What is Optics: Definition and 999 Discussions

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. T

    Real Image Optics: Selecting Correct Answer

    Homework Statement Doing some practice problems to prepare for upcoming exam and ran across this: A real image is a. One in which light does not pass through the image point but appears to diverge from that point b. One for which the magnification equal 1 c. An excellent image d. An...
  2. E

    Why does a 90° phase difference in light waves cause slower travel?

    I read in a book!If the electrons emit a light wave which is 90° out of phase with the light wave shaking them, it will cause the total light wave to travel more slowly. BUT I don't know why?anybody can help? Thank you!
  3. A

    Optics Problem: A real object and a converging lens

    Homework Statement A real object is placed 9.00 cm from a converging lens that has a focal length of 24.0 cm. The image is________. My classmate answered "14.4 cm from the lens, virtual, and enlarged," but apparently this is incorrect. I solved it out and chose the option "14.4 cm from the...
  4. S

    Geometrical Optics (lens and refraction)

    Homework Statement 1. A cylindrical tank 2.4 m deep is full to the brim with water. Sunlight first hits part of the tahnk bottom when the rising maes at 22o angle with the horizon. Find the tank's diameter 2. An aquarium is made from a thin-walled tube of transparent plastic 50 cm in...
  5. L

    Archived Optics: Shift in y from a thin pane of glass, young's experiment.

    Homework Statement With regard to Young’s Experiment, derive a general expression for the shift in the vertical position of the mth maximum as a result of placing a thin parallel sheet of glass of index n and thickness d directly over one of the slits. Identify your assumptions. Homework...
  6. R

    Optical Home-Made Fiber Optics: Alternatives to Food Jelly?

    Hello. I know how to realize an homemade fiber optic using some food jelly. Are there other materials, at amateur grade; to replace jelly ? ( NB this item has to be used in high vacuum, and jelly is not convenient for this use)
  7. L

    Optics: Concentrating light with a lens

    I'm looking at concentrating light (e.g. sunlight) with a lens, and trying to figure out the maximum concentration I can get. If you have a perfectly collimated source, a lens can focus that light down to a point, but when the source has some divergence, the point you can focus down to will have...
  8. L

    Bivariate gaussians for ion beam optics

    Hello, here is something that's been bothering me for a while: say I have a charged particle beam that can be described by one bivariate Gaussian in X dimension and another bivariate Gaussian in Y dimension. The parameters of the bivariate gaussian are the position (X) of an individual...
  9. E

    Optics: Total Internal Reflection with Triangular Prisms

    Homework Statement When the striking ray is held perpendicular to the prism, there are four general configurations possible (in the attachment below). Use the figure on the next page to determine analytically which of these four configurations will result in total internal reflection of the...
  10. P

    Optics: Interference and Phase

    Homework Statement Two flat slides of glass are separated at one edge by a thin wire, as shown below. The top surface of the upper slide and the bottom surface of the lower slide have special coatings on them so that they reflect no light. The system is illuminated with light of wavelength...
  11. X

    Why does someone with normal vision not need glasses?

    Homework Statement These are more-so explanation based and there is no math involved. 1) How come someone with "normal vision" does not require glasses? 2) Why does a far sighted person require glasses with a positive focal length? 3) Why does a near sighted person require glasses with a...
  12. Darth Frodo

    Calculating Angular Magnification and Image Position in Compound Lens Systems

    Homework Statement 1. An object is placed 1.5m in front of a convex lens of focal length 500mm. Find the position of the image formed and state its nature. 2. A second convex lens of focal length 25mm is placed 770mm behind the first convex lens. Find the position of the final image formed and...
  13. tsuwal

    Fiber optics: using continous variation refractive indexes hold light?

    My teacher said that instead of using a fiber optic made of just one material we could use a set of materials with progressively low refractive index to turn the light back in, like so: In the case of a continuous variation of refraction index, how can you do the math. Can you please show...
  14. J

    Help with optics, telecentric lens, and focusing at infinity

    Hi Guys, I have a question about a telecentric lens I've been studying and was wondering if you guys could help clear some cobwebs in my head. For starters, I am simplifying the TC lens as a compound lens. Also, this lens has 2 degrees of freedom: (1) it can be extended and retracted (2) it...
  15. S

    What are caustics as they apply to optics?

    I've searched the web for caustics and optics, but mostly see pictures of them. They seem to have some positive use. In some fashion they seem to magnify. They seem to be somehow related to critical curves, whatever they are. Both seem to be helpful in gravitational lensing. How?
  16. C

    OPTICS: How to solve a two lens system with the object in a medium?

    Hi All, I need help determining focal length value in a two lens system. In the set up, the light source (object) is within a tube, a medium surrounds it with refractive index n1=1.52. The end of the tube is met with a curved convergent surface, the center of which is 0.635 cm away and focal...
  17. Darth Frodo

    Geometric Optics: Solving for Position & Nature of Image

    Homework Statement An object is placed 400 mm in front of a convex lens of focal length 80 mm. Find the position of the image formed. State the nature of this image. A second convex lens of magnifying power X8 is placed 125 mm behind the first convex lens. What is the focal length of...
  18. heycoa

    Optics, Superposition of waves

    Homework Statement Using expansion of sin and cos functions, show that the resultant of adding the following two waves: a) E1 = E01*sin(wt-k(x+Δx)) b) E2 = E01*sin(wt-kx) Gives: E = 2E01*cos((1/2)kΔx)*sin[wt-k(x+Δx/2)] Homework Equations N/AThe Attempt at a Solution I don't know how to sum...
  19. M

    (Optics) Why is lecturer in risk of getting speeding ticket?

    Homework Statement An optics lecturer bought his first multifocal eye glasses a while ago. The correction for looking far away was –2.25 diopters. Compared to this, the reading part had an additional correction of +1.75 diopters to achieve the convenient reading distance of 40 cm. He also...
  20. N

    Experiments Involving Lasers and Optics

    Hello all, I need to design an experimental apparatus that involves manipulating the path of a laser. Thus far I only know the bare basics about optics and I have never attempted optical apparatus design, does anyone know a book that is a really good reference for experimental applications of...
  21. L

    Find the Best Optics Book for Your Course

    Hello, I have about a month to learn a whole course in optics. I do not particularly like the two books I have, Principals of Physical Optics by Bennett and Optics by Hecht. I was wondering if anybody knew of a good book? Thanks.
  22. C

    What Causes Scattering in Optics and How Does it Apply to X-rays?

    You can put a diffuser in front of a visual light source (i.e. lightbulb) that will scatter light in all directions. In effect, the diffuser acts as an analog lightsource by making light go in all directions (some of the enegry will be absorbed). LCD screens use diffusers to spread out their...
  23. G

    Optics question - coin at the bottom of a swimming pool

    Optics question -- coin at the bottom of a swimming pool The apparent depth of a pool depends on the angle of viewing. Suppose that you place a coin at the bottom of a swimming pool filled with water (n = 1.33) to a depth of 2.16m. Find the apparent depth of the coin below the surface when...
  24. R

    Optics in Lobachevsky geometry

    Homework Statement In the upper half of a (x,y) plane endowed with a refractive index of n(y) = 1/y, find the form of light ray. Homework Equations l = ∫n dl The Attempt at a Solution My method is to construct a functional for optical path, obtaining the result using...
  25. K

    Energy flux in optics in hydrogen gas

    Homework Statement There is a half space z>0 full with hydrogen gas with density n atoms / metres cube. An incident wave plane with pulsation ω coming from z = -∞ arrives at the surface of incidence. This wave transports a flux of energy ∅0 at z=0. We consider a elementary cylinder whose axe...
  26. T

    Solving Ray Optics Problem 2: Mirror Positions and Image Formation

    Hi friends, Please help me in answering this problem The problem is as follows, https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-prn1/s480x480/11130_2937865262994_1085043361_n.jpg Well, Friends when the lower mirror would be at position 'A', which is moving in the upward direction...
  27. T

    Solving Ray Optics Problem: Understanding Refraction and Deviation

    Hi friends, Please help me in answering this problem The problem is as follows, https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash3/s480x480/557923_2937818221818_1718139220_n.jpg Well, As far as I am concerned, When white light fall on the first surface, after refraction...
  28. heycoa

    What are the Fresnel Equations and how do they relate to polarized light?

    Homework Statement Use the Fresnel Equations to prove that light incident at θp=1/2*∏-θt results in a reflected beam that is indeed polarized. Homework Equations N/A The Attempt at a Solution I cannot find a Fresnel equation that has θp in it. And even if I did, I wouldn't know...
  29. Saitama

    Optics - Refraction and a transparent sphere

    Optics -- Refraction and a transparent sphere Homework Statement A spider is hanging by means of its own silk thread directly above a transparent fixed sphere of radius R=20 cm as shown in the figure. The refractive index of the material of the sphere is equal to ##\sqrt{2}## and the height...
  30. N

    Wrong proof in textbook of optics?

    In textbook on optics by Pedrotti (and I think Fowles does the same) on page 493 it is said that: kr=krr=ktr from which follows (k-kr)r=(k-kt)r=(kr-kt)r=0, where k, kr and kt are wave vectors of incident, reflected and transmitted wave. Than Pedrotti concludes that kr and kt must...
  31. heycoa

    Determining Beam Diameter in Glass Using Index of Refraction

    Homework Statement A non-expanding/non-contracting laser beam having a diameter 0.132 m in air strikes a piece of glass (ng = 1.62) at an angle of 52°. What is the diameter of the beam, in m, in the glass? Homework Equations snell's law, n1sin(θ1)=n2sin(θ2) The Attempt at a...
  32. T

    Optics Problem: Solving for Refraction on a Spherical Surface

    Hi friends Please help me in solving this issue too. The problem is as follows : https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash3/526477_2890689763636_1631084369_n.jpg As it seems that the rays are striking on the the spherical surface parallel to the principal axis so u → ∞...
  33. T

    Solving an Optics Problem: Convex Lens, Plane Mirror, and Virtual Image

    Hi friends, I am sticking in a problem of Geometrical OPTICS, The problem is as https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-snc6/285225_2890687243573_1306065782_n.jpg Attempt - Here for the convex lens applying the lens formula 1/v - 1/u = 1/f so, 1/v = 1/u + 1/f 1/v = -...
  34. Saitama

    Optics, refraction at spherical surface

    Homework Statement (see attachment) Homework Equations The Attempt at a Solution I don't quite understand the question. It asks the distance of the "unilluminated patch" from the cylinder. There will be only a single point where the rays will intersect. Rest everywhere, it is...
  35. C

    Confused about definitions in optics

    The width of a pulse is typically given in the time domain, correct? The effective width is the term to describe this. What is the spectral width in the frequency domain? How do you calculate spectral widths and effective widths? Thanks for your time.
  36. heycoa

    Optics | Amplitude of Electric Field Given Radiant Flux Density

    Homework Statement A laser provides pulses of EM radiation in vacuum lasting 7.47* 10-12 s. If the radiant flux density is 2.65 * 1020 W/m2, determine the amplitude of the electric field (x *1011) of the beam. Units are required as listed in instructions. Homework Equations Irradiance =...
  37. heycoa

    Optics | Energy Density, Irradiance

    Homework Statement Suppose a laser produces a pulse of light with duration 1 ns, a diameter of 1 cm, and a total energy of 1 mJ. In free space, the pulse length is this 30 cm, the energy density is 42 J/m3, and the irradiance is 1.3*1010 W/m2. Calculate the length, energy density, and...
  38. heycoa

    Optics | Electromagnetic Waves | Electric/Magnetic Fields

    Homework Statement An isotropic quasimonochromatic point source radiates at a rate of 100 W. What is the flux density at a distance of 1 m? What are the amplitudes of the E- and B- fields at that point? Homework Equations I think (but not at all sure) that the equation for flux density...
  39. P

    Optics question: light reflecting off a colored surface

    From my understanding, when white light hits a surface, all of the frequencies within the white light are absorbed except one, which is reflected, and that is the color of the object. For instance, a blue plastic appears blue because it absorbs all frequencies except that of blue. Why then, can...
  40. jbrussell93

    Optics: Complex exponentials for sine

    Homework Statement Imagine that we have two waves of the same amplitude, speed and frequency over-lapping in some region of space such that the resultant disturbance is \psi(y,t) = Acos(ky+\omega t) + Acos(ky-\omega t +\pi) Using complex exponentials show that \psi(y,t) = -2Asin(ky)...
  41. A

    Optics: Finding the wave equation given position and amplitude information

    A harmonic wave traveling in +x-direction has, at t = 0, a displacement of 13 units at x = 0 and a displacement of -7.5 units at x = 3λ/4. Write the equation for the wave at t = 0. Homework Equations The equation for a harmonic wave is r = asin(kx-vt+θ) a being the amplitude k...
  42. S

    4 nonlinear optics problems: susceptibility, polarization

    [Wasn't sure if each problem needed a separate post. Please feel free to edit if needed.] Also \~ and \^ are tilde and hat respectively. 1a. Homework Statement Use perturbation theory to derive the 3rd order nonlinear susceptibility \chi^{(3)}(3w;w,w,w) (problem gives potential energy, etc...
  43. heycoa

    Spherical waves, Optics, phase, homework help please

    The question is as follows: A point source emits a spherical wave with λ = 500 nm. If an observer is far away from the source and is only interacting with the light across a small area, one can approximate the local wave as a plane wave. How far from the source must the observer be so that...
  44. S

    Optics; Deriving the index of refraction from Snell's law

    Homework Statement There is a diagram in the problem statement so here is a link to the image of the problem: http://imgur.com/KDrRsyO Homework Equations Snell's Law: n_{1} * sin(\theta_{1}) = n_{2} * sin(\theta_{2}) The Attempt at a Solution My attempt using Snell's law...
  45. N

    Good book for undergrad optics

    Iam a high schooler starting grade 10 this year . i have been reading undergrad texts for some time now . i need a good book for OPTICS . any ideas or suggestions
  46. N

    Optics - Do I live in a smaller world with glasses?

    Okay, question, do I live in a smaller world than people with normal eyes? I noticed that when you look over your glasses (minus 3.5) half through the glasses and half to the real world, that the blurry real world is larger. My 28" computer screen seems 32", my cats head looks larger, my hands...
  47. N

    Grating Spacing With Fourier Optics

    Just ahead of time, no this is not related to homework or coursework in my case. I am a TA for an optics lab and need to know it so I can help the students in my class. I am trying to find an expression for the x-spacing for a grating imaged using the 4f method, which is a grating that is 1...
  48. H

    Apparent and actual radius (Optics)

    I know the radius of a circle. I'm taking pictures of the circle as I bring it closer to the camera. Obviously the radius is getting larger. I want to know what the relationship is to find this out? I know the distance from the camera that the circle is at all times.
  49. S

    Optics question, locate mirror and its focal length

    Homework Statement "An object 10 cm tall is placed at the zero mark of a meter stick. A spherical mirror located at some point on the meter stick creates an image of the object that is upright, 4 cm tall, and located at the 42 cm mark of the meter stick. Where is the mirror located and what...
  50. Greg Bernhardt

    Classical Optics by Eugene Hecht | Buy on Amazon

    Author: Hecht, or Hecht & Zajak, depending on the edition Title: Optics Amazon Link: https://www.amazon.com/dp/0805385665/?tag=pfamazon01-20 Cheaper, used, older edition: https://www.amazon.com/dp/B004HX9WXM/?tag=pfamazon01-20 Prerequisities: Electricity and magnetism; multivariable...
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