WaveOpt_21 - Department of Electrical and Computer...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
Department of Electrical and Computer Engineering ECSE 527 Optical Engineering iffraction Diffraction eferences: Hecht ‘Optics’ Ch 10 References: Hecht Optics Ch. 10 Goodman ‘Introduction to Fourier Optics’ Andrew Kirk 2010 Diffraction 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Wave and ray optics •G e o m e t r i c a l optics assumes that the wavelength is zero As a result –R a y s travel in straight lines unless they reflect or refract –L i g h t can be perfectly collimated i g h t can be focused to an infinitely small spot •T h i s is of course not true ! e already have the Gaussian beam model for beam diffraction We already have the Gaussian beam model for beam diffraction •I n this module we will further investigate the wave nature of light and see the way that apertures cause light to diffract and spread. ©AGK 2010 Diffraction 2
Background image of page 2
Aspects of wave optics • Diffraction – Waves diverge after passing through an aperture –Pe r iod i c structures diffract light to produce a periodic iffraction pattern diffraction pattern – Gaussian beams are a simple approximation of diffraction • Interference –Wave s can combine in and out of phase – Results in bright and dark intensity fringes • Polarization ©AGK 2010 Diffraction 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Contents •R e v i e w of scalar wave equation •O r i g i n of Rayleigh Somerfeld equation Diffraction integrals: Near field, Fresnel and Fraunhofer gimes regimes •B r i e f overview of Fresnel diffraction from edges and apertures Fraunhofer diffraction from square and circular apertures Limits to resolution of optical systems ©AGK 2010 Diffraction 4
Background image of page 4
Learning outcomes After taking this class you will be able to: Explain the difference between 3 diffraction regimes • Determine when to use which regime •S k e t c h typical Fresnel diffraction patterns (no calculation) •C a l c u l a t e Fraunhofer diffraction of rectangular and circular apertures ©AGK 2010 Diffraction 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Diffraction •R a y optics–ignored diffraction • Diffraction theory: study of wavefront propagation, through space and through apertures and periodic ructures structures •I t is important to know what approximations we can make in different situations Region of interest ©AGK 2010 Diffraction 6 Aperture Wavelength
Background image of page 6
Examples Fresnel diffraction Short istance distance Screen Knife edge Long distance Rectangular aperture ©AGK 2010 Diffraction 7 Photos from Hecht ‘Optics’ Fraunhofer diffraction
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Effect of increasing distance 06 0.08 0.1 16 z=160 0.25 0.3 0.35 4 z=40 0.015 0.02 64 z=640 00 0 0.04 0.06 0 0.05 0.15 0.2 0 0 0.005 0.01 100 200 300 400 500 z d 15 0.175 8 =80 32 =320 128 z=1280 025 0.075 0.125 z=80 0.03 z=320 0.001 0.002 0.003 0.004 ©AGK 2010 Diffraction 8 d=100, =10 0.025
Background image of page 8
Effect of decreasing aperture size =1 d z=1000 256 128 64 32 16 8 0.0008 0.001 0.0012 0.0014 .0008 0.0006 0.00015 0.0002 0.00025 0.00004 0.00005 0.00006 0.0004 0.0001 0.00001 0.00002 0.00003 ©AGK 2010 Diffraction 9 250 500 750 1000 1250 1500
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Other examples •F o r a Java diffraction simulation on the web: http://www.falstad.com/diffraction/ ©AGK 2010 Diffraction 10
Background image of page 10
Huygen’s principle Christiaan Huygens (1629 1695) uygen’s rinciple: each point on a avefront • Huygen s principle: each point on a wavefront
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/28/2010 for the course ECSE ECSE 527 taught by Professor Kirk during the Winter '10 term at McGill.

Page1 / 161

WaveOpt_21 - Department of Electrical and Computer...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online