Development of a dynamic surface shape measurement for magnetic fluid

2019 ◽  
Vol 66 ◽  
pp. 50-59
Author(s):  
Xining Zhang ◽  
Zhou Xiang ◽  
XinRui Xia ◽  
Haixing Zhang
Keyword(s):  
Magnetic Fluid ◽  
Surface Shape ◽  
Shape Measurement ◽  
Dynamic Surface

Modeling of the Dynamic Surface Profile in Magnetic Fluid Mirrors

2006 ◽  
Author(s):  
Azhar Iqbal ◽  
Foued Ben Amara
Keyword(s):  
Magnetic Field ◽  
Dynamic Response ◽  
Magnetic Fluid ◽  
Retinal Imaging ◽  
Surface Shape ◽  
Effective Control ◽  
Control Input ◽  
Mirror Surface ◽  
Dynamic Surface ◽  
Imaging Application

Magnetic fluid deformable mirrors (MFDMs) present a simple alternative to the expensive and delicate wavefront correctors currently in use in adaptive optics (AO) systems. Such mirrors are particularly suitable for retinal imaging AO systems. The practical implementation of a retinal imaging AO system incorporating a MFDM requires an effective control system to control the shape of the mirror surface. The real-time control of the mirror surface requires a model of the mirror that can be used to determine the dynamic response of the mirror to a magnetic field applied as the control input. This paper presents such a model that not only determines the dynamic response of the MFDM but also takes into account the unique requirements of the retinal imaging application of the mirrors. The mirror is modeled as a horizontal layer of a magnetic fluid. The dynamic response of the mirror to the applied magnetic field is represented by the deflection of the free surface of the layer. The surface deflection is determined by the modal analysis of the coupled fluid-magnetic system. Considering the requirements of the retinal imaging application, the effects of surface tension and depth of the fluid layer are duly represented in the model. The mirror model is described in a state-space form and can be readily used in the design of a controller to regulate the mirror surface shape.

New Method for Surface Shape Measurement Based on Brox Optical Flow Algorithm

2020 ◽  
Vol 40 (17) ◽  
pp. 1712004
Author(s):  
唐钰欣 Tang Yuxin ◽  
孙平 Sun Ping ◽  
代晴 Dai Qing ◽  
范超 Fan Chao ◽  
类智方 Lei Zhifang
Keyword(s):  
Optical Flow ◽  
Surface Shape ◽  
New Method ◽  
Shape Measurement ◽  
Flow Algorithm

PRECISE SHAPE MEASUREMENT OF DYNAMIC SURFACE VIA SINGLE CAMERA STEREO

2006 ◽  
Vol 03 (01) ◽  
pp. 53-60
Author(s):  
LUPING AN ◽  
YUNDE JIA ◽  
MINGTAO PEI ◽  
HONGBIN DENG
Keyword(s):  
Stereo Vision ◽  
Stereo Matching ◽  
Vision System ◽  
Least Square ◽  
Shape Measurement ◽  
Single Camera ◽  
Dynamic Surface ◽  
Moving Least Square ◽  
Stereo Vision System ◽  
Precise Shape

In this article, a method of the precise shape measurement of dynamic surfaces via a single camera stereo vision system is presented, a cross-curve pattern is painted on the surface of an object, and the intersections of cross-curves which represent the shape of the object are measured by the stereo vision system. The system with a single camera is modeled as a virtual binocular stereo by strong calibration technique. Binocular epipolar rectification is used to make the stereo matching efficient, and principal curves theory is employed to extract curves in images for stereo matching. Under the framework of RANSAC, the curves are interpolated robustly with cubic spline based on moving-least-square (MLS). Experimental results on both static and dynamic deforming surfaces illustrate the effectiveness of the proposed method.

Determination of Phase Shift by Digital Holography

2019 ◽  
Vol 888 ◽  
pp. 43-46
Author(s):  
Yoshitaka Takahashi ◽  
Masatoshi Saito ◽  
Toru Nakajima ◽  
Masakazu Shingu
Keyword(s):  
Phase Shift ◽  
Noise Reduction ◽  
Digital Holography ◽  
High Accuracy ◽  
Measured Data ◽  
Phase Shifting ◽  
Surface Shape ◽  
Shape Measurement ◽  
Phase Shifting Interferometry

In phase shifting interferometry phase shift is applied by various ways, but applying it with high accuracy, especially by LD current modulation, is not easy. In order to determine the accurate phase shift a new method has been proposed that the value of LD current corresponding to π/2 phase shift can be determined by phase shifting digital holography. The measured data of standard in surface shape measurement were used for calibration, and the obtained value was confirmed to cause noise reduction and improvement of holographic reconstructed images in digital holography.

Real-time surface shape measurement by an active interferometer

1997 ◽  
Vol 4 (1) ◽  
pp. A216-A220 ◽  
Author(s):  
Ji-Yuan Liu ◽  
Ichirou Yamaguchi ◽  
Jun-ichi Kato ◽  
Toshinori Nakajima
Keyword(s):  
Real Time ◽  
Surface Shape ◽  
Shape Measurement ◽  
Active Interferometer
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