Clear imaging specular surface and fringe patterns by using a concave mirror in phase measuring deflectometry

2021 ◽  
Author(s):  
Ziyu Li ◽  
Xiaohong Liu ◽  
Caixia Chang ◽  
Yanqing Shi ◽  
Nan Gao ◽  
...  
Keyword(s):  
Concave Mirror ◽  
Specular Surface ◽  
Fringe Patterns

scholarly journals A Calibration Method for System Parameters in Direct Phase Measuring Deflectometry

2019 ◽  
Vol 9 (7) ◽  
pp. 1444
Author(s):  
Xiaoting Deng ◽  
Nan Gao ◽  
Zonghua Zhang
Keyword(s):  
Liquid Crystal Display ◽  
Three Dimensional ◽  
Calibration Method ◽  
Concave Mirror ◽  
System Parameters ◽  
Dimensional Shape ◽  
Phase Map ◽  
Specular Objects ◽  
Fringe Patterns ◽  
Three Dimensional Shape

Phase measuring deflectometry has been widely studied as a way of obtaining the three-dimensional shape of specular objects. Recently, a new direct phase measuring deflectometry technique has been developed to measure the three-dimensional shape of specular objects that have discontinuous and/or isolated surfaces. However, accurate calibration of the system parameters is an important step in direct phase measuring deflectometry. This paper proposes a new calibration method that uses phase information to obtain the system parameters. Phase data are used to accurately calibrate the relative orientation of two liquid crystal display screens in a camera coordinate system, by generating and displaying horizontal and vertical sinusoidal fringe patterns on the two screens. The results of the experiments with an artificial specular step and a concave mirror showed that the proposed calibration method can build a highly accurate relationship between the absolute phase map and the depth data.

Stress Analysis of Tire Sections

1996 ◽  
Vol 24 (4) ◽  
pp. 349-366 ◽  
Author(s):  
T-M. Wang ◽  
I. M. Daniel ◽  
K. Huang
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Stress Analysis ◽  
Strain Analysis ◽  
Experimental Stress ◽  
Inflation Pressure ◽  
Substantial Agreement ◽  
Finite Element Stress Analysis ◽  
Strain Components ◽  
Fringe Patterns

Abstract An experimental stress-strain analysis by means of the Moiré method was conducted in the area of the tread and belt regions of tire sections. A special loading fixture was designed to support the tire section and load it in a manner simulating service loading and allowing for Moiré measurements. The specimen was loaded by imposing a uniform fixed deflection on the tread surface and increasing the internal pressure in steps. Moiré fringe patterns were recorded and analyzed to obtain strain components at various locations of interest. Maximum strains in the range of 1–7% were determined for an effective inflation pressure of 690 kPa (100 psi). These results were in substantial agreement with results obtained by a finite element stress analysis.

Image Processing Techniques Applied to Enhancement of Holographic Fringe Patterns

1996 ◽  
Vol 25 (1) ◽  
pp. 61-68
Author(s):  
A. G. Khadakkar ◽  
R. Madhana Sundari ◽  
R. Narayanan
Keyword(s):  
Image Processing ◽  
Image Processing Techniques ◽  
Fringe Patterns ◽  
Processing Techniques

scholarly journals Fringe Patterns

Nature ◽  
1970 ◽  
Vol 226 (5251) ◽  
pp. 1179-1180
Author(s):  
W. T. WELFORD
Keyword(s):  
Fringe Patterns

scholarly journals A Whole-Field Interferometric Scheme for Measuring strain and Flow Rates of Glacier and Other Natural Surfaces

1983 ◽  
Vol 29 (103) ◽  
pp. 492-497
Author(s):  
Gary Cloud ◽  
Edgar Conley
Keyword(s):  
Displacement Vector ◽  
Surface Displacement ◽  
Time Lapse ◽  
Speckle Interferometry ◽  
Narrow Beam ◽  
Coherent Light ◽  
Ice Surface ◽  
Glacier Ice ◽  
Fringe Patterns ◽  
Small Overlap

AbstractThe flow of glacier ice is mapped using high-resolution photography and non-coherent-light speckle interferometry. Young’s fringe patterns result when a double-exposed photoplate image of the straining surface is illuminated by a narrow beam of coherent light. Geometry gives a relationship between the ice surface displacement vector and the interference fringe patterns. This displacement vector is corrected for rigid-body (camera) movement and projected onto the ice surface using topological maps. The strain during the time-lapse interval is thus known. Comparison with data acquired by surveying techniques at Nisqually Glacier, Washington, U.S.A., is limited because of small overlap of the surface studied. In the areas for which results can be compared, our experiments yield a flow of 0.6 m/d where conventional methods yield about 0.4 m/d.

3D Profile Variety Measurement of Pectoral Fin in Fish Fast Start

2011 ◽  
Vol 83 ◽  
pp. 280-284
Author(s):  
Ming Jiang ◽  
Shu Zhang ◽  
Xiao Yuan He
Keyword(s):  
Fourier Transform ◽  
High Speed ◽  
Kinetic Characteristic ◽  
Three Dimensional ◽  
Pectoral Fin ◽  
Fourier Transform Profilometry ◽  
Fast Start ◽  
Fringe Patterns ◽  
3D Information ◽  
3D Profile

Fast-starts are brief, sudden accelerations used by fish during predator-prey encounters. In this paper, a three-dimensional (3D) test and analysis method is critical to understand the function of the pectoral fin during maneuvers. An experiment method based on Fourier Transform Profilometry for 3D pectoral fin profile variety during fish maneuvers is proposed. This method was used in a carp fast-start during prey. Projecting the moiré fringes onto a carp pectoral fin it will produce the deformed fringe patterns contain 3D information. A high speed camera captures these time-sequence images. By Fourier transform, filter, inverse Fourier transform and unwrap these phase maps in 3D phase space, the complex pectoral fin profile variety were really reconstructed. The present study provides a new method to quantify the analysis of kinetic characteristic of the pectoral fin during maneuvers.

Target resolvability from single-tone fringe patterns of digitally spotlighted SAR image

1998 ◽  
Author(s):  
Shih I. Chou ◽  
Michael E. Pollock ◽  
Mehrdad Soumekh
Keyword(s):  
Sar Image ◽  
Single Tone ◽  
Fringe Patterns
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