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. U

    Optics: Whispering gallery modes in large systems

    While reading about whispering gallery modes, I have learned that whispering gallery modes can be seen for "microscopic spheres or toruses" -Wikipedia- , But can they practically be observed in relatively large prisms or glass spheres (m or even cm magnitude) ?
  2. E

    Classical Optics / Lagrange multipliers

    Homework Statement A ray of light enters a glass block of refractive index n and thickness d with angle of incidence θ1. Part of the ray refracts at some angle θ2 such that Snell's law is obeyed, and the rest undergoes specular reflection. The refracted ray reflects off the bottom of the block...
  3. H

    Optics Textbook: Find the Best for Learning & Rigor

    Greetings, I have never formally studied optics, and am looking to do so. I have looked around a little bit, and I have the impression that there are not really any "go-to" textbooks on the subject that everyone uses. Does anyone have any recommendations for a good (classical) optics...
  4. W

    Understanding Geometric Optics: The Role of Ray Intersection in Image Position

    Why is the position of an image the intersection of 2+ rays?
  5. W

    Understanding Basic Optics: Exploring Light, Reflection, and Images

    Very basic optics questions: 1. So light is a type of radiation, due to which we see objects. Some objects, like a candle, are luminous and we can see them without another light source. Some other objects are non-luminous, and we need a light source to have light reflected upon them. How does...
  6. C

    Solving Telescope Optics Homework Question Involving Five Lenses

    Homework Statement *The diagram of the telescope is attached* Question states A telescope is constructed from five thin lenses of Diameter D and focal lengths 2F, F, F,F,2F located at x = 0,2F,4F,6F,8F Trace the path of a ray entering the system parallel to the optical axis The...
  7. Q

    Optics question: converging lens with virtual object

    Hi everyone, I was thinking about an optics question in a physics textbook. I think the solutions I saw in the solution manual may be wrong. The question is: When you do the calculations using 1/p + 1/q = 1/f you find that the lens first creates an image 400 cm to the...
  8. F

    Nonlinear Optics Books: Recommendations for Robert Boyd Style

    Hi, I'm an electrical engineering student starting research in nonlinear optics, and I'd like some good books to do with nonlinear optics. I'm looking for book similar in style to Nonlinear Optics by Robert Boyd as I really quite like that book. Other books I've gone through include Optical...
  9. I

    Taylor Series, Binomial Series, Third Order Optics

    Homework Statement Show that if cosΦ is replaced by its third-degree Taylor polynomial in Equation 2, then Equation 1 becomes Equation 4 for third-order optics. [Hint: Use the first two terms in the binomial series for ℓ^{-1}_o and ℓ^{-1}_i. Also, use Φ ≈ sinΦ.] Homework Equations Sorry that...
  10. G

    Optics: Thin Lenses - Determining Focal Length

    Homework Statement In the photo (which I cannot post now, but it is a magnifying glass, and a dollar bill) the images through the lens appears twice the size and it is at a distance of 3.0cm from the lens of the magnifying glass. Determine focal length. Homework Equations 1. -di/do=m...
  11. B

    Optics: What is phase matching, and mode locking

    Homework Statement The other day in lecture my professor mentioned the words mode locking and phase matching (same as velocity matching apparently) while on the topics of lasers. However, i can't find anything that can provide a simple explanation of what they are. Is there anyone who would...
  12. P

    Geometric optics on microscopes

    An infinity corrected microscope objective has a magnification of 100× for a tube lens with focal length 180 mm. The numerical aperture of the objective is 0.90. Calculate the the diffraction limited spatial resolution if the objective is used with red light (660 nm). (Ans.: f=1.8 mm; d=447...
  13. R

    Optics Newton’s ring apparatus Problem

    Homework Statement Here is a worked problem: I don't see why they've used "m-1/2" instead of "m+1/2"?Homework Equations According to my textbook the radius of mth bright fringe is: ##x = ((m+\frac{1}{2})\lambda R)^{1/2}## Where R is the radius of curvature of the convex lens.The Attempt...
  14. E

    Nonlinear Optics: Split Method & Results

    Hello I want to ask you about the split method used to solve the nonlinear schrodinger equation numerically I just want to know what are the results that I am expecting to get how many graphs ??
  15. R

    Optics: Interference - Calculate Order of Maximum Intensity

    “Light is emitted with a central wavelength of 500 nm. First it is analysed with a Michelson Interferometer: starting from uniform illumination, one of the mirrors is displaced 2.5 mm until no new fringes can be distinguished. Then it is analysed with a Young´s Double Slit: it is observed that...
  16. A

    Archived (Optics) Vignetting and field of view

    Homework Statement An 80 mm focal length thin lens is used to image an object with a magnification of -1/2. The lens diameter is 25 mm and a stop of diameter 20 mm is located 40 mm in front of the lens. How big is the unvignetted field of view [in terms of object size (in mm) and in terms of...
  17. R

    Application-oriented areas in Optics & Photonics

    Hello all, I am considering applying for PhD programs in Physics/EE (specifically - Optics/Photonics). Considering pervasive posts about the dismal job market, I understand Optics/Photonics is more applied, and hence more sought-after in industry. However, what areas within Optics/Photonics...
  18. D

    How High Should the Mirror Be Placed for Full Reflection?

    Homework Statement A man stands 1.85m in front of a mirror hanging on a wall. His eyes are 10 cm below the top of his head. At what height from the floor, must the mirror be placed? Homework Equations Snells Law: n1*sin(omega)1=n2*sin(omega)2 The Attempt at a Solution I converted...
  19. S

    Stargazing Saving the telescope with damaged optics

    I have a Celestron NexStar 4SE, I damaged the optics. Is there a company who just sells the telescope without the computerized mount?
  20. Saitama

    Optics - Find the location of object

    Homework Statement A concave mirror of focal length 30 cm is placed on the flat horizontal surface with its concave side up. Water with refractive index 1.33 is poured into the lens. Where should an object be placed if its image is to be captured on a screen with a magnification of 2. Ans...
  21. D

    Optics issue with focusing beam

    Hello all, I've got an optics problem that I'm having some difficulty with, where I want to send a beam through a converging lens to obtain a certain image size. My incident profile is that of a ring with a certain thickness and use I use this as my object. I want an image of a certain size, so...
  22. Saitama

    Optics - Find the refractive index

    Homework Statement An object is located at a distance R from a sphere of radius R. The final image is formed at the same distance R on the other side of the sphere. Calculate the refractive index of the material of the sphere.Homework Equations Since we are dealing with refraction at spherical...
  23. J

    How Do You Calculate Focal Length in a Two-Lens System?

    Homework Statement An object is placed at 25 cm to the left of a diverging lens. A converging lens with a focal length of 12 cm is located 30 cm to the right of the diverging lens. The two-lenses-system forms a real inverted image 17 cm to the right of the converging lens (see attachment)...
  24. G

    Why Is the Small Angle Approximation Used in Optics Problems?

    Homework Statement Had the same problem as this threadstarter: https://www.physicsforums.com/showthread.php?t=109059 Homework Equations The Attempt at a Solution I managed to find a ratio of tangents for the two angles. From there, it seems you're supposed to go "well tan(x)...
  25. A

    Optics: Can a magnified real image be larger than the lens diameter?

    Hi all, This is probably a silly questions, but I want to be sure :). I'm wondering if a real image, created by a convex lens, can appear larger than the lens diameter itself. As an example, I'm thinking about the following: - I have a an object of height h_0=7.76" (display size of...
  26. G

    How Does Thin Film Thickness Affect Interference Patterns?

    Trying to get my head around constructive/destructive interference in thin film optics. The book does a good job of throwing formulas at you but I want some intuition. If we shine a laser with λ = 600 nm on a thin film of a material with refractive index 1.5, at what thicknesses will we get...
  27. M

    Optics for Biomedicine: Limited Programs & Duke's Plans

    I have a very strong interest in optics with biomedical applications, and I have been noticing this field growing over the last few years; however, the number of programs seem very limited. The big programs are University of Central Florida, University of Rochester, and University of Arizona. I...
  28. L

    Physics Italian Student Seeking Advice on Quantum Optics Thesis

    Hi! I'm an Italian student. I I would like to became an experimental quantum optics. In particular I'm interested in Bose-Einstein condensate. I must decide where do my thesis. Can sameone help me? Thank you so much.
  29. M

    Good Quantum Optics Books - Recommendations Needed

    I was wondering if anyone could suggest a good quantum optics book. I know Quantum at the liboff text level. I am not sure if the wolf and born texts are too advanced for me, since I do not have the book, and it has a reputation for intense mathematical rigor. I appreciate the recommendations.
  30. O

    Optics Question, where is the lens

    Homework Statement A 3 cm tall object is placed 11 m from a wall. If the image is to be projected upside down with a 20 cm focal lense, what is: A} The type of lens used? B] Where is the lens placed? C] What is the height of the image? D] What is the magnification of the...
  31. O

    Solving Optics Lens Problems: 2 Possibilities for Object Placement

    Hello, If you have an object, and a bi-convex lense, you are given the focal length, and you are given the magnification factor (M) to be 2, how are there two possibilities to place the object? One question I was doing asked this, and said: a) if the image is virtual, and M=2, find the...
  32. W

    Understanding Fourier Optics in Electro-Optics Lab: Theory vs Experiment

    Hi all Last week i had an exam in electro-optics lab. we were given a question in optical Fourier setup (attached) and then we have some questions about the purpose of the setup. I claimed that the aim of the proposed setup is very similar to 4-f system for inverse Fourier...
  33. tsuwal

    Need a suggestion for an assignment on fiber optics.

    I am finishing a course on Eletromagnetism and Optics. I am currently a physics student in the second year of university. I passed the final exam and now I'm supposed to do a work on fiber optics. Do you know any interesting problem that i could adress? It can be a hard one, I am supposed to...
  34. S

    Smallest curvature radius in gradient index optics

    Hello, would someone know what is the smallest radius of curvature achievable with current gradient index optics (GRIN) technology? I mean, how much could one "curve" a ray of light? Many thanks! :smile:
  35. P

    Optics Question: How do I clean polar sheets?

    So right now I am working on an amature astronomy project to develop a simple lab about the sun's declination. I am borrowing the cheapets linear polarized sheets that I could find ... Because they are least 10 - 15 years old, I would really like to clean them, but I don't know what to use...
  36. T

    Laser Sheet Optics: Generating w/ Spherical Lenses

    Hello, I've been helping a graduate student out with his project which is planar laser-induced fluorescence. Part of the procedure involves generating a laser sheet with which to illuminate over the flame under study. Now, typically a usual procedure involves using a beam expander to...
  37. Saitama

    Calculating Velocity of Reflected Image in Concave Mirror

    Homework Statement Water level in the tank is decreasing at a constant rate of 1 cm/s. A small metal sphere is moving downwards with a constant velocity of 5cm/s. Base of the tank is a concave mirror of radius 40 cm. Find the velocity of the image seen (refractive index of water=4/3)...
  38. Saitama

    Ray optics - Reflection from sphere

    Homework Statement A light ray parallel to the x-axis strikes the outer reflecting surface of a sphere at a point (2,2,0). Its center is at the point (0,0,-1). The unit vector along the direction of reflected ray is ##x\hat{i}+y\hat{j}+z\hat{k}##. Find the value of ##yz/x^2##. Homework...
  39. A

    [Optics] Guide required to solve achromatism numerical.

    Hello guys, First of all this is not a homework. I am preparing for my exams and this question was asked in my previous exams so I tried to solve this question myself, I have tried to solve this numerical by myself, but couldn't get the answers right. So, I am posting this question here, in...
  40. X

    Fourier Optics: Why Does a Lens Perform a Fourier Transform?

    I have been studying Fourier Optics and I have a basic conceptual question. I understand the mathematics of how to perform Fourier Transforms however the part of this topic I seem to have missed is why the action of a lens on light is the same as performing a Fourier Transform on the functional...
  41. A

    Optics mirrors problem with rearview of car

    Homework Statement I'm riding my car. My eye is 40cm from the rearview mirror. I want to know if I can see the car behind me. The car behind me is 2.5m large. Can I entirely see the car behind me in his whole wideness? The mirror is 23 cm long. The car is 4 meters behind us. Homework...
  42. W

    Matlab code for geometrical optics

    Hello all, i have frustrating task in my lab... i have to generate a code in MATLAB that will get the focal length and the object distance from the lens, i.e image (1000X1000 pixels). transfer it through the lens and, for the output it should be the result of it...
  43. ShreyasR

    Basic doubt about a concept in Optics

    This may sound really silly but yeah, a plane mirror, and a white sheet of paper, both reflect all the wavelengths of light incident on them. So Instead of a plane mirror, if I use a white sheet of paper, Why don't I see a reflection of myself? I have studied ray diagrams, and i know how an...
  44. Spinnor

    What are some recommended free Quantum Optics PDFs for learning and reference?

    Searching for free Quantum Optic tutorials came up with the following. Any other suggestions? http://iftia9.univ.gda.pl/~sjk/QO-SK.pdf http://physics.stfx.ca/~pmarzlin/lectures/phys673-winter07/marzlin-phys673-2007.pdf http://www.st-andrews.ac.uk/~jmjk/keeling/teaching/quantum-optics.pdf...
  45. sunrah

    Laser optics suppliers in Europe

    Fresnel biprism sorry if this is the wrong place. Does anyone know a supplier for a Fresnel biprism with apex angle approx 168° should be reasonably small (approx 2cm x 2cm). Looked everywhere but no joy.
  46. PhizKid

    Velocity of an image in optics

    Homework Statement An object 20 cm. to the left of a converging lens with focal point 0.3 cm is moved to the left at a constant 5 cm/s. How fast is the image moving? Homework Equations v = vo + at 1/f = 1/u + 1/v The Attempt at a Solution Since there is no acceleration, I got 5 m/s...
  47. K

    Quantum Optics fails to explain origin of natural line width?

    "Quantum Optics," by Scully and Zubairy, attempts to explain the natural line width of an emitting atomic ensemble (in a resonant cavity with leakage) using random spontaneous emission events of the atoms (which in turn is due to interactions with the vacuum field). The basic idea and...
  48. jaumzaum

    Solving a Weird Optics Question: IIT-JEE 1991 Problem Explained

    I was attempting to solve the following problem from IIT-JEE 1991 (actually I first found it on the book Solved problems in Physics) It asks for the image viewed by an observer at left. Ok, an observer at left would seen an image that passes through a spherical dioptre glass-air only...
  49. S

    Microwave Optics Lab Experiment - PSU Manual

    Homework Statement We're working through the first Microwave Optics lab described in the following PASCO Scientific manual: intro.phys.psu.edu/class/p457/experiments/html/pasco_microwave_optics_WA-9314B.pdf We're using a slightly modified version of this setup, with a voltmeter hooked...
  50. M

    Optimizing Polymer Coating Thickness for Reflectivity at 500 nm Wavelength?

    Homework Statement A polymer coating has a n=1.30 and a base of n=1.50. What is the minimum thickness of the coating to reflect 500 nm least strongly? Homework Equations The Attempt at a Solution
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