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. B

    Optics problems - real vs, virtual / thin film

    Homework Statement 33. This experiment projects a red laser light beam of wavelength λ through a diffraction grating labeled 750 lines/mm onto a screen that is positioned a distance l from the diffraction grating. The diffraction grating has a distance d between adjacent lines. The...
  2. S

    Quick check on telescope optics calculations please

    Homework Statement A Cassegrain telescope has a 500mm diameter , a focal length of 5000mm and a central obstruction of 80mm diameter. Calculate: 1) the magnification with a 25mm eye piece 2) the light gathering power compared to aye of 5mm in diameter 3) the angular field in the sky if the...
  3. N

    Liouville's theorem and atom optics

    Hi Say I have an oven, from which atoms are effusing through a very small aperture. By "small" I mean such that it does not disturb the thermal equilibrium of the atoms. Now say I choose to e.g. shine laser light onto the atoms transversely to the direction from which the atoms emerge out of...
  4. P

    Optics Terms: Definitions & Help

    Can you please help me find which terms match these definitions: 1. Reflection from a smooth surface in which the angle of incidence equals the angle of reflection. 2. Imaginary line perpendicular to the surface and serves as a reference line for angular measurement. 3. Straight...
  5. R

    Optics: finding the width of an image produced through a lens

    Homework Statement This is more of a general conceptual question. When finding the image produced through a convex or concave lens, I know that you can use the equation magnification = (height of image/height of object) to find the magnification of the image produced. But does this...
  6. F

    Geometrical optics - lens floating in mercury

    Homework Statement Consider a thin bi-convex lens with refractive index n which has spherical surfaces with equal radii of curvature r and a measured focal length f. The lens floats horizontally on the surface of liquid mercury so that its lower surface effectively becomes a spherical mirror...
  7. jbrussell93

    Optics: Physics vs. Engineering

    I am curious about the differences between optics in the fields of (Bio)engineering and physics. Mainly, I'm interested in finding out how the research differs between the two fields and which would be the best for an undergraduate who is interested in graduate school. From what I understand...
  8. S

    Projecting an Image in a Dark Room - Optics Question

    Hi guys, I have an optics question. I am running an activity for kids to simulate being inside a camera. So I am in a dark room, and I have a small hole in one of the doors which allows light in. An image comes in through the hole, and a magnifying glass can be used to focus this image, which...
  9. P

    Optics: Determining focal length for collimated beam

    Hello all. I am in the process of designing a mechanism for collimating laser diodes for a personal project. I don't have training in optics so I am stuck with this problem: I need to determine the focal length of a lens that can be used to collimate a laser beam with divergence 45 degrees...
  10. A

    Amplitude and energy relation in optics

    Hi Guys I have a very simple and basic question. Assume interface of two dielectric mediums. If the t is transmition cofficient for electricfield from medium 1 to medium 2 with refractive indexs n1 and n2, what is the transmitivity of power from medium 1 to medium 2? I know it is...
  11. G

    Quantum Optics Lab: Biting off more than I can Chew?

    So, I am a freshman signing up for classes next year. I have only taken Physics I - Mechanics, and I am done with Calc III, and I have the opportunity to take a lab course on quantum optics. I am obviously not very prepared, but I have been exposed to surface level quantum concepts quite a bit...
  12. S

    Infinity optics - position of tube lens

    Hi, I was hoping someone would be able to help me with a microscopy problem that has been puzzling me for a while. I'm building a basic microscope from scratch using a 50x long working distance Nikon objective (LU Plan ELWD, wd = 10.1mm, NA = 0.55). The sample is illuminated from above using...
  13. E

    Masters in Optics: Pros & Cons for Physics Majors

    Hi, I'm in my junior year as a physics major. I started out convinced that I wanted a Ph.D., but now I'm not so sure, so I've been looking around for interesting paths that don't involve one. I've run across the optics/optical engineering masters programs at URochester, UArizona, and a...
  14. P

    Why is a Soap Bubble Colored?

    Homework Statement 1. A soap bubble is colored because of: a. dispersion b. diffraction c. thin film interference d. all of the above Homework Equations The Attempt at a Solution I don't understand the concepts very well...at first I though the answer was dispersion...
  15. N

    Geometric Optics: Speed of light and Reflection in a glass cube

    Homework Statement A large cube of glass has a metal reflector on one face and water on an adjoining face (the figure). A light beam strikes the reflector, as shown. You observe that as you gradually increase the angle of the light beam, if Theta is greater than 58.7 no light enters the water...
  16. N

    Quantum optics is a reference to a c-number

    quantum optics is a reference to a "c-number" Hi In my lecture notes on quantum optics is a reference to a "c-number" electric field, and it is stated that, since it is a c-number, there is no corresponding Hamiltonian. As far as I have understood, a c-number is a classical value of some...
  17. C

    Another sign convention issue (optics)

    I read through all of the previous sign convention posts on this forum (and googled a lot and checked a bunch of textbooks) before posting this question. I don't understand the sign convention properly for geometric optics. There are two conventions that I've understood so far, and I've got a...
  18. L

    Possible methods for measuring light absorption in optics experiment?

    So far my friends and I figured out that we will take a solution of chlorophyll, carotene and something else, then place it between white light and prism to see the spectrum on a screen. For a physical part of this experiment (there are also chemical and biological), we want to take photos of...
  19. C

    Optics - Reflection of image from a moving mirror

    Optics -- Reflection of image from a moving mirror I have a dufficult question which I couldn't find an answer to, yet: If I am standing in front of a mirror - I can see my image, naturally. Now, let's say that the mirror is actually a very long train and it moves parallel to me . And...
  20. ShayanJ

    Uncertainty principle in classical optics

    As you know,a pure sine wave extends infinitely in both directions and a wave which is the composition of some different frequencies,has a limited extent.Does it mean that such a wave is a pulse moving in space or it has limited range?(I know its crazy to talk about the range of light,but I've...
  21. P

    Calculate Microwave Frequency for Interference Pattern | Wave Optics Question

    Homework Statement a microwave source is placed behind two identical slits, as represented in the diagram above. The slit centers are separated by a distance of 0.20m, and the slit widths are small compared to the slit separation but NOT negligible. The microwave wavelength is 2.4X10^-2m. The...
  22. B

    Why do mirrors reflect light but white surfaces don't?

    Hi, today a question crossed my mind. I was thinking about mirrors and colors, why they exist and how does light interact with them. And I always heard that white is the mix of all colors, and that white reflects all the colors. It makes sense because one points a red light to a white wall, the...
  23. L

    Answer Physics Homework: Optics, Distance between Patient's Eyes & Glasses

    Homework Statement A nearsighted patient's far point is 0.717 m from her eyes. She is able to see distant objects in focus when wearing glasses with a refractive power of -1.45 diopters. What is the distance between her eyes and the glasses? di = 0.717m refractive power = -1.45 diopters...
  24. Darth Frodo

    How Does Lens Focal Length Affect Image Size on a Wall?

    Problem 1 A flat screen TV is place on a wall in a room. A lens of focal length 50cm is placed between the television and the opposite wall so that a sharp image with one quarter of that of the area of the television is produced on the opposite wall. Answer: Magnification =...
  25. S

    What Is the Focal Length and Magnification in Multi-Lens Systems?

    Homework Statement 1) I have five lenses with f=25 placed at distance 50 from each other, what is the focal length of this system? 2) A light source is placed in the focal point of a lens with f=50, at d=600 a lens with f=400 is placed, at the focal point of the second lens the image is...
  26. A

    Optics Instrumental with thins lens

    Homework Statement In a thick lens, how we do to get the primary and secondary principal planes Homework Equations (1/Si)+(1/So)=1/f The Attempt at a Solution I tried to get to get that with the Newtonian equation
  27. H

    Intro. to Modern Optics Question

    Homework Statement Show that the displacement current density which flows when a parallel plate capacitor gets charged is ε(dE/dt) where ε is the permittivity of the medium between the capacitor. What is the energy density stored in the capacitor and the force per unit area (pressure) on the...
  28. M

    Matrix optics; simple lens system

    Homework Statement Calculate the matrix for the optical system which takes rays from the object plane to the image plane for a simple lens and show how this leads to 1/v = 1/u + 1/f Also show that the matrix can be written in the form \left[ \begin{array}{cc} 1/M & b \\ 0 & M...
  29. A

    How Does a Diverging Lens Affect Image Position and Size?

    1.An illuminated arrow 2 cm high is placed 108 cm from a diverging lens of focal length-36 cm. Find the position and height of the image. The answers are supposed to be -27 cm and 0.5 cm. Any help would be great. Thanks:!)
  30. V

    Calculate Image Diameter of Sun in Concave Mirror with Given θ and f

    θHomework Statement The sun of (diameter D) subtends an angle of θ radians at the pole of the concave mirror of focal length f. The diameter of the image of the sun formed by mirror is _____ Homework Equations 1/v+1/u=1/f The Attempt at a Solution confused with question. Either i...
  31. J

    Modern Wave Optics Question

    Homework Statement Given two counter propagating monochromatic electromagnetic plane waves with equal strength and frequency but orthoganal polarization, (one is y polarized, the other is z polarized). More specifically, the z polarized wave is traveling in the positive x direction and the y...
  32. L

    Laser for optics experiments

    I'm looking for a good laser for optic experiments. All the professional papers I've read show the use of a 351nm Argon Ion laser. A new 30 mW one of these is about $6,000, but I see used ones pop up on Ebay from time to to time. My question is, is there a difference between this laser used...
  33. A

    RFC own vs. provided solution of optics task

    Hia all. I would like to request comments and maybe clarificaions on the task and solutions provided in the attached PDF. It was one of our homework tasks and, IMO the provided solution does not solve the task at hand. I'm currently in a dispute with the chief TA about this and so far...
  34. Z

    Understanding colors (Lights And Optics)

    Well, This isn't a homework , but today in class we talked about how lights shining on a object produce different color. But I do not know what color it produces?? I know that Primary colors of light are red green and blue. Secondary are magenta and cyan and yellow. If we have a red cherry...
  35. F

    Understanding Fourier Optics: Object Distance & Image Formation Explained

    Dear Forum, Consider an object, illuminated with coherent light, that is located very far away from a positive lens. The object is considered to be at "optical infinity" (its distance is simply very large compared to the focal length of the lens). In that case, the image of the object (real...
  36. A

    Fiber Optics - Absolute and decibel Power Gains

    Homework Statement Problem is very simple but the textbook used for this class is complete garbage and has confused me to no end. a) Convert the following absolute power gains (dBm) to decibel power gains (dB). 10^-3 dBm, 2^n dBm b) Convert the following decibel power gains (dB) to...
  37. T

    What Additional Math Skills Are Essential for Studying Undergrad Optics?

    My physics dept offers an optics class with the following descriptive summary: Geometric optics, periodic and non-periodic waves; Doppler effect; interference and diffraction, diffraction gratings; theory of polarization of light; fiber optics and introduction to lasersIt says the math you need...
  38. P

    Additional Text for Optics Class

    Hello. I am currently taking Physical Optics and I do not particular like the textbook I am using and was wondering if anyone had any recommendations on study tools (books or websites) to help me with what we are learning. The class is of the undergraduate level, and the book we are using...
  39. N

    Understanding Polarization and Phase Changes in Optical Systems

    Homework Statement Hi This isn't homework, but something I've wondered about. I post it here, because it might be helpful to others. Say I am looking at the attached optical system: I have polarized light in the plane. Then it hits a lambda/4-plate, where the angle between the fast axis...
  40. S

    Quantum Optics help - Single photons

    Hi. Was wondering if anyone could recommend some good introductory quantum optics textbooks? I have a good grounding in quantum mechanics, but have never looked at quantum optics. Basically my problem is that I am doing my project work in this field(to start in a couple of months) and have...
  41. P

    Sign convention in geometric optics.

    Until today I learned in geometric optics that Object distance +ve for real object else -ve Image distance +ve for real image else -ve Radius of curvature +ve for if light comes to the surcace from the side lying center of curvature else -ve On the basis of this the lens formula...
  42. Drakkith

    I've been thinking about getting into something in Optics, but I don't

    I've been thinking about getting into something in Optics, but I don't know anything about the different courses and such. Anyone here have any suggestions or know a good source of info on getting into optics?
  43. K

    Optics - reduce image and launch into optical fiber

    Dear all, I'd like to know if there is a way of reducing an image and launching it into the core of an optical fiber. By other words, I'm not interested in the spatial distribution of the light (the image itself) but I'm interested in gathering all the light coming from the scene and...
  44. K

    Optics Question, unpolarized light

    Homework Statement Hello, I am reading an intro book on optics and it is discussing the polarization of light and unpolarized light. My question is with unpolarized light I quote: "This sinusoidally varying electric field can be thought of as a length of rope held by two children at...
  45. C

    Introduction to Optics (by Fowler) any good?

    Hello, I have recently been looking into purchasing this book. I know it’s only ten dollars, but money is money, and if some of you pleasant people have any experience with this book I’d appreciate any feedback (of the book). Thank you and have a Merry X-mas. :tongue2:
  46. E

    Optics of lenses and mirrors question:

    So I was going through the playlist of videos here, and have understood everything so far. However, they are going through this question and he introduces this chart, so the student can use it as a reference to know if he got the answer correct...
  47. X

    Optics: Beams through a Prism

    My big problem here is with the geometry... Homework Statement I just took a picture of the problem. It's 15-10. http://img839.imageshack.us/img839/9712/optics.jpg Homework Equations n_1sin\theta_1=n_2sin\theta_2 n_{\bot}=1.6584 n_{Parallel}=1.4864 (I can't find the Parallel sign) The...
  48. S

    Quantum optics - dirac notation

    Homework Statement http://quantum.leeds.ac.uk/~almut/section2.pdf Please note i am referring to the above notes I basically don't get how the maths works to get (eq(25))(eq(22))(eq(24)) = eq(26) am i missing something interms of the commutator relations ? Homework Equations The Attempt at a...
  49. X

    Optics: I do not understand what this question is asking

    Homework Statement Call the irradiance at the center of the central Fraunhofer diffraction maximum of a single slit I_0 and the irradiance at some other point in the patterm I. Obtain the ratio I/I_0 for some point on the screen that is 3/4 of a wavelength farther from one edge of the slit...
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