간섭계를 이용한 나노 계단 형상 측정 및 레이저 안정화

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In this thesis, we introduced two experiments. One is height measurement of reference step with 93.1 nm thickness by using stabilized interferometer and FFT method, another one is laser stabilization and hyperfine structure measurement by using tilt locking method. The PID controller was employed in two experiments for stabilization system.
In order to measure the height measurement of reference, we developed a program in mathcad software. First we simulated FFT in 1D and 2D profile to check whether our generated mathcad codes are correct or not by using Tekeda and Kreis method. Before we did the simulation, we had introduced some basic knowledge about FFT and compared FFT with phase shift method. Then we used FFT method to measure the reference step height with thickness 93 nm in the highly windy environmental conditions. After obtaining the value of the reference step height, we compared it with the measurement in vibrationless conditions with commercial Mirau type interferometer using Accura2000 system. Except above contents, we also introduced some basic knowledge and procedure of tuning the parameters of PID controller so as to get the stabilization of Twyman-Green interferometer.
As the result, the reference step height with the thickness (93.1±1.2 nm) has been measured.
In another case, we introduced how to stabilize the frequency of diode laser using tilt locking technique. First we introduced the historical background of tilt locking method and drew the comparison between it with other traditional methods. We set up a Sagnac interferometer to create an error due to phase shift. Phase shift is derived from the changing of refractive index of atom. In order to demonstrate the principle clearly, the first two Hermite-Gauss modes TEM00 and TEM01 are introduced. The hyperfine manifolds [5²S_((1)/(2)) F3→F’=2, 3, 4, 5²P_((3)/(2))^(85)Rb] is obtained using the error signal finally. The PID controller is employed in the experiment with the Sagnac interferometer together to make up of the servo loop and get the modulation-free frequency locking of a diode laser. As the result, the laser frequency is stabilized up to sub-megahertz lev`el in the experiment.
Alternative Title
Nano Step Profile Measurement and Laser Stabilization by Using the Interferometer
Alternative Author(s)
Liu, Zhen
朝鮮大學校 大學院
일반대학원 광응용공학과
Awarded Date
Table Of Contents
Contents = Ⅰ
List of figures = Ⅲ
List of tables = Ⅵ
Introduction = 1
Ⅰ. Stabilization of surface measurement with Fast Fourier Transform method by PID controller = 4
1. The numerical simulation of surface profile measurement by Fast Fourier Transform method = 4
1.1 Introduction of Fast Fourier Transform method = 4
1.2 The simulation of the profile measurement in one-dimension = 16
1.3 The simulation of the profile measurement in two-dimensions = 33
2. The experiment and analysis of stabilization of surface profile(step height) measurement with FFT method by PID controller = 40
2.1 Introduction of PID controller = 40
2.2 Introduction of experiment = 45
2.3 The procedure of tuning the parameters of PID controller = 46
2.4 Discussion about the order of fringe stabilization = 48
2.5 Application of the PZT controller = 49
2.6 The results of the step height measurement with FFT method and roughness amplitude parameters = 52
2.7 Surface measurement by ACCURA system = 55
2.8 The comparison of the results between with stabilization and without stabilization, and comparison of results between by FFT method and by ACCURA 2000 system = 57
Ⅱ. The frequency stabilization of diode laser by PID controller = 59
3. The frequency stabilization of diode laser with PID controller = 59
3.1 Introduction and Principles = 59
3.1.1 Introduction = 59
3.1.2 Basic knowledge about characteristic of Rubidium = 60
3.2 Experimental setup and analysis for the results of experiment = 61
3.2.1 Tilt locking = 62
3.3 The set up of the experiment = 65
3.4 Results of the experiment and Discussion = 68
Acknowledgement = 73
References = 74
Appendix = 77
朝鮮大學校 大學院
류진. (2005). 간섭계를 이용한 나노 계단 형상 측정 및 레이저 안정화.
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General Graduate School > 3. Theses(Master)
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