In this module, we shift the emphasis from light rays to light wavesfrom geometrical optics to physical optics. Physical optics covers polarisation, interference and diffraction of light. Voiceover youngs double slit experiment looked a little something like this. The figure shows two students listening to two coherent sound sources. Assume that the slit is very long in the direction perpendicular to the page so that we can neglect diffraction effects in the perpendicular direction. The reason these effects had not be seen previously was a result of lights extremely small wavelengths. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacleaperture.
The problem of diffraction from a perfectly conducting wedge is examined with the modified theory of physical optics mtpo. On pcs, the physlets work best with the internet explorer 4 web browser or higher. Other phenomena, such as refraction scattering, and dif fraction describe how light interacts with its physical environment. Mastering physics solutions chapter 28 physical optics. Technically, opal is not a mineral, but a mineraloid, a noncrystalline mixture of silica and water. Diffraction b slit, grating, diffraction integral, diffraction in optical systems, point spread function, aberrations 3 19. If the slit spacing, d, were less than the wavelength, the condition for a bright fringe equation 281 could be satisfied only for the central bright fringe m 0.
Optical information and optical image processing optical signal processing. Intensity in interference and diffraction pdf download book. Intensity in interference and diffraction pdf download. Geometrical optics, studied in the first year, ignored the wave nature of light and so, in this course, we focus particularly on physical optics where the primary characteristic of waves viz. This was the original experiment that showed that light is a wave. Youngs interference experiment, along with the diffraction effects seen in fresnels prediction and the subsequent demonstration by dominique arago of poissons spot, showed that light did have a wave nature.
Diffraction b slit, grating, diffraction integral, diffraction in optical systems, point spread. We shall see that interference occurs when two or more light waves pass through the. Physical optics is used to explain effects such as diffraction in physics, physical optics, or wave optics, is the branch of optics that studies interference, diffraction, polarization, and other phenomena for which the ray approximation of geometric optics is not valid. Diffraction from a threedimensional periodic structure such as atoms in a crystal is called bragg diffraction. Physical optics is treated in chapters 6, 7 and 8, with three important properties of light. It is similar to what occurs when waves are scattered from a diffraction grating. This integral is named as modified theory of physical optics mtpo integral. When they are regular in size and stacking, they produce the colors of precious opal. The geometry of the doubleslit interference is shown in the figure 14.
The positive and negative values of m account for the symmetry of the pattern around the center. On the microscopic scale, opal is made of tiny colloidal silica spheres. The slits are attached to a base of melanin, a material that absorbs. Interference and diffraction superposition and interference youngs two slit experiment interference in reflected waves diffraction resolution diffraction gratings. The diffracting object or aperture effectively becomes a secondary source of the propagating wave. The physical optics po approximation harrington, 2001.
It is the process whereby two or more waves of the same frequency or wavelength combine to form a wave whose. Wave optics g complex fields, wave equation, kvectors, interference, light propagation, interferometry 2 12. With wave opticscommonly referred to as physical opticswe are able to account for important phenomena such as interference, diffraction, and polarization. Bragg diffraction is a consequence of interference between waves reflecting from different crystal planes. Interference results from the superposition of two or more electromagnetic waves. Physical optics 3 diffraction, resolution and image quality v10. The final expressions can be achieved through the equivalence principle as it will be. The reflected, reflected diffracted, incident and incident diffracted fields are evaluated by stationary phase method and edge point technique, asymptotically. This file contains the interference and diffraction chapter of a potential book. The total field may be regarded as a geometric series.
Physical optics lecture notes pdf 44p this note covers the following topics. Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit. Diffraction and interference light summary the physics. Fraunhofer diffraction from a single slit consider the geometry shown below. Since student a is equidistant from both speakers the difference in path lengths from each speaker is zero. Interference and diffraction scienceworkshop ex9918 page 6 of 6 written by ann hanks 1. Content 2 no date subject ref detailed content 1 05. This usage tends not to include effects such as quantum noise in optical communication, which is studied in the subbranch of coherence theory.
This book presents a comprehensive tutorial on propagation, diffraction and scattering problems from the basic principles of physical optics. Physical optics po far fields backscattered by acoustically hard and soft objects differ from each other only in sign. Colors such as these are direct evidence of the wave character of light. This lab serves to familiarize the phenomena of physical optics. The scattered electric fields are expressed by using these current components. The recommended system requirements to use physlets are.
How does the distance from the central maximum to the first minimum in the singleslit pattern compare to the distance from the central maximum to the first diffraction. Pedrotti cord waco, texas in module, basic geometrical optics, we made use of light rays to demonstrate reflection and refraction of light and the imaging of light with mirrors and lenses. Understand the creation of doubleslit interference and singleslit diffraction patterns. Physical optics where the wave nature of light is taken into account. The study of the interference and diffraction of light is referred to as wave optics or physical optics, to distinguish it from geometrical optics, which deals with the straightline motion of light and its reflection and refraction.
Physical optics interference and diffraction patterns. Beginning with the fundamental differential and integral equations for wavefields, the text presents an exhaustive discussion on the extinction theorem as a. Physical optics lecture notes pdf 44p download book. Physical optics definition is a branch of optics that deals with the description and explanation of all optical phenomena in terms of physical theories as undulatory theory, electromagnetic phenomena, or quantum mechanics. Historically, the raybased model of light was developed first, followed by the wave model of light. Diffraction by slit 0 increase the wave sources to a large num ber in sin 2 with sin sin 2 sin sin sin, sin sin resolution limit of telescope 1. Physical optics definition of physical optics by merriam. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The method is applied to the reflection and edge diffraction from a perfectly conducting half plane problem. The exact wedge diffraction coefficient is compared with the asymptotic edge waves of mtpo integral and related surface currents are evaluated.
The final expressions can be achieved through the equivalence principle as it will be shown in section 2. This results from the fact that the slit can be divided into a even number of halfwavelength regions which cancel out each other. For the case l a, we have farfield, or fraunhofer diffraction. In physics, physical optics, or wave optics, is the branch of optics that studies interference, diffraction, polarization, and other phenomena for which the ray approximation of geometric optics is not valid. Pdf on jan 1, 1994, nahum kipnis and others published physical optics find, read and cite all the research you need on researchgate. As the width of the single slit increases, describe how the intensity pattern changes. Interference and diffraction interference of two circular waves, snapshots of absolute value of real,scalar wave field for different wave lengths and distances of point sources.
The section on aberrations was when we first started looking more at the wave nature of light, which is. The central maximum becomes less intense, but the intensity decreases more gradually. Hence, it is sufficient to exhibit the po calculations only for the case of scattering at a hard cylinder. The study of the interference and diffraction of light is referred to as wave optics or physical. And so now we turn to a study of the wave nature of light and to the fascinating phenomena of interference, diffraction, and polarizationand of such devices as gratings and thinfilm coatings. It is interference that causes diffraction the bending of light around obstacles. Youngs double slit introduction video khan academy. Osa modified theory of physical optics approach to wedge.
Diffraction b slit, grating, diffraction integral, diffraction in optical systems, point spread function, aberrations 3. A wave generator sends periodic water waves into a barrier with a small gap, as shown below. Youve got a barrier with two holes in it, but these holes are so small and so close together we characterize them as slits, and double because theres two of them. Diffraction fringes can be observed by holding your finger and thumb very close together it helps not to be too farsighted. Balanis, 1989 is a wellknown high frequency technique based on the determination of the equivalent current densities induced on the surface of an illuminated perfect electric conductor pec plane. Huygens wave theory supported the phenomena of interference and diffraction of light it had just never been observed. It was first performed by the english scientist thomas young at the end of the 18th century and is often called youngs double slit experiment. Teachernoteson diffractionandinterference page1of14 notes for teachers onmodule%07. From a classical optics perspective, interference is the mechanism by which light interacts with light. Interference of the secondary waves results in the diffraction. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. These easy notes cover the following topics with numerical and short solved exercises questions. Scattering and diffraction in physical optics article pdf available in applied optics 314. Diffraction and interference occur together in many situations.
For nonzero values of m there are no solutions, because. Interference and diffraction answers to evennumbered conceptual questions 2. Jan 01, 2016 the broader diffraction peak is actually made of several fringes of smaller width due to doubleslit interference and the number of interference fringes occurring in the broad diffraction peak depends on the ratio of the distance between the two slits to the width of a slit. Since diffraction represents the interference between component rays within a single slit, dark fringes occur when the. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as xrays, microwaves, and radio waves. Nature of light, geometrical optics, optical instrumentation, dispersion, prisms, and aberrations, wave equations, em waves, polarization, fresnel equations, production of polarized light, superposition of waves interference of light, coherence, fraunhofer diffraction, fourier optics, characteristics. The distance between the maxima decreases, and the width of the maxima decreases.
Lecture notes optics pdf 57p this note covers the following topics. Fraunhofer diffraction last lecture numerical aperture of optical fiber allowed modes in fibers attenuation modal distortion, material dispersion, waveguide dispersion this lecture diffraction from a single slit diffraction from apertures. In a two finite slit diffraction pattern, characterize the relationship between slit width and separation based on the number of bring fringes in the central diffraction maximum. Physical optics 3 diffraction, resolution and image. What physical quantity is the same for the single slit and the double slit. Interference and diffraction chapter outline 281 superposition and interference 282 youngs twoslit experience 284 diffraction 285 resolution. In this chapter, we will study the wave nature of light. Introduction in previous optics labs we have described the properties of light simply in terms of rays, using the laws of reflection and refraction.
According to the superposition principle, the net displacement is simply given by the. Wave optics g complex fields, wave equation, kvect ors, interference, light propagation, interferometry 2 12. The scattered field is evaluated for the backscattering direction in the far zone. State the principle of superposition and show how it is used to combine two. Diffraction fringes can be observed by holding your finger and thumb very close together it. This description works well for many phenomena, including image. Color due to diffraction in nature optical engineering. Double slit interference or double source interference. If you are using netscape, we recommend netscape communicator 4. Diffraction huygens principle huygens principle 1 each point on a wave front is the source of a spherical wavelet that spreads out at the wave speed.