Browsing by Author "Su, Der-Chin"

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4-Port polarization-independent wavelength-interleaving bidirectional circulator
(2008-01-15)
Hsieh, Po-Jen
;
Chen, Jing-Heng
;
Hsieh, Hung-Chih
;
Jian, Zhi-Cheng
;
Su, Der-Chin
This study develops an alternative type of 4-port polarization-independent wavelength-interleaving bidirectional circulator. In this circulator the even- and odd-channels circulate with opposite handedness regardless of the state of polarization of signals. It has a pair of orthogonal holographic spatial- and polarization modules (HSPMs) and a Lyot-Ohman filter (LOF). Each HSPM has two holographic spatial walk-off polarizers (HSWPs), two glass plates and two half-wave plates. The function of the HSWJP is firstly described. Next, the structures and the operating principles of the HSPM and the LOF are also described. Then, the operating principle and the performance of this circulator are discussed. It has such merits as polarization-independence, compactness, high isolation, lack of polarization mode dispersion and ease of fabrication. (c) 2007 Elsevier B.V. All rights reserved.
A method for measuring the geometrical topography of a Rockwell diamond indenter
(2010-01-01)
Chen, Yen-Liang
;
Su, Der-Chin
;
光電工程學系
;
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.
A method for measuring two-dimensional refractive index distribution with the total internal reflection of p-polarized light and the phase-shifting interferometry
(2006-12-01)
Jian, Zhi-Cheng
;
Hsieh, Po-Jen
;
Hsieh, Hung-Chih
;
Chen, Huei-Wen
;
Su, Der-Chin
Based on the total internal reflection of p-polarized light and the phase-shifting interferometry, an alternative method for measuring the two-dimensional refractive index distribution of a material is presented. The p-polarized light is incident on the boundary between a right-angle prism and a tested material. When the total internal reflection occurs at the boundary, and the p-polarized light has a phase variation. It depends on the refractive index of the tested material. Firstly, the two-dimensional phase variation distribution of the p-polarized light at the boundary is measured by the four-step phase shifting interferometric technique. Then, substituting the data into the special equations derived from Fresnel equations, the two-dimensional refractive index distribution of the tested material can be obtained. (c) 2006 Elsevier B.V. All rights reserved.
A new type of liquid refractometer
(2008)
Lin, Jiun-You
;
Chen, Jing-Heng
;
Chen, Kun-Huang
;
Su, Der-Chin
;
光電工程學系
A new liquid refractometer is proposed based on the phenomenon of total-internal reflection and the technique of heterodyne interferometry. A special designed glass probe is immersed in the tested liquid, and a light beam is guided within this probe due to the total internal reflections. After the light beam is totally reflected at the other end of the probe, it goes back in an anti-parallel direction of the original path. Because of multiple total-internal reflections, the phase difference, which is determined by the heterodyne interferometry between the p- and s-polarizations, is greatly enhanced to result in an accurate refractive index. The feasibility of this method was demonstrated by our experimental results, and a resolution of 5x10(-3) is obtained with our method. This method should, therefore, bear the merits of high accuracy, high stability, and easy operation.
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
;
Hsieh, Hung-Chih
;
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.
An alternative method for simultaneously measuring cell parameters of a twisted-nematic liquid crystal cell
(2008)
Chen, Kun-Huang
;
Chen, Jing-Heng
;
Lin, Jiun-You
;
Su, Der-Chin
;
Su, Jung-Chieh
A phase-sensitive method is developed to simultaneously measure the cell parameters of a TNLC (twisted-nematic liquid crystal) cell based on Jones calculus and the heterodyne interferometric ellisometry. These cell parameters include the twist angle, the cell gap, and the angle of the entrance LC director. When a circularly polarized heterodyne light beam normally passes through a TNLC cell, the phase difference between the p- and s- polarization of the interference signal can be measured accurately with an analyzer and the heterodyne interferometric ellisometry. The phase difference depends on the azimuth angle of the analyzer and the parameters. By substituting the measured values of the phase differences at three different azimuth angles of the analyzer into the special equations derived with Jones calculus. Hence these three para meters can be esitimated by using a personal computer with numerical analysis technique. Because of its common path optical configuration and its heterodyne interferometric ellisometry, this method has many merits such as high stability against the surrounding vibration, high resolution, and easy operation.
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
;
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
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
Multiport polarization-independent wavelength-interleaving bidirectional quasicirculator
(2008-05-01)
Hsieh, Po-Jen
;
Su, Der-Chin
;
光電工程學系
;
Department of Photonics
An alternative type of multiport polarization-independent wavelength-interleaving bidirectional quasicirculator is proposed. It contains holographic spatial and polarization modules (HMs), a Lyot-Ohman filter (LOF), a quarterwave plate, and a mirror. Each HM contains a holographic spatial walk-off polarizer, a half-wave plate, and a glass plate. The LOF consists of three half-wave plates and three identical pairs of crystals. The functions of the HM and the LOF are described. Then, the operating principle and the performance of this quasicirculator are described and discussed. In this circulator, the signals in the even and odd channels can circulate with opposite handedness regardless of signal polarizations. It offers a high isolation level, polarization independence, low polarization-mode dispersion, parallel input/output ports and ease of increasing the number of ports.(c) 2008 Society of Photo-Optical Instrumentation Engineers.
Nano-roughness measurements with a modified Linnik microscope and the uses of full-field heterodyne interferometry
(2008-12-01)
Chen, Yen-Liang
;
Jian, Zhi-Cheng
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Hsieh, Hung-Chih
;
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
;
Chen, Yen-Liang
;
Hsieh, Hung-Chih
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Hsieh, Po-Jen
;
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
;
Wu, Wang-Tsung
;
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]
Phase geographical map for determining the material type of a right-angle prism
(2006-09-10)
Chiu, Ming-Hung
;
Lai, Chih-Wen
;
Wang, Shinn-Fwu
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Su, Der-Chin
;
Chang, Springfield
A phase geographical map for determining a right-angle prism is presented. The proposed method is based on total-internal-reflection effects and chromatic dispersion. Under the total-internal-reflection condition, the phase difference between the S and P polarizations, as a function of the wavelength and refractive index, can be extracted and measured using heterodyne interferometry. Various wavelengths correspond to various refractive index values. The proposed map is convenient in ensuring the prism material using a specific V number. The method has the following merits: high stability, ease of operation, and rapid measurement. (c) 2006 Optical Society of America.
Two-wavelength full-field heterodyne interferometric profilometry
(2009-02-01)
Hsieh, Hung-Chih
;
Chen, Yen-Liang
;
Jian, Zhi-Chen
;
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.