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. Mr_Allod

    Reflection and Refraction in an Elliptical Imaging Mirror

    My thoughts so far: a. Since the critical angle occurs at the origin for the given parameters I would imagine that the maximum power reflected would be 100% since at the critical angle ##\theta_t = \frac \pi 2## and ##r_ {\perp} = r_{\parallel} = 1##. I do not know how I might go about finding...
  2. AndreasC

    Classical Problems for Born-Wolf Optics textbook

    I decided to go through Born and Wolf's bible of optics but... Um... The book has no problems. Which kinda sucks. Does anyone know if there's some kind of resource to supplement that?
  3. P

    Combination of thin lens and concave mirror

    I created the following ray diagram to help me solve the problem: Then I applied the mirror equation 3 separate times. However, the final image distance I got is wrong. I'm wondering if I'm mistaken in taking the last object distance to be negative. However I only have one more try to get this...
  4. Mayan Fung

    I Refractive index of a medium in relativistic motion

    I once naively think that the speed of light is also a constant in a medium in all inertial frames which is not the case. I tried to derive the result yet there is a discrepancy from the results I read in some articles. For example, from [Link to unpublished paper redacted by the Mentors], the...
  5. P

    Why 0.3m From Lens Is Optimal Focus?

    Apparently, it must be placed at the focus (0.3m away from the lens). Why is this so?
  6. P

    Problem on thermal radiation and lenses

    I know that the Sun is at a very far distance from the lens, so I assume the rays are parallel and the image is formed at the focus (500mm away from the centre of the lens). How do I calculate the diameter of the image? The hint to solving this problem says that "The angular diameters of...
  7. Mr_Allod

    Rotation and Polarisation of Light using Jones Matrices

    Hello there I am having trouble with part b) of this exercise. I can apply the rotation matrix easily enough and get: $$ R(-\theta) \vec J= \begin{bmatrix} A\cos\theta + B\sin{\theta}e^{i\delta} \\ -A\sin\theta + B\cos{\theta}e^{i\delta} \end{bmatrix} $$ I decided to convert the exponential...
  8. Mr_Allod

    Approximating the Edge of a Lens as a Prism

    Hello there, for part a. of this problem I thought I should try to find the radius of curvature R of the lens using the Lensmaker's Formula. Then it would be quite easy to find the minimum thickness T by just finding the thickness of the circle segment using Pythagoras' Theorem. But part of...
  9. N

    Optics homework: Why is this equation called a standing wave?

    ψ(y,t)= -2A sinky sin wt Why is this called a standing wave?
  10. Pyter

    I Speed of light not an invariant in GR

    Hi all, I need help understanding the light ray bending in the original GR 1916 paper, Die Grundlagen.... First of all, Einstein states the ##c## is not an invariant in GR. In fact, from (70) and (73), it stems that $$\gamma = \sqrt{ -\frac {g_{44}}{g_{22}} }, $$ where ##\gamma## is ##|c| <= 1##...
  11. C

    Courses The right Curriculum for a Physics Master's Degree (Quantum Optics & Info)?

    Hello everyone. I'm starting my M.Sc. in Physics in the summer term. I'm studying in Germany and completed a standard programm in the bachelor programm which consisted of the obligatory courses like Quantum Mechanics, Electrodynamics, Statistical Mechanics and Mechanics. I have to mention...
  12. wcjy

    Can Small Errors in Path Difference Affect Double Slit Interference Patterns?

    $$Δφ = 2π \frac{L_2 - L_1}{λ}$$ $$Δφ = 2π \frac{\sqrt{0.016^2+10^2}-\sqrt{0.014^2+10^2}}{560*10^{-9}}$$ $$Δφ = 33.659 rad$$Answer = 2.24 rad (unsure if the answer provided is correct/wrong)
  13. H

    Phase lag of light in materials

    There are 5 fantastic videos in this website: http://www.alfredleitner.com/ He is a very good educator and it is also very good to see those authentic experiments and aparatus. Anyway, in the following one at exacly 8:00 minutes he says that the phase lag induced by the dipole is always 90...
  14. J

    Coupling of resonant modes in a 1D Photonic Crystal

    In 1D Photonic crystals, a defect can be introduced to create a defect/resonance mode and enable transmission. At first considerations, the thickness of the single defect layer determines the transmission frequency. Moreover, if it is a half-wavelength layer it will enable a resonance condition...
  15. AryaKimiaghalam

    A Interface between Biological Physics and Quantum Physics

    Are there areas of studies which could be characterized as an interface of biological physics and quantum physics? Does such an interface even exist?
  16. R

    Interference in thin films; confusion regarding geometry

    Instead of talking about the simple of case of reflection interference due to a single film, this book starts off with two films with an angled air wedge between them. They talk about the "thickness", ##t##, of the wedge, but this thickness varies along the length of the films (Figure 35.`12)...
  17. fresh_42

    I Exploring the Galactic Center: Adaptive Optics & GR

    https://indico.cern.ch/event/977179/ Description The proximity of our Galaxy's center presents a unique opportunity to study a galactic nucleus with orders of magnitude higher spatial resolution than can be brought to bear on any other galaxy. After more than a decade of diffraction-limited...
  18. R

    Deriving the Law of Reflection from Huygens Principle

    Attached is section 33.7 from my book, which introduces Huygen's principle in order to derive the law of reflection. I am more used to the ray model rather than the wave model, so I'm constantly going to try to relate everything back to rays. Making this connection also helps with completeness...
  19. F

    I Why find the highest order maxima/minima in slit equations?

    I have been seeing interference and diffraction problems involving the double slit and single slit equations that ask for things like the "highest order maxima" or minima, which I have learned are basically found by setting the angle to 90 degrees. My question is are there any real world...
  20. C

    Newton's rings optics question

    I have no idea where to start with this. My professor didn't give an example and I am very confused.
  21. xpell

    B How small is the smallest hole that would still allow you to see through it?

    This is not for a homework or anything, I'm just a curious person who was wondering... that: how small is the smallest hole in an opaque material that would still allow to see the "world beyond it", using your eye or any kind of existing or prospective technology? (English is not my mother...
  22. qnach

    How to calculate shadows in nanophotonics

    Could anyone tell me how to calculate the shadow of an object in nanophotonics. Is there any book discussed such issue? I emphasize nanophotinics becuase at that scale there might have diffraction etc.
  23. C

    I Photons and wavelength in ultrafast optics

    I am not understanding how to think of photons and wavelength in ultrafast optics. An ultrashort pulse is the summation of many wavelengths. So, if you refract an ultrafast pulse it will actually spread out spatially? Can you define a wavelength as sort of an average wavelength? And most of the...
  24. J

    A Nonlinear Wave Equation (Nonlinear Helmholtz)

    I am trying to solve a PDE (which I believe can be approximated as an ODE). I have tried to solve it using 4th Order Runge-Kutta in MATLAB, but have struggled with convergence, even at an extremely high number of steps (N=100,000,000). The PDE is: \frac{\partial^2 E(z)}{\partial z^2} +...
  25. A

    Image in a glass sphere (Ray Optics)

  26. nish95

    Final Image position for a setup with two lenses

    First image is an object for the concave lens so won't +ve direction change from right to left?! In that case, object distance will be -ve (from concave lens towards right side). Any ideas? Solution in the book takes first image's distance to be +ve. See attached ray diagram for clarification...
  27. P

    Position of the object and image in this optics problem

    I know how to solve the problem but the only thing that's bothering me is what is A? According to me A is should be 2F ie 2 times the focal length distance. I thought of it like this: 1. First there will be an image formed due to the lens. 2. The image will be formed below the lens but the...
  28. P

    To find the resultant intensity

    So I thought of calculating the path differences between all the 3 points by taking them in pairs of 2. S1 and S2 S2 and S3 S3 and S1 I got the path differences as λ/3 , λ and 2λ/3 I can now find their phase differences using the equation Cosx=2π/λ* (path difference) Then I can apply the...
  29. aspodkfpo

    Improving Optics Accuracy with Digital Filtering and Ray Interpolation

    Just wondering whether it is actually possible to do this question accurately enough for it to basically look similar. Personally my diagram for the lines drawn in bold in the first diagram are slightly to the left compared to their diagram, by like 1cm on the x-axis, and in the second graph I...
  30. Ozen

    Concentric Meniscus Lenses Design

    Hello Everyone, I have been working on a lens design that requires a concentric meniscus lens. Initially I was under the impression that r1 should equal r2 for the light to exit at infinity when entering at infinity. However my ray diagram shows different, it shows the light is being bent...
  31. S

    Modes of laser propagation in cylindrical optics

    I saw the solution of the light propagates in cylinder.. so in every solution there is the first order Gaussain function (the slandered one) times another function which gives I think the separation, both of them gives the intensity separation.. So what does that mean?! is it as I draw on the...
  32. S

    Elliptical facet cylindrical optical fiber - Mathieu equation

    Let's say I have three modes in a fiber that is elliptical cylinder shaped (cylinder with elliptical facet), as in the image below (the source:Optical Engineering, 46(4), 045003 (2007)) so what is the equations that describe these fields..
  33. JD_PM

    Quantum Optics Question Involving Coherent States

    I've tried to square and compare ##\Delta X## and ##\Delta P## but they are not equal I have to say I am pretty lost here and a hint would be appreciated. I have studied coherent states and I know how to proof some properties related to it. For instance, I see how to proof that the state is...
  34. A

    Are Polycarbonate Sunglasses Effective Against UV Rays?

    Is sunglasses test with UV flashlight correct or not?
  35. G

    Internal reflection equation question

    As you can see we have 3 media here. Only focus on the glass and coating medium. Assume an incident ray comes from the air medium and is refracted inside the glass and then it is refracted again in the coating medium. The x angle is the angle inside the glass medium. In this case, if the...
  36. Haorong Wu

    Courses I am a graduate student in quantum optics. Should I learn QFT?

    I am particularly interesting in QFT, and I am going to be a graduate student in quantum optics and quantum information this autumn. Strangely, I find that there is no courses for QFT. After all, I though QFT are about quantum and field, and quantum optics are about quantum and field, too...
  37. TimeDoctor

    Whom to contact about my improvement on telescope optics?

    Hey guys. If you have a prototype of a new telescope, whom do you contact? This telescope uses the same lenses that we have but enhances their power in a n^4 So, if you have a lense that is supposed to magnify things twice, it'll magnify them 8 times. I just don't know whom to contact or where...
  38. mike2020

    Strange optical phenomenon: lighting a candle in front of a TV screen

    I observed a strange optical phenomenon when lighting a candle in front of a tv screen, in the dark (attached picture). There seems to be two lines forming an 'X' figure with a colored pattern (of diffraction, I suppose). I think it must be related to the material structure of the TV screen...
  39. Jaffer2020

    Refraction of Light: Myth or Reality?

    In my latest 10th grade physics lesson, we were learning about the refraction of light. I decided to share what I knew about why light slows down in a vacuum, which is, in short, because the electric field of the electromagnetic wave exerts a force on the charged electrons of a medium, which in...
  40. iya

    This problem is a combination of optics and derivatives

    According to Cartesian second law, we can get this formula. but wo don't know how to do next. because we just know the sinr and sini.
  41. Sokolov

    Irradiance of light trapped between two parallel mirrors

    The setup of the problem is shown in the image below. I know that I must add all the contributions of each reflected ray and that its amplitude will be reduced by a factor ##r## each time it is reflected. So after the n-th reflection, its amplitude will be ##E_0r^n##, with ##E_0## the amplitude...
  42. Sokolov

    Intro Physics Textbooks on Optics: Alternatives to Hetch-Zajac's "Optics"

    I'm looking for an alternative textbook to the Hetch-Zajac's one. I am a physics undergraduate student, and this is the recommended book for the subject, so I would like to find a book that covers more or less the same topics. There are two main problems I find at Hetch: Firstly, its extreme...
  43. S

    A Evanescent field of a waveguide

    If we look to the figure, in several articles they mentioned that the part of the mode field, the tail of the mode field diameter, travel in the cladding, this maybe I can understand that because of a little change between the refractive indices of the core and the cladding, then the transverse...
  44. S

    Polarization and intensity of a Gaussian beam

    The equation above (from Wikipedia), assumed that the Gaussain beam has polarization in x-direction, as I know that the polarization means that the oscillation direction of the electric field and so the intenisty... so how we get circular intensity in every direction which means in x and y...
  45. Haorong Wu

    Quantum Need suggestions about textbooks on optics

    Hi, guys. I need 2 textbooks for my graduate courses, including quantum optics and nonlinear optics. Thanks!
  46. Ozen

    Ray Diagram for an Experimental Lens Systems

    Hello, I wanted to confirm a suspicion with how the Aimpoint optics work, but to do that I need to do some ray diagrams. I only ever did them with simple convex, concave, and spherical systems while at college. From what I already know of how reflex sights work, the LED is placed at the focal...
  47. A

    A Piezoelectricity and the Lorentz Harmonic Oscillator?

    Hi! As I outlined in my https://www.physicsforums.com/threads/hello-reality-anyone-familiar-with-the-davisson-germer-experiment.985063/post-6305937, I'm curious to ask if there is anyone with knowledge on the theory of the piezoelectric effect on this forum? I think it's fascinating how a...
  48. K

    Calculate the focal distance of the duplicate

    The picture below shows a so-called chromatic doublet, which is designed to minimize chromatic aberration, ie the wavelength dependence of the refractive index of the glass. The first lens has a flat first surface and a concave second surface with radius of curvature R and index of refraction n1...
  49. H

    Problem about compound optics in microscopes

    angular magnification=9.62 part a 1/s+1/s'=5 1/(25-s-s')+1/s"=1/2.6 -s"/s=m can't find m, don't know how to use the info that a person of normal eyesight is looking into the microscope.
  50. S

    Optics: Destructive Interference

    I thought if the question asks for the first minimum or the first dark fringe you use (m+1/2) but i am not getting the right answer. I was hoping if someone could tell me in what situations the (m+1/2) would apply? Thanks in advance.
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