What is Optical: Definition and 696 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

    Difference between optical and geometrical length in optical path

    I'm searching for a week from now and can't find out difference between optical and geometrical length in optical path. Can anyone explain or give me idea or how can I find it out?
  2. T

    Van Cittert Zernike Theorem and associated Optical phenomenon

    Hello colleagues So I've been trying to make head and tail of a paper concerning coherence holography. As I see it, it involves a sound understanding of the Van Cittrt Zernicke theorem I have linked the paper below, and I was wondering if someone could explain the physics going on behind and...
  3. S

    Optical Pumping (Zeeman Effect)

    I am a bit confused about optical pumping-style experiments, and why increasing the strength of the magnetic field increases the amount of optical pumping --> increases the transmission of light through rubidium So basically we have Rubidium with energy levels like this...
  4. U

    Optical Transfer Function of a microscope

    Hi all, I am wondering in the 3D optical transfer function as shown below: http://www.purplebark.net/mra/research/votf/otf-sliced-volume.png The m and n axes represent support of lateral spatial frequencies and the s axes axial. If we were talking about a microscope then it has what's called...
  5. mishima

    Optical Low Pass Filter, how does it hit CCD?

    I'm confused about optical low pass filters (found on CCD imaging devices). As I understand it is a double layer of birefringent material which in effect splits light into 4: (2*25%) green, 25% red, and 25% blue (for a standard bayer matrix). The part I'm not sure about is if all 4 fall on the...
  6. S

    Optical Photonic Devices: Ring Resonator

    Hi there, I have been researching an optical Ring Resonator and have been given the following values: FSR=100GHz, Q=10000, Wavelength (λ)=1.55um (micro), ng=3.7 and neff=2.3. Using these values I was asked to calculate the k value (coupling coefficient), length of ring, length of the...
  7. P

    Converting Electrical Signals to Optical Signals for Wireless Li-Fi

    Can anyone tell me how to convert electrical lan signals into optical signals for wireless transmission via LEDs like they use it Li-Fi systems.
  8. D

    Optical path difference of air wedge

    Homework Statement i can't understand why the optical path diffrence is 2nt+0.5λ. why is it so? the 0.5λ is due to the path difference change of 180 degree of when it is reflected lower ray when it is reflected from the lower glass surface... why there's also phase change of 2nt. since both...
  9. D

    Is the Upper Optical Path Longer than the Lower One in Diagram 2?

    Homework Statement for diagram 2 , i just can't understand why S1P -t + ut (upper ray ) is longer than the lower light ray (S2P) , ? if I take S2P minus ( S1P -t + ut ) , then i would get mt t (thickness ) is negative , which is indeed wrong! so it has shown that optical path of the upper...
  10. D

    Optical path difference caused by double slit

    Homework Statement In this question, when S2 is covered with a very thin glass, the fringe move toward Y . why is it so? Homework Equations The Attempt at a Solution
  11. E

    Radial polarization and optical vortex

    hi, What is the difference between radial polarization and optical vortex? thx http://en.wikipedia.org/wiki/Radial_polarization http://en.wikipedia.org/wiki/Optical_vortex http://en.wikipedia.org/wiki/Angular_momentum_of_light http://en.wikipedia.org/wiki/Orbital_angular_momentum_of_light...
  12. S

    Optical tweezers for manipulating atoms together to form new structure

    I am trying to figure out a method for using optical tweezers to manipulate individual atoms into new meta-material structures. I understand this would require a very complicated process. I thought of some general steps this process might use. This is roughly what I think it might require...
  13. C

    Optical molasses at high intensity (forces in OL's)

    Hey there. My goal is to understand the origin of the main forces that keep together an optical lattice created by two identical counter-propagating laser beams. I quote a small excerpt about the forces in optical molasses with high intensity, which I'm having trouble in understanding...
  14. V

    What are the next steps for my new optical device patent?

    Wow! A physics forum! Here's the device I filed a U.S. patent for, so I'm wondering what to do next? http://www.youtube.com/watch?v=wYgfRzxc-Hs I've talked to the chair of my physics department and he said the amount of light arriving at each pixel is very small. CCDs are becoming...
  15. S

    Why Does a Convex Lens Create a Flower-Like Light Pattern?

    I have a long tube (aout 30 cm) with a convex lens of diameter 7.5 cm on the one end and a small hole of diameter 2 cm on the other. When i shine a light through the hole and let it pass through the lens, i get a flowery pattern on the wall, looked very strange to me. There is a maxima in the...
  16. L

    Two atoms in an optical cavity.

    Hello,I have a question about 2 (or more) atoms coupled to an optical cavity. The equations of motion in the interaction picture for 2 atoms in resonnance with an optical cavity starting from 1 excited atom (C_{eg,0}(t_0) = 1 ) (g is the coupling constant) \begin{cases} \dot{C}_{eg,0} &= -...
  17. A

    Simulation of a Gaussian beam in an optical waveguide

    I am trying to simulate a Gaussian beam through an optical waveguide having a circular cross-section in matlab. I am familiar with the theory of modes in an optical fiber and can analytically calculate the evolution of the beam by breaking down the beam into a sum of infinite modes. However, I...
  18. Y

    How does atmospheric dissipation affect UV light measurements?

    I am looking around for some sort of equation regarding optical power dissipation of light (ultraviolet light in particular) in the atmosphere but i cannot find anything. I know that UV light obeys Rayleigh scattering but I don't know much else. I'm trying to figure out for example, if I shined...
  19. T

    What Exactly is an Optical Mode in a Waveguide?

    I have been working with equations throughout the semester and using them to find cutoff frequencies and such, but when you say something like TE10, TE20, TE21, etc., I am realizing that I am having trouble getting a physical idea of what exactly these things are. Of course if you transmit at a...
  20. naima

    Matrix description of optical devices

    I read that Jones matrices can descibe optical devices with polarized light. They are 2 by 2 matrices.A basis can be Linear polarization along x or along y for a photon moving along z. I can use when there is a device with one input channel. Consider now a Mach Zehnder Interferometer (MZI)...
  21. P

    Synge: optical observations in GR

    A couple of questions about this paper, which, unfortunately, I can't access in is entirety http://link.springer.com/article/10.1007%2FBF02923262#page-1 1) Re: optical coordinates. From what I've read (here and some other sketchy sources), these are similar to fermi-normal coordinates, but...
  22. S

    Building an Optical Transistor - Can it Work?

    I was recently looking in lasers and and their uses and while watching Cosmos with Newton using a prism to shows the different colors of light from white light i got thinking. I stumbled onto the top optical or photonic computers a while ago and I decided to look into building one. After...
  23. D

    Laser facets reflectivity calculation from measured optical power

    Hi Every one, I measured optical output power from both laser facets, front facets emits 120 mW and back facets 10 mW. Assuming front facets reflectivity of 30%(for cleaved facets). What will be the reflective of back facets? Please suggest formula and reference this problem.
  24. Rahulr2k

    Number of reflections in an Optical fibre

    How many reflections will be made by a light entering a 2m long optical fibre cable. If the angle of incidence with the axis of the core is 3.43° . Given that the core diameter and refractive index are 60μm and 1.48 respectively I got the answer as 36368.48 is this correct? L=2m...
  25. 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...
  26. andre_teprom

    Infra-Red optical filters: What are made of ?

    Dear friends, I wish know what is/are the chemical elements commonly used for build filter lens applied on moderns night vision cameras. Thanks in advance. +++
  27. G

    Optical trapping of non-spherical particles

    Hey I just have a kind of broad question, typical derivations of the optical trapping force involve the approximation that the particle is spherical. I'm about to start looking into papers which discuss deviations from this but before I do I just wanted to see if I could reinforce some...
  28. kq6up

    Optical Transmission through a thin Film

    Homework Statement In optics, the following expression needs to be evaluated in calculating the intensity of light transmitted through a film after multiple reflections at the surfaces of the film: {\sum _{ n=0 }^{ \infty }{ { r }^{ 2n } } cos\quad n\theta })^{ 2 }+{ \sum _{ n=0 }^{ \infty...
  29. Y

    Return loss of transmission line and optical fiber

    In wikipedia, it said for optical fiber, a loss that takes place at discontinuities of refractive index, especially at an air-glass interface such as a fiber endface. At those interfaces, a fraction of the optical signal is reflected back toward the source. But what I learned in tranmission...
  30. P

    Scattering force in optical trapping

    hello, reading about the theoretical background of optical trapping. I was wondering how the scattering force originates. Often it is written, that the scattering force is due to reflection, but also the central rays refracted by a dielectric object should contribute ? So the scattering force...
  31. BiGyElLoWhAt

    Optical Tweezers experiment =]

    I'm an undergrad at IPFW and I just got on this project setting up an optical trap. Our (my professors) main goal is to find out at what intensity (he keeps saying temperature) of light the objects behave as free particles. I see where this could be of interest, but aren't there bigger things...
  32. Ritzycat

    Engineering Optical Engineering: Exploring Career & University Options

    I have been looking at a few universities I plan on attending and I have noticed some offer an "optical engineering" major. This was a bit intriguing, and reading descriptions and some of the classes that these majors take interested me a bit. Who here has experience in actual optical...
  33. 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...
  34. N

    Does optical switch have another name?

    I need to know about optical switch for my optoelectronics course for physics majors. So far I only know its a switch which is controlled by light. I tried to search net but couldn't find any thing. Is optical switch have another name?
  35. B

    Exploring Optical Phenomena on iPad

    Hello. I played with my new, first ipad yesterday. I inverted sceen colors and activated the cam. How comes there is an image of me reflected in my eyes with NORMAL colors?
  36. D

    4 Lens optical system/fourier transform

    Question on my study guide: An optical systems consists of 4 lenses spaced apart. Each lens has a focal length f. Each lens is located a distance "z" away from each plane as shown. The total length of the system is 8z. Find the distance z needed to satisfy a FOURIER TRANSFORM condition...
  37. E

    Incident Angle Limitation Derivation in Optical Fibre

    Homework Statement derive the angle of limitation sinθ=[(n2^2-n3^2)^1/2]/n1 n1 is the air out side of the fibre n2 is inside of the fibre n3 is the fibre wall Homework Equations Snells Law: n1sinθ1=n2sinθ2 The Attempt at a Solution I'm pretty stuck and don't really know...
  38. U

    Single and multimode optical fibers

    Hi everyone, Sorry this is probably a really dull question but I'm intrigued nonetheless. I use a microscope that has multiple visible light lasers for excitation. The incident light is fed to the microscope through optical fibers. There is a single mode and a multimode fiber. I have been...
  39. T

    Optical Misalignment: Estimating Error and Its Impact on Focal Length

    Hi all I was just wondering if anyone could help me with estimating error caused by misalignment of an optical arrangement. I am interested in how the focal length of this arrangement will be affected by say a misalignment of just one of the lenses. I'll assume that every component is aligned...
  40. U

    Optical Transfer Function of a microscope

    Hi all, I have a question about the "missing cone" problem in wide-field microscopy. The Fourier equivalent of the PSF is the OTF. The OTF has a toroidal (doughnut) shape. I'm a little confused by how to interpret the OTF support in the Z dimension. In 2D and considering lateral...
  41. tipu_sultan

    What is the meaning in the 144 Optical Fiber Cable? Especially why 144

    During studying the telecom underground cable network I came across the Optical Fiber Cable having the 144 fibers (single mode). I want to know why 144? Is this a Some standard to have 144 fibers in one cable? I have also viewed some of the datasheet having 144 fibers Optical Fiber Cable...
  42. E

    Optical thickness of the second harmonic cyclotron motion in a plasma

    Homework Statement Let's consider a Tokamak with major radius R=1m and minor radius a=0.3m, magnetic field B=5T with a deuterium plasma with central density 10^{20}m^{-3}, central temperature 1keV and parabolic temperature and density profiles \propto (1-r^2/a^2) a) Find the electronic...
  43. E

    Stimulated Brillouin scattering inside an optical fiber

    Hello everyone I need some one once and for all to give me the steps to have a clear step by step idea about the stimulated Brillouin scattering inside an optical fiber please and thank you
  44. V

    Optical Activity: How Do Chiral Molecules Rotate Light?

    "Optical activity is the tendency of chiral molecules to rotate ppl" how does a chiral molecule rotate light? Is it because of interaction of electric fields? Anyone please help me? I just need to know how a molecule physically does that?
  45. N

    Understanding Degenerate and Hybrid Modes in Rib Waveguide Structures

    Hi, I am looking into some simulations of rib waveguide structures using Finite Element Method. I particularly solving modes for a 2D cross section of the optical waveguide, looking at TE and TM modes. My questions is about modes called "degenerate" and "hybrid" modes. I haven't found...
  46. B

    Optical design for a tent camera obscura

    Hello all, I've been trying to come up with an optical design to basically form images onto a sheet positioned near the ground, in an old camera-obscura fashion. Hopefully this image helps to visualize. http://www.pinholeblender.com/COimages/mirror.gif I know that I will require a 45...
  47. N

    Optical components - lens and mirror

    Homework Statement a) Despite the diverging lens with focal length f we observed object which is perpendicular to the optical axis (Figure 6 in the article ,,5. Rozptylka a zrcátko"). To what distance from the diverging lens we have to put the subject to be scaled twice? (cross-magnification Z...
  48. E

    Deriving optical- and acoustical branches

    On the book "Introduction to Solid State Physics" by Kittel, on page 98 he derived the roots for optical and acoustical branches for the equation: M_1 M_2 \omega^4-2C(M_1+M_2)\omega^2+2C^2(1-cos(Ka))=0 where the roots are: \omega^2=2C(\frac{1}{M_1}+\frac{1}{M_2}) and...
  49. J

    Optimizing Tubular Optical Filter for Selective Photon Paths - Jim Adrian

    A tube having an inside diameter of 2 microns is one centimeter in length. A photon entering the tube will reach the sensor on other end only if its wavelength is not greater than 2 microns and the direction of its travel is does not cause it to be absorbed by the inner walls of the tube. I...
  50. S

    Optical path length change due to absorption

    Hey, so I am trying to figure out the optical path length change of an optical fiber due to absorption. I'll post what I have so far and let me know if I have done anything wrong or if you have suggestions. so the optical path length is L' = nL (L' is optical path length, n is refractive...
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