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School of Mechanical EngineeringChung-Ang University
Micro/Nano Optical Engineering
1st week
Prof. Seok-min Kim
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School of Mechanical EngineeringChung-Ang University
Administrative DetailsInstructor : Prof. Seok-min Kim
Office : Bobst hall #429 E-mail : [email protected]
Tel. : 02-820-5877 Class Meeting Time and Place Thursday 7, 8, 9 ( Room # 234, Bldg. #207)Text bookMain : Lecture note (http://nmtl.cau.ac.kr)Sub : 1. Micro/Nano Replications
(http://book.naver.com/bookdb/book_detail.nhn?bid=6891416)2. Optics , Eugene Hecht, Addison Wesley
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Midterm exam : 45%, Final exam : 45 %, Others : 10%English Spoken Class
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Class scheduleDay Contents03/04 Introduction of Class03/11 Introduction of Optics
03/18 Image Formation Lens maker's formular03/25 Lens maker's formularPolarization/Retardation Plate 04/01 Reflection & Refraction Fresnel Equations 04/08 No. Class (Interference)04/15 Anti-Reflection Coatings High-Reflection Coatings 04/22 Mid Term Vacation
Week Contents04/29 Mid Term Exam.
05/06 Patterning technology for micro/nano optical components (2)05/13 Surface treatment technologies for micro/nano molding05/20 Micro/nano injection molding05/27 Thermal imprinting06/03 UV imprinting process06/10 Roll imprinting06/17 Final Exam.
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Introduction of Micro/Nano
Optical Engineering
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Introduction of Optics
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Fermat Principles
Fermat Principles- The path taken between two points ( A, B) by a ray
of light is the path that can be traversed in the least time (General definition)
Ray - Path along which light travels- Does the light go straight ?The light only goes straight in 1) homogeneous, 2) isotropic 3) uniform medium.
http://physica.gnu.ac.kr/phtml/optics/light/reflect/reflect.html
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What is Reflection ?Change in direction of a ray at an interface between two different media
Total path
Fermat Principles
Specular reflection Diffuse reflection
Law of reflection
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MirrorsPlanar MirrorsThe image formed by a plane mirror is always virtual () (meaning that the light rays do not actually come from the image), upright (), and of the same shape and size as the object it is reflecting
a = b, c = d
a b
c d
Normal vector
mirror
Virtual image
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Spherical Mirror(1)Spherical MirrorsFocal point is located at the half point of its radius. (focal point : light rays originating from the focal point becomes a collimating (parallel) ray after reflection)
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Spherical Mirror(2)
http://physica.gnu.ac.kr/phtml/optics/geometric/mirror/mirror.html
Focal point of spherical mirror
Spherical Aberration
http://physica.gnu.ac.kr/phtml/optics/geometric/aberration/aberration.html
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Paraboloidal MirrorsParaboloidal MirrorsA circular off-axis portion of a paraboloidalreflector mounted on a base. These mounted reflectors are convenient for a variety of applications in which diffraction-limited performance is not essential. The optical or symmetry axis of the reflector segment does not pass through the reflector segment itself, as shown in the diagram below, but passes by instead in nearby space. The user has unrestricted access to the focal point and a sizable region surrounding it, without shadowing.
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Elliptical MirrrorsElliptical MirrorsA front-surface mirror cut in an elliptical shape with an aspect ratio of 1.44:1. It is designed to be mounted at 45 and to deflect a beam by 90. At 45, the mirror appears circular from the direction of the beam.
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Micro Mirrors(1)Optical Switches
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Micro Mirrors(2)DMD (Digital Micromirror Devices)
Texas Instrument
Projection TV LCD Projectorhttps://www.youtube.com/watch?v=IlDG3PKTc7s&list=PLEFBB7D7FAE0D61AE
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)90'sin('sin oCC nn
Snells Law
critical angle (n>n)
total internal reflection
Snells Law (1)
'sin'sin nn
Note : Law vs. principle
- Law : Verified by physical or mathematical methods- Principle : Can not verified perfectly.
http://physica.gnu.ac.kr/phtml/optics/light/refract/refract.html
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What is Total Reflection ?If the light travels from a medium with a higher to one with a lower refractive index and the incident angle is greater than the critical angle, no light can pass through and all of the light is reflected.
n1n2
:
Water
Air
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Optical Fibersn2
coren1 c
ca2 aa
10 nCladding
Acceptance angle : 2/1222
11 )(sin nna
)/(cos 121 nnc
Critical angle :
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Refractive Index
C : Velocity of light in vacuum, V : velocity of light in medium
Optical Path
optical path for the light going straight (length L)in a medium (RI = n)= nL
VCn
dsnB
A
Refractive Index & Optical Path
http://imnews.imbc.com/replay/2014/nwdesk/article/3423514_13490.html
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What is Refraction ?The change in direction of a wave due to a change in its speed.
Total time of light traveling from A to C
Fermats principle
Law of refraction (Snells law)
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Young's experiment1st experiment to show the wave characteristic of light
http://blog.naver.com/ogs6403?Redirect=Log&logNo=40066136302&jumpingVid=D828F0C6AE1ADF901A3098A0F2C124DDFBBE
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Huygenss Principle
Principle of Wave propagation (Huygens' principle)- Every point to which a luminous disturbance reaches
becomes a source of a spherical wave, and the sum of these secondary waves determines the form of the wave at any subsequent time ( .)http://physica.gnu.ac.kr/phtml/optics/light/huygens/huygens.html
Point Source - Elementary infinitesimal region of space which emit light- It has only position, not size. - The wavefronts of light from point source
are concentric circle.
Wave front () : - A surface passing through all points
in the light that have the same travel time.- Usually perpendicular to the direction
of rayhttp://physica.gnu.ac.kr/phtml/optics/light/ray/ray.html
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Modified Huygens principle (HuygensFresnel-Kirchhoff principle)- The intensity of light from each point of previous wavefront is a function of - The point at wavefornt generate spherical wave but the intensity is maximized
at the normal direction to the wavefront (propagation direction) and opposite direction is 0.
- Relative intensity of wave
http://physica.gnu.ac.kr/phtml/optics/light/huygens/huygens.html
HuygensFresnel-Kirchhoff principle
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A light wave traveling in a medium with a greater refractive index ( n1> n2) suffersreflection and refraction at the boundary.
Snells Law (2)
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What is Dispersion ?The refractive index is affected by wavelength of light
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Vacuum Wavelength Range for the Various Colors
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Refractive Index
Dense is higher then n is higher Wavelength is higher then n is lower
- The light is slowed in the material due to the interaction between molecules
- The refractive index is related to the how much the light is slowed.
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Definition of optical properties
iv. Abbe constant or Abbe number
v-value (or #) or V-value (or #)Dispersive indices
Cauchys equation
simply
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Design of Optical Glass
Glass Type (specified by nd, vd)abc( : ) defnd = 1.abc vd = de.f
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Principle of Rainbow
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Prism (chapter 5.5)Prism. Dispersive device (ex. Spectrum analyze)
( Refractive index is a function of wavelength). Reorientation or deviation of image. Polarizers or interferometer
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Prism Adventage: Effectively increase optical path in small space Disadvantage : After image due to the reflection of surface
chromatic aberration
Role of Mirror in optical system Deviation Folding an optical path Changing Parity
Penta Prism
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90deviation Prism
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