing, defoaming and solidification were used to analyze, quantify and calculate the bubbles. It was found that the hot air defoaming can effectively eliminate the bubbles generated during the encapsulation, and the bubbles will be further reduced during the curing process. The subsequent production of micro-rectangular electrical connectors provides a factual reference.

A method based on multiple Fiber Bragg Gratings (FBG) and a structure fabricated using a 3D printer for diameter measurement is proposed and experimentally demonstrated. The sensor is easily developed inserting the FBG on the structure and fixing the FBG in two points. Due to this arrangement, when the diameter is reduced a force is applied on the sensor and this causes a wavelength shift. The study is divided in two steps using one experimental setup. At first, each FBG response is independently evaluated concerning the diameter variation and after that, the FBGs are evaluated together. The results demonstrated that the structure can be used as a way to monitor the diameter variation in some applications.

The diameter of cylindrical openings is conventionally measured with the mechanical and contact method. In this paper, we propose a contactless optical approach to measure dimensions of inner profile by a disk beam probe. The measurement is carried out illuminating the inner cylindrical opening with a light sheet generated by the disk beam probe, acquiring the light-section image of the object with an image sensor through a widefield lens, then numerically extracting the diameter. During measurement, the probe is aligned inside the openings with high freedom, which causes the optical section to manifest a variety of ellipses besides a circle accordingly. The measurement method copes with extracting the diameter of openings from various ellipse optical sections. The high freedom of probe alignment allows optical diameter measurement to be flexible and simple. The dimensions of cylindrical openings of manufactured parts were practically measured with the disk beam probe, and the results were confirmed with those measured with the vernier caliper.

Fiber formation behavior of the blend fibers consisting of two types of isotactic polypropylene (iPP), i. e. high stereo-regularity/high molecular weight iPP (HPP) and low stereo-regularity/low molecular weight iPP (LPP), was investigated. In the melt spinning of blend fibers of various HPP:LPP compositions, the spinnability was improved significantly not only by blending LPP into HPP but also by blending HPP into LPP. On-line diameter measurement of the spin-line revealed that the increase of LPP composition caused the shift of solidification point to downstream, indicating that the crystallization temperature was lowered. Wide-angle X-ray diffraction (WAXD) analysis of the as-spun fibers clarified that only the α-form crystal was formed, and the crystalline orientation increased with the increases of take-up velocity and HPP weight fraction. The crystallinities obtained from the WAXD patterns of the as-spun fibers of various HPP/LPP compositions prepared at the take-up velocity of 1 and 5 km/min were lower than the values estimated based on the rule of additivity, where the difference was more prominent for the 1 km/min fibers. Analyses of crystallinity through differential scanning calorimetry measurements also suggested the suppression of the crystallization of HPP in the HPP/LPP blend fibers. The thermal analyses basically clarified that in the melt spinning process of the blends of HPP and LPP, both components crystallized independently even though the two polymers are considered to be miscible in the molten state, however, detailed analyses of melting behavior of the as-spun fibers suggested the possibility of the formation of crystals with a certain level of mixing of the HPP and LPP molecules, i. e. the mixing of a certain amount of LPP molecules into the HPP crystals and also the mixing of a certain amount of HPP molecules into the LPP crystals.

Whispering gallery mode (WGM) resonance is used for the diameter measuring method of a microsphere smaller than φ 1 mm. It is aimed to achieve measurement accuracy better than 10 nm. There are two electromagnetic modes for WGMs, and then mis-detection of the electromagnetic mode expands measurement errors more than 100 nm, so it is indispensably to distinguish the electromagnetic mode. As theoretical simulation implies, polarization mode of WGMs can be selectively excited by controlling polarization of the incident light in optical coupling. Based on the analysis, it was proofed experimentally that the polarization of WGMs could be classified. As a result, the diameter measurement for a microsphere was performed with measurement error of ± 1 nm.

The Brinell hardness test method has been in common use for over 100 years. The Brinell test method provides hardness measurement near the deformed or cracked zone. In this work, there is an approach to obtaining several railway steel samples' hardness by using a spherical indenter without optical measurement. Spherical indentation diameter is commonly effected by sink-in and pile-up effect that influences optical measurement negatively. Because of that, the purposed approach aims to obtain average hardness values by using indentation and relaxation curves.

The optic nerve is a part of the central nervous system surrounded by cerebrospinal fluid and is encased in a sheath. Changes to the cerebrospinal fluid due to injury, tumor rupture and so on can increase intracranial pressure (ICP) and can result in changes in the sheath diameter. Measuring the changes in the sheath can be done through ultrasound imaging with which the optic nerve sheath diameter can be measured. Since this approach is non-invasive, it would reduce the cost for patients and healthcare if sheath diameter could be used as a predictor of increase in ICP. However, the manual measurement of the nerve sheath diameter is very time consuming and could be affected by human errors. In this paper we propose an image processing approach in which the optic nerve sheath diameter is measured automatically. In our proposed method, we first denoise images and then detect the region of interest using a simple line integral method. After that by analyzing super-pixels we measure the diameter. We compared the results of the proposed method with manual measurements from two experts. The average percentage of error between the proposed method and the experts' measurements did not substantially differ from the error between the two experts.

A hole diameter measurement is a common task in mechanical engineering metrology. Inner hole dimension is usually measured with contact gauges touching the inner wall. Another approach is the hole diameter estimation by a contact or optical measurement of the diameter at the top or bottom of the hole. Such approach does not allow for the measurement of the real geometry of the hole inner walls. As the hole diameter decreases, small geometry variations along the hole axis lead to a large relative error between the actual and measured diameter value. We assessed several different optical schemes allowing for an optical measurement of a hole diameter by reflection of light towards the hole inner wall. We selected and tested a reflection optical laser triangulation approach for measurement of side wall of a recess and we analyzed the allowable depth of a bore enabling the hole diameter estimation by scanning of the inner wall along the hole axis.

While electron tomography can be used to visualize objects at nanoscale, it is difficult to perform reproducible quantitative measurements. Here we measure the shape and size of nanoparticles (NPs) in three dimensions (3D) using electron tomography. We evaluated the accuracy of maximum Feret diameter (Feretmax), minimum Feret diameter (Feretmini) and volume of NPs measurements from reconstructed 3D images which were obtained from data acquired with varied electron dose. We perform both simulations and experiment to clarify what factors effect on the accuracy of the NP shape measurement. Based on the results, suitable reconstruction methods and threshold for binarization were evaluated. We also report comparison results obtained on exactly the same samples in two different laboratories.

Made available in DSpace on 2021-06-25T11:15:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Objetives: this study aimed to fabricate electrospun-based polyetherimide (PEI) fibers, under controlled parameters, and to perform a diameter analysis for potential mechanical improvement of dental materials. Material and Methods: PEI pallets (0.75 g) were dissolved in 2 mL of chloroform and then processed by electrospinning, under a flow rate of 1mLh- 1, three different electrical voltages (10kV, 15kV and 20kV) and three distances (10 cm, 15 cm and 18 cm) between the needle tip and collector. These parameter combinations resulted in nine experimental groups that were analyzed using scanning electron microscopy (SEM) and image processing program for diameter measurement. Statistical analysis was performed using two-way ANOVA with post-hoc Tukey (5% significance). Results: from SEM images it was possible to observe formation of solid, misaligned and flawless defect-free fibers. And from the statistical analysis, distance (p = 0,0026) and the electric tension (p = 0,0012) showed a significant difference, but not for interaction between then (p = 0,4486). Conclusion: thus, it can be concluded that there is a possibility of the morphology control of PEI electrospun fibers, such as diameter, that can be used for a variety of applications such as incorporation in dental materials in order to improve its properties. Institute of Science and Technology of Sao Jose dos Campos São Paulo State University (UNESP) Institute of Science and Technology of Sao Jose dos Campos São Paulo State University (UNESP)

A strain gauge sensor based on Fiber Bragg Grating (FBG) for diameter measurement is proposed and experimentally demonstrated. The sensor is easily fabricated inserting the FBG on the strain gauge—it was fabricated using a 3D printer—and fixing the FBG in two points of this structure. The idea is to vary the diameter of the structure. We developed two experimental setups, the first one is used to evaluate the response of the FBG to strain and the second one to assess the possibility of using the structure developed to monitor the desired parameter. The results demonstrated that the structure can be used as a way to monitor the diameter variation in some applications. The sensor presented a sensitivity of 0.5361 nm/mm and a good linear response of 0.9976 using the Strain Gauge with FBG and fused taper.

Owing to their favorable properties including small sizes, tight optical confinement, large fractional evanescent fields, and low waveguiding losses, optical micro-/nanofibers have attracted broad research interest and technological applications in recent years, in which the precision in micro-/nanofiber fabrication is critical to determine their waveguiding properties and performances. Here, we firstly introduce the principles of high-temperature taper drawing of glass fibers. Next, we review typical fabrication methods including flame-heated manual drawing approach, flame-heated mechanical drawing technique, electric-heated mechanical drawing technique and laser-heated mechanical drawing technique. Cons and pros of the above-mentioned techniques are discussed, followed by a brief introduction to the fabrication of polymer micro-/nanofibers. Thirdly, we introduce the principle and techniques of high-precision diameter control in glass micro-/nanofiber fabrication based on a in-situ feedback from the cutoff of high-order waveguiding modes, which can offer a diameter precision down to nanometer level. In addition, several techniques for diameter measurement of a micro-/nanofiber are also introduced. Finally, we end the review with a brief summary in micro-/nanofiber fabrication, as well as an outlook to future possibilities.

A precise and in-situ measurement of diameter of optical nanofibers (ONFs) is presented. Mounting a commercial micronscale-period ruled grating on ONF forms a high-order Bragg reflector, making possible convenient diagnosis of the ONF diameter.

OFDA 2000 is a widely used fibre diameter measurement instrument. The instrument can provide improved statistical accuracy measurements in comparison with traditional technology. In this paper, a new technique has been developed to enable fibre diameters to be measured in an aqueous environment using the OFDA 2000 instrument. This new technique was utilised to assess the effects of pH and temperature on the diameters of Merino wool fibres in aqueous environments. Significant changes in fibre diameter under aqueous conditions were found as a function of pH and temperature. It is also demonstrated in this paper that the fibre diameter measurement results can be affected by fibre colour. In both dry and aqueous conditions, variation in fibre diameter was observed on fibres with different colours. This could be due to an optical effect or more likely due to physical changes in the dyed fibres as a result of the presence of dyes. Apart from their physical bulk, dyes may also affect the water content of fibres and hence have an influence on the swelling of fibres when they are measured under ambient regain and wet conditions.

Despite the growing use of nanofiber scaffolds for tissue engineering applications, there is not a validated, readily available, free solution for rapid, automated analysis of nanofiber diameter from scanning electron microscope (SEM) micrographs. Thus, the goal of this study was to create a user friendly ImageJ/FIJI plugin that would analyze SEM micrographs of nanofibers to determine nanofiber diameter on a desktop computer within 60 seconds. Additional design goals included 1) compatibility with a variety of existing segmentation algorithms, and 2) an open source code to enable further improvement of the plugin. Using existing algorithms for centerline determination, Euclidean distance transforms and a novel pixel transformation technique, a plugin called “DiameterJ” was created for ImageJ/FIJI. The plugin was validated using 1) digital synthetic images of white lines on a black background and 2) SEM images of nominally monodispersed steel wires of known diameters. DiameterJ analyzed SEM micrographs in 20 seconds, produced diameters not statistically different from known values, was over 10-times closer to known diameter values than other open source software, provided hundreds of times the sampling of manual measurement, and was hundreds of times faster than manual assessment of nanofiber diameter. DiameterJ enables users to rapidly and thoroughly determine the structural features of nanofiber scaffolds and could potentially allow new insights to be formed into fiber diameter distribution and cell response.

Work is devoted to modeling instrumental errors of a laser beam diameter measurement using a method based on a lambertian transmissive screen. Super-Lorenz distribution was used as a model of the beam. To determine the effect of each parameter on the measurement error were performed computational experiments, results of which were approximated by analytic functions. There were obtained the errors depending on relative beam size, spatial non-uniformity of the transmission screen, lens distortion, physical vignetting, beam tilt, CCD spatial resolution, ADC resolution of a camera. There was shown that the error can be less then 1 %.

Tests for quality control of rockbolts are introduced in this chapter. The tests include tensile tests of bolt steel, tests of nut and plate, strength tests of cementitious grout, onsite viscosity tests of cementitious grout, tests of bond strength, borehole diameter measurement, pull tests, and proof tests.

Yarn pore size and its distribution influence the structural, physical, thermal behaviour and moisture content of the fabrics. Analysis of the microscopic view of cut-cross sectional of yarn is a way forward to measure the yarn pore size and its distribution. The method of yarn sample preparation is important for capturing the cut cross sectional view of different yarns. Three different yarn sample preparation methods were developed for this purpose. Yarn outer and core diameter measurement using microscopic image help to predict the hollow yarn pore size, packing density and linear density. These three methods used to prepare the yarn for cross sectional microscopic study and comparison study was also made. There is a good correlation found among the selected methods.

Automated countersink measurement methods which require contact with the workpiece are susceptible to a loss of accuracy due to cutting debris and lube build-up. This paper demonstrates a non-contact method for countersink diameter measurement on CFRP which eliminates the need for periodic cleaning. Holes are scanned in process using a laser profilometer. Coordinates for points along the countersink edge are processed with a unique filtering algorithm providing a highly repeatable estimate for major and minor diameter.

Background Ultrasound (U/S) and MRI measurements of the optic nerve sheath diameter (ONSD) have been proposed as intracranial pressure measurement surrogates, but these methods have not been fully evaluated or standardized. The purpose of this study was to develop an ex-vivo model for evaluating ONSD measurement techniques by comparing U/S and MRI measurements to physical measurements. Methods The left eye of post mortem juvenile pigs (N = 3) was excised and the subdural space of the optic nerve cannulated. Caliper measurements and U/S imaging measurements of the ONSD were acquired at baseline and following 1 cc saline infusion into the sheath. The samples were then embedded in 0.5% agarose and imaged in a 7 Tesla (7T) MRI. The ONSD was subsequently measured with digital calipers at locations and directions matching the U/S and direct measurements. Results Both MRI and sonographic measurements were in agreement with direct measurements. U/S data, especially axial images, exhibited a positive bias and more variance (bias: 1.318, 95% limit of agreement: 8.609) compared to MRI (bias: 0.3156, 95% limit of agreement: 2.773). In addition, U/S images were much more dependent on probe placement, distance between probe and target, and imaging plane. Conclusions This model appears to be a valid test-bed for continued scrutiny of ONSD measurement techniques. In this model, 7T MRI was accurate and potentially useful for in-vivo measurements where direct measurements are not available. Current limitations with ultrasound imaging for ONSD measurement associated with image acquisition technique and equipment necessitate further standardization to improve its clinical utility.

Due to the high surface area, porosity, and rigidity, applications of nanofibers and nanosurfaces have developed in recent years. Nanofibers and nanosurfaces are typically produced by electrospinning method. In the production process, determination of average fiber diameter is crucial for quality assessment. Average fiber diameter is determined by manually measuring the diameters of randomly selected fibers on scanning electron microscopy (SEM) images. However, as the number of the images increases, manual fiber diameter determination becomes a tedious and time consuming task as well as being sensitive to human errors. Therefore, an automated fiber diameter measurement system is desired. In the literature, this task is achieved by using image analysis algorithms. Typically, these methods first isolate each fiber in the image and measure the diameter of each isolated fiber. Fiber isolation is an error-prone process. In this study, automated calculation of nanofiber diameter is achieved without fiber isolation using image processing and analysis algorithms. Performance of the proposed method was tested on real data. The effectiveness of the proposed method is shown by comparing automatically and manually measured nanofiber diameter values.

Aim: To measure and study the recovery coefficients of pre-clinical hollow spheres in clinical PET/CT scanners. Materials and Methods: Seven small hollow spheres with inner diameters ranging from 3.95mm up to 15.43mm, were imaged in a Jaszczak ECT Phantom, in air and with sphere to background activity concentration ratios of 15 to 1 for 16 minutes. The images were reconstructed to 2×2×2 mm voxel size images using the default clinical reconstruction method supplied by the scanner. The imaging protocol was performed on five different PET/CT scanners; the Gemini TF and Vereos by Philips, the mCT and HRRT by Siemens, and the Discovery 710 by General Electric. Results: The NEMA NU2 recovery coefficient for the 15.43 mm and 12.43 mm diameter spheres were about the same within each scanner. The Philips Vereos and HRRT scanners had RC values of 108% and 104% respectively, while the GE Discovery 710 was 118% and the Siemens mCT was 126%. The Gemini TF was 76%. For the smallest hollow sphere of 3.95 mm, the RC were 6.6%, 3.6%, 13%, 8.9% and 6.1% for the Gemini TF, Vereos, Discovery 710, mCT and HRRT respectively. An anomalous increase in the RC for the Discovery 710 and mCT was found for sphere sizes 9.89 mm diameter spheres where the RC was 161% and 145% for each respectively. A related recovery coefficient parameter called RC I which measures the recovery coefficient of the integrated activity in the spheres did not show this anomaly of increased recovery above 100% at the 9.89 mm sphere diameter measurement. Conclusion: The recovery coefficient data resulting from scanning five different scanners is presented. An increase in the recovery coefficient is seen in two scanners which is possibly due to over correction by the iterative reconstruction used to generate the images. This effect is not present when measuring the total activity in the sphere.

In this paper, a new technique has been developed to enable fibre diameters to be measured in an aqueous environment using the OFDA 2000 instrument. The existing OFDA instrument has only been used to measure diameters of animal fibres under dry conditions. This new technique was utilised to assess the effects of pH and temperature on the diameters of merino wool fibres in aqueous environments. Significant changes in fibre diameter under aqueous conditions were found as a function of pH and temperature. Wool fibre diameters were at a minimum close to the wool isoelectric point (pH 4.8) and increased at both lower and higher pHs. Swelling of merino wool fibres was observed to increase linearly by around 15% as the temperature rose from ambient to 70°C.

A novel diameter measurement device by laser scanning of which a flat-crystal was used as the core scanning part was designed. The device can generate high parallel scanning beam by means of the property that a beam won’t change its propagation direction after transmitting a flat-crystal. The influences on measurement error and range by using flat-crystal were analyzed in details. Theoretical analysis showed that the method was easy to realize and achieve high precision.

Electrospun nanofiber web has many potential applications due to its large specific area, very small pore size and high porosity. However, the mechanical properties of nanofiber web are very poor for use in textile application. To remedy this defect, the laminating process could accomplish in order to protect nanofiber web versus mechanical stresses. In this paper, direct tracking method as an image analysis based technique for measuring electrospun nanofiber diameter has been presented. The usefulness of the method for electrospun nanofiber diameter measurement is discussed. Such automated measurement of nanofiber diameter can be used to obtain better laminated webs.

The indentation diameter measurement is the important issue for Brinell hardness test. The large dependence of optical system is found in the first world-wide international comparison for Brinell hardness, conducted in 2005. After the comparison, some studies was carried out especially for this issue. Finally, the definition regarding the Brinell indentation edge was studied. However, the practical guide for good measurement condition of Brinell indentation diameter by using measurement microscope is not detailed explained. In this paper, we present the cause of the numerical aperture dependence of Brinell indentation diameter and also present the practical guideline of the selection of objective lens used to the observation.

A new method based on image analysis for electrospun nanofibre diameter measurement is presented. First, the SEM micrograph of the nanofibre web obtained by electrospinning process is converted to binary image using local thresholding method. In the next step, skeleton and distance transformed image are generated. Then, the intersection points which bring about untrue measurements are identified and removed from the skeleton. Finally, the resulting skeleton and distance transformed image are used to determine fibre diameter. The method is evaluated by a simulated image with known characteristics generated by ?-randomness procedure. The results indicate that this approach is successful in making fast, accurate automated measurements of electrospun fibre diameters.

This article describes a simple approach for diameter measurement of fine electrical wire using a high-resolution flatbed scanner and image analysis technique. Wire diameter measurement is normally carried out manually using a vernier caliper, micrometer, microscope, or profile projector. Such methods are difficult to use for checking small diameter wires in the micrometer range. A simple wire diameter measurement method was developed using a high-resolution flatbed scanner, a standard PC, and Matlab software. The specimen wire was placed at the center of the glass plate of the scanner and covered with a 2 mm thick glass sheet. The image was scanned in grayscale using scanning resolutions of 1200, 2400, and 3600 dpi. The measurement results obtained using the flatbed scanner were compared with those obtained using a profile projector. The maximum percentage difference between the two readings for the 3600 dpi resolution setting is 4.5%.

The use of an optical coordinate measuring machine (CMM) for the diameter measurement of optical apertures is described. The traceability and mechanical stability of the aperture areas are of importance for accurate photometric and radiometric measurements. Detailed evaluation of the measurement uncertainty for the aperture diameter is presented. High-accuracy mechanical CMM was used to confirm the validity of the optical CMM results. The difference between the contact and non-contact measurement was 0.1 µm for the mean diameter result. If the required standard uncertainty for the mean diameter is of the order of 1 µm, the optical CMM provides an efficient method for aperture area measurements.

A photon correlation spectroscopy (PCS) apparatus has been developed for measuring nanoparticles with diameters below 10nm by improving the individual components and the data reduction methods. The PCS is capable of sampling and storing photon counting data with multi-bit capability at the same time interval on each channel. We evaluated the performance of the new PCS apparatus: (1) accuracy of average size measurement as compared with a conventional PCS apparatus, (2) accuracy of particle size distribution measurement at a constant flow rate, and (3) ability for in-situ hydrodynamic diameter measurement for metallic single nanoparticles. Experimental results show that the newly developed PCS has an improved performance over the conventional PCS system for in-situ hydrodynamic diameter measurement for nanoparticles below 10nm in diameter.

We demonstrate a novel method which is simple, real-time, and non-destructive to measure the core diameter of a coaxial cylinder. An optical fiber is an example of coaxial cylinder. The diameter measurement method is based on side-light-incidence scattering principle. For a cladding diameter 126μm coaxial fiber, our method could be used to measure core diameter ranging from 8 to 40μm. We could measure the core diameter of a coaxial cylinder for cladding diameter varying from 50 μm to 125 μm from our database. The accuracy of core diameter measurement could reach over 95%.

A method for measuring diameters of metal cylinders is proposed. In this method a sinusoidally vibrating interference pattern (SVIP) of 100μm-period is used to generate an exact spatial scale along x-axis. Detection of the amplitude and the phase of the SVIP are carried out easily and exactly with sinusoidal phase-modulating interferometry. First, phase values of the SVIP on the pixels of the CCD image sensor are measured as the exact scale along the x-axis. Next, an image of the end-points of the cylinder surface is formed by extracting lights from the end-points of the cylinder. The phase of the SVIP on the end-point of the cylinder appears at a position where the amplitude of the image has maximum value along the x-axis. The x-coordinate of the end-point of the metal cylinder is calculated from the phase value of the end-point and the exact scale. The diameter is obtained from the x-coordinates of the two end-points. Metal cylinders of 9mm and 8mm-diameters are measured with an error of about ±2μm., ICO20: optical devices and instruments : 21-26 August 2005 : Changchun, China. : Aug 2005, Changchun, China

BACKGROUND The aims of the present study were to assess the effect of the stent diameter, convolution kernel, and vessel orientation to the z-axis on the evaluation of coronary stents, in vitro with computed tomography (CT) angiography. METHODS AND RESULTS Seven vascular models (2 models without stenosis, 2 with obstruction, and 3 with stenosis) with an approximate inner diameter of 3 or 4 mm, filled with contrast material (79 or 330 HU) were scanned with a 16-detector CT. The diameter measurement of the stent lumen and stenosis evaluation were both done in an orientation parallel to the z-axis of the scanner using 4 convolution kernels. The measured diameters of the stented lumen were 47-57% and 36-45% smaller than the actual inner diameter of the 3- and 4-mm diameter models, respectively. The diameter measurement of the stent lumen and visualization of the in-stent stenosis were improved by using convolution kernels with higher spatial resolution. The in-stent artifacts were evaluated in 4 orientations (0 degrees , 30 degrees , 60 degrees , 90 degrees ) to the z-axis. The artifact was the minimum in 0 degrees to the z-axis, and the maximum in 90 degrees . CONCLUSION Visualization of the lumen of a stent by CT is affected by its diameter, convolution kernel, and vessel orientation to the z-axis, and these factors should be taken into consideration in the stent evaluation.

According the diameter measurement of single crystal silicon in the growth process to put forward a diameter detection method that a circle defined by three points not in the same straight line. First, pretreat the growth image of single crystal silicon. Then, according the algorithm that a circle defined by three points not in the same straight line to extract the feature points, and the diameter pixel value of single crystal silicon accuratly detected. Finally transformed diameter pixel value into length value of the monocrystalline silicon rod through the measurement of diameter pixel value of draft tube. Tests show that error is very small between the test results and the true value, and meet the system requirements in a certain precision.

Retinal vessel diameters have been used to assess the vascular changes associated with possible systemic abnormality. The measured vessel lengths vary in different measurement protocols. This has impact on reliability of retinal vascular assessment but is lack of study. To study this impact, we developed a method to assess the diameter longitudinal change along the retinal vessel walls. Results demonstrate that the longer length of measured vessel has less variation and provides a more reliable result. It also suggests that the minimum measured vessel length should be over 400μm. This finding will be useful for the methodology and protocol development of retinal vessel diameter measurement.

Comparison measurements of the diameter of small ring gauges (0.1 mm to 1 mm) were carried out by six European national metrology institutes (NMIs). The participants applied different measurement principles: mechanical contacting measurement and optical measurement with respect to the projection of the inner diameter or with respect to the position of the cylinder edges. The uncertainties associated with the diameter measurement results vary considerably among the different participants, from U = 10 µm to U = 5 µm. In general the measurement results agree within their associated uncertainties, with the exception of the optical measurements of the position of the cylinder edges which exceed the reference values by between 10 µm and 30 µm, probably because of the lacerated edges of the ring gauges.

Interference of scattered light is easy and inexpensive to observe using a flashlight, mirror, and talcum powder. Using this phenomenon, the thickness of plastic wrap was measured using a light emitting diode point source.