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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Semiclassical description of EM waves reflection from metallic surfaces

Imagine an EM wave impinging on a metal. Fresnel's formulas tell us that no wave can propagate through the metal, or that the transmitted field is an evascent wave with some penetration depth ...
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30 views

Thin Film Interference in Fluid Dynamics: Many are welcome to throw ideas in here, Please!

It was a few days ago, and there was a very heavy storm(currents were flowing beside the sidewalks as normal). I became intrigued by a thin film of gasoline that got caught in one of the currents. The ...
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16 views

How to block coupling between adjacent waveguides?

I have a number of nonlinear waveguides, say six. I don't want coupling between specific two waveguides. Other than keeping them large distance away, what are the other possibilities to ensure no ...
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56 views

Is the plane wave model always valid in reflection and transmission?

my question is related to another one I asked, but I foolishly made that question about several things (experiment, computation, theory) at once so it was confused. I was talking to my boss about ...
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47 views

Understanding the mathematical formulation of the Faraday effect

The Faraday Effect is a magneto-optical effect which results in the polarisation of light being rotated I would really want to understand the theory of this, but I only have a basic EM knowledge, ...
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771 views

How to turn water opaque by pouring the smallest quantity of matter into it? [on hold]

Consider a glass of water and a glass of coffee. Their contents differ by no more than a few grams of particles coming from the roasted and ground coffee, yet the former lets almost all visible light ...
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2k views

How does the grid on the microwave oven window prevent microwave radiation from coming out?

If I look through the microwave window I can see through, which means visible radiation can get out. We know also that there is a mesh on the microwave window which prevents microwave from coming out. ...
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1k views

Car headlights glass - why such uneven shape/texture?

Why does the glass on my car's headlights have such a strange shape/texture? Are there physics-based explanations or insights for these features? Wouldn't it be better if it was just transparent and ...
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1answer
25 views

What will be the effect of placing a light source very close to a photodiode?

What will be the effect of placing a photodiode really close to a laser source and what should be the appropriate distance between a light source and photodiode to get maximum output current?
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1answer
38 views

Practical hardware question regarding optical source for an array of fiber bragg gratings [on hold]

I have a single 1 meter array of 5 fiber bragg gratings that has FC/APC connectors on both ends. I will be embedding the array in a material and want to be able to do a quick check that the array is ...
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2answers
253 views

Finding the illuminance from a triangular light source

Since most light sources in games are point-like, it's pretty difficult to approximate area light sources with point sources. As triangles are a universal form to represent 3D models (thus area light ...
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19 views

What could be the use cases of optics in a computer algebra system? [on hold]

I am working on optics module in sympy. As of now I've only implemented Transverse wave, Medium and some functions for ...
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3answers
74 views

Can light be trapped theoretically?

My question is a little silly I know, but I'm curious to know if a particle of light can be theoretically trapped between two reflective screens. For example once the particle of light has left it's ...
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1answer
85 views

Has the photon both gravitational and inertial mass?

The theory of relativity shows that the inertial mass of a body increases with the energy it contains; if the increase of energy amounts to $E$, the increase in inertial mass is equal to $E/c^2$, ...
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2answers
242 views

Why does heterodyne laser Doppler vibrometry require a modulating frequency shift?

On the wikipedia article (and other texts such as Optical Inspections of Microsystems) for laser Doppler vibrometry, it states that a modulating frequency must be added such that the detector can ...
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1answer
36 views

Total internal reflection and waveguides

I'm looking at a model of a planar dielectric waveguide along the lines of this picture: For the wave inside the $n_1$ dielectric slab to totally internally reflect $\theta_M$ needs to be smaller ...
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3answers
72 views

Can you explain Fermat's Principle to me?

The textbook(F.A.Jenkins and H.E.White Fundamentals of Optics) states that the Fermat's principle is that the path taken by a light ray in going from one point to another through any set of media ...
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48 views

Does ordinary refraction exert a couple on the refracting medium?

Refraction gives rise to a momentum change orthogonal to the propagation direction. This must result in an equal and opposite change to the medium at the boundary. Entry and exit cancel, and the ...
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50 views

New focal point of converging light through a concave lens

Suppose I pass rays of already converging light through a concave lens. The rays are equally centered on the lens such that the original focal point is through the lens and centered on the lens axis. ...
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32 views

Which Optics textbooks are good? [duplicate]

After September,I will be a sophomore.During the vocation, I am learning optics by myself. And I learn it by reading Ajoy Ghatak's ...
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38 views

Frequency of a photon as related to the change of its frequency

I think that bob maybe already, at least partially, has answered my following question: "Is it true or false that the frequency of a photon is not related to the change of its frequency caused by ...
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1answer
174 views

Myopia / Hypermetropia eye glasses inverting image on retina

As far as I'm aware, the eye acts like a pinhole camera in that it inverts the image on the rentina. This makes sense as the rays converge and form a focal point that is upside down. Myopia ...
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2answers
943 views

Where is a good place to learn (classical) optics?

I need to learn basic optics for a high school academic competition. Does anyone know any good places, preferably free and online, to learn the basics of optics, like lenses, angles of incidence, ...
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69 views

Spatial and Temporal Coherence

How is it possible to achieve waves which are spatially, but not temporally, coherent? Can this be done with a bandpass filter? Conversely, how is it possible to achieve waves which are temporally, ...
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How to make the projected image smaller by adding one ore more lenses in front of the built in projector lense?

I have a projector that creates a large image, even if the distance to the screen is short. The device is very small, approximateley 10x10 cm if you look from above. The height is only 3 cm. I ...
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36 views

Why does a single mode fibre have a cutoff wavelength?

I earlier had a doubt based on ray theory that light must reflect and so all wavelengths should propagate through SMF. This Q/A Single-mode fibers and ray-theory of light does specify that we have to ...
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3answers
41 views

In an optical system with a single convex lens, where should the image area be placed in order to take pictures at infinite focus?

I'm trying to learn how camera lenses work, and have gotten stuck. Say that we have an optical system consisting of a single lens with focal length f, and we want to take pictures of objects which are ...
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117 views

Third-order susceptibilities of metals?

Can anyone point me to a source for measurements of the third-order nonlinear electric susceptibilities $\chi^{(3)}$ of various metals? Specifically in relation to the AC Kerr effect, so measurements ...
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26 views

what is the reflective index of given liquid? [closed]

In this question the refractive index of a liquid is to be calculated considering the given two cases.
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79 views

How is the theory of partial coherent light related to quantum-mechanics?

Background Let me start this question by a long introduction, because I assume that only few readers will be familiar with the theory of partial coherent light and concepts like a mutual coherence ...
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162 views

Magnification for a concave mirror

Here is the question as given in my textbook: Find the distance of the object from a concave mirror of focal length 10 cm so that the image size is 4 times the size of the object. The solution ...
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1answer
39 views

Why do the RGB gamut vertexes not intersect the edges of human vision on the CIExy plot?

As I understand, the CIExy graphic maps "greenness", or rather middle-wavelengthness, to the Y axis and "redness", or rather long-wavelengtsness, to the X axis. The trapping used to reduce the 3d ...
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100 views

Why is Erbium Doped Fiber Amplifier (EDFA) preferred over Erbium Doped Waveguide Amplifier (EDWA)?

Why is Erbium Doped Fiber Amplifier (EDFA) preferred over Erbium Doped Waveguide Amplifier (EDWA)? The question has been asked from an engineering point of view, but obviously I would also be ...
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30 views

Difference between single mode and multi mode optical fibres?

What is the difference between single mode and multi mode optical fibres? First off, I guess that by modes we mean the spatial modes of the electric (or magnetic?) field right? Now: what makes a ...
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14 views

Anomalous Total Transmittance

I am measuring with a Spectrometer UV-Vis-NIR Lambda 900 the total transmittance of a sample made by a sheet of Ethylene vinyl acetate (EVA) between two glasses of 3 mm thickness. I am obtaining an ...
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50 views

How to calculate transmission of photonic band gap fiber?

How to calculate transmission of hollow core photonic fibers (multilayer fiber and 2D band gap fiber)? Which books/article you can recommend ? I see that comsol can do it, but is there a model that ...
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56 views

Optically thick media

What does "optically thick media" mean? Does this property depend on the length of an enclosure? Why is the diffusion approximation for the radiative transfer equation applied to optically thick ...
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22 views

Variance of daylight over short periods of time?

I've searched various publication archives but I'm a signal processing engineer and not an applied physicist, so I might not be using the right terms. While I can find various average values for the ...
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Are Fresnel lenses widely used for solar electricity? If not, why not?

I was just wondering why Fresnel Lenses are not widely used in the production of solar electricity. Their use there would mean that you could produce heat within a fraction of a second, up to a few ...
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1answer
44 views

Is a lens with a focal point that doesn't shift as sun shines from different angles possible? [closed]

My question: Is it possible to manufacture a lens whose focal point doesn't shift in any direction during the day when the sun shines from different angles? It is understood that the focused energy ...
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1answer
42 views

Help calculating field of view for ball lens I just bought

I have a 5 mm (diameter) solid ball lens that I intend to place in front of a 36mm X 24mm camera sensor (I have already made preparations for the image to be focused and for the sensor to not be ...
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1answer
28 views

How does the color of fine dispersed metal particles change between silver and black?

Small dispersed particles of metals are often black, while a solid object of the same material would be some shade of silver. The most notable example is the use of metallic silver as the black color ...
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31 views

Expectation value for the time of a photon reflection

A photon is reflected by matter (by an electron in empty space). How long does the reflection take? (i.e. is there any infinitesimal time elapsing during the reflection process?), or more precisely, ...
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26 views

How is the imaginary part of angular frequency omega related to the imaginary part of the refractive index?

I'm trying to find the attenuation constant (leak rate) $\alpha$ from the imaginary part of the refractive index of a lossy material. I have the eigen frequency $\omega$ for my structure which has an ...
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1answer
99 views

Magnification in compound microscope

I was studying about compound microscope here I don't see why we multiply linear magnification of objective with angular magnification of eyepiece. Shouldn't it be both angular or both linear? Can ...
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1answer
24 views

Reducing the distortion of transmitted light through a prismatic array

I'm wondering if there is a way to reduce the distortion of light transmitted through a prismatic array (without touching the surface of the prisms). The obvious thing to try is a corresponding ...
2
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1answer
71 views

Why do i see bright red hand when i place flashlight behind my hand?

When I place a working flashlight behind my hand, I see my hand bright red because of the light. So my question is, why do I only see red light after transmission even if incoming light from the ...
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1answer
14 views

Light Focus Guider [closed]

How can I easily guide a focused light source to a different location without losing focused light intensity? If there is an item, where can I buy this? I heard about fiber cable, but I do not know ...
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40 views

Anti-reflective coating effect on total internal reflection?

If the surface of prism is coated with an anti-reflective coating, (specifically an index matching, refractive index gradient, or moth-eye structure), and light impinges at a greater than critical ...
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1answer
39 views

Experimentally measuring coherence length of laser

So I am trying to figure out the coherence length of my laser source. I am using a mach zehnder interferomter (image attached). I have theoretically calculated $L_c$ to be somewhere between 800-1200 ...