Browsing by Author "Chen, Yen-Liang"

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A method for measuring the geometrical topography of a Rockwell diamond indenter
(2010-01-01)
Chen, Yen-Liang
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Su, Der-Chin
;
光電工程學系
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Department of Photonics
Firstly, a Rockwell diamond indenter tip is tested at different angles and positions by using a scanning white light interferometer, and several image data are obtained. Then, these data are merged together to form the associated geometrical topography with the image stitching method. Moreover, both the tip radius and the cone angle can be obtained with the least-squares Gauss-Newton sphere and cone fitting algorithm. Its validity is demonstrated.
Alternative method for measuring the full-field refractive index of a gradient-index lens with normal incidence heterodyne interferometry
(2010-12-20)
Chen, Yen-Liang
;
Hsieh, Hung-Chih
;
Wu, Wang-Tsung
;
Chang, Wei-Yao
;
Su, Der-Chin
A linearly/circularly polarized heterodyne light beam coming from a heterodyne light source with an electro-optic modulator in turn enters a modified Twyman-Green interferometer to measure the surface plane of a GRIN lens. Two groups of periodic sinusoidal segments recorded by a fast complementary metal-oxide semiconductor camera are modified, and their associated phases are derived with the unique technique. The data are substituted into the special equations derived from the Fresnel equations, and the refractive index can be obtained. When the processes are applied to other pixels, the full-field refractive-index distribution can be obtained similarly. Its validity is demonstrated. (C) 2010 Optical Society of America
An alternative bend-testing technique for a flexible indium tin oxide film
(2010-12-01)
Chen, Yen-Liang
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Hsieh, Hung-Chih
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Wu, Wang-Tsung
;
Wen, Bor-Jiunn
;
Chang, Wei-Yao
The two-dimensional refractive index distribution of a flexible indium tin oxide film deposited on a PET layer is measured before/after the bend-testing with an alternative technique based on Fresnel equations and the heterodyne interferometry. Their standard deviations are derived and they vary more obviously than the resistance variations measured in the conventional method. Hence the standard deviation of the refractive index can be used as the indicator to justify the durability of a flexible indium tin oxide film. The validity is demonstrated. (C) 2010 Elsevier B.V. All rights reserved.
Full-field measurement of the phase retardation for birefringent elements by using common path heterodyne interferometry
(2009-03-01)
Chen, Yen-Liang
;
Su, Der-Chin
;
光電工程學系
;
Department of Photonics
A collimated heterodyne light passes through the tested material and an analyzer, full-field interference signals are taken by a fast CMOS camera. The series of interference intensities recorded at any pixel are the sampling points of a sinusoidal signal. From those points, the associated argument of that pixel can be derived by a least-square sine fitting algorithm on IEEE 1241 Standards. Subtracting the average argument of the reference signal, the phase retardation of that pixel can be obtained. The phase retardations of other pixels can be obtained similarly. Its validity is demonstrated. (C) 2008 Elsevier Ltd. All rights reserved
Full-field refractive index distribution measurement of a gradient-index lens with heterodyne interferometry
(2010-10-01)
Hsieh, Hung-Chih
;
Chen, Yen-Liang
;
Wu, Wang-Tsung
;
Chang, Wei-Yao
;
Su, Der-Chin
A light beam coming from a circular heterodyne light source with an electro-optic modulator is incident on a gradient-index lens obliquely. The reflected light passes through an analyzer and an imaging lens, and is recorded by a fast CMOS camera. A group of periodic sinusoidal segments recorded by each pixel is modified, and its associated phase is derived with a unique technique. The processes are applied to other pixels; the two-dimensional phase distribution can be obtained similarly. The estimated data are substituted into the special equations derived from Fresnel's equations, and the full-field refractive index distribution of the gradient-index lens can be obtained. This method has the merits of both common-path interferometry and heterodyne interferometry.
Full-field refractive index distribution measurement of a gradient-index lens with heterodyne interferometry
(2010-10-01)
Hsieh, Hung-Chih
;
Chen, Yen-Liang
;
Wu, Wang-Tsung
;
Chang, Wei-Yao
;
Su, Der-Chin
A light beam coming from a circular heterodyne light source with an electro-optic modulator is incident on a gradient-index lens obliquely. The reflected light passes through an analyzer and an imaging lens, and is recorded by a fast CMOS camera. A group of periodic sinusoidal segments recorded by each pixel is modified, and its associated phase is derived with a unique technique. The processes are applied to other pixels; the two-dimensional phase distribution can be obtained similarly. The estimated data are substituted into the special equations derived from Fresnel's equations, and the full-field refractive index distribution of the gradient-index lens can be obtained. This method has the merits of both common-path interferometry and heterodyne interferometry.
High-accuracy thickness measurement of a transparent plate with the heterodyne central fringe identification technique
(2011-07-20)
Wu, Wang-Tsung
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Hsieh, Hung-Chih
;
Chang, Wei-Yao
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Chen, Yen-Liang
;
Su, Der-Chin
In a modified Twyman-Green interferometer, the optical path variation is measured with the heterodyne central fringe identification technique, as the light beam is focused by a displaced microscopic objective on the front/rear surface of the test transparent plate. The optical path length variation is then measured similarly after the test plate is removed. The geometrical thickness of the test plate can be calculated under the consideration of dispersion effect. This method has a wide measurable range and a high accuracy in the measurable range. (c) 2011 Optical Society of America
Improved technique for measuring full-field absolute phases in a common-path heterodyne interferometer
(2010-09-01)
Chen, Yen-Liang
;
Su, Der-Chin
;
光電工程學系
;
Department of Photonics
When an asymmetric triangle voltage signal is applied to drive an electro-optic modulator, interference signals with two groups of periodic sinusoidal segments with different frequencies are obtained. An improved method is proposed to fit these two groups of segments, and their associated phases can be determined. The absolute phase can be obtained by subtracting the initial phase from the phases of these two groups. This technique is applied to all pixels, and the full-field absolute phase measurements can be achieved. The validity of this method is demonstrated. (c) 2010 Optical Society of America
Investigation of Polarization Hysteresis and Transient Current Switching in Ferroelectric Aluminum-Doped Hafnium Oxides
(2018-01-01)
Liu, Chien
;
Fan, Chia-Chi
;
Tseng, Chih-Yang
;
Hsu, Hsiao-Hsuan
;
Cheng, Chun-Hu
In this work, we investigated ferroelectric and antiferroelectric effects in ferroelectric HfAIO capacitor with various aluminum doping concentrations. With the increase of aluminum doping concentration, the transition from ferroelectric to weak anti-ferroelectric properties can be observed by measuring polarization hysteresis and transient current response. The experimental results prove that the aluminum doping concentration of HfAIO material not only affects the ferroelectric-antiferroelectric transition, but also determine the leakage issue during domain switching.
Method for determining full-field absolute phases in the common-path heterodyne interferometer with an electro-optic modulator
(2008-12-10)
Chen, Yen-Liang
;
Su, Der-Chin
;
光電工程學系
;
Department of Photonics
When a sawtooth voltage signal with the amplitude lower than its half-wave voltage is applied to drive an electro-optic modulator, the interference signals become a group of periodic sinusoidal segments. A new algorithm is proposed to modify these segments to an associated continuous sinusoidal wave, and then its initial phase can be determined. Subtracting the characteristic phase of the modulator from the initial phase, the absolute phase can be obtained. This technique is applied to all pixels, and full-field absolute phase measurements can be achieved. The validity of this method is demonstrated. (c) 2008 Optical Society of America.
Method for gauge block measurement with the heterodyne central fringe identification technique
(2010-06-01)
Wu, Wang-Tsung
;
Chen, Yen-Liang
;
Hsieh, Hung-Chih
;
Chang, Wei-Yao
;
Su, Der-Chin
In a modified Michelson interferometer, the top face of the wringing platen is first identified using the heterodyne central fringe identification technique. Then the reference mirror located in the other arm is moved by a precision translation stage until the top face of the tested gauge block is also identified with the same technique. The displacement of the mirror is exactly equivalent to the length of the tested gauge block. The measurable range of the interferometer relates to the maximum travel range of the translation stage and its uncertainty depends on the uncertainty of the heterodyne central fringe identification method and the resolution of the translation stage. (C) 2010 Optical Society of America
Monitoring Debris Flows Using Spatial Filtering and Entropy Determination Approaches
(2013-10-01)
Kao, Hung-Ming
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Ren, Hsuan
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Lee, Chao-Shing
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Chen, Yen-Liang
;
Lin, Yen-Shuo
We developed an automatic debris flow warning system in this study. The system uses a fixed video camera mounted over mountainous streams with a high risk for debris flows. The focus of this study is to develop an automatic algorithm for detecting debris flows with a low computational effort which can facilitate real-time implementation. The algorithm is based on a moving object detection technique to detect debris flow by comparing among video frames. Background subtraction is the kernel of the algorithm to reduce the computational effort, but non-rigid properties and color similarity of the object and the background color introduces some difficulties. Therefore, we used several spatial filtering approaches to increase the performance of the background subtraction. To increase the accuracy entropy is used with histogram analysis to identify whether a debris flow occurred. The modified background subtraction approach using spatial filtering and entropy determination is adopted to overcome the error in moving detection caused by non-rigid and similarities in color properties. The results of this study show that the approach described here can improve performance and also reduce the computational effort.
Nano-roughness measurements with a modified Linnik microscope and the uses of full-field heterodyne interferometry
(2008-12-01)
Chen, Yen-Liang
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Jian, Zhi-Cheng
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Hsieh, Hung-Chih
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Wu, Wang-Tsung
;
Su, Der-Chin
A collimated heterodyne light enters a modified Linnik microscope, and the full-field interference signals are taken by a fast CMOS camera. The sampling intensities recorded at each pixel are fitted to derive a sinusoidal signal, and its phase can be obtained. Next, the 2-D phase unwrapping technique is applied to derive the 2-D phase distribution. Then, Ingelstam's formula is used to calculate the height distribution. Last, the height distribution is filtered with the Gaussian filter, the roughness topography and its average roughness can be obtained and its validity is demonstrated. (c) 2008 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3050357]
Optimal condition for full-field heterodyne interferometry
(2007-11-01)
Jian, Zhi-Cheng
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Chen, Yen-Liang
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Hsieh, Hung-Chih
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Hsieh, Po-Jen
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Su, Der-Chin
An area scan digital camera is used to record the full-field heterodyne interference signals, and the processes to derive the associated phases from the data of the recorded frames under a convenient condition are described. By calculating the possible errors under several different cases, an optimal condition to get better results is proposed. (c) 2007 Society of Photo-Optical Instrumentation Engineers.
Optimal sampling conditions for a commonly used charge-coupled device camera in the full-field heterodyne interferometry
(2011-04-01)
Hsieh, Hung-Chih
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Wu, Wang-Tsung
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Chang, Wei-Yao
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Chen, Yen-Liang
;
Su, Der-Chin
The processes to derive the associated phase of an interference signal from the data of a series of recorded frames are performed, and we find that the sampling frequency being lower than the Nyquist sampling rate can also be applied to the full-field heterodyne interferometry. Two optimal sampling conditions for a commonly used CCD camera are proposed based on the relation between the heterodyne frequency and the contrast of the interference signal under the condition that the phase error is set to be 0.05 deg. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.356712]
Two-wavelength full-field heterodyne interferometric profilometry
(2009-02-01)
Hsieh, Hung-Chih
;
Chen, Yen-Liang
;
Jian, Zhi-Chen
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Wu, Wang-Tsung
;
Su, Der-Chin
An alternative full-field interferometric profilometry is proposed by combining two-wavelength interferometry and heterodyne interferometry. A collimated heterodyne light is introduced into a modified Twyman-Green interferometer, the full-field interference signals are taken by a fast CMOS camera. The sampled intensities recorded by each pixel are fitted to derive a sinusoidal signal with the least-square sine wave fitting algorithm, and its phase can be obtained. Comparing the phase of the reference point, the relative phase of the pixel can be calculated. Next, the same measurement is made again at a different wavelength. The relative phase with respect to the effective wavelength can be calculated and the profile of the tested sample can be derived with the two-wavelength interferometric technique. Its validity is demonstrated. It has merits of both two-wavelength interferometry and heterodyne interferometry.