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. P

    Quadrature distribution for an optical mode in the coherent state

    Hey there, the task I'm working on is written below. Find the quadrature distribution ρ(q), for an optical mode being in the coherent state |α>. Hint: use ∑Hn(x)*(t^n)/(n!) I really am struggling with this type of tasks :D I tried to follow a solved example that I found in my workbook, but...
  2. E

    Rearranging the equation for the cutoff condition in optical fibers

    Hello! In Optical fibers, let ##k_1## and ##k_2## be respectively the propagation constants in core and cladding, ##\beta## the propagation costant of a mode along the direction ##z##, ##a## the radius of the fiber. Using the normalized quantities ##u=a \sqrt{k_1^2 − \beta^2}## and ##w=a...
  3. P

    Chemistry Structural formulas & optical activity

    How do I determine which group is dash (into the page) and which is wedge (out of page)? Won't that literally change which isomer it is? How to determine optical activity then? (I believe that in order for something to be optically active it has to be an enantiomer--a non-superimposable mirror...
  4. E

    Modeling/Analysis of optical fibers

    Hello PF, I need some guide points to help me formulate a project idea on the topic of optical fibers. Namely, the professor suggested I should look for topics on modeling of optical fibers, analysis of different optical fibers, characteristics etc. and to work in a simulator, or perform a...
  5. N

    Image position in an optical system?

    I have an plano-convex lens with focal length 75 mm. The object is 325mm from the lens. a) Where is the location of the image after the lens? b) Where is the location of the image if an beamsplitter is placed after the lens? My solution, questions: a) a = 325 mm b = ? mm f = 75 mmm...
  6. E

    Optical wireless communication ideas

    Hello PF! I have developed a recent interest into electro-optics used in communication systems. Specifically speaking, I am mostly interested into Optical wireless communications and their applications, for terrestrial to satellite communication. I am considering to do a research project for my...
  7. C

    A What is the role of transverse optical (TO) phonons?

    Phonons can be acoustic or optical in their character and transverse or longitudinal in their polarization. While the importance of longitudinal acoustic (LA), transverse acoustic (TA), and longitudinal optical (LO) phonons is clear to me for the emergence of different quantum phenomena and for...
  8. S

    Gradient Force of an optical near field

    Source: Principles of Nano-Optics, for Lukas Novotny and Bert Hecht.The equations above represent the electric field in the second medium when a light hit a surface and the condition of TIR (total internal reflection) is satisfied. Actually this is what called Evanescent field. The point is if I...
  9. E

    TE and TM modes in optical fibers

    In a step-index optical fiber, considering Bessel functions of order ##\nu = 0## and no ##\phi## dependence, it is possible to obtain two separate sets of components, which generate respectively TE and TM modes. In the former case, only ##E_{\phi}##, ##H_r##, ##H_z## are involved; in the latter...
  10. C

    Optics focal length and optical power Question

    1/f = 1/dₒ + 1/dᵢ = 1/1.0 + 1/0.33 = 4.03 m (focal length) Power: 1/4.03 m or 0.248 (0.25) *around to the2 decimal points? or leave it as a fraction? ((Did I do this correctly? I am not sure if this is correct and is it okay to be in meters not centimeters?)) Please let me know!
  11. berkeman

    Optical Illusions - Enjoy Creative & Fun Illusions

  12. M

    Combination lens equation questions

    Homework Statement: Lens questions. Homework Equations: idk Hello, so I was wanting to use a laser beam and purchase a few lens' online for a project and wanted to get something similar to the image below, where i would end with a horizontal light ray i was wondering if anyone knows the...
  13. e101101

    Optics Problem: What optical instrument does this?

    Im thinking that this is a telescope, but I am having a lot of trouble answering this question. If the plane waves arrive at different angles, wouldn't the image be distorted?Would the lenses possibly be spherical because of this?
  14. Vishesh Jain

    Chemistry Optical isomerism in spite of plane of symmetry ....?

    Shown above is an octahedral coordination complex and it's mirror image. The complex has a plane of symmetry (shown in the left diagram, a diagonal plane passing through bottom left and top right corner, perpendicular to the square plane) ... but still it's mirror image is non-superimposable ...
  15. B

    An ambigious optical system with ambigious solutions [JEE Adv - 20`16]

    This problem was asked in one of the most prestigious exams in India: JEE Advanced, unfortunately it was considered to be ambiguous for the scope of given examination and hence no official answer is issued for it as such.(BONUS marks to all) And so many solutions were posted on Internet which...
  16. T

    Strange Optical Effect: See CD Fully Visible & Ruler Bulging

    In the picture a CD is held in front of a ruler. The light source is an ordinary lamp. You can see a shadow of the CD on the ruler. Remarkable is the shadow on the screen behind it, because you can see that the CD is fully visible and the ruler bulges instead. Does anyone know this optical...
  17. Haorong Wu

    I Questions about an optical photon quantum computer

    Hi. I'm learning the optical photon quantum computer from Nielsen's QCQI. Since I'm not familiar with quantum optics, I got some questions about it.Q1. In page 288, the book reads: A laser outputs a state known as a coherent state ##\left | \alpha \right > = e^{- \left | \alpha \right | ^2 /2 }...
  18. A

    I Quantum Interpretations of this optical effect

    I generally stay away from discussion about the interpretations of QM, but just for this time I would like to know what's the point of view from Bohmian, many worlds, thermal and other interpretations of the following: https://arxiv.org/abs/1305.0168
  19. D

    I What optical filter to use for Raman spectroscopy?

    Raman spectroscopy involves Illuminating a target with a laser Beam. This produces Raleigh scattering. Does The releigh scattering have the same frequency as the laser beam? So use an optical filter to block the same frequency as the laser?
  20. D

    I Compute the optical gain of a quantum well

    Summary: Search to compute gain of a quantum well. Stuck with maths or programming. Hi everyone ! For a personal project, I search to compute the optical gain occurring on a semiconductor quantum well. I have based my calculations on a paper called Investigation and comparison of optical gain...
  21. F

    Derivation of the Optical Law of Reflection

    Problem Statement: Derive the optical law of reflection. Hint: Let light go from the point A (x1, y1) to B (x2, y,2) via an arbitrary point P = (x, 0) on a mirror along the x axis. Set dt/dx = (n/c) dD/dx = 0, where D = distance APB, and show that then theta = phi. Relevant Equations: t = nD/c...
  22. mikenw

    Curious optical effect related to light passing through a mesh

    I hope someone here can explain this curious light effect! Some background: I have a table with a laptop on it, and a chair sitting at this table that has a mesh back on it that has a pattern of ~2mm holes cut into black material in a regular pattern. I happened to notice one day that I could...
  23. E

    How can the electric field of optical fibers be visualized?

    Hello! For dielectric slab waveguides, starting from the field expressions, it is possible to draw the Electric field corresponding to a specific mode, showing its (possible) zeros inside the core and its exponential decay in the cladding: A Google search can provide plenty of images like...
  24. mwatts

    Mouse Blinking: Microsoft Wireless Desktop 900 (PT3-00001)

    I have this mouse/keyboard combo Microsoft Wireless Desktop 900 (PT3-00001) (Amazon link for reference), and I noticed that if I leave the bottom of the mouse suspended from my desk for about 56s, the light emitter starts blinking -- has anyone seen the same thing with this model or, more...
  25. H

    Optical Simple optical lens design help (small projector)

    I need to design a mini projector as a part of a project I am working on. The body of the projector is approximately 7 inch tall and 5 inch wide. I don't know what kind of a lens I need to ensure the projection is sharp and crisp (it is only black and white writing). I know I would need a zoom...
  26. davenn

    Stargazing Australia's largest optical telescope

    Have been doing a bit of a road trip around the state of NSW, Australia, over this last week. Visited the Parkes 36m radio telescope. Then on to Coonabarabran and the home of the Siding Springs Observatory complex. One of the several scopes here is the 3.9m AAT (Anglo-Australian Telescope)The...
  27. C

    Is this the simplest optical cloak possible?

    https://www.researchgate.net/publication/273269952_A_Simple_Unidirectional_Optical_Invisibility_Cloak_Made_of_Water Why did the authors of this cloak not choose a system with only three refractions for each light ray, so that the cloaked area would be a parallelogram? Is this impossible, or...
  28. ThomOnTheBus

    Optical effect seen on a bus: mirrored screen shows different colors

    Hello Physics People, i was on bus 59 lately and i noticed a typical optical effect. There is a monitor/screen in the front of the bus that lists the current and coming stops and updates when you pass one. Its colour scheme is was blue/lightblue/white (see first picture). But when i looked at...
  29. R

    Optical Coatings for Metal Mirrors in Optical Applications

    Does anyone know what kind of optical coatings are used for metal mirrors in optical applications to prevent the surface from oxidizing and that also does not degrade the reflectance of the aluminum itself? I am guessing the aluminum would have to be cut to shape then placed in a vacuum to...
  30. I

    Optical Path with a light source inside a gradient medium

    Hi, I am wondering if anyone could point be to any references for gradient optics. The current literature seems a little haphazard. The model I am looking for would need to consider the following. Single medium whose optical density (index of refraction) is some gradient index of refraction...
  31. DariusP

    How Does Optical Coherence Tomography Work to Image Different Tissue Layers?

    Anyone familiar with how this device works? I'm having trouble understanding how different layers of tissue can be imaged using interference. I am sort of familiar with michaelson interferometer and what is low coherence light if that helps.
  32. L

    A How to calculate the on-site interaction in optical lattice

    We know the on-site interaction in optical lattice can be expressed as U=4pi*ħ2 a/m ∫d3x |w(x)|4 It's simply understood in a 3d system. But how to calculate this term in 1d and 2d system?
  33. T

    Wavelength of a laser within an optical cavity

    1. The problem statement, all variables and given/known date Homework Equations $$\delta v=\frac{c}{2nL} \:[1]$$ $$N=\frac{\Delta v}{\delta v}=\frac{2nL\Delta v}{c} \:[2]$$ The Attempt at a Solution I am having trouble with question 5, but have come to realize I think my cavity length is...
  34. S

    Optical filter that blocks infrared and allows UV?

    Hello. I want to build camera for ultraviolet photography and reflectography. I plan to use debayer'ed backlit CMOS camera with or without Wood's ZWB3 glass UV filter. But I also need to find infrared cut filter because abudant IR radiation will ruin photos. Problem is that there are plenty of...
  35. S

    Attenuation Coefficient in an optical fibre

    Homework Statement In a particular fibre, the attenuation coefficient for Rayleigh scattering is measured to be 0.30 dB/km at 1.20 μm. (a) How large would it be expected to be at 0.80 μm? (b) Ignoring other sources of attenuation, if a signal of a certain initial power was sent over a...
  36. Twigg

    Entropy Production in an Optical Cavity?

    Howdy, Say you've got two highly reflective mirrors forming a cavity. Some broadband light goes in, but only narrowband light comes out. Entropy is definitely decreased as far as the photons are concerned. Where does it go? This has been bugging me. I have a partial solution I was hoping you...
  37. Zubair Ahmad

    Optics question -- Object and Image on the optical axis....

    Is it necessary that the image of the point object placed on the axis of optical system has its image formed on the axis? Consider paraxial approximation.
  38. A

    A Use of the Optical Theorem and Regge trajectories

    Cutkosky rule states that: $$2Im \big(A_{ab}\big)=(2\pi)^4\sum_c \delta\Big(\sum_c p^{\mu}_{c}-\sum_a p^{\mu}_{a}\Big)|A_{cb}|^2\hspace{0.5cm} (1)$$ putting ##a=b=p## in Cutkosky rule we deduce the Optical Theorem for ##pp## scattering: $$2Im \big(A_{pp}\big)=(2\pi)^4\sum_c \delta\Big(\sum_c...
  39. P

    A The Optical Theorem for Feynman Diagrams

    In Peskin's textbook section 7.3 The Optical Theorem for Feynman Diagrams(Page233), he said it is easy to check that the corresponding t- and u-channel diagrams have no branch cut singularities for s above threshold. But I can't figure out how to prove it. Can angone help me? Thanks!
  40. Ajaroy

    What is the internal radius of the optical fibre

    Homework Statement A Capillary tube is made of glass of refractive index n1 . The outer radius of the tube is R.The tube is filled with a liquid of refractive index n2 < n1 .what should be the minimum internal radius of the tube so that any ray that hits the tube would enter the liquid...
  41. Paul Colby

    Can Crystal Symmetry Explain the Lack of Optical Activity in Quartz?

    Hi, I've been looking at the optics of ##\alpha##-quartz which comes in two parities, left and right. Quartz is optically active which means that the plane of a linearly polarized beam propagating along the optic axis is rotated by an angle proportional to the distance traveled. I would like...
  42. S

    Modes of Optical Fiber propagation

    What actually is a mode of optical fiber propagation?Is it similar to modes which correspond to various configurations as in standing waves on a string ? Also How correct is it to consider no. of rays as no of modes?
  43. Michael Sullivan

    ABCD matrix for an optical system of two thick lenses

    Homework Statement I have an object at distance x1 from the first thick lens(convex) then air at distance x2 to the next thick lens(concave) then air of distance x3 to a mirror. I need to build an ABCD matrix representing this. Homework Equations thick lens equation: [ A B ] = [ 1-d/R1...
  44. harambe

    I Optical reflection by metals

    https://eng.libretexts.org/Core/Materials_Science/Optical_Properties/Metallic_Reflection According to this article,metals are good reflectors at low frequencies.What about at high frequencies like visible or UV spectrum?Will this show deviation
  45. BillTre

    3D Printing Small Optical Structures

    Specialized 3D printers can now produce small optical elements: Described here. There is also a company that makes light shaping diffusers (for lamps) that control the light by controlling the interference patterns of the light due to microscopic structures on the surface of the diffuser film...
  46. microsansfil

    I Can Optical Angular Momentum Revolutionize Open-Space Light Communication?

    HI In a new report published the Thursday 26 October in the journal Science Advances, a team of physicists based in the UK, Germany, New Zealand and Canada describe how new research into "optical angular momentum" (OAM) could overcome current difficulties with using twisted light across open...
  47. Derek P

    I Kim et al DCQE optical details

    I am (still) trying to understand the optics of the Kim et al DCQE set-up. It is the optics of the "erased" cases that I don't understand. These are the entangled pairs where the "idler" photon is detected by D1 and D2. Each detector receives a contribution, from one slit, that has passed...
  48. Wrichik Basu

    I Explanation of optical phenomena in light of Feynman's Theory

    In his second lecture of the QED series (see below), Prof. Richard Feynman explains the phenomenon of reflection from a plane mirror, and then the working of a diffraction grating with his theory of arrows (probability amplitudes), and we see that how the new theory, which is much moved from the...
  49. SchroedingersLion

    Birefringence in in uniaxial optical media and Snell's law

    Hey guys, is anyone here familiar with birefringence in uniaxial optical media? In such a medium, there are only two types of polarizations allowed for a wave to propagate. A wave with any other polarization will split into two waves with the allowed polarizations (ordinary + extraordinary wave...
  50. K

    PDLC film or glass for optical shutters or shutter glasses

    A PDLC film or glass also known as "smart glass" is a transparent film or glass with liquid PDLC crystal inside which, when electrical field is generated, can act as an optical shutter. Unlike the traditional LCD shutter it 1) doesn't block light but scatters it 2) it makes no use of polarizers...
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