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. L

    LASER Applications help please

    Can someone tell me about the characteristic of LASER that enables it from the following usage: 1-holography 2-orienting missiles 3-star wars 4-CD and DVD 5-medical surgery 6- telecommunications and fiber optics 7-LASER printer 8-cutting metals
  2. S

    Fresnel Lens - Solve for Lithography & Power

    For the first part, I got correct: M = (lambda*f)/r_n Converting units to meters (m) then plugging them in: (550x10^-9 m) * (0.67 m)/(0.0125 m) = 2.948x10^-5 or 29.48x10^-6 m or 29.48 nm This checked out. For the second part, using the information from the first part: f = r^2/(n*lambda) =...
  3. Daniel Petka

    A Fourier Optics: Why a Plane Wave contributes to just a single point

    If the distance between the input and the output screen d is large enough, then for a plane wave (with some spatial frequencies vx and vy) at the input, the spot at the output will be a point. But if the plane wave is confined (aperature size b in the picture), it's no longer a plane wave... but...
  4. N

    I Permittivity (epsilon) change via temperature + optics effect?

    I got this from chatgpt: It says "not simple and straightforward", but can we assume proportional ? So is there a visible alteration in Snell angle ? Also, for applied physics databases, what would be a pubmed equivalent, hosting all titles and synopses ? In physics the articles seem to be...
  5. E

    Is an invisible LED mouse more accurate than one with a red LED?

    I have a bluetooth Logitech M557 mouse with invisible led (it's written "invisible optics underneath) that I had for 5 years and I could use on any surface most often on a pure white bond paper. It can move smoothly. My only problem at present is the buttons are not so stable now due to dusts...
  6. vera1

    Total Internal Reflection and Transmitted Wavelength

    In my electrodynamcis assignment I'm being asked to derive the wavelength of the normally polarised wave transmitted through a glass/air interface as a function of ##n_1## (the refractive index of the first medium) using the concept of phase continuity and the fact that maxima should be equal at...
  7. shea

    I Where to Find In-Depth Resources on the Physics of CDs/DVDs?

    There are many rudimentary diagrams and 'pop'-explanations of the physics underlying the apparatus used to read optical disks. I am looking for more concrete resources - experimental design data or in-depth theoretical analysis of the pickup head. Thanks! Edit: Sorin's The CD-ROM Drive is...
  8. G

    An optics question concerning pictures taken by camera

    Answer from the book: We need to draw two diagrams, one assuming the photo on p. 644 is right side up, and another assuming it is upside down. Figure 23–9 is drawn assuming the photo is upside down. In this case, the Sun blocked by the tree would be the direct view, and the full view of the Sun...
  9. D

    B How are 'fringe shifts' in the Michelson-Morley experiment calculated?

    Ok for the interferometer let the arm lengths be ##L##, speed of light relative to the aether be ##c## and the speed of the setup relative to the aether be ##v##. By calculation you can show that the distance between the two 'heads' of the beams of light is ##\frac{v^2L}{c^2}##, and using the...
  10. Overdose_

    Finding the focal length of a converging lens with VERY limited info

    This is the solution but I do not understand??? How could they just assume the object distance equals 2f? No magnification is given here. We know the candle produces a real image and the distance is limited, so that means it must be somewhere between the principal focus, the center of curvature...
  11. BiGyElLoWhAt

    Data analysis by guessing, checking and fixing

    Hi, I'm trying to come up with a section of an optics based physics lab designed for 2nd year Calc-based college students. Calc 2 is a co-req. There are 2 labs that are intimately linked together. The first effectively revolves around taking ##d_i(d_o)## data from a lens, source and screen...
  12. R

    A About collimation in Czerny-Turner spectrometers

    Goodmorning, I'm designing an unfolded Czerny-Turner spectrometer like the one in picture I'm trying to use toroidal mirrors to decrease off axis astigmatism. In my first try i made an optimal off-axis collimator (Mirror 1), a mirror that has a good collimation in both the planes: the plane...
  13. brochesspro

    Effect on visibility of thin films due to interference

    So, what I do not understand 1st and foremost is, when they say "see the film", does the light have to be reflected from the film or can I consider refraction of light through thin film also a case using which image can be formed? To be honest, I have solved this question before, but the problem...
  14. W

    I Need Help Identifying Old Optic Device

    I got this out of an old chemistry lab I cleaned out to use for experiments when I was in college in 1983. I kept it but never knew what it was for. Neat antique box specifically designed for this device. Some optic device with a pivoting mirror. Almost looks like it would be for a laser table...
  15. ace

    B Why is there a second black ring in Pfund's method with water on the Petri Dish?

    I have looked through all the sources to ever exist for Pfund's method, yet I cannot understand why in the situation of having water on the Petri Dish, is there a 2nd black ring after the second white illumination (first in the center from the laser i assume?). What stops the second white...
  16. Echo12

    What is the Relationship between Plasmons and Excitons in Optics Research?

    My major is optics,I love Physics, and my research mainly focuses on the interaction between plasmon and exciton
  17. aferrie

    I Help with sourcing a specific type of integrating sphere

    I am looking for a specific type of integrating sphere that can be used to capture diffuse reflectance measurements, and I would appreciate help with locating a commercially availably version of this sphere. The diagram below illustrates the type of sphere I am looking for [1]. Two ports are...
  18. O

    I Creating a wavelength selectable light source with diffraction grating

    Could a miniature wavelength selectable light source (lamp + monochromator) be created by using a broad spectrum led or tiny xenon/deuterium lamp as a light source combined with a small diffraction grating (and other necessary optics like mirrors, lenses)? Thinking of an application in spectrometry.
  19. S

    I What website/software can draw optics setups like this?

    Some time ago, I drew a simple drawing. But now I can't remember how I drew it. Did I use a software or a website? I remember I could choose some optics components, like the small laser in the image, the mirror mount, etc. It can do basic light tracing. It was free.
  20. deuteron

    I Physical Meaning of the Imaginary Part of a Wave Function

    We know the wave function: $$ \frac {\partial^2\psi}{\partial t^2}=\frac {\partial^2\psi}{\partial x^2}v^2,$$ where the function ##\psi(x,t)=A\ e^{i(kx-\omega t)}## satisfies the wave function and is used to describe plane waves, which can be written as: $$ \psi(x,t)=A\ [\cos(kx-\omega...
  21. aferrie

    I Measuring reflectance of a non-planar object w/ an integrating sphere

    I am designing an experiment to measure the reflectance (diffuse+specular) of insect specimens, and I plan to use an integrating sphere to collect the measurements. Typically, I have seen that reflectance measurements with integrating spheres are done with planar (i.e. flat) sample objects. So...
  22. Marth

    I Optical Effect: curved light source when seen through the bus window

    During the night, I was traveling by local bus. And as I viewed through the window, the light from the street lights and the headlights of other vehicles appeared curved, as shown in the images below: One common answer is: because of refraction Is there any more explanation for this behavior?
  23. Tone L

    I Can an Aspheric Lens Narrow the FOV for Motion Detection Systems?

    I want to build a motion detection system, however I want to narrow field of view. I cannot find a Fresnel lens with a narrower FOV than 30 degrees. Was looking for something around 20 degrees. Can I use an aspheric lens to achieve this, does anyone know?
  24. kori2003

    Physics Lost undergrad looking for advice on career path and grad school

    Hello, First of all, I'd like to thank everyone who takes their time to read through my post and make a response, I really appreciate your help that is given for free. Background. I’m a Physics student in his last year, my expected graduation date is June 2024. I study at one of the best...
  25. Sciencemaster

    I How does one time-evolve a quantum state with its kernel function?

    I'd like to model the evolution of a squeezed state and its properties (such as phase at different spatiotemporal coordinates). I know one can represent them using kernel functions (and I have found a paper that gives a kernel function for a squeezed state: https://arxiv.org/pdf/2105.05990.pdf)...
  26. Jenab2

    I Calculating the Raleigh Criterion constant to 99 significant figures

    I set about trying to use HiPER Calc Pro on my phone to solve the integral for the Bessel function of the first kind and of order one, so that I could get the ordinate value for the first root of the function to 99 significant figures, then divide that by π to 99 significant figures, in order to...
  27. V

    I Sagnac Interferometer (Fiber Gyro)

    How does one determine which direction a sagnac interferometer is turning in a fiber optic gyro? ("FOG") I have been reading about them and found some DIY examples where the output is taken using a photo-diode. Now my understanding is that these photo-diodes are simply measuring intensity but...
  28. C

    A Calculating the optical depth of an inhomogeous gas

    My question emerges from my desire to calculate the optical depth, which should be unitless, for an inhomgeneous cloud of radius ##r##. For a homogeneous medium, the optical depth can be defined in terms of the density of a cloud relative to the density of the condensed medium: $$\tau = \alpha...
  29. benagastov

    I Photodetector Output & Refractive Index of FO Cladding/Coating

    After I finished preparing gas chamber for testing optical fiber as gas sensor, my supervisor asked me to measure the difference of refractive index from several optical fiber with different coatings. I knew there is Evanescent Field and Skin Depth effect, but what kind of mathematical formula...
  30. Sciencemaster

    I How can I model squeezed states in 3D optical modelling software?

    I would like to model squeezed light and its evolution (such as when passing through lenses after being generated) using optics software such as OptiFDTD or ZEMAX. However, I don’t see any way to make such states…my plan was to simulate an Optical Parametric Amplifier to generate these states...
  31. M

    Microscope Optics: questions and calculations

    For this problem, Distance from objective to object ##𝑑𝑂 = 10.6cm## Distance between the objective and eyepiece ##𝐷 = 34cm## For (b) I got ##d_I = 26 cm## and ##M_1 = -2.4## which means that firsts image is inverted and real For (c) I got ##dI' = 35 cm## and ##M_2 = -1.3##. However, I...
  32. S

    I Optics: infinite light source illusion question - can you help?

    Hi. I’m trying to solve an optics problem and really struggling. The problem is best described as follows… Imagine you have a section of a wall that you want to look like a window on a spaceship. So you want to look at this “window” and see through it some “stars” (i.e. pinpoints of light) that...
  33. H

    A What’s the meaning of decay rate in optical Bloch equations?

    i have some questions about decay rate. 1:why do we need decay rate in these equations? 2:is it a constant for a specific medium? 3:it can be changed with respect to some conditions like temprature or pressure? 4:how can i know the decay rate of some energy levels in 85Rubidium
  34. Rymazon

    I Outer layer refractive index - total internal refection on waveguide

    I am interested in experimenting with AR lenses and one of the main technologies is a waveguide. They rely on total internal reflection, which needs light to go from a higher to lower refractive index medium. I am reading that current AR lenses use an outer layer with a lower refractive index to...
  35. dykuma

    I Fabry-Perot Interferometer mirrors

    I am trying to build a Fabry-Perot interferometer to make some narrow band filters, and I was wondering if anyone can go into the specifics of whether there's anything special about the types of mirrors used in construction. I started by trying to see how hard it really is to make one on my...
  36. M

    Optics for High Resolution Laser Imaging: Finding the Best Path

    Objectives: - best path for optics needed to focus and "draw"/project a high resolution image onto a workspace around 500mm square (for a Laser Direct Imaging machine) - where to cost effectively purchase or make the optics necessary to build a prototype The problem: I need to project a high...
  37. Skaiserollz89

    A Fourier optics model of a 4f system

    In my system I am trying to represent two lenses. L1 with focal length f1=910mm and the other lens, L2 with focal length f2=40mm. These lenses are space such that there is a distance of f1+f2 between the lenses. I have a unit amplitude plane wave incident on L1. My goal is to find the...
  38. Sciencemaster

    I What are the units of the squeezing parameter?

    As I understand it, when the squeezing operator acts on an annihilation/creation operator, a function of sinh(r) and cosh(r) is produced, where r is the squeezing parameter. I've been reading some papers that say that up to '15 dB of squeezing' have been produced in a laboratory. Does this mean...
  39. P

    Find pupil locations w/ paraxial ray tracing (thick lens, Geary CH 5)

    Per the description given in the book, one can trace rays FROM the physical aperture stop into object space to find the size and location of the entrance pupil (EP). Also, one can trace rays FROM the physical aperture stop into image space to find the size and location of the exit pupil (XP). In...
  40. P

    I Paraxial ray tracing: fixing image/height w/o knowing stop location

    In recent coursework, I was taught that one locates the image and identifies the image height using the marginal and chief rays. These descriptions are: Marginal ray: that ray traced from [top or bottom] of the object, through the outermost edge of the stop. The place where that ray crosses the...
  41. LittleSchwinger

    Quantum What are some good modern Quantum Optics textbooks?

    What would people here say are good modern Quantum Optics textbooks?
  42. Anish Joshi

    B Geometrical Optics: Explaining the Effects of Small Wavelengths

    Read this in my textbook:- The reason Geometrical optics works in case of formation of shadows, reflection and rarefaction is that the wavelength of light is much smaller compared to the reflecting/refracting surfaces as well as shadow causing objects that we use in day-to-day life. I...
  43. J

    I Minimum light bulb wattage for solar simulator

    I am trying to design a simple homemade PV solar simulator. I have picked metal-halide lamps as my light source. If the PV panel has an area of 1m^2 and I wanted to achieve spatial uniformity across the irradiated surface with an irradiance of 1000 W/m^2, how do I go about selecting what...
  44. rogdal

    I Hologram recording on photorefractive material

    Good morning, I am developing an experiment on how to study the kinetics of etching/erasure of holographic lattices in a photorefractive material and I have some doubts about the procedure to follow. I have a single-mode He-Ne laser with monochromatic light of wavelength 632.8 nm and the...
  45. H

    I Plane wave decomposition method in scalar optics

    Suppose an optical scalar wave traveling in Z direction. Using the diffraction theory of Fourier Optics, we can predict its new distribution after a distance Z. The core idea of Fourier Optics is to decompose a scalar wave into plane waves traveling in different directions. But this...
  46. Jan Berkhout

    Calculate the best angle for maximum light dispersion through a medium

    I first thought that the angle would have to be maximum when it is closest to the critical angle for total internal reflection. From my lectures the equation for the critical angle is ##\theta _1>\ sin ^{-1} \left( \frac {n_2} {n_1} \right),## so as ##n_2 = 1##, we have ##\theta _1=\sin...
  47. Z

    I Scattering and non-imaging optics

    I have seen the term "conventional scattering lens" being used (see https://arxiv.org/pdf/2112.08144) and I was wondering whether the term scattering lens is accurate? I always envisioned a lens as a refractive element, and wondering if the reference means refracting rather than scattering...
  48. OliverFroelich

    A Iphone Reflection has a pattern

    Hi all! I'm sitting in the office on what would normally be a dive day so I'm slightly over observant. The sun is coming in heavy through my window, and holding my iPhone I began playing with the reflection on my office wall it produced. The reflection at first was no different then any light...
  49. S

    Solid State Researching Gold Thin Films: Electrical & Optical Properties

    Hi Physics folks,I am currently collecting resources for my senior seminar project at my university and would like to ask if anyone has any good references for gold thin films. I am planning on focusing primarily on the electrical and optical properties of gold thin films. I appreciate any...
  50. Aymangh994

    I Using simple lenses to image AFM Probes

    Hello, Using a CCD camera and simple lenses, the probe of the cantilever and its surroundings are to be imaged. Since the cantilever is 50 um wide and some of the surroundings are to be imaged, the optimal image magnification is from 4 to 8. I therefore used a convex lens with a focal length of...