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. D

    What is the Velocity of a Bullet Reflected by a Plane Mirror?

    A gun of mass 'M' fires a bullet of mass 'm' with a horizontal velocity 'v'. The gun is fitted with a plane mirror facing towards the receding bullet. Find the velocity relative to its image just after the gun is fired.
  2. Greg Bernhardt

    What are Nonlinear Optics - 2nd Order Processes

    Definition/Summary Nonlinear optical processes that occur due to the presence of a second-order nonlinear susceptibility are termed 2nd order processes, or three-wave mixing processes. There are four second order processes, second harmonic generation, sum and difference frequency generation...
  3. Greg Bernhardt

    How Does Nonlinear Optics Impact Light Propagation in Media?

    Definition/Summary Light propagating through a vacuum will obey the principle of superposition, however this is not generally true for light propagating through gaseous or condensed media. As light propagates through transparent media, it induces a dipole moment on any atoms present in the...
  4. L

    Optics: how to make eye focus in distance?

    Hello! I have a theoretical & practical question. Theorecical: I noticed that when I turn on my smart phone camera application and look 'through it' on some distant object, holding smart phone 30 cm from my eyes, then my eyes are focused on 30 cm and not in distance. Is there a way...
  5. K

    Optics: Lens for capturing light from parabolic reflector

    I was wondering what type of lens would be best for capturing the light incoming from a parabolic reflector into a container? The Fresnel lens looks like a good candidate, but I am still not quite sure. Does anyone have any insight on this subject? Just for info, the parabolic lens redirects...
  6. M

    Comparing K and k in Hecht's Optics Book

    What is the difference between propagation number(K) and wave number(k) described in Optics book written by hecht He defined K=2π/λ and k=1/λ and both of them have the same units (i.e, meter inverse) What does wave number of a Harmonic function tells about?
  7. E

    Understanding the Phase Shift Formula in Stimulated Brillouin Scattering

    Good morning I need to ask about the exact formula for the phase shift used in stimulated Brillouin scattering especially in the phase shifter thank you
  8. DataGG

    Optics - Image formation (lenses)

    Homework Statement A lense with a focal length of ##-48.0cm## forms an image ##17.0cm## to the right of the lense. Where is the object positioned? Homework Equations $$\dfrac{1}{d_0}+\dfrac{1}{d_i}=\dfrac{1}{f}$$ The Attempt at a Solution Well, since the focal length is negative, we know...
  9. DataGG

    Optics - right handed circular polarization

    Homework Statement Write an expression for a light wave circular polarized to the right, traveling in the positive ZZ direction, such that the electric field points in the negative XX direction at z=0, t=0.Homework Equations Right handed polarization is the same as clockwise, I think...
  10. DataGG

    Optics - Three polarizers with 1 moving

    Homework Statement Thee linear polarizers are in sequence. Let first and last polarizer be crossed (perpendicular to each-other) and the middle polarizer rotate with angular frequency ##\omega##. Show that under such circumstances, ##I## is given by: $$I = I_0 \frac{1}{16}(1-\cos (4\omega...
  11. P

    Simulating Closed Timelike Curves through Quantum Optics

    This paper experimentally simulates Closed Timelike Curves (CTC) through quantum optics experiment. Since I have no experience/background in this, I found it hard to understand how exactly the CTC is implemented in the circuit. [Note: I do understand QM, so no need to explain this].
  12. SquidgyGuff

    Optics from a Quantum Mechanical stand point

    I've tried looking this up online, but people only ever talk about the basic principles and formulas involved instead of the concepts behind it. My question is this: "What is happening at a quantum level when light is refracted or reflected?" How does the light interact with the atoms of medium...
  13. E

    Optics Homework- 11th grade

    So I originally posted a thread for my optics homework listing every question from a worksheet AND my attempts. Apparently, it's seen as spam so I have tried and am now posting the second question. Homework Statement A concave mirror has a focal length of 40 cm. Determine the object...
  14. E

    Calculating Wavelength in Young's Interference Experiment

    So I got a warning for just posting questions so I'll do as best as I can to try and put effort lol Homework Statement A Young's interference experiment is performed with monochromatic light. The separation between the slits, d, is .50 mm, and the interference pattern on a screen L =...
  15. S

    Refraction and Magnification of a Coin in a Glass Cylinder

    Homework Statement A penny is placed at the bottom of a glass cylinder that is 30 cm in height. If the cyclinder is filled to 2/5 its volume: How much closer to an eye does the coin appear when viewed from directly above? 2. The attempt at a solution I don't quite know how to...
  16. A

    [Thin-Film Optics] Incident white light to color

    Hello, as you might have guessed, my question revolves around thin film optics. My intention is: Given a two thin-film system residing on top of a semi-infinite (bulk) layer, how can I estimate the reflecting color (RGB preferably) when illuminated by white light? (Illustrated below). I...
  17. Matt atkinson

    Optimizing Lens Focal Length for Micro-Structure Laser Experiment

    Homework Statement In an experiment a laser beam is focussed on a sample by a lens. The sample has micro structures spatially separated by 5 microns. In the experiment, each micro-structure has to be studied individually using the laser, so that illumination of two or more adjacent...
  18. I

    Why in Optics total internal reflection happens this way?

    why total internal reflection happens only when a beam of light travels from a medium with higher index of refraction to a medium with lower index of refraction and not the other way around (i.e from a medium with lower index of refraction to a medium with a higher one)?
  19. N

    I have a theory, optical physics related (pinhole optics)

    Some of you may have see the pinhole method of seeing without having to use glasses. My question is this, could this same pinhole application of viewing clearly be useful in optical microscopes? And if so, can it be used in series? By my understanding the pinhole technique works by...
  20. Feodalherren

    Optics: Solving for Slit Size Missing Fringes

    Homework Statement Laser light is projected into two small slits that are 1mm apart. The fringe pattern on the screen is missing the 4th bright fringe. That is, there is a bright center fringe and three more bright fringes to either side of the central bright fringe, but the 4th one is...
  21. binbagsss

    Optics aperture modeling rect functions

    I am trying to model a shape T aperture through 2D rect functions. Both the horizontal and vertical 'lines' have length b and width a, and do not overlap. The origin should be taken to be the centre of the vertical line. The question has hinted at the function describing the aperture to be...
  22. S

    Plane Mirror Optics: Determining Minimum Mirror Size for Viewing Entire Image

    Homework Statement While you were looking at the reflection of your feet in a plane mirror, you saw a dark spot on the glass. Assuming your height is 1.50 m, and that the eyes are located 0.1 m below the top of the head (a) What is the distance between the spot and the floor? (b)...
  23. E

    Lots of questions about optics

    Hi, I am new here and I've got lots of questions about optics physics. I hope everybody can help me out. First, please check my understanding of diffuse reflection: http://www.physicsclassroom.com/Class/refln/u13l1d6.gif As shown in the diagram, I am sure that it will still follow the law of...
  24. J

    Fibre optics for use in lighting?

    Is it possible to send enough light down a fibre optic cable to produce say 1000 Lumens? How would I go about calculating this? My thoughts here are using fibre optic cables to transfer light from the rooftops of buildings to the rooms inside. Is it possible? I know fibre optics are used to...
  25. H

    What is the Distance d in Snell's Law and the Pythagorean Theorem?

    In the following diagram find the distance d if a=4.0 mm, Θ=30° n_asinΘ_a=n_bsinΘ_b: snells law a^2+b^2=c^2: pythagorean theorem I think I got the angle to the problem correct. I am not sure if this is correct. Is this correct Θ_b=sin^-1(1sin30/1.52)?
  26. H

    Finding Refraction Angle and Wavelength in Water for Sodium Light?

    A narrow beam of sodium light (λ=5893 A) is incident from air on a smooth surface water at θ=35°. Find the refraction angle and wavelength in water. n=λ_0/λ:wavelength of light in a material n_asinΘ_a=n_bsinΘ_b: snells law n=c/v:index of refraction I tried using the wavelength of light...
  27. B

    How Do Newton Rings Help Calculate Lens Curvature?

    Homework Statement These are problems from a Newton rings experiment where a lens was placed on a flat surface and the interference patterns created Newton rings. I measured the diameter of the first five rings and then plotted a graph of d^2 against N (number of the individual ring). These...
  28. P

    How to Determine Focal Length and Power of Lenses for Farsightedness

    Homework Statement A farsighted woman cannot see objects clearly that are closer to her eye than 60.0 cm. Determine the focal length and power of the spectacle lenses that will enable her to read a book at a distance of 25.0 cm. Homework Equations The equation I have been using to find...
  29. D

    Understanding Refraction and Reflection in Silvered Lenses

    When dealing with lenses which have one curved/flat surface silvered why do we consider light to refract twice before hitting the silver side? This diagram should show what i mean: The way it appears to me is that after light enters the un-silvered surface it refracts then it does...
  30. Feodalherren

    Optics: How much light required to heat water?

    Homework Statement How many grams of water could have its temperature raised by 1.13 °C by a mole of photons that have a wavelength of 510 nm? Homework Equations E=hf λf=c The Attempt at a Solution (3x10^8) / (510 x 10^-9) = 5.88 x 10^14 Hz multiply by Planck's constant...
  31. Daaavde

    Optics: Why not polished surfaces reflect less than polished ones?

    Hello, I would like to ask why, when a surface is not polished, it reflects less. I understand that when the surface is not polished, microscopically it presents a lot of irregularities so that when the light strikes the surface it gets reflected in all directions and instead of getting...
  32. X

    Optics: Focal length of Koenig eyepiece

    Homework Statement A Koenig eyepiece with a focal length of 100mm is constructed in the following way: The first lens is made of 755276 glass which is 10 mm thick on axis. The radius of curvature of its left hand surface is -225mm, the radius of curvature of it right hand surface is 83.6...
  33. P

    Chapter 21 Ray D'Inverno Scalar Optics, congruence of null geodesics

    First of all this is my first thread, so I apologize for any mistake. Perhaps this is a stupid question, but i need some help in exercise 21.10 of D'Inverno, to write down geodesic equation for l^a, which is a vector tangent to a congruence of null geodesics and then by a rescaling of l^a...
  34. U

    OPTICS: finding image position using matrix methods

    Homework Statement Hello! The question I'm looking to solve is asking me to "analytically evaluate the image" produced by a concave mirror (which I'm assuming is telling me to use matrix methods to find image position, though I'm not sure). I've come across matrix methods which give me the...
  35. C

    Should optical cables be water tight? Geometric optics

    Homework Statement Explain the physical principle of total internal reflection used by optical cables. Calculate the critical angle of incidence that corresponds to a refracted angle θair = 90 Next, calculate the critical angle for a bare glass fiber submerged in water nH2O = 1.33...
  36. C

    Geometric optics - thickness of acrylic ?

    Homework Statement A ray is deflected by 2.37cm by a piece of acrylic. Find the thickness t of the acrylic if the incident angle is 50.5 degrees. http://imgur.com/kx2VT5c Homework Equations n1sinΘ1 = n2sinΘ2 The Attempt at a Solution n of acrylic is 1.5. Therefore, the refracted...
  37. djh101

    How difficult is quantum optics lab?

    I'm currently a chemistry major (senior), but I intend to go to graduate school for physics, so quantum optics lab would me more useful to me than materials chemistry lab. I emailed the physics counselor (since the class is restricted to physics majors) and she said that it would be to...
  38. M

    Optics: white object reflection properties

    If a red light drops on a red object, we know that all of the red light is reflected, and none is absorbed. But what happens if a red light drops on a white surface, is all of the red light reflected, will the intensity of the reflected light be the same? Or will the reflected light be of a...
  39. P

    Diffraction Grating problem (waves and optics)

    Homework Statement Visible light passes through a diffraction grating that has 900 slits per centimeter, and the interference pattern is observed on a screen that is 2.58m from the grating. In the first-order spectrum, maxima for two different wavelengths are separated on the screen by 3.16...
  40. Choisai

    What are Fourier transforms of optics?

    So I'm currently busy studying a Digital Micromirror Device which is used for top-hat beam generation. Programming the input pattern and error diffusion needed for optimal top-hat generation is heavily based on Fourier Optics. The problem however is: I don't know Fourier optics. I know this...
  41. D

    Nonlinear optics: second order polarization calculation

    This is a problem from Boyd Nonlinear Optics chptr 1 problem 2. Homework Statement Numerical estimate of nonlinear optical quantities. A laser beam of frequency ω carrying 1 W of power is focused to a spot size of 30μm diameter in a crystal having a refractive index of n =2 and a second order...
  42. T

    [Quantum Optics] Scully and Zubairy Section 6.2

    Homework Statement I've been reading through Quantum Optics by Scully and Zubairy and have been stuck in section 6.2 getting from the definition of the atomic inversion given by equation (6.2.20, pg 199) W(t)=\sum_{n}\left[|c_{a,n}(t)|^2-|c_{b,n}(t)|^2\right] to the atomic inversion for the...
  43. M

    [OPTICS] Faraday Rotator with waveplates

    Hi all I'm trying to replicate the effect of a 45° Faraday rotator using a series of waveplates instead. I've encountered some difficulties using the jones matrix notation, due to the differencies of the matrix formulas between the books I'm referring to. The main book I'm using is...
  44. J

    Gas: The New Frontier of Laser Optics

    What filters are to optics, could gas be to a laser?
  45. Spinnor

    Neutrino beam passes through optics lens, focus the neutrinos?

    If a neutrino beam passes through an optics lens in principle does the matter in the lens focus the neutrino beam granted it may be ridiculously small amount? If the lens were instead made of compressed matter of nuclear densities would the answer change much? Thanks for any help!
  46. E

    Nonlinear optics: second harmonic generation

    Hello, I'm studying basic nonlinear optics and I would like to solve a couple doubts about (basic) photon interaction. Let a monocromatic (of frequency ω) electromagnetic field propagate through a nonlinear medium and let the third(and higher)-order terms in the relation between the...
  47. U

    Michelson Interferometer: Optics

    Homework Statement A Michelson Interferometer has incident light in range 780-920 nm from a source. Intensity as a function of x (distance from central maxima) is given by: I_{(x)} = 3I_0 + 3I_0 cos(K_1x) cos (K_2x) - I_0 sin (K_1x) sin (K_2x) where ##K_1 = 1.3 x 10^7 m^{-1}## and ##K_2 =...
  48. F

    Optics Brewster's Angle Reflected Light Intesity

    Homework Statement An incident unpolarised light beam of intensity I_{0} strikes glass plate B at Brewster's Angle. The reflected light travels vertically and strikes a second glass plate A, again at Brewster's Angle. (We ignore the light transmitted by the glass plates.) Plate A is then...
  49. H

    A lot of questions about wave optics

    Homework Statement In this picture,the ray b and c are parallel.So why there are interference occur? Homework Equations The Attempt at a Solution
  50. U

    Optics: Whispering gallery modes in large systems

    While reading about whispering gallery modes, I have learned that whispering gallery modes can be seen for "microscopic spheres or toruses" -Wikipedia- , But can they practically be observed in relatively large prisms or glass spheres (m or even cm magnitude) ?
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