Questions tagged [optical-materials]

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What formalism is used to model thin film optical coatings that function across a range of angles of incident light?

Thin film optical coatings [0] are atomically/molecularly thin layers of material applied to a substrate with the intent of affecting the optical properties of the substrate. For example, magnesium ...
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How to get rid of unnecessary signal in Photoluminescence Spectroscopy?

I am having some issues figuring out have to get rid of laser residues (might be) or scattering from the setup itself (please see attached pic). In the lab, we have AUREA PIXEA 405nm laser, Horiba ...
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How thick would glass need to be for no light to pass trough?

There are no ideal materials, and even though glass is used for optics due to its low absorption of light, how thick would normal window glass (rough idea for specific material) need to be so that it ...
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Development of the incident light transfer matrix on a multilayer structure

I am trying to read an article whose objective is to simulate a DBR (Distributed Bragg Reflector), however I do not understand very well why the matrix that represents the change that light undergoes ...
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How can we generalize the definition a non-linear media?

According to the definition: Nonlinear media are dielectric materials whose polarization density changes nonlinearly if a strong field is applied to them. If the field is small the nonlinear terms ...
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Calculating magnification of a put together telescope

My objective lens has focal length of 50 cm and I am using a 10x eyepiece (I don't have anymore info). I am not sure how to calcuate the focal length of eyepiece. How do I find the total magnification ...
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1 answer
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How to measure the wavelength of a laser? [duplicate]

I'm building an enclosure for a laser engraver that emits light at ~455nm. I want to be able to measure the wavelength of the light that is refracting off the item being engraved. I would want to be ...
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What can be the possible causes for variation in stress-induced birefringence in an isotropic material?

Birefringence is the phenomenon of a material having a refractive index that depends on the polarization and propagation direction of light. When an unpolarized light passes through such a material, ...
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What vacuum is kept in gen-2 image intensifier night vision devices?

MCPs usually require a vacuum lower than 5e-6 Torr to prevent dielectric breakdown. It seems implausible that small image-intensifier tubes could maintain this level of vacuum for an extended period ...
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Material that lets light through only when slightly deformed/vibrating?

I'm curious if there is a material that is porous to light, but only when it is slightly deformed / vibrating. Do such materials exist? In particular I want to prevent a (cheap) laser's light from ...
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Variations in Refractive Index of Materials

It's quite a common fact that different types of glass have different refractive indices. Most sites I've found attribute these differences to variations in the 'density' of the glass, which is not ...
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Deriving Wavelength from Relative Intensity with Broad Spectrum Light Sensor [closed]

I have this broad spectrum light sensor and it gives me readings in relative intensity, but says that it's able to measure the wavelength. The documentation is rather unhelpful, so I was wondering how ...
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Does crystalline silicon have a higher (~3.0 eV) band gap than amorphous Si (~1.75 eV)? Or lower (~1.12 eV)? [closed]

Some sites claim that crystalline silicon has a band gap of approximately $1$ to $1.2$ or so electron volts, and others say it is about $3$ to $3.4$ eV.... Amorphous silicon is usually described as ...
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Can plasmon nanoparticles be displaced by EM field’s?

As at specific frequencies of light, a plasmonic nanoparticle’s electron cloud will predominately shift to one part of the material, will this cause the material to shift in that direction?
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Experimental detection of Anderson localization of light in 3D vs 2D

I have a question about the experimental realization of Anderson localization of light. I am a theorist, and have not worked much in optics, so please bear with me. Anderson localization of light in ...
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Hi everyone, could anyone help me understand how two cylindrical lens can be used to form a laser sheet?

If you look at the below link under 'Laser Sheet', https://www.edmundoptics.com/campaigns/cylinder-lens/ the equation is much easier for a single line generator. I am stuck at the point where I use a ...
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How do anti-reflection coatings in solar cells make light stay inside a solar cell?

We know that silicon is too shiny to absorb incoming light that's why anti-reflection coating is needed to make the incoming light stay inside the cell. However, the problem is, even though the cell ...
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Question on calculation of refractive index and extinction coefficient from relflection and transmittance data

I have reflection (R) and transmittance (T) data and I want to calculate refractive index (n) and extinction coefficient (k) from these data. But I have taken the reflection spectra at 45 degree angle ...
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Is it possible to create a conventional light microscope that has a higher Z- than X/Y resolution?

Looking at the Abbe resolution limits, I was wondering if there could be a conventional light microscope that has a higher Z resolution than X/Y-resolution. Equating $\text{res}_{x/y} = \frac{\lambda}{...
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Can someone help me in understanding what actually plasmons are?

This question might have been asked several times but I am confused on this topic. What actually are the plasmons? Do they only exist in the case of metals or they can be found even in semiconductors? ...
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How effective are privacy screens at blocking blue light in the presence of other protective measures?

For quite a while, I've been using privacy screens, which not only increase... well, privacy, but also purportedly block blue light. However, web search results generally yield very broad statements ...
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1 answer
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Birefringence in uniaxial materials

In linear optics, when treating anisotropic uniaxial materials we get the frensel equation this equation gives us two solution for n. My problem is that according to Snell's law, if I have two ...
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Obtaining both relative permittivity and permeability from refractive index

The complex refractive index $\tilde{n}$ is related to the relative electric permittivity and the magnetic permeability with the relation \begin{equation} \tilde{n} = n + \mathrm{i} k= \sqrt{\...
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4 answers
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How can the speed of light in matter be measured?

Experiments such as Focault's measure speed of light in matter. Focault's experimental set-up is based on the idea that it takes more time for light to travel through matter, which will result in the ...
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Can paint on a wall considered to be a thin film?

In know that general thin films are as thin as few microns to nanometres and have technical and optical uses. But can a dry paint on wall be considered the simplest example of thin films? I mean its a ...
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Does reflection depend on wavelength?

I'm aware of processes like Rayleigh scattering, Compton scattering and pair production. But as these processes treat light as being particles(?) I'm not sure whether they are helpful to understand ...
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Nonlinear Optics: SHG and OPO

I am new to nonlinear optics, and recently I started studying about the second harmonic generation (SHG) and the optical parametric oscillation (OPO) where these two nonlinear interactions are ...
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If we repeatedly divide a colorful solid in half, at what point will the color disappear?

Suppose I have some colorful solid, which I cut into two halves (both are identical). Take the first and cut it into two parts, and then repeat this again and again. I know that a single atom doesn't ...
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1 answer
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How to control the refractive index of semiconductors?

I keep seeing/hearing that the refractive index can be controlled in semiconductors, but every time I read something like that it's always something very specific, like "Refractive index ...
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Why is Sellmeier's equation an even function of $\lambda$?

According to Sellmeier's formula, the dispersion formula of a transparent material can be written as $$n^2(\lambda) = 1 +\sum_i\frac{B_i \lambda^2}{\lambda^2 - C_i},$$ where $B_i$ and $C_i$ are ...
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Why a single piece of optical fibre is not used rather a light pipe is used? [closed]

A bundle of optical fibres called a light pipe is used.A single optical fibre is not used to see the complete image.
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1 answer
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Regarding measurements on traveling microscope

In a experiment with traveling microscope to determine thickness of a glass slab , what is the physical significance of the readings that we get from the vertical scale ?, Means What are two points ...
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Quantum Dot Surface Area to Volume Relationship

Do the properties off quantum dots depend more on their surface area rather than the volume they occupy? Depending on the case, then would quantum dots of different shapes show different properties?
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Transparency of oil paints with the passage of time

I know that oil paints become transparent after the passage of time (as in the case of many of the Old Masters), because air oxidizes oil, raising its refractive index, so that scattering of light ...
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1 vote
1 answer
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Phase shifted Optical Fiber Bragg grating Response

As we know there is a narrow notch in the reflectance spectrum of a Phase shifted FBG. We have Bragg condition for reflected band of any uniform FBG. My question is that, does anyone know any relation ...
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11 votes
1 answer
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How do non-mechanical solid-state optical switches work?

I am currently looking for a fiber-optical switch (FOS) in order to be able to change the light source of a spectrometer. As this will be used in harsh conditions, I was hoping to find a FOS with no ...
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1 vote
2 answers
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Why does $\rm TiO_2$ require less thickness for thin-film interference than light wavelength suggests?

TL;DR: Why does titanium oxide layer produce visible thin-film interference at thicknesses 10x smaller than the wavelengths of light? Background: I am currently trying to model thin film interference ...
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1 vote
1 answer
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Is there a nonlinear optical material that absorbs visible light stronger with increasing intensity independent of its wavelength?

One of the main shortcomings of digital image sensors is the quite "unnatural" behaviour for rendering highlights compared to film (and the human eye, I guess). Typically, with increasing ...
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What, really, makes glass transparent? [duplicate]

I don't mean to be cheeky with the question, but it reflects the myriad of often seemingly conflicting answers I've seen around this. And that's not surprising of course given the dual nature of light ...
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Why is Indium Tin Oxide (ITO) transparent to visible light and have low transmission to infrared light?

I read that Indium Tin Oxide transmits most of visible light while blocking a high percentage of infrared light. What is the principle behind this property?
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Can titanium dioxide ($\rm TiO_2$) be used to block IR?

I know that titanium oxide ($\rm TiO_2$) is mostly used to block UV lights, but can it be used for the blocking of near-infrared light? If yes, then what are the principles behind it? I would ...
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36 votes
4 answers
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Why are the edges of a broken glass almost opaque?

Unfortunately I broke my specs today which I used in this question. But I observed that the edges are completely different then the entire part of the lens. The middle portion of the lens was ...
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What determines the penetration of electromagnetic waves?

What is it that determines whether or not an electromagnetic wave can penetrate different materials and how far it can go? For example light can penetrate through glass, but not concrete walls, but ...
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2 answers
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Could we see through objects if our eye could detect other wavelengths of light?

We see objects around us because light reflects off the surface and enters our eye. So if our eyes could see a wider range of the spectrum (maybe lower wavelength as they would scatter less) then ...
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1 vote
1 answer
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Coupling of resonant modes in a 1D Photonic Crystal

In 1D Photonic crystals, a defect can be introduced to create a defect/resonance mode and enable transmission. At first considerations, the thickness of the single defect layer determines the ...
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1 vote
3 answers
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Microscopic origin of non-linear optical effect

I know that a non linear optical medium is a medium in which the optical response for example polarisation vector varies as \begin{equation} \vec{P}=\epsilon_0\chi^{(1)}\vec{E}+\epsilon_0\chi^{(2)}\...
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29 votes
7 answers
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Why don't opaque objects reflect light?

My sister was doing a quiz and I tried to point her in the right direction by giving her scenarios to imagine. One of the questions in the quiz was: Which of the following objects do not reflect light:...
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Do metals have negative permittivity (real part) at microwave frequencies?

I have been studying metamaterials from Electromagnetic Metamaterials: Transmission line theory and microwave applications by Caloz and Itoh. They have commented that metals at optical frequencies ...
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How does a broadband dielectric Mirror work?

It is widely known that dielectric mirrors work with several layers of at least two materials which differ in refractive index that are layered, such that partially reflected waves interfere ...
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Reason for particular pattern of clouds near sun

In this picture it is clear that there is a larger no. Of clouds near the sun as compared to a distance farther. Moreover the clouds seem to form vortex rings around sun. why is there more density ...
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