Optics Definition and 999 Threads

Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.Most optical phenomena can be accounted for by using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. 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. Historically, the ray-based model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that light waves were in fact electromagnetic radiation.
Some phenomena depend on the fact that light has both wave-like and particle-like properties. Explanation of these effects requires quantum mechanics. When considering light's particle-like properties, the light is modelled as a collection of particles called "photons". Quantum optics deals with the application of quantum mechanics to optical systems.
Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, and medicine (particularly ophthalmology and optometry). Practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics.

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  1. Vaibhav Sahu

    Snell's law for an interface with variable refractive index

    Consider an interface along x-axis which separates two media. The medium below y = 0 is air or vacuum and light is incident from this medium onto the surface. The refractive index of the medium above y = 0 varies with x as some function of x : μ = f(x). Does the Snell's law still hold good ?? If...
  2. P

    What is the true nature of white light?

    Hi, I studied 'A' level physics back in the '80s, my dad was a physics teacher, and I have an ongoing interest in the subject. I'm particularly interested in optics. The main thing that I remember being taught incorrectly at school is that white light is a combination of red, green, and blue...
  3. YogiBear

    Optics and waves, mirage. University physics

    Mirage: we consider the x-y plane describing vertical y and horizontal x directions, with an inhomogeneous index of refraction n(y). In this case, using calculus of variations, Fermat’s principle for the trajectory of a ray of light may be re-written as n(y)/√1+(dy/dx)^2 = A. Where A is a real...
  4. J

    Light Polarization and Jones Matrices

    Light reflecting off a mirror actually penetrates a short distance into the mirror surface material. In metals, this distance is very short (much less than a wavelength) and so can be neglected. But metals tend to also absorb ~10% of the light, which is undesirable. Today’s modern multilayer...
  5. H

    ...review article on atom optics - need recommendation.

    Before life got in the way I used to follow this field as a science fan up until the early 90's. Any good review articles for a general readership that can fill the gap in from early 90's till now. I would like to see how a lot of that research progressed and if any applications / devices came...
  6. W

    Geometric optics and Fermat's principle

    Homework Statement A ray travels as shown in the image attached below. In this case, Fermat's principle may be written as ##A =\frac{n(1+ay)}{\sqrt{1+(y')^2}}## Where y' is dy/dx, n is the index of refraction and A is a real constant. The trajectory of a ray of light is given by ##y =...
  7. pioneerboy

    Quit undergrad physics -- Wishes and options? Advice please

    Hello everyone, I am brand new here in the PhysicsForum and this is my very first message. So it's apleasure to meet likeminded people sharing the same interest and probably also profession. The latter is also the reason why I finally registered in this forum and I sincerely hopethat I am given...
  8. E

    When is a Numerical Aperture considered High?

    When will you consider that the numerical aperture is high? I was told that the numerical Angular Spectrum Method is only valid low numerical aperture values, I want to know the boundary of this value. Thank you in advance.
  9. szopaw

    Possible non-burning visible beam mock-up?

    To give a little idea for what I'm aiming for: I want to make a prop laser gun. It doesn't have to actually do anything, but I've decided it'd be awesome if it did. I could use a 2-5W blue laser diode like some people who make awesome contraptions with lasers show on YouTube, but I'd frankly...
  10. B

    Compound Thick Lens: Calculating Refractive Power with Thick Lens Equation

    Homework Statement I have a compound thick lens problem that I need to find the sign of the refractive power. Homework Equations Thick lens equation and focal length equation. The Attempt at a Solution I believe all I need to do is calculate the focal length of the first two thick lenses and...
  11. E

    What is the intensity of an electromagnetic radiation?

    How can I compute the intensity of an electromagnetic radiation if I know ##e_x, e_y, e_z, h_x, h_y,## and ##h_z##, where ##e_i## is the electric field component at ##i## and ##h_i## is the magnetic field component, also at ##i##? Thank you in advance.
  12. UchihaClan13

    Hamiltonian Optics Basics: Explained for Beginners

    Alright I was browsing through feynman's lectures VOL.1 When I came across Hamiltonian Optics I am not quite able to understand it in its entirety Could someone explain the basics of hamiltonian optics to me Help would be much appreciated !
  13. UchihaClan13

    Ray Optics Doubt: Can an Equilateral Triangle Form?

    Alright I was doing some basic questions on ray optics when this doubt came to my mind So my doubt goes like this:(IT may be silly) Consider a concave mirror with pole P and centre of curvature C Its principal axis is extended on both sides Now consider a ray parallel to the principal axis Call...
  14. isnainidiah

    Geometrical Optics: Explaining Concepts with Fermat's Principle

    How do you use Fermat's principle of least time to explain various concepts in geometrical optics?
  15. F

    Fiber Optics Qs: Mini-DIO, Fusion, Fanout Cable

    I am working in a project that contain several switchboards that will receive an optical fiber from encoders of the motors that they feed (through an optical transmitter). It appears that to do this we will need Mini-DIOs to connect this fiber cord to optical receivers, which in turn will be...
  16. F

    Low-cost low threshold optical beam limiter?

    Do you guys know a low-cost low-threshold optical beam limiter, with cost somewhere ~$100. Or if you know certain method to fabricate such. I would be greatful if you could include links and/or references. I am still noob in photonics so I am only familiar with a beam limiter that blocks the...
  17. P

    Classical What Are the Best Optics Textbooks for a Junior Course?

    I'm taking a junior course on optics. The professor said it would be up to us to find a textbook to use. For this course the prerequisites are E&M (Griffiths level), classical mechanics (Morin level), and multivariable calculus. Anyone have recommendations on a textbook for this class? Course...
  18. I

    Optics Question -- small glass spheres to couple to fiber optic cables

    Homework Statement Homework Equations I know that yin = 0.7mm, y2 = 0mm, the index of refraction for the sphere is 1.8 and the indices of refraction for the air surrounding it is 1. The Attempt at a Solution Not sure how to even begin with the given information. I was thinking I could...
  19. isnainidiah

    Fermat's Principle to explain lenses and mirrors

    How do we use Fermat's principle of least time to explain the required shapes of lenses and mirrors?
  20. Max Matiauda

    Image formed from object at focal point of concave mirror

    The question posed: "An object is located to the right of a mirror that in concave in its [the object's] direction. If the object sits on the focal point of the mirror, what answer best describes the image formed?" Our class is united in the notion that as the rays would be parallel...
  21. T

    Optics Problem -- possible values for the object distance?

    Homework Statement An object and its lens-produced real image are 2.4 m apart. If the lens has 55-cm focal length, what are the possible values for the object distance? Homework Equations 1/s+1/s'=1/f The Attempt at a Solution The object and the image are 2.4m apart so I thought "Hey, that...
  22. C

    Solving an Optics Exam Problem: Interference Fringes

    So, I'm about to take an Optics exam, and while I can easily do most of the last years' exam problems, there are some which I cannot solve for different reasons (perhaps some gross oversight?). Yesterday I stumbled upon this: 1. Homework Statement (my own translation from Catalan) We have a...
  23. J

    Optics for Graduate Engineering: Pre-Req E&M Knowledge?

    Does anyone know how much undergraduate E&M you need to know in order to do well in a graduate engineering Optics course? Is it an absolute pre-requisite?
  24. kelvin490

    How Holography Works: Explained

    To make a hologram a film is exposed to an incident plane wave and wave from the object to record the interference pattern on the film. The principle is commonly explained in a way like that in p.1212 of "University Physics" (...
  25. lfqm

    Fixed amplitude of electric field operator in quantum optics

    Hi guys, I'm trying to understand why does the amplitude of the electric field operator in a cavity is fixed at \left ( \displaystyle\frac{\hbar\omega}{\epsilon_{0}V} \right )^\frac{1}{2} Every book I read says it is a normalization factor... but, normalizing an operator?, what is the meaning...
  26. kelvin490

    Why an array of telescopes is used?

    To increase the resolution of an instrument, smaller wavelength and larger aperture is desirable. It is mentioned in some textbooks that the "effective" diameter of a telescope can be increased by using arrays of smaller telescopes. I just wonder why it is possible because every telescope is...
  27. R

    Classical Want help in finding a book for questions on geometric optics

    guys i want a book where i can find questions on geometric optics especially for questions based on locating position of mirror by ray diagram when only object and image are given? I have already found 2 questions in I.E. Irodov but i want more so please suggest other books..... thnx
  28. R

    A question on geometric optics

    a concave mirror of 5cm radius of curvature whose circular ring has a radius of 4cm is blackened except for a narrow strip round the edge. A beam of light parallel to the principal axis falls on the mirror. Find the distance between the centre of curvature of mirror and the point at which light...
  29. A

    Mathematical descriptions of opacity

    Hi https://en.wikipedia.org/wiki/Mathematical_descriptions_of_opacity it is mentioned above that "in non attenuating media, the refractive index and angular wavenumber are related by: A complex refractive index can therefore be defined in terms of the complex angular wavenumber defined...
  30. L

    What is Nonlinear Fourier Transform in Optical Fiber Communication?

    Hi I am Ali, Liaquat. i am doing my PhD at University of Melbourne at Department of Electrical and electronics Engineering, my majors is optics and photonics. I am currently working in optical fiber communication.
  31. M

    Are there exceptions to the rule of speed and energy for waves?

    Today I was presented with dispersion in my introductory physics class. Before this topic was presented we were told of two important rules for waves: 1) The speed of a wave is dependent on the medium in which it travels and 2) the frequency of wave does not change when going from one medium to...
  32. kelvin490

    Question about lens maker's formula

    I am trying to follow the derivation of lens maker's formula from the textbook "University Physics", p.1133 (https://books.google.com.hk/books?id=nQZyAgAAQBAJ&pg=PA1133#v=onepage&q&f=false ) I can understand the first equation because it is just the object–image relationship for spherical...
  33. Christian Grey

    Astrophysics uses wave optics or geometrical optics?

    I know Astrophysics uses concepts like relativity etc. But I want to know does it uses wave optics or geometrical optics? The phenomenon of light,wave optics(reflection,refraction,polarization,diffraction and interference) that we see everyday, is used in Astrophysics? Or does it uses...
  34. Ornit

    How to get to this Surface slope formula?

    This is no homework; but I cannot work it out so I assume one of my assumption is off... no matter how much I looked at it I can't get to the textbook answer. I tried searching (Google is my friend); I got to Prof. Burge's wonderful lectures slides (Arizona.edu) but he follows a different path...
  35. G

    Optics - focused vs. defocused image

    Hello, (I am new here, so hopefully this is the right location to ask my question. please let me know if there is more relevant forum) I am trying to understand 2 situations: A) I have an object, lens and a detector. The detector is at the focal plane of the lens. I am reducing the aperture...
  36. W

    Need help understanding ray optics question

    Homework Statement http://i.imgur.com/q6EaspT.png 2. The attempt at a solution why is the answer C? shouldn't the aperture in front of the screen create a shadow that blocks all the light except the rays that go through slit? (the width of the slit is >>>1mm so it won't make a diffraction pattern.)
  37. E

    Is the Wave Vector of a Plane Wave Affected by Diffraction?

    Considering a plane wave propagating in one specific direction, does its wave vector dependent on a certain point in the plane wave or is it dependent on a certain point on a plane parallel to the wave?
  38. F

    Finding lens diameter - German physics task

    Hey everybody, I'm right now trying to solve a question I found in a German physics competition 2006 concerning the diameter of a thin camera lens. I'm not able to find a solution, since there is basically nothing given. Here the task (I underlined phrases which might be important): A ruler...
  39. EJC

    Schools Chances of Getting Into Graduate School Ph.D Programs

    I am a rising senior at a small liberal arts college, with an incredibly small (and therefore unrecognized) physics program. I am seeking advice regarding which Ph.D programs are within my reach. I plan on applying to AMO (Atomic, Molecular, and Optics) Ph.D programs with the intention of...
  40. S

    Where to place a thin lens to couple a ray into a fiber

    Homework Statement i need to couple a ray (point source 15 deg) into a fiber with a small core diameter, the fiber located 8cm from the source. the focal distance of the lens is 1.5cm i need to choose 2 possible locations Homework EquationsThe Attempt at a Solution first suggestion: i placed...
  41. L

    Light Polarization Reflected from Parabolic Mirror

    Let's say I have a linearly polarized laser beam, and I focus it to a small spot using a parabolic mirror. Does the light retain its polarization at the focal point? Why or why not? I understand that flat mirrors and concave/convex mirrors preserve linear polarization, and I would like to make...
  42. I

    Dispersion and the dependences of refractive indexes

    I'm revising for a uni exam with past exam papers, and have gotten stuck on the details of dispersion. The two exam questions prompting this are a) What is the physical reason why the index of refraction for blue light is bigger than that of red light? and b) Explain how dispersion makes a...
  43. D

    Where Can I Find Free Software for Caustics/Cusps?

    Hello folks, I'm looking for a free programme to play with caustics/cusps. Does anyone know where I can find one? If not does anyone have any suggestions as to how to write a script for one in gfortran? Preferably all I'm after is a way to make quick plots of cusps in 2D. Cheers and thanks a...
  44. A

    How do you explain this? (Optics)

    Hi. As you can see in the video attached, the image of the street is projected on the ceiling! Only a window glass and a simple curtain is involved. How does this happen? And how can I optimize (the window angle curtain etc) to get the most clear picture?
  45. M

    How Does Degenerate Four-Wave Mixing Create a Frequency Comb?

    Hi all, I've some questions for you which challenge my brain a lot! :nb) I'm dealing with a Photonic course and our professor introduced us a little bit of Non-Linear Optics. We spoke about Four-Wave-Mixing (4wm for brevity) and we said that when we shine a material with ##\chi ^{3}## with two...
  46. marcis

    Optics problem --- absorbtion index

    Hello I have an optic problem I want to calculate absorbtion index I know transmittance by 90% ;refraction index to material 1.586 ; thickness 2 mm ; power of source 21 lm
  47. arpon

    Optics Problem: Find Smallest Refractive Index of Slab

    Homework Statement Light falls on the surface AB of a rectangular slab from air. Determine the smallest refractive index n that the material of the slab can have so that all incident light emerges from the opposite face CD. Homework EquationsThe Attempt at a Solution Let's think about this...
  48. E

    Fresnel Relations and the Sensitivity of a Camera

    Reflectance, according to the Fresnel Relations, is given by ##R \equiv \frac{I_r}{I_i}##, and Transmittance is ##T = \frac{I_t \cos \theta_t}{I_i \cos \theta_i}##. Do these values depend on the wavelength of light? For example, if I have a beam of white light rather than a monochromatic...
  49. M

    Fabry Perot Free Spectral Range

    Hi all, the question which I'd like to share is the following: if you look at the formal theory of any random optics book for FP interferometer you will get to the formula of the FSR (Free Spectral Range), defined as "The wavelength separation between adjacent transmission peaks" (Wikipedia)...
  50. andrewm94

    Career Options in Applied Physics

    Hello to all of you! This is my first post on this forum, though I have visited this site many times to learn from its wealth of information and insights. A bit about me, I just finished the second year of my undergraduate career and am looking forward to beginning my upper level physics...
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