Optics is the study of light, and its interaction with matter. It includes topics such as imaging systems, fiber optics, lasers, quantum optics, and more.

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Increasing the efficiency of solar cell systems

As far as I know, there are currently two main approaches to utilising solar radiation for maximum energy conversion to electricity. These are either direct conversion to electricity, using ...
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29 views

Fabry-Perot Spectroscopy

Suppose you have a source of variable wavelength, and you are sweeping the wavelength while monitoring transmission through a Fabry-Perot cavity at normal incidence? What (qualitatively) could you ...
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46 views

Rayleigh length determination for Laguerre-Gaussian Modes

Recently I have measured the Rayleigh length of a Gaussian electron beam probe in a scanning electron microscope, using the function: $$w(z) = w_0 \times \sqrt{1 + (z/z_r)^2}$$ Where $w$ is beam ...
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54 views

How to calculate the focal length of spherical shell (zero meniscus lens)

I can get my head around the optics of a spherical shell (a meniscus lens that neither diverge nor converge, being neither positive nor negative etc). I don’t see how I can describe in a formula how ...
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17 views

Phase change by reflection [duplicate]

Let's consider a light ray falling on a cuboid made of glass at the angle $\alpha$. Then there will be a reflected ray $A$. The ray will also refract. Let the refracted ray be $B$. Ray $B$ will be ...
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54 views

Determining the focal length of a gradient index lens

There are three subquestions in this question, all marked bold. Let's consider a planoconvex gradient index lens of thickness $d$, radius $R$ whose refractive index changes with the distance from ...
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40 views

image transmission through waveguides

in general optics we study the transmission of image information through lenses, basically governed by Fourier optics laws. how can images be transmitted through waveguides at smaller propagation ...
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59 views

Calculating the beating length of the directional coupler

I want to determine the coupling length needed to achieve a certain power coupling coefficient of a directional coupler. Recently, I read a paper titled "Ultra-compact high order ring resonator ...
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71 views

Why do snorkelers not need to wear corrective glasses when snorkeling with goggles on?

I am myopic ~ -2.75 sph +1cyl. When I went snorkeling they tell you not to wear glasses behind the goggles. Surprisingly, underwater, things remain in focus with goggles on even without prescription ...
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168 views

Determining the refractive index of a foil

(59th Polish Olympiad in Physics, final stage, experimental part, 2010) You have at your disposal: a sample of blue foil of a homogeneous material, placed between two glass panes in a ...
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23 views

What will my diamond fibre shirt look like?

So, during an idle moment when I mused that our experimental setup would be a lot less hassle if it was made from a 1kg single crystal of diamond, this thought occurred to me... Since single crystal ...
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33 views

What is the “Obscuration Factor (OBF)”?

In a paper I am reading for my master thesis I came across this "obscuration factor (OBF)". The authors indicate that it is a measurement of the average intensity of reflection. They do not give a ...
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21 views

Design process of directional coupler

I know that when two wavegudies are brought sufficiently close enough, the electromagnetic fields overlap and light can be coupled from one waveguide to the other. However, how to calculate the ...
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123 views

Why is there a negative sign in front of the optical wave?

In undergrad I lost (a lot) of marks in my optics class for writing: $$A(t) = \exp(i(\omega t + \phi))$$ Instead of: $$A(t) = \exp(i(-\omega t + \phi))$$ In a derivation where I must have needed ...
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43 views

Interference and windows

The other day i was learning about interference patterns with the effect of a bubble making a rainbow on the surface. I learned that the reflections from both sides of the soap can interfere ...
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29 views

What's the difference between on-axis and peak intensity for a Gaussian beam?

I am asked to find the ratio of the on axis intensity at z=zR (Rayleigh range) to the peak intensity, given that the Gaussian beam solution is: ε(ρ,z) = ε0 (ω0 / ω) exp(ikρ^2 / 2R) exp(-ρ^2 / ω^2) ...
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35 views

Path length requirement for diffraction problem [closed]

The following question has been asked in a problem sheet I have been asked to answer: "The above diagram relates to the path lengths of radiation, with an angle of incidence, θ, reflecting off ...
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47 views

Color of objects in Yellow sun

The sun appears yellow but the objects on the earth appear as if they have been illuminated in white light. Are all objects that we see in sunlight actually in a yellow shade, and would appear ...
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38 views

Could satellites achieve orbit using current laser technology

My question is, could we, using current laser technology sufficiently scaled up, launch a lightweight, say a GPS navigation satellite, into earth orbit? The main objection to me is maintaining the ...
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28 views

Florescents and radio waves

Okay so if you put a florescent light bulb in front of a certain radio, the radio waves excite the mercury inside a causes them to emit UV light which makes the outer coating of the light bulb light ...
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53 views

Compact Disc Optics - Why use a linear polariser and a quarter wave plate?

I just came across this website about the application of a quarter wave plate. Link: Compact Disc Optics. My question is why does the beam need to be linearly and then circularly polarised before ...
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62 views

A lens with a variable refractive index

(60th Polish Olympiad in Physics) A planoconvex lens of radius of curvature $R$ and thickness $d$ (on the optical axis) is made of a material, whose refractive index changes with the distance from ...
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40 views

Liquids that change refractive index with magnetic fields

I am trying to find out liquids that would change their refractive index with applied electromagnetic field. Do they exist? I cannot seem to find a lot of research on it. A super basic example is ...
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Why subwavelength objects can not be seen with optical microscope?

What would happen if we would take a very small sphere around 200nm diameter and try to detect it from the most efficient optical microscope? Technically, the Rayleigh diffraction limit prevents the ...
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58 views

Metal Refractive index

I'm working on Fresnel equation for calculation of reflection of a light (532 nm) on Iron. I've got a question: Is metals refractive index always a real number or it can be a complex number?
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Cumulative Aberrations of Two or More Lenses

Suppose I have two lenses, and I can analyze and determine the Zernike aberrations coefficients of both lenses together in a given setup, and also the coefficients of one of the lenses seperately. ...
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70 views

Diffraction in Circle of light? [duplicate]

I'm working on a project that refers to optics. the question says when a laser beam is aimed to a wire ( perpendicular to the surface ), a circle of light then will be seen on a the surface. I somehow ...
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Model of scattering in wet things

You know that clothes and some surfaces become darker when wet (covered in an earlier question: why wet is dark?), because of the disordered reflections or of the refractive index of water or ...
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Optics - Photodiodes - minimum photon energy that a photodiode will be sensitive to [closed]

I'm foraying into the world of photodiodes, and I'm trying to calculate the minimum photon energy required for the photodiode to be sensitive to. Symbolic expressions desired. Minimum detectable ...
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38 views

Could laser speckle patterns be used in diagnosing vision defects?

At the London Science Museum some years back, I saw a device which projected a laser speckle pattern and had a sign explaining that it would appear stationary for people whose eyes were correctly ...
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When (or what is the meaning of) $I \propto E^2$?

For a monochromatic plane wave: $$\mathbf E = \mathbf E _0e^{i(\mathbf k \cdot \mathbf r -\omega t)},\qquad \mathbf H = \dfrac{\mathbf B}{\mu _0}= \mathbf H_0e^{i(\mathbf k \cdot \mathbf r-\omega ...
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37 views

Significance of colours in photoelasticity

I already checked similar question at Physics SE, but none gives me a clear answer, also it is a bit difficult for me to understand it from wikipedia as I couldn't find relating material to my ...
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88 views

Refraction of light marching band analogy

When trying to understand the refraction of light when it hits a slower medium, lots of people seem to be enlightened by the 'marching band' or 'marching soldiers' analogy, which 'explains' that when ...
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Does the Abbe limit hold for a single lens?

Let us say I have a single (converging lens) could I use the Abbe diffraction limit (for a microscope) to find its resolution or do I have to use the Rayleigh criterion. (i.e. Is the Abbe diffraction ...
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Image formed by Refracting light

A jellyfish is floating in a water-filled aquarium 1.33 m behind a flat pane of glass 4.30 cm thick and having an index of refraction of 1.5. (The index of refraction of water is 1.33.) Where is ...
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Constant part of a photo taken [closed]

(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 ...
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Any suggestion of laser pointer for everyday life study of fluorescence?

I want to buy a laser pointer to study fluorescence in my kitchen. Any suggestion? What kind of laser pointer? What stuff for demonstration?
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What's the meaning of partial derivative for radiance?

The definition of radiance is: $$L\equiv\frac {\partial^2 \Phi}{\partial A\,\partial\omega\,\cos\theta}$$ where: $\Phi$ is the radiant flux $\omega$ is the solid angle $A\cos\theta$ is the ...
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Can a nuclear bomb be used as the power source for a laser beam

My previous post "Using nuclear bombs to detect near earth orbit objects" asked about using nuclear devices to detect Earth directed asteroids and low albedo comets. Now I want to explore a method of ...
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65 views

Light absorption according to “Beer-Lambert” law [closed]

Beer-Lambert equation tells us the measure of absorption of light when it enters to a liquid and comes out from the other side. But I have a question there: Suppose a glass that filled with water. ...
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Beating the Diffraction Limit with NSOM

I am trying to understand exactly why we can beat the diffraction limit when using near-field scanning optical microscopy (NSOM). For those who aren't familiar with NSOM, check out this article: ...
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A Circle of light

I'm working on a project that refers to optics. the question says when a laser beam is aimed to a wire ( perpendicular to the surface ), a circle of light then will be seen on a the surface. I ...
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1answer
61 views

What happens if light is trapped between two points?

The image can explain my question In the image light is clearly trapped.Even if the mirror absorbs energy the light is continously being added, will there be enough force to break the mirror?
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Light absorption for different liquid

when I was working on a cylindrical glassy bottle that filled with water, I found that the initial light intensity is less than the final light intensity. (It's clear but I experiment this) This is ...
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74 views

Do off axis sources produces the same diffraction pattern as on axis sources?

Let's say I have a simple lens and I am viewing two sources of light A and B through this lens. A is on the axis and B is not as shown in the digram below. Will A and B produce exactly the same ...
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Fresnel coefficient

I dont think I have enough backgrounds for optics. I am sorry for asking this elementary question. I am reading a paper Phyc Rev A, Vol 59 # 6, 1999 they introduces discontinuity matrix ...
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1answer
67 views

James Bond and the invisible car [closed]

For a seminar paper with the topic "Illusion of Invisibility in the James Bond movies" I have to investigate, whether the invisible car from "die another day" is (at least from a theoretical point of ...
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1answer
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Why does light reflected on water tends to 'smear' in the vertical direction? [duplicate]

I have noticed that in city lights reflected on the water are very often smeared more in the vertical direction (relative to the reflecting plane I presume), than in the horizontal direction. See, for ...
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Can the insertion of impurities (doping) influence optical properties of ZnS?

I am currently trying to simulate a scintillator system with silver doped zinc sulfide (ZnS:Ag). To simulate the propagation of photons inside the crystal accurately, optical properties like index of ...
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Why does the chief ray not bend like other rays at the optical axis but goes straight?

1 pg In this picture the chief ray is not bending which is going through the optical axis. It passes straight while other rays from the same object are refracted because they change the medium.