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. C

    Exploring Light Transmission with Lasers & Optical Fibers

    Why is it that we are able to use a laser beam with optical fiber but not with a white light source?
  2. deccard

    The length of laser's optical cavity. Multiple of wavelength?

    In order to produce coherent laser light is it necessary that the length of optical cavity between the mirrors is a multiple of the wavelength of laser light? I cannot see how otherwise the laser been could bee coherent. On the other hand I don't see how it is possible to place the mirrors with...
  3. D

    Optical absorption in Semiconductors

    [SOLVED] Optical absorption in Semiconductors Homework Statement I'm doing a lab report on the optical absorption of semiconductors. More specifically it was to determine the bandgap values of the semiconductor samples. This is the experimental setup...
  4. D

    Name a physical quantity used to measure optical density of a Medium

    1.A rectangular loop and a Circular loop are moving out of a uniform magnetic field to a field free region with a constant velocity V.In which loop the induced e.m.f is constant during the motion of the loop. 2.Name two Physical quantifies other than velocity,wavelength and C,associated with...
  5. O

    Mastering Optical Depth: Simplifying the Concept for Beginners

    Hi Everyone! I was wondering if someone could help me with Optical Depth, I read some articles about it but since my English isn't that good I couldn't Get it well! I have some views about the Opacity But when it comes to optical depth I'll get lost :D help!
  6. G

    Solving Questions on Optical Characteristics and Image Formation

    Can anyone solve me these questions, please 1. A convergent lens has one 8 cm focal length. One places a 2 cm height object at 4 cm of his optical center. Find the various characteristics of the image obtained. 2. A divergent lens has one 8 cm focal length. One places a 2 cm height object...
  7. J

    Calculating Optical Interferometry Telescope Resolution

    I can't find any useful page which explains in detail how to calculate the equivalent resolution of an optical interferometric telescope. I found out, after LONG search, the formula to calculate standard-telescope resolution: Resolution (Km) = 5,5680 * 10^-4 * Distance (Km) / diameter (mm)...
  8. S

    Multipath dispersion of a pulse of light in an optical fiber.

    Homework Statement Multipath dispersion of a pulse of light in an optical fiber. How is this problem solved?
  9. A

    Optical Extinction Help Needed: Calculating A_v for Spherical Cloud

    Help Needed! Optical extinction Homework Statement Spherical cloud (gas to dust ratio 100) with mass = 1 M(sun), diameter = 1pc. Radial density can be described by power law (see below). Determine the maximum optical extinction, ie. the function A_{v}(\alpha). Homework Equations Power...
  10. M

    Atomic clock - optical pumping

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  11. P

    Convergence of light rays and Optical Path Length (OPL)

    Why do all rays coming from far off distance from a source(may be planar)... converging at a point need to travel the same Optical Path Length(OPL)
  12. P

    About Optical and Solid State Physics

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  13. 1

    Optical computers and the speed of light

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  14. N

    Optical Insanity: Solving the 45km Challenge

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  15. E

    Why? question about optical encoder

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  16. L

    Thermo Optical Effect: Resources & Textbooks

    Basically, I have a project involving thermally tunable photonic crystals and part of the essay in the run up to the experiment work I want to write a bit on the thermo optical effect, but I have searched in vain for a resource for this. Can anyone suggest a textbook or something online? Thanks.
  17. W

    Explaining the Optical Illusion on a Spoon

    Hello! I have a problem - a non-physics student has asked: "Why do I see my face upside down on one side of a spoon, while it is O.K. on the other side?" How to explain it? The only method I thought of was geometrical optics. Is it possible to clarify this phenomenon without drawing...
  18. B

    Refraction/Smallest curve of optical fibre.

    Homework Statement "figure 3" (below) shows an optical fibre bent in a curve. The diameter of the fibre is 4mm. If light is not to escape, calculate the smallest radius of R of the curve round which the fibre can be bent. Assume that the fibre is surrounded by air (refractive index 1) and...
  19. R

    HELP Kinetmatics or Optical Measurement?

    I'm currently working towards a masters in mechanical engineering, however I plan to focus in physics once this is complete. Which Mechanical Eng class would be most relevant towards a future in physics? - Kinematics and Mechanisms - Traditional Kinematics of mechanisms, joints...
  20. N

    Rectangular Optical Wavguide - EM Wave

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  21. DaTario

    Quantum optical application of Pascal Principle

    Hello, Supose you have an U tube, in which the inner walls are made absolutelly reflective. Now, put a termical state (temperature T) for the radiation field inside the tube and close it with reflective discs which can slide without friction. Supose further that de diameter of the tube in its...
  22. A

    Calculate Power & Energy Loss in Optical Fibre: 0.8dB/km @ 1250nm

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  23. B

    Optical Phonons in Single Atom Crystals: Unraveling the Mystery

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  24. M

    How do other types of optical spectrum analyzers work?

    Okay, I'm writing about optical spectrum analysers as part of my AS coursework, but I've been having some problems finding more in depth information on how they work. Can anyone explain to me how they work? Or link me to a website that can tell me? Thanks,
  25. A

    Are There Any Geometric or Optical Isomers in Ni(OH)2Cl(NH3)3?

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  26. T

    Optical Fiber attenuation coefficient

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  27. WolfOfTheSteps

    Optical Phonons and Monatomic Model

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  28. K

    Optical Instruments-Cameras

    You are taking pictures of the beach at sunset. Before the Sun sets, a shutter speed of 1/125 s at f/11 produces a properly exposed picture. Shortly after the Sun sets, however, your light meter indicates that the scene is only one third as bright as before. (a) If you don't change the...
  29. P

    Understanding Optical Coupling: A Key Concept in Modern Optics

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  30. K

    Why Generating a Purely Optical Standing Wave is Impossible

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  31. dontdisturbmycircles

    Optical Illusion: Maximize for Creepy Effect

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  32. N

    Info in nanotechnology, optical tweezers

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  33. C

    Setting up an optical sensor with a dot sequence

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  34. C

    Optical Model of Nuclear Reactions

    hye.. i want some theoratical detail on optical model of nuclear reactions.. no hard mathematical detail. just theoratical explanation of things ... thanx...:smile:
  35. R

    Calculate how much radiant power goes through an optical system

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  36. T

    Coherent Optical Processor [Photonics]

    In my course on Microphotonics there is a brief mention of a coherent optical processor system. My problem is I don't exactly know what it's for. Basically, what is said that a transparent input image (like a photograph) is lighted monochromatically and then focussed by a lens to a spot with...
  37. B

    Optical Isomerism of [Fe(H2O)6] Complex

    Hi. I'm asked the following question: What isomers does the complex [\text{Fe}(\text{H}_2\text{O})_6] give rise to? Is it optically active? My answer to the first question would be 'none': The 6 identical H2O molecules are arranged in an octahedral fashion around the central Fe-atom, so...
  38. DaveC426913

    Meteorological optical phenomenon

    Snapped this pic the other day. At first, I was drawn by the subtlety of the central tip of the cloud, which is illuminated by reflected light from the sunlit mound of cloud between it and us, but I was wowed by these fanlike structures in the sky above the cloud. Those are not digital...
  39. P

    For those of you who use a optical mouse

    hey guys, For those of you who use optical mouses, have you noticed any kind of weird behaviour like the cursor crawling up the screen diagonally? This happens especially when you don't do anything and just leave the mouse by itself...I was wondering does anyone know why this happens and...
  40. H

    Optical field question (very easy)

    When an optical field is written as: E=A_1e^{i(\vec{k}\vec{r}-\omega t)}+A_2e^{i(\vec{k}\vec{r}-\omega t)}+c.c what does the c.c. for?
  41. D

    How do photodetectors convert light into electromagnetic signals?

    Hi to everyone... I had a silly question to ask... I know that the light in a fiber travels faster than a electromagnetic signal in a wire. I was wondering how photodetectors work because we all know that they convert the ligh to electromagnetic signals. But if the light travels faster than the...
  42. Z

    Is Optical Engineering Covered in This Subforum?

    Are topics on Optical Engineering also included in this subforum?
  43. W

    Optical Interference: Photon Energy Conservation & Vector E

    If you have two photons traveling in opposite directions, that destructivly interfere witheachother, is energy conserverd0? Is the E, in E=hf a vector quantity, that will take in account the directions in which they are travelling? I believe the answer has something to do with treating the light...
  44. L

    Optical spectrometer experiment

    Hi, I need to do an experiment to calculate Planck's constant from LEDs. Basically what I'm intending to do is a fairly simple variable dc supply->voltmeter->LED->spectrometer->diffraction grating->my eye type setup. I know how to do that, but the trouble is I'll need to track down a...
  45. N

    Making hologram without optical table ?

    I read the instruction on how to make a hologram at http://www.3dimagenery.com and it says that you need optical table in order to make a hologram but the optical table is quite expensive for me . So, I want to ask that can I make the hologram as in the 3dimagenery website without using a...
  46. E

    Medical Optical Illusion: Wheels Spinning Backwards in Real World

    We are all familiar with the illusion of the wheels on a car on television appearing to spin backwards when the car is traveling forward, this being caused by a mismatch of the picture frequency and the wheel's rotational speed. However I have also observed this phenomenon in the real world...
  47. S

    Reason for optical activity(of optical isomers)

    Can anyone tell me the reason why an enatiomer rotates the plane of polarised light? Or at least tell me where i can read more on the reason why some compounds exibit optical activity. Thanx Saurya
  48. L

    Why is there negative group velocity in the optical mode?

    The group velocity is always negative except k=0 and k=Pi/a in the optical mode, is there a reason from the general picture of crystal vibration? Well, it seems to me that optical mode describes the situation that different atoms in a unit cell have opposite motions. Also, in the optical...
  49. Z

    The Physics Behind Optical Mouse Technology

    How optical mouse to work? What's principle of the physics? thanks b4
  50. D

    How Do Optical Mice Detect Movement?

    How does an optical computer mouse know which way it is moving?
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