Browsing by Author "Lu, MH"

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A calcium vapor cell for atomic spectroscopy
(2002-11-01)
Huang, MS
;
Lu, MH
;
Shy, JT
;
物理研究所
;
光電工程學系
A calcium vapor cell used in laser spectroscopy usually suffers from calcium coating on the cell windows. To solve the problem, we add two mirrors in the cell to reflect the laser beam, then the calcium will coat on these mirrors instead of on the windows. Calcium coating degrades the reflectivity of the mirrors at the beginning, but the mirrors become calcium mirrors after a certain period of coating and their reflectivity will not change by further calcium coating. Using this cell in a conventional saturated-absorption spectroscopy, the observed saturated-absorption peak at 657 nm is about 2.4% of the probe beam power and its linewidth is below 300 kHz. Therefore, a portable secondary calcium-wavelength standard at 657 nm having an accuracy better than 1x10(-11) is possible. In addition, our cell has a continuous working time longer than 3 d and it can be easily extended to 10 d. (C) 2002 American Institute of Physics.
A two-stage up-convertor made of AgGaSe2 and beta-BBO crystals
(2000-01-01)
Wang, HW
;
Lu, MH
;
光電工程學系
;
Department of Photonics
A two-stage infrared up-convertor made of AgGaSe2 and beta-BBO crystals has been built up, that can up-convert the mid-infrared radiation of 11-16 mu m into the 0.8-mu m range where the sensitive photomultiplier can be used. This up-convertor is pumped with a near-infrared radiation of 1.7-1.8 mu m wavelength range generated by a beta-BBO optical parametric oscillator. In this experiment, we also measured the o-ray refractive index of AgGaSe2 in the 11-16 mu m mid-infrared range and extended the fitting range of the Sellmeier equation to the 16-mu m wavelength range.
Analysis of the focal characteristics of cylindrical lenses made of anisotropically dielectric material based on rigorous electromagnetic theory
(2003-05-01)
Dong, BZ
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Ye, JS
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Liu, J
;
Gu, BY
;
Yang, GZ
The focal characteristics of refractive cylindrical lenses made of anisotropically dielectric material (uniaxial crystal) are analysed based on rigorous electromagnetic theory and the boundary element method. The performances of the lenses with different f numbers are appraised for both incident waves of the TE (transverse electric) and TM (transverse magnetic) polarizations. Numerical results show that the focal performance of this kind of lens for the TE polarization and the TM polarization of incident light wave is a difference, in particular, different focal lengths, owing to the anisotropy of the material. However, for the conventional isotropic lens, the focal features for both the TE and TM polarizations are the same. It is anticipated that this new kind of lens proposed for the first time may serve as a light switching device with high speed used in the micro-optical communication.
Analysis on the depth of focus in flying optics
(1998-05-01)
Fang, CH
;
Lu, MH
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光電工程學系
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Department of Photonics
Based on a simplified model of Gaussian beam focusing, in which nontruncating, thin-lens, aberration-free, and on-axis optical systems are assumed and the thermal-lensing effect is neglected, a general and concise expression is derived to describe the variation of 1/e(2) radius of the focused beam as a function of input beam waist to lens spacing, lens-to-target plane spacing, input beam Rayleigh range, and focal length of lens. From this expression, we get the depth of focus (DOF) of flying optics with a fixed flying range, which is used as a merit function to determine the optimal solutions for system parameters. The results are very useful in the design and analysis of flying optics in laser material processing. Finally, a practical example describing the optimization of the output coupler for CO2 laser resonator is given. (C) 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)02505-7].
Design and fabrication of a dense wavelength division demultiplexer with grism structure
(2005-02-01)
Sze, JR
;
Lu, MH
;
光電工程學系
;
Department of Photonics
The implementation of a low-loss demultiplexer with a KRS-5 grism structure for a dense wavelength division demultiplexing (DWDDM) system in fiber communication is carried out. The system has 16 channels with wavelength spacing of 0.8 nm in the C-band wavelength region. This device is successfully fabricated by a precise plunge-cut diamond-turning technology. Numerical calculations and measurements indicate that this DWDDM is polarization independent and has higher optical efficiency and signal to noise ratio (SNR). (c) 2005 Society of Photo-Optical Instrumentation Engineers.
Design and fabrication of the diffractive phase element that synthesizes three-color pseudo-nondiffracting beams
(2002-12-01)
Sze, JR
;
Lu, MH
;
光電工程學系
;
Department of Photonics
The experimental implementation of the diffractive phase element (DPE) that synthesizes three-color psudo-nondiffracting beams (PNDBs) is described. This DPE is designed with the amplitude-phase retrieval method and fabricated by using optical contact lithography and reactive-ion etching (RIE). Measurements demonstrate that the fabricated DPE has the desired function, i.e., it forms a six-segment PNDB over a finite axial region and is monochromatic in each segment. (C) 2002 Society of Photo-Optical Instrumentation Engineers.
Direct focusing modifications of elliptical Gaussian beam by non-circular apertures
(1998-11-01)
Chan, SH
;
Shiue, SG
;
Lu, MH
;
光電工程研究所
;
Institute of EO Enginerring
For focusing the elliptical Gaussian beam directly, the effects of a non-circular aperture on the focusing properties are studied. The focusing properties for different shapes of apertures, which include a circle, an ellipse and a rectangle, are calculated and compared. Moreover, for different elliptical Gaussian beams, an empirical aperture selection rule that can be used to circularize the focusing spot is proposed. The energy transmission ratios are also considered in this paper.
Direct focusing modifications of elliptical Gaussian beam by non-circular apertures
(1998-11-01)
Chan, SH
;
Shiue, SG
;
Lu, MH
;
光電工程學系
;
Department of Photonics
For focusing the elliptical Gaussian beam directly, the effects of a non-circular aperture on the focusing properties are studied. The focusing properties for different shapes of apertures, which include a circle, an ellipse and a rectangle, are calculated and compared. Moreover, for different elliptical Gaussian beams, an empirical aperture selection rule that can be used to circularize the focusing spot is proposed. The energy transmission ratios are also considered in this paper.
Double-diffraction planar encoder by conjugate optics
(2005-02-01)
Kao, CF
;
Chang, CC
;
Lu, MH
;
光電工程學系
;
Department of Photonics
A planar encoder using conjugate optics is proposed for sensing the 2-D displacement of a 2-D grating. A Doppler frequency shift of diffracted light is generated when the grating moves. The optical conjugate path can compensate for the error arising from the relative tilt between the optical head and the scale (head-to-scale tilt). Additionally, the optical head is easily integrated, having high tolerance in component-to-component placement. The 2-D displacement system with the 2-D grating, which has period of 1.6 mu m in both the X and Y directions, provides a signal period of 0.4 mu m by using a double-diffraction configuration. This system and associated electronics provide interpolation with a factor of 400, corresponding to a measurement resolution of 1 nm. (c) 2005 Society of Photo-Optical Instrumentation Engineers.
First-order analysis of a three-lens afocal zoom system
(1997-04-01)
Yeh, MS
;
Shiue, SG
;
Lu, MH
;
交大名義發表
;
光電工程學系
A general analysis for the first-order design of a three-lens afocal zoom system with one lens fixed is presented. The reasonable solution areas in the focal length diagrams with positive or negative magnification are derived and shown graphically. The relation between the two separations of the three lenses in zooming is found to be a hyperbola. According to the different locations of hyperbola centers, four cases are analyzed. From the four hyperbolic graphs, we get five different types of zoom systems. For each zoom type, we find the maximum range of magnification and the position where the maximum or minimum system length occurs during zooming. The zoom loci for the first or second lens fixed are also discussed. (C) 1997 Society of Photo-Optical Instrumentation Engineers.
First-order analysis of a three-lens afocal zoom system
(1997-04-01)
Yeh, MS
;
Shiue, SG
;
Lu, MH
;
光電工程研究所
;
Institute of EO Enginerring
A general analysis for the first-order design of a three-lens afocal zoom system with one lens fixed is presented. The reasonable solution areas in the focal length diagrams with positive or negative magnification are derived and shown graphically. The relation between the two separations of the three lenses in zooming is found to be a hyperbola. According to the different locations of hyperbola centers, four cases are analyzed. From the four hyperbolic graphs, we get five different types of zoom systems. For each zoom type, we find the maximum range of magnification and the position where the maximum or minimum system length occurs during zooming. The zoom loci for the first or second lens fixed are also discussed. (C) 1997 Society of Photo-Optical Instrumentation Engineers.
First-order analysis of a three-lens zoom system with the last lens fixed
(1998-02-01)
Yeh, MS
;
Shiue, SG
;
Lu, MH
;
光電工程學系
;
Department of Photonics
A general analysis for the first-order solutions of three-lens zoom system with the last lens fixed is presented. The reasonable solution areas in the focal length diagrams are derived and shown graphically. The relation between the separation of the two front lenses and the image distance of middle lens in zooming is found to be a hyperbola. According to the different locations of centre of hyperbola, four cases are analysed. From the four hyperbolic graphs, we get six different types of zoom system. For each zoom type, we find the maximum range of focal length and the position where the maximum or minimum system length occurs during zooming.
First-order analysis of a two-conjugate zoom system
(1996-11-01)
Yeh, MS
;
Shiue, SG
;
Lu, MH
;
光電工程學系
;
Department of Photonics
A general analysis for the first-order design of the two-conjugate zoom system, which consists of three lenses and has a real or virtual image, is presented. The design formulas are derived. Of two-conjugate zoom systems, we analyze the solution areas in the system parameter diagrams under two particular initial conditions in which the object/image and pupil magnifications of the middle lens are taken to be 1 and -1 or -1 and 1. Two design methods are proposed. Several examples are given to demonstrate the proposed design procedures. (C) 1996 Society of Photo-Optical Instrumentation Engineers.
High resolution planar encoder by retro-reflection
(2005-08-01)
Kao, CF
;
Lu, SH
;
Lu, MH
;
光電工程學系
;
Department of Photonics
This investigation presents a planar diffractive laser encoder system (PDLENS), which serves as a two-dimensional (2D) position detection apparatus for precision machine applications. Traditional 2D position detection utilizes a pair of linear encoders in crossed construction and so maintaining the perpendicularity between this pair of encoders is difficult. Besides, the rigorous alignment requirements among various components of the encoder system impose a serious user adaptation bottleneck. Of all alignment tolerances, the head-to-scale alignment tolerance is the most important problem for applications. In this work, a 2D grating is employed as the scale and the PDLENS is based on the retro-reflection configuration. Therefore the new encoder can provide good perpendicularity and tolerate larger alignment errors than the conventional encoder does. The grating pitch is 1.6 mu m and the period of the output signal is 0.4 mu m due to the double diffraction. Electronic interpolation with a factor of 400 leads to a readout resolution of 1 nm. The new encoder and a capacitive sensor were employed to simultaneously measure a circular motion with a radius of 1 mu m generated by a piezo stage. Comparing the measured positions, the deviation is less than 30 nm and the repeatability is better than 8 nm. (c) 2005 American Institute of Physics.
High sensitivity bulk electro-optic modulator field sensor for high voltage environments
(2004-12-01)
Huang, MS
;
Lu, MH
;
Shy, JT
;
光電工程學系
;
Department of Photonics
An optical electric field sensor is an effective instrument for surveying the electric or magnetic field around a high voltage electrical system. A Mach-Zender interferometer type modulator is generally used in this kind of sensor. The sensor has good sensitivity to electric or magnetic fields, but an unexpected high field could easily destroy the modulator owing to its short electrode separation. A bulk modulator usually has long separation between the two electrodes, which can prevent modulator breakdown, but its sensitivity is usually worse than the Mach-Zender interferometer type sensor. To solve this problem, a Fabry-Perot cavity is used to improve the sensitivity of the bulk modulator type sensor. This work also discusses the optimization of the sensor sensitivity. When the sensor works on the point where a cavity resonance has maximal slope, the proposed sensor has approximately the same sensitivity for sensing a field as the Mach-Zender interferometer type sensor. (C) 2004 American Institute of Physics.
Locating faults on cables by applying the principle of the transmission line oscillator
(2003-05-01)
Liu, WC
;
Lu, MH
;
光電工程學系
;
Department of Photonics
A new method for locating the break point of a cable has been developed. It operates by application of the principle of the transmission line oscillator. Coaxial cables of four different lengths (1.5 m, 5 m, 10 m, 20 m) were measured in accordance with this method. The results show high precision (deviation <0.5 cm) and accuracy (error &LE;3 cm).
Method of solving a triplet comprising a singlet and a cemented doublet with given primary aberrations
(1997-07-01)
Chen, CH
;
Shiue, SG
;
Lu, MH
;
交大名義發表
;
光電工程學系
A simple algebraic algorithm is proposed as a computational tool for the thin-lens design of a triplet which consists of a singlet and a cemented doublet. The triplet is required to yield specified amounts of lens power, primary spherical aberration, central coma, longitudinal chromatic aberration and secondary spectrum. The three element powers of the triplet are first obtained by solving the simultaneous linear equations of the total lens power, longitudinal chromatic aberration and secondary spectrum. A quadratic equation is obtained by combining the equations of spherical aberration and central coma, and the lens shapes are then obtained by solving this quadratic equation. The solving process is purely algebraic and is therefore easy to calculate and guarantees that all the solutions can be found.
Method of solving a triplet comprising a singlet and a cemented doublet with given primary aberrations
(1997-07-01)
Chen, CH
;
Shiue, SG
;
Lu, MH
;
光電工程研究所
;
Institute of EO Enginerring
A simple algebraic algorithm is proposed as a computational tool for the thin-lens design of a triplet which consists of a singlet and a cemented doublet. The triplet is required to yield specified amounts of lens power, primary spherical aberration, central coma, longitudinal chromatic aberration and secondary spectrum. The three element powers of the triplet are first obtained by solving the simultaneous linear equations of the total lens power, longitudinal chromatic aberration and secondary spectrum. A quadratic equation is obtained by combining the equations of spherical aberration and central coma, and the lens shapes are then obtained by solving this quadratic equation. The solving process is purely algebraic and is therefore easy to calculate and guarantees that all the solutions can be found.
Method of solving cemented triplets with given primary aberrations
(1997-04-01)
Chen, CH
;
Shiue, SG
;
Lu, MH
;
交大名義發表
;
光電工程學系
An effective algorithm is proposed for solving the structure of thin-lens cemented triplets which consist of three different glass types and have the given target values of power, primary spherical aberration, coma and longitudinal chromatic aberration. The formulae for the aberrations are combined with the power formula into a fifth-order polynomial equation in one variable, whose roots can all be solved by a combination of numerical and algebraic methods.
Method of solving cemented triplets with given primary aberrations
(1997-04-01)
Chen, CH
;
Shiue, SG
;
Lu, MH
;
光電工程研究所
;
Institute of EO Enginerring
An effective algorithm is proposed for solving the structure of thin-lens cemented triplets which consist of three different glass types and have the given target values of power, primary spherical aberration, coma and longitudinal chromatic aberration. The formulae for the aberrations are combined with the power formula into a fifth-order polynomial equation in one variable, whose roots can all be solved by a combination of numerical and algebraic methods.