Research on Subsurface Damage Layer Detection during Substrate Processing

2013 ◽  
Vol 797 ◽  
pp. 673-678
Author(s):  
Hai Zhou ◽  
Xiao Ming Xu ◽  
Xiang Gao ◽  
Huan Feng
Keyword(s):  
Aqueous Solution ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Crystal Surface ◽  
Surface Damage ◽  
Subsurface Damage ◽  
Damage Layer ◽  
Improve Measurement ◽  
Double Substrate ◽  
Substrate Processing

Double-substrate angle polishing is presented for detecting depth of sub-surface damage layer during sapphire substrate grind process. Bimorph overlap bond is used in the double-substrate angle polishing, and when measuring the beveled corrosion crack, measurement errors caused by the traditional angle polish which results in fussy boundaries between polished bevel and the edge of the original wafer plane is avoided. Also digital length measurement is used to measure specimens polished bevel machining contours, then calculate accurate slant angles, eliminate errors of inaccurate angle values and improve measurement accuracy. This experiment has tested the length of mono-crystal polished bevel crack is 175um, the angle of slant is 4.85°. According to theoretical calculation, the double-sided grinding substrate subsurface damage layer is 15um, and the depth of double-sided crystal surface is about 30um. Grinding parameters: 320# boron carbide aqueous solution, lapping pressure 110g/cm2, grinding speed 30r/min.

Research on the Distribution of Subsurface Damage Layer on SiC Substrate After Double-Side Lapping

2015 ◽  
Vol 14 (01) ◽  
pp. 1-10 ◽  
Author(s):  
Hai Zhou ◽  
Xiaoming Xu ◽  
Xiang Gao ◽  
Yuan Zhang
Keyword(s):  
Silicon Carbide ◽  
Surface Damage ◽  
Damage Mechanism ◽  
Processing Parameters ◽  
Subsurface Damage ◽  
Shape Measurement ◽  
Theoretic Model ◽  
Damage Layer ◽  
Silicon Carbide Substrate ◽  
Measurement Laser

In this paper, the surface damage mechanism of silicon carbide lapping process was studied. A theoretic model between the depth of subsurface damage and surface scratch of silicon carbide substrate double-side lapping has been built. An experiment of two-sided lapping combining VK-X100/X200 shape measurement laser microscopy system with HF mild chemical etching experiment on SiC substrate was processed to obtain the distribution of surface scratch and subsurface damage layer with depth. The study shows that the thickness of subsurface damage layer decreases as the depth increases, which centrally distributes in the depth of 0–15.6 μm from outer fragmentation and scratch damage layer, which accounted for about 98.6%. The result can help us to optimize processing parameters of silicon carbide substrate double-side lapping to control the depth of subsurface damage layer.

Research on Subsurface Damage of Lapping Sapphire with Diamond Fixed Abrasive

2020 ◽  
Vol 866 ◽  
pp. 143-151
Author(s):  
Jian Bin Wang ◽  
Yong Qiang Tong ◽  
Ben Chi Jiang ◽  
Da Shu ◽  
Gang Wang
Keyword(s):  
Surface Quality ◽  
Surface Damage ◽  
Subsurface Damage ◽  
Indentation Fracture ◽  
Damage Layer ◽  
Damage Depth ◽  
The Difference ◽  
Fixed Abrasive ◽  
Free Abrasive

The depth of surface/subsurface damage layer is the key index of surface quality of sapphire. In this paper, that depth model of the surface/subsurface damage lay characterized by the crack length was established according to the mechanical theory of indentation fracture. The cutting relation between abrasive and workpiece and the difference of the depth of subsurface damage crack are analyzed. It is preliminarily estimated that the length of sub-surface damage crack of free abrasive sapphire is about 2.46 times that of fixed abrasive when considering only the contact hardness of abrasive grain under static load. Diamond abrasives with size of W20 were adopted to carry out experiments in free and fixed lapping methods. The results show that the surface/subsurface damage depth is 9.87μm and 3.63μm respectively. It is easier to obtain good sub-surface quality by using the fixed abrasive method than free abrasive at the same particle size.

Error-Correction Processing in Timing Lights for Measuring Sprint Performance: Does It Work?

2018 ◽  
Vol 13 (10) ◽  
pp. 1400-1402
Author(s):  
Stefan Altmann ◽  
Steffen Ringhof ◽  
Benedikt Becker ◽  
Alexander Woll ◽  
Rainer Neumann
Keyword(s):  
Error Correction ◽  
Gold Standard ◽  
Measurement Errors ◽  
High Speed ◽  
Measurement Accuracy ◽  
Sprint Performance ◽  
Upper Body ◽  
High Speed Camera ◽  
Improve Measurement ◽  
Almost All

Purpose: To investigate if error-correction-processing (ECP) algorithms in timing lights are able to eliminate or reduce measurement errors (MEs) and false signals due to swinging arms or legs. Methods: First, a dummy was used to check if ECP generally works. Second, 15 male sport students performed sprints over 5 and 10 m. Timing lights with ECP and a high-speed camera as a gold standard were used to simultaneously capture the athletes when passing the timing lights at start, 5 m, and 10 m. MEs of the timing lights were calculated for hip and upper body. Results: The dummy condition revealed that ECP is able to eliminate MEs. In real sprint conditions, MEs were highest for timing light at start and when using the hip as a reference. Overall, out of 120 trials, only 4 false signals were not detected by ECP. They all occurred at the start timing light, with highest MEs being 0.263 s (hip) and 0.134 s (upper body). Regarding 5 and 10 m, all false signals were eliminated. Conclusions: As proven through video analyses, ECP eliminated almost all false signals. The largest MEs at the start timing light were associated with a distinct forward leaning of the athletes. Therefore, clear instructions concerning starting posture should be given to further improve measurement accuracy of the start timing light. This approach could also enhance comparisons between athletes. Nevertheless, based on the results, timing lights employing ECP can be recommended for measuring short sprints.

scholarly journals Effectiveness of Variable-Gain Kalman Filter Based on Angle Error Calculated from Acceleration Signals in Lower Limb Angle Measurement with Inertial Sensors

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Yuta Teruyama ◽  
Takashi Watanabe
Keyword(s):  
Kalman Filter ◽  
Lower Limb ◽  
Measurement Accuracy ◽  
Inertial Sensors ◽  
Angle Measurement ◽  
Angle Error ◽  
Variable Gain ◽  
Improve Measurement ◽  
Kalman Gain ◽  
Acceleration Signals

The wearable sensor system developed by our group, which measured lower limb angles using Kalman-filtering-based method, was suggested to be useful in evaluation of gait function for rehabilitation support. However, it was expected to reduce variations of measurement errors. In this paper, a variable-Kalman-gain method based on angle error that was calculated from acceleration signals was proposed to improve measurement accuracy. The proposed method was tested comparing to fixed-gain Kalman filter and a variable-Kalman-gain method that was based on acceleration magnitude used in previous studies. First, in angle measurement in treadmill walking, the proposed method measured lower limb angles with the highest measurement accuracy and improved significantly foot inclination angle measurement, while it improved slightly shank and thigh inclination angles. The variable-gain method based on acceleration magnitude was not effective for our Kalman filter system. Then, in angle measurement of a rigid body model, it was shown that the proposed method had measurement accuracy similar to or higher than results seen in other studies that used markers of camera-based motion measurement system fixing on a rigid plate together with a sensor or on the sensor directly. The proposed method was found to be effective in angle measurement with inertial sensors.

Double-sided and single-sided polished 6H-SiC wafers with subsurface damage layer studied by Mueller matrix ellipsometry

2020 ◽  
Vol 128 (23) ◽  
pp. 235304
Author(s):  
Huihui Li ◽  
Changcai Cui ◽  
Subiao Bian ◽  
Jing Lu ◽  
Xipeng Xu ◽  
...  
Keyword(s):  
Mueller Matrix ◽  
Subsurface Damage ◽  
Damage Layer

Research on Data Aggregation Algorithms Based on OPT in Wireless Sensor Networks

2013 ◽  
Vol 427-429 ◽  
pp. 1991-1994
Author(s):  
Xue Wen He ◽  
Le Ping Zheng ◽  
Kuan Gang Fan ◽  
Sun Han ◽  
Qing Mei Cao
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Data Aggregation ◽  
Measurement Accuracy ◽  
Wireless Sensor ◽  
Data Traffic ◽  
Fusion Model ◽  
Design Goal ◽  
Improve Measurement ◽  
Battery Energy

Since wireless sensor networks consist of sensors with limited battery energy, a major design goal is to maximize the lifetime of sensor network. To improve measurement accuracy and prolong network lifetime, reducing data traffic is needed. In the clustering-based wireless sensor networks, a novel data aggregation algorithm based on OPT and Layida Method is proposed. In the proposed method, Layida Method preprocesses data and data fusion model for data integration are used. Its availability is proved by comparing with the results of two existing algorithms.

scholarly journals Nondestructive Evaluation of Functionally Graded Subsurface Damage on Cylinders in Nuclear Installations Based on Circumferential SH Waves

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Zhen Qu ◽  
Xiaoqin Shen ◽  
Xiaoshan Cao
Keyword(s):  
Mechanical Properties ◽  
Phase Velocity ◽  
Nondestructive Evaluation ◽  
Surface Damage ◽  
Subsurface Damage ◽  
Functionally Graded ◽  
Horizontal Shear ◽  
Steel Cylinder ◽  
Sh Waves ◽  
Subsurface Layers

Subsurface damage could affect the service life of structures. In nuclear engineering, nondestructive evaluation and detection of the evaluation of the subsurface damage region are of great importance to ensure the safety of nuclear installations. In this paper, we propose the use of circumferential horizontal shear (SH) waves to detect mechanical properties of subsurface regions of damage on cylindrical structures. The regions of surface damage are considered to be functionally graded material (FGM) and the cylinder is considered to be a layered structure. The Bessel functions and the power series technique are employed to solve the governing equations. By analyzing the SH waves in the 12Cr-ODS ferritic steel cylinder, which is frequently applied in the nuclear installations, we discuss the relationship between the phase velocities of SH waves in the cylinder with subsurface layers of damage and the mechanical properties of the subsurface damaged regions. The results show that the subsurface damage could lead to decrease of the SH waves’ phase velocity. The gradient parameters, which represent the degree of subsurface damage, can be evaluated by the variation of the SH waves’ phase velocity. Research results of this study can provide theoretical guidance in nondestructive evaluation for use in the analysis of the reliability and durability of nuclear installations.

A weighted fusion method with multi-system for improving measurement accuracy of structured light 3D profilometry

2021 ◽  
Author(s):  
Chao Xing ◽  
Junhui Huang ◽  
Zhao Wang ◽  
Jianmin Gao
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Structured Light ◽  
Profile Measurement ◽  
Complex Surfaces ◽  
3D Profilometry ◽  
Weighted Fusion ◽  
Multiple Measurements ◽  
Geometric Relationship ◽  
3D Profile

Abstract It is a challenge to improve the accuracy of 3D profile measurement based on binary coded structured light for complex surfaces. A new method of weighted fusion with multi-system is presented to reduce the measurement errors due to the stripe grayscale asymmetry, which is based on the analysis of stripe center deviation related to surface normal and the directions of incident and reflected rays. First, the stripe center deviation model is established according to the geometric relationship between the stripe center deviation, the incident and reflected angles at any measured point. The influence of each variable on stripe center deviation is analyzed, and three subsystems are formed by a binocular structured light framework to achieve multiple measurements based on the influence regularity. Then in order to improve the measurement accuracy, different weights are assigned to the measured point in different subsystems according to the stripe center deviation model and its relationship with measurement error, and the weighted data from different subsystems are fused. Experiments are carried out to validate the presented method, and the experimental results demonstrate that it effectively improves the measurement accuracy of complex surfaces and measurement accuracy is improved by about 27% compared with the conventional method.

scholarly journals The Effect of Deflections and Elastic Deformations on Geometrical Deviation and Shape Profile Measurements of Large Crankshafts with Uncontrolled Supports

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5714
Author(s):  
Krzysztof Nozdrzykowski ◽  
Stanisław Adamczak ◽  
Zenon Grządziel ◽  
Paweł Dunaj
Keyword(s):  
Correlation Analysis ◽  
Quantitative Assessment ◽  
Measurement Accuracy ◽  
Qualitative Comparison ◽  
Elastic Deformations ◽  
Point Support ◽  
Improve Measurement ◽  
Amplitude Spectra ◽  
Geometric Deviations ◽  
Multi Criteria Analysis

This article presents a multi-criteria analysis of the errors that may occur while measuring the geometric deviations of crankshafts that require multi-point support. The analysis included in the paper confirmed that the currently used conventional support method—in which the journals of large crankshafts rest on a set of fixed rigid vee-blocks—significantly limits the detectability of their geometric deviations, especially those of the main journal axes’ positions. Insights for performing practical measurements, which will improve measurement procedures and increase measurement accuracy, are provided. The results are presented both graphically and as discrete amplitude spectra to make a visual, qualitative comparison, which is complemented by a quantitative assessment based on correlation analysis.

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