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.

View More On Wikipedia.org
Recent contents Top users
  1. S

    Reason behind so called Optical illusion or Simultaneous contrast

    Hello everyone, I am really looking out for some literature which has reported the physics behind the occurrence of the phenomena in which two blocks of same color seems different when kept in different background. I have attached an image which depicts the query in a very evident manner...
  2. S

    Number of images formed by two concave lens, one displaced from optical axis

    Homework Statement A biconvex symmetrical lens is cut in two halves and placed as shown in figure. if a point object is placed in the left how many images will be formed options - (a) Two images (b) Three images Homework Equations The Attempt at a Solution As I...
  3. F

    Dielectric materials in Optical Traps

    Why are optical traps constructed using beads that are made of dielectric materials? What property of dielectrics is being employed here? Would a non-dielectric material still experience radiation force from photons? Thanks!
  4. P

    Is it possible to see twins in Si under an optical microscope?

    Is it possible to see twins in Si under an optical microscope?
  5. R

    Proving Optical Law in plane mirror

    I tried to prove that distance of image is same as the distance of object in a plane mirror. The image attached is the ray diagram. First of all, I have assumed object and image to be parallel to mirror. First I proved angle TSA = angle TSa Then I have made similar triangle TSA and...
  6. A

    Shaping optical pulses with linear optics? Where's Von Neumann?

    I'm trying to get to the bottom of things concerning the shaping of an optical pulse(change of state) with linear optics. Using linear optical apparatus we can shape the pulse of a photon in such methods as cavity dumping. You feed an optical cavity with near monochromatic(short bandwidth)...
  7. M

    Solid State Heat capacity optical and acoustic

    Homework Statement A material has 104 atoms in its primitive cell with a speed of sound of 1500 m/s. It is well above the debye temperature. From Cv=3kb per atom, we calculate the volumetric heat capacity of 1.4*10^6 J m^-3 K^-1. What fraction of he heat capacity is in the acoustic branches...
  8. H

    Help Deriving Intensity Equation for Optical Michelson Interferometer

    Homework Statement I am currently studying the optical Michelson Interferometer and I am in need of help with a derivation. The equation I need to derive is that for the intensity of the light arriving at the viewing point. The equation is given below.Homework Equations I(Δ)=I/2 +...
  9. hxtasy

    If you wear glasses please look at this picture optical illusion?

    While drawing a computer chassis I'm designing, i came across a really weird optical illusion. it only seems to work with my glasses on. i put sun glasses on and could see it move a little, but with classes if you stare at the hexagons and move your head while looking at them, everything shifts...
  10. B

    Optical Properties: DFT, Pseudopotential, Plasma Frequency, Transmission

    Hello 1- I calculate optical properties of a pure compound in framework of DFT with pseudopotential by software. I get several picks in loss function. Does only the highest , determine plasma frequency or all of them with different density of valence electrons? 2-can we conclude the...
  11. T

    Constant in Modes of Optical Fiber

    Dear All, Many thanks for reading this query. Actually, I am having problem in measuring the mode fields of Optical fiber at the core-cladding interface analytically for modes LP01 and LP11. The modes are normally given by eq 2.165 (image attached). To my knowledge these constants A and C...
  12. Dembadon

    Does anyone else like optical illusions?

    http://www.michaelbach.de/ot/ I just spent the last 45 minutes looking at some of the demonstrations on that site. Apart from sore eyes and a minor headache, I find it fascinating. Most of the demonstrations allow you to manipulate sliders to adjust different aspects of the illusion. Some...
  13. F

    Ideal optical collimation system

    Hi, I have been stuck on a project that I am working on. I am trying to collect light using optics from a FOV of 200x200mm at 200mm distance. I have two major problems: 1. My detector is small so I need to collimate the light (my application is not imaging so I don't worry about the...
  14. P

    Can Optical Tweezers Manipulate Conducting Microscopic Particles?

    it typically states that optical tweezers are used to manipulate dielectric particles or whatnot. Is it also possible to do the same with conducting microscopic particles? what are the limitations besides mass being not too large? obviously optical trapping can be used down to the atomic scale...
  15. cepheid

    Optical Source Modulation with a Chopper

    What is the purpose of using a chopper to modulate an optical source? The Wikipedia article is not that informative.
  16. M

    General rule of resolution of optical systems

    According to Faynman Lectures on physics in the chapter of geometrical vol1 ch27, the general rule for the resolution on any optical instrument is this: Two different point sources can be resolved only if one source is focused at such a point that the times for...
  17. Y

    Optical Design and Simulation Software

    Hi all, I am seeking for an optical design an simulation platform. There will be splitters, combiners and mirrors with precisely adjusted angles/positions. I will input the specs and position of all the components (including the light source) and want to view the corresponding optical path...
  18. M

    Refractive index of optical fibre

    http://www.fiberoptics4sale.com/Merchant2/fofs_img/how-optical-fiber-works.gif The refractive index of the core is higher than that of the cladding, I don't understand why!
  19. N

    Spectral width of an optical pulse

    If we take a CW laser,say, and operate a pulsed regime, will this directly effect the spectral content of the emitted light? Is there anyway that we can pulse this laser without introducing linear chirp? Thank you
  20. M

    What is the relationship between physical density and optical density?

    I read two definitions about optical density and I'm very confused about that 1.the sluggish tendency of the atoms of a material to maintain the absorbed energy of an electromagnetic wave in the form of vibrating electrons before re-emitting it as a new electromagnetic disturbance. 2.the...
  21. F

    Optical design of surgical loupes

    First of all, I am new to this forum and I would like to thank you for accepting me here. I am a dental student and I would like to make a set of dental-surgical loupes. The loupes are actually small Galilean telescopes-microscopes with a fixed focus at 400-500mm, Field Of View of around 6"...
  22. N

    Question related to Optical Waveguides and power

    I am doing a 2D COMSOL mode analysis of an optical waveguide. The mode analysis shows you the electric/magnetic field and you want to find out the power of the guided mode. How could I do this? Power is P = I*V or dE/dt with units of Joules per second. In the FEM simulation I have given...
  23. D

    Optical trap, choosing the right condenser NA illuminate QPD

    Hi, I am looking to illuminate a quadrant photo diode using a condenser/ lens combination in a optical trap setup. I see thorlabs has a kit that has a 100x objective as a trap and a 10x objective as a condenser. Does that mean that one doesn't need to collect all the laser light scattered from a...
  24. S

    Is length contraction an actual occurrence or merely an optical illusion?

    Hello everyone. I was thinking about length contraction in Special Relativity last night. I looked up information on the internet, and from what I understand, length contrtaction has never been measured (I'm not completely sure if I simply failed to find information to the contrary). So my...
  25. Y

    Optical Antennas: Experiencing Light Differenly?

    Hi everyone, Light has a dual nature ; wave and particle. Particle part can be explained using Quantum approaches while the wave nature is described by Maxwell Equations. I am interested in light - matter interactions from wave approach which is also my thesis subject. (also I would like to...
  26. V

    Understanding Classical & Quantum Coherence in Optics

    Hello all, I'm studying classical and quantum coherence in optics and I can't understand what's the physical meaning of second order coherence. I mean, what's the fundamental difference between it and the first order one? I know they are defined differently but I can't see in which case and why...
  27. P

    Could the acceleration of expansion (of the universe) be an optical illusion?

    Physics & astronomy are interests of mine (I don't understand the granular details & apologize if this is a silly question) Could it be that the increasing rate of expansion be similar to how two points on a balloon would appear to distance themselves as you fill it with air?
  28. M

    Which Techniques Are Best for Optical Characterization of Semiconductors?

    Hello Everybody, I am going to build an optical lab. to characterize semiconductors which have a luminescence over a wide range 200 nm - 1500 nm. I hope to have a setup which flexible to carry more than spectroscopic technique and be able to study this wide spectral range. I would...
  29. N

    Measuring the Optical Power of a Pulsed Source

    Hi. I was wondering if someone can provide me with some advice on the proper way for measuring the optical power of a pulsed laser system? My optional methods are: - Photodiode detector: measuring average power - Oscilliscope with optic-electric converter...
  30. U

    Help me in choosing optical chopper

    hi friends I am going to buy optical chopper system for my work. But i need some clarification about system. If i want to chop say 2mm diameter of the beam, say it has of chopping frequency from 500Hz to 1000Hz. What is the difference if i chop at 500Hz and 900 Hz except the frequency...
  31. S

    Optical Instruments: Solving Homework Problems

    Homework Statement 1. Peter cannot see distinctly objects closer than 40 cm from the eye. Find the power of lens that enable him to see objects at distinct vision 2. A man has near point of 50 cm and a far point of 200 cm. a. What kind of glass should he used to see normally? b. What are...
  32. T

    Modes of Propagation in an Optical Fibre

    I'm having trouble understanding why only certain angles of propagation can transmit down an optical fibre. My lecturer produces this formula for the allowed angles: \sin \theta = p \frac{\lambda}{2dn} where \theta is the angle of the ray from the optical axis \lambda the wavelength of light d...
  33. P

    Optical Mouse-How it works+what are these components

    Homework Statement Pictures of an optical mouse I took apart are attached. We had to find a circuit, take a picture, draw the circuit diagram and explain how it works. I'm not sure what a few of the components are. U3 is for the scroll wheel but what is it? U1 (the big IC) is the guts of...
  34. J

    Optical incremental encoder

    I was given the following question "An optical incremental encoder that produces 1,000 pulses per revolution is connected to the shaft of a motor. Determine the angular resolution of the encoder in degrees and the motor speed in RPM, if the encoder outputs 5,000 pulses in 1 second." I am...
  35. V

    Excitation of optical branch phonons

    As I studied, the optical branch of a crystal is called so because it can be excited with e.m. fields but I wondered whether it is possible to excite the optical branch also with chargeless particles like neutrons or the charge/action-on-charge is necessary for the process? And if so, why? I...
  36. D

    Medical Have you ever had an optical fiber shoved up

    ... your nose and down your throat? I had a throat ache that wouldn't go away, and so to see what was going on, they did this medical procedure. The interesting part is that I never saw it coming. They asked questions, cleaned away ear wax, sprayed a liquid in my nostrils, and out of no...
  37. S

    Optical Properties of Materials presentation

    Hi everyone, I'm trying to gather some ideas of subjects for an oral presentation in my Optical Properties of Materials class: I'd love to find something pleasant or at least nice to develop (like I heard "how a cameleon changes color?"^^), not too theoretical if possible... And with some...
  38. N

    Finding the circle of least confusion for a multi-element optical system

    Hi, I'm a mechanical engineer that's new to optics. I'm trying to determine the best location to place an image sensor for an optical system with multiple lenses and mirrors. In doing so, I've come to the understanding that the best position to put the sensor is at the circle of least...
  39. G

    Is it difficult to find an optical job in USA?

    I was told that optical fiber communication market starts to recover. But I'm very frustrated in seeking an optical job here. Could anyone give some seeking hints? Many thanks.
  40. V

    Sakurai's proof of the Optical Theorem

    Right now, I'm self-studying from J. J. Sakurai's book Modern Quantum Mechanics. In section 7.3, Optical Theorem, there is one step in the proof that he uses that escapes me. His proof involves using the transition operator T defined as: V \mid\psi^{(+)} \rangle = T \mid\phi \rangle \\...
  41. C

    Optical Spectrum Analyzers - Confused on Units

    Hi! I am new to these, and off the bat am confused by the units. Manufacturers quote resolution either in units of length, e.g. 0.04 nm, or HZ. For example, 0.04 pm / 5MHz 0.16 pm / 20 MHz 0.8 pm / 100 MHz. I am thrown by this since I thought frequency was the inverse of...
  42. C

    Understanding Optical Tunneling

    So i was messing around with a wax prism and a microwave emitter. So I have an emitter and a detector and the microwaves are being shot straight across to the detector. But when I place a Wax prism in between it stops getting the signal . But then when we place a second wax prism next to it, it...
  43. M

    Laser power in optical tweezers

    Hi, I'm currently recalibrating an optical tweezer for my undergraduate thesis. The alignment did turn out well so far but I'm a little bit concerned about the power loss within the microscope (here's a picture of the relevant part, without prisms). I read in a paper that 20 to 100mW are...
  44. C

    Understanding the Mechanism of Linear Optical Tweezers for Cell Stretching"

    Hi, I work with a diode laser, astigmatic Gaussian beam (elliptic), that has two foci positions. One is for to focus the width of the beam and the other one to focus the length of the beam. I trap particles using the first focus. The two parts of the beam act as two orthogonal beams. So, the...
  45. N

    Optical path length and phase difference

    Homework Statement Light of wavelength 612nm in a vacuum travels 1.57pm in a medium of index of refraction 1.51. Find a)The wavelength in the medium. b)the optical path length c)the phase difference after moving that distance, with respect to light traveling the same distance in vacuum...
  46. M

    Optical scattering: Converting BRDF to PSD

    edit: the TeX is still being screwy, not putting the equations in the right places. stay tuned. editII: fixed, I think. Homework Statement I'm working on converting a BRDF to a PSD, S(fx,fy). Homework Equations In the book 'optical scatter: measurement and analysis', the BRDF is given as...
  47. S

    Resolution of Optical Instruments Question

    Homework Statement A 3.1 cm--tall object is 26 cm to the left of a lens with a focal length of 13 cm. A second lens with a focal length of 8.0 cm is 42 cm to the right of the first lens. Homework Equations 1/s + 1/s' =1/f M=-s'/s and I'll have to multiply the two M's together to get the...
  48. M

    Optical Phase Detection Techniques for Improved Noise Floors in Interferometers

    Let's say you have two pulses from the same source, one whose phase is slightly delayed relative to the other one. Now, I know that you can use an interferometer and a balanced detection-type scheme to measure the phase shift (in which case you can be shot-noise limited), but I'm wondering if...
  49. U

    Change in velocity of light with change in optical density

    hey guys! we know that velocity of a wave = wavelength x frequency. and speed of light changes with change in optical density. so there must be change in either frequency or wavelength or both. which of these quantities change with change in optical density? and why?
  50. P

    Light in an optical fiber - variational calculus

    Homework Statement Homework Equations \frac{\delta{F}}{\delta{y}} - \frac{d}{dx}\frac{\delta{F}}{\delta{y'}} = 0The Attempt at a Solution I'm having trouble setting this one up. If I let the functional be F(x,x',y) = n(y)\sqrt{1+(x')^2} Applying the LE equation I obtain...
Back
Top