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. W

    Optics - Imaging from focal plane

    Hi! Assume paraxial rays. If I have a lens with a focal length ##f## and I place an object at the focal length to the left of the lens, the image will be at infinity. Correct? But will it be imaged in infinity to the left or right of the lens? If I am looking into the lens from the right I...
  2. S

    Microscope magnification using Ray Optics

    Homework Statement Basically, derive the formula ## m = \frac{ 25 cm}{f_e} \frac{L}{f_o} ## using ray matrices. This just has variable tube length and assumes eye to object distance is 25 cm. Homework Equations Ray matrices: ## \left[ \begin{array}{cc} 1 & d \\ 0 & 1 \end{array} \right] ##...
  3. E

    How to know the shape of a specific location on Earth?

    How do you know the shape (land altitude, roughness, etc.) of a specific location on Earth through a satellite? For example, if a specific place is covered by clouds is there a way to know the shape of the ground at this specific point? I have read through the absorption spectra of the...
  4. A

    Simple Optics Problem (plane mirror and lens)

    Homework Statement A plane mirror is placed at the origin. A converging lens with a focal length of 5.00m is located at x=12.50m. A object is placed at x=22.5m Find the final location of the image in terms of its X coordinate & magnification. Homework Equations 1/q + 1/p = 1/f (lens)...
  5. W

    Geometric Optics: Find Fish Apparent Position & Length in Fishtank

    Homework Statement A fish 2cm long is floating in a spherical glass fishtank with radius 20cm. The glass is 0.8cm thick and has index of refraction n=1.56. The index of refraction of water is 1.33. Find the apparent position and length of the fish. Homework EquationsThe Attempt at a Solution I...
  6. M

    Focal length of lens at border of two liquids

    Homework Statement I need to find optical power (reciprocal focal length) of this system with thin lens Homework Equations I tried to solve this using spherical diopter equation n1/a+n2/b=(n2-n1)/R where a is object distance and b is image distance The Attempt at a Solution equation for...
  7. I

    Real World Applications of Optical Cavities: What Can They Be Used For?

    Are there any real world uses for optical cavities. Optical (or laser Cavities) description: where lasers continually bounce off two reflecting mirrors.
  8. Z

    Double Slit Diffraction:Finding Greatest Angle for Minimum

    I'm at wits end. I hate WileyPlus. Part A, B and C are correct. I cannot figure out what Part D is -- all of the answers I am getting are wrong. Homework Statement Homework EquationsThe Attempt at a Solution
  9. W

    Modeling Converging Spherical Waves in Optics

    Hi. A spherical wave ##e^{i(kr-\omega t)}## diverging from a single point ##(x=0,y=0,z=-z_0)## can be approximated as a parabolic wave in the paraxial case around the z-axis. I.e., ##k r = k \sqrt{x^2+y^2+z^2} \simeq k (z +\frac{x^2+y^2}{2z})##. OK, then let's say a lens is placed such that its...
  10. Qiao

    Fourier optics with concave (diverging) lenses

    Hey, I was wondering, since for a convex lens the Fourier transform of a fields is in their real focus plane. Is it for a concave lens that the Fourier transform of a field is in the virtual focus plane? I can't find any book or paper that talks about how concave lenses work in terms of...
  11. D

    Detecting Falling Objects with a LiDAR

    I am experimenting with a LiDAR system, one of my goals is to detect falling objects. The scanning frequency is 100Hz with an angular resolution of 1°. I have been able to detect an object if it is a certain size or greater moving horizontally but I'm not sure what I should focus on to make sure...
  12. Padrepapp

    Coupling Xe Arc Lamp into Fiber Bundle

    Hey, we are trying to couple the light of a 75 W Xe Arc Lamp (Hamamatsu L2194) into a 800um(0,8mm) diameter fiber bundle (7 fibers). Now we have 2 plano convex lenses (25mm diameter, 30mm EFL, edmund serial #45-364), the first for collimating the second for focusing onto the fiber. We are...
  13. henil

    Project for masters in applied optics

    i want to prepare a project in applied optics but i am to confused about what topics should i select.
  14. A

    How can I determine the properties of a thin lens using basic formulas?

    Homework Statement I've tried to attached the image of the diagram. If that isn't working please let me know.Height of incident marginal ray now 25. Assume a thin lens. Find: a. the effective focal length b. the power of the lens c. surface curvature for front and back surfaces (assume...
  15. T

    Light and Optics: Shoplifter's Distance and Height

    Homework Statement A shoplifter is spotted using a convex mirror, in which the image appears to be 22.0cm behind the mirror, which has a focal length of 24.0cm. HIs apparent height, in this image, is 14.0cm tall. A)How far away is the shoplifter from the mirror? B) How tall is the shoplifter...
  16. M

    Determining the focal length of a gradient index lens

    Homework Statement There are three subquestions in this question, all marked bold. Let's consider a gradient index lens of thickness ##d##, whose refractive index changes with the distance from the axis with the following formula $$ n(r) = n_1 + a r^2 $$. Determine the lens's focal length...
  17. S

    How to Obtain a Magnification of -2 from a Convex Lens?

    Homework Statement You wish to obtain a magnification of -2 from a convex lens of focal length f. The only possible solution is to: A) place a virtual object at a distance 2f/3 from the lens. B) place a virtual object at a distance 5f/3 from the lens. C) place a real object at a distance...
  18. L

    Optics cornu spiral and diffraction

    Hi, i am in second year of university and doing optics I have a questions in one ofmy assignment : Fresnel diffraction is observed behind a wire 0.37 mm thick, which is placed 2 m from the light source and 3 m from the observation screen. If the light of wavelength 630 nm is used, find, using...
  19. DrewHizzy

    Diverging and Converging lenses in a system

    Homework Statement A)Find the final position of the image (from the object, I assume?) B)Find the size of the final image of the object. Homework Equations 1/f = 1/do + 1/di The Attempt at a Solution 1) Solved first distance: 1/5 - 1/4 = 1/di --> 4/20 - 5/20, di = -20cm 2) Use di1 for do...
  20. J

    Ray Tracing - Optics - Bend light with circular lenses

    Hey guys first time poster. I have written a 2D ray tracer in Mathematica. It's very basic, all it does is use Snell's law to trace ray refraction and very basic absorption. The set up is a central absorbing circle surrounded by circular lenses. The central circle is a perfect absorber, so if a...
  21. ryanuser

    Fibre optics and multipath disspersion

    Hey I don't understand why multipath disspersion doesn't occur still when monochromatic lights are directed at a fibre obtic. (For example sending dozens of infrared waves at the same time). Wouldn't they still overlap and perhaps superpose?
  22. G

    Concentrating sunlight to accomplish projection (Art project)

    Hello! First of all I want to say that I am not a physicist, but an artist currently doing my master thesis. I have been trying to build a solar powered slide projector. It works very simple – I reflect sunlight through a slide and enlarge it with a lens. My problem was that I wanted more...
  23. M

    A constant part of a photo taken

    Homework Statement (56th Polish Olympiad in Physics, II stage) A photographer has a camera with a lens of focal ##f## with can be set to a value from the interval ##[f_{min}, f_{max}]##. The diameter of the diaphragm is ##d##. The photographer wants to make a photo of a friend so that the...
  24. Qiao

    Spatial Light Modulators and Fourier Optics

    Hi, I'm working with a Digital Micro-mirror Device type SLM and my goal is to convert my laser from a gaussian to flat-head intensity profile. And then the tricky part is to make the beam oscillate up and down on the camera using just the SLM. Apparently I was to naive to think that moving my...
  25. N

    Interpreting Seidel Aberration coefficients

    I am trying to model a simple system, but the ray-tracing does not seem to be consistent with the analysis of the system in terms of Seidel aberration values. Here's the system layout: When the system contains only the Eye model and the OL lens, it can be referred from the Seidel diagram that...
  26. W

    Understanding Telecentricity in Newtonian Telescopes

    Homework Statement See the image I uploaded. Homework Equations Paraxial approximations The Attempt at a Solution I think the image is formed after the ocular, and I understand the system is afocal. The magnification is also less than 1, but the angular magnification is >1. What I am stuck...
  27. W

    Telecentric entrance pupil - Optics

    Hi. As you guys know, an object-telecentric system (a system with constant magnification) has per definition an entrance pupil that is infinitely far away. One can construct such a system by taking a lens and placing an aperture stop (AS) at its focal point. My issue is that I am struggling to...
  28. J

    Optics question with radius of curvature

    Hi, I am a first time poster and I am completely lost with this question. Any help would be greatly appreciated Filling the space between a contact lens and the cornea is a small quantity of liquid of refractive index of 1.336. Assuming the refractive index of the lens material is 1.490 find...
  29. A

    Need some info about light heat amplified by lens

    It is known that a magnifing glass can start a fire, but I don't fully understand the phenomenon and I have the next questions: - Does the effect depend on the shape and the material of the lens you use? - Where can I find some details about heat produced by light or particulary on this...
  30. S

    How Does Snell's Law Help Calculate Distance Between Parallel Lines?

    I can't seem to find the proof for the distance between the two parallel lines. Homework Equations : Snells law: μ1sinθ1=μ2sinθ2 Sin (A+B)= sinAcosB + sinBcosA[/B]The Attempt at a Solution : tried using the parallel lines to get a result in terms of the initial angle of incidence ϑ, as the...
  31. A

    The smallest angle flashlight beam can make with horizontal

    Homework Statement At the aquarium where you work, a fish has gone missing in a 10.5m -deep, 9.45m -diameter cylindrical tank. You shine a flashlight in from the top edge of the tank, hoping to see if the missing fish is on the bottom. What’s the smallest angle your flashlight beam can make...
  32. Fallen-S36

    Bending the Rules (Gamma ray lenses)

    http://news.sciencemag.org/sites/default/files/styles/thumb_article_l/public/article_images/sn-gammarays.jpg?itok=vYTMw8My Researchers at Institut Laue–Langevin have found a way to bend gamma rays. Gamma ray lenses, which theory had suggested were impossible, could be made from heavy elements...
  33. M

    Why is the general form of the wave equation a second order partial derivative?

    When I deduct the the general form of wave equation, I noticed it has a second order partial derivative form. I am wondering why wave equation has a second order partial derivative form nor a first order partial derivative form?
  34. R

    Divergine Lens Embedded within Converging Lens

    Homework Statement A thin converging lens made of glass (##n_g=1.55##) happens to have an inclusion of water (##n_w=1.33##) at the center. The lens surfaces have radii of curvature ##R_{out} = r_1=r_2=10m##, and the water inclusion has the shape of a diverging lens with radii of curvature...
  35. B

    Solve Depth of Pool w/ Snell's Law

    Homework Statement A stone lies to the very edge at the bottom of a pool. The pool is filled with water to the top. The person standing three meters away from the pool is 1 meter tall and he can see exactly the half of the stone. Calculate the depth of the pool.Homework Equations Snell's law...
  36. S

    Can a real image be formed by a virtual image?

    That is, take the virtual image as the object for a second lens?
  37. AdityaDev

    Changing electric field and refractive index

    I am learning sky wave propagation and in my book, a relation between refractive index, dielectric constant and electro field strength is given. \mu=\mu_0\sqrt{1-\frac{Ne^2}{\epsilon_0m\omega^2}} Is this a form of Kerr opto-electric effect? How do you get this expression? If you think I cannot...
  38. G

    Unclear geometry in optics problem

    Homework Statement [/B] A parallel quadratic slab of glass (n = 1.55 and thickness d = 2 cm, L = 21 cm) rests on a large slab of glass (n = 1.55). To prevent the optical contact weld forming between the two polished surfaces, a small teflon ball (D = 1 cm) is inserted between the slabs on one...
  39. H

    Schlieren Optics Homework Help: Visualizing a Supersonic Wind Tunnel

    Homework Statement My final year project at university is to visualise the test section of a supersonic wind tunnel by schlieren method, though I'm having a bit of trouble setting it up. The light source I am using is a halogen bulb, in an old lamp housing, with a condenser on the end with a...
  40. P

    Why objects reflect light instead of absorbing or transmitti

    So I've searched all over the internet for an explanation as to why when light of a certain wavelength hits an object, it absorbs it or reflects it. The best answer I've found is some light is absorbed and turned into heat, some is absorbed and re-emitted in the same direction (transmitted) and...
  41. Robsta

    Calculate focal length of lens by diffraction.

    Homework Statement A collimated beam from a white-light source is incident normally on a transmission grating with 500 lines per mm. The transmitted light then passes through a lens which is used to project the visible (380–780 nm) spectrum of the light source on to a strip of photographic film...
  42. faofao

    Difference betweend Fizeau and Wedge Interferometry

    Hey everybody, I have a question concerning the difference (if any) of the Fizeau and Wedge Interferometry. I am currently writing my thesis on a project which uses a glass wedge with air in between. This concept is fairly well discussed and background of this can be found in several textbooks...
  43. S

    Refraction through an optical fiber

    Homework Statement Given a "new type" of optical fiber (index of refraction n = 1.23), a laser beam is incident on the flat end of a straight fiber in air. Assume nair = 1.00. What is the maximum angle of incidence Ø1 if the beam is not to escape from the fiber? (See attached file for...
  44. W

    Problem with wave optics - diffraction grating?

    Homework Statement For your science fair project, you need to design a diffraction grating that will disperse the visible spectrum (400-700nm) over 30 degrees in first order. How many lines per mm does your grating need?Homework Equations sin(Θ) = mλ/d y = Ltan(Θ) I'm pretty sure the only...
  45. N

    Current Areas of research in Optics?

    Hello, I'm not sure whether this thread should be in a guidance section or here, but I think its more closely related to this area. As the title of the thread says, what are some current areas of research in Optics, if any? Thanks for any and all replies
  46. A

    Optics: Working out distance of an object from single digital camera using the captured image

    Hi, I'm working on a project to determine the distance a pedestrian is away from a single digital camera but having never done optics before I'm struggling to find the right equation to use. I'd really appreciate any help! The method I am trying to use assumes you know the height of the camera...
  47. QuantumThinker

    Programs Bs.physics (optics) or major in physics minor in C.S

    hi guys ! i am currently in my 3rd year of my B.s in physics with a specialization in optics , but , i don't like optics at all , so i had this idea of taking a major in physics and minor in computer science. i would like to know if you think its a good combination . need some insights...
  48. L

    International Year of Light: Article Collection

    2015 is the International Year of Light and Taylor & Francis have a free online article collection. Find out more and read the articles here: http://explore.tandfonline.com/content/est/physics
  49. R

    What materials are best for creating fiber optics from seaweed or jelly?

    I want to make fiber optics from seaweed or jelly.. It will be happen? Please give me the literature or journal.. Thank you very much for helping me.. :)
  50. S

    Does a diffraction grating with a shape form fourier image

    i just wanted to get this cleared that a beam falling on a diffraction grating with a shape gives the Fourier images of the grating object which can be reobtained by placing a biconvex lens that would converge the rays and form a focussed Fourier image at its focal length and the image of the...
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