lecture note 01 introduction of optics

School of Mechanical EngineeringChung-Ang University

Micro/Nano Optical Engineering

1st week

Prof. Seok-min Kim

[email protected]

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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


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.

School of Mechanical EngineeringChung-Ang University4

Introduction of Micro/Nano

Optical Engineering


Introduction of Optics


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


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


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


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)


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


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.


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.


Micro Mirrors(1)Optical Switches


Micro Mirrors(2)DMD (Digital Micromirror Devices)

Texas Instrument

Projection TV LCD Projectorhttps://www.youtube.com/watch?v=IlDG3PKTc7s&list=PLEFBB7D7FAE0D61AE


)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


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


Optical Fibersn2

coren1 c

ca2 aa

10 nCladding

Acceptance angle : 2/1222

11 )(sin nna

)/(cos 121 nnc

Critical angle :


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


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)


Young's experiment1st experiment to show the wave characteristic of light

http://blog.naver.com/ogs6403?Redirect=Log&logNo=40066136302&jumpingVid=D828F0C6AE1ADF901A3098A0F2C124DDFBBE


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


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


A light wave traveling in a medium with a greater refractive index ( n1> n2) suffersreflection and refraction at the boundary.

Snells Law (2)


What is Dispersion ?The refractive index is affected by wavelength of light


Vacuum Wavelength Range for the Various Colors


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.


Definition of optical properties

iv. Abbe constant or Abbe number

v-value (or #) or V-value (or #)Dispersive indices

Cauchys equation

simply


Design of Optical Glass

Glass Type (specified by nd, vd)abc( : ) defnd = 1.abc vd = de.f


Principle of Rainbow


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


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


90deviation Prism

lecture note 01 introduction of optics

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