Questions tagged [optical-materials]
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In a uniaxial crystal, what determines the optical axis, extraordinary axis, and ordinary axis?
In a uniaxial crystal there is an optic axis, an extraordinary axis, and an ordinary axis. The optic axis is not the direction in which we plan to propagate light. The light is propagating in a ...
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What happens when screen is not placed where Image is focused but elsewhere?
When we try to form a real image on a screen by a convex lens, we place the screen at a distance where the image is focused. But if we try to place the screen at a distance less than the distance ...
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Why are things reflective, absorbent, transparent etc? [duplicate]
What determines whether a material reflects, absorbs or transmits a certain wavelength of light? Just a layman's question.
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How can we optimize gathering light through a finger from an LED?
We aren’t getting enough optical receive signal (ie. energy).
We have a finger ring with LEDs on either side of a photo detector, all on inside of ring.
Photo sensor has fixed field of view (FOV).
How ...
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Are barium titanate ($\rm BaTiO_3$), magnesium titanium oxide ($\rm MgTiO_3$) transparent to near-infrared rays?
Barium titanate (BaTiO3) and magnesium titanium oxide (MgTiO3) are commonly used dielectric materials in MLCCs. Are barium titanate (BaTiO3), magnesium titanium oxide (MgTiO3) transparent to near-...
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Why can't we create a laser with wavelength of 13.5nm?
I was reading about EUV and the extraordinary process of firing two different lasers as tin droplet to collect 13.5nm wavelength light and I was wondering why this is required and we can't just create ...
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Confusion about dimensions on optical absorption near the bandgap formula for direct band gap semiconductor
I'm trying to replicate some results from this paper (http://ieeexplore.ieee.org/document/44924/) on the changes in refractive index due to the band filling effect, however I'm stuck at some ...
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Why does light either get reflected, absorbed, or passes through a surface or obstacle?
For each of these 3 cases, I'm having trouble understanding...
If light is reflected, does that mean that there was not sufficient energy by the photons to excite the electrons of the surface to ...
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Why does (oxidized) aluminum have a diffuse optical appearance?
Unoxidized aluminum has a shiny appearance like typical metals. However in air aluminum rapidly oxidizes, giving it a more diffuse appearance (or bidirectional reflectance distribution function). ...
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What difference between metallic reflection and polished/mirror reflection [closed]
At the moment I am studying materials in raytracing (I am writing my own personal project)
I found out that there are several types of reflections.
I read this article from wikipedia:
https://en....
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Laser confocal microscope filter
I wanted to mount a narrow bandpass filter which allows to transmit 405 nm wave, i. e. the laser wavelength. I wanted to cut off other light, cause my detector is also sensitive to other wavelengths.
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How to describe an imperfect beam splitter?
A polarization beam-splitter (PBS) transmits horizontal polarization and reflects vertical polarization, i.e. $PBS|\Psi\rangle =PBS(\alpha |x h \rangle + \beta |y v \rangle) = \alpha |x h \rangle$. ...
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Recording Analog Data in Optical Disc Using Laser Beam Mechanism [closed]
Is it possible to storing/writing any Analog Audio Signal (i.e. Vinyl Record & etc) into a little bigger and thicker Optical Disc as compared to the other conventional Compact Disc while using the ...
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Are there everyday materials that change color, depending on illumination spectrum?
Initially I wanted to ask this exact question about color change due to "white" light source spectrum change, and the accepted answer satisfies me fully.
However the answer says that most of ...
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Why do non-linear optical effects occur?
Why do non-linear optical effects occur? Why do the materials respond differently at high intensities and at some resonant frequencies?
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Classical EM wave: Wavelength dependence of modelling material as Lorentz oscillator vs Bragg diffraction?
For convenience, consider a classical EM wave within a perfect crystal.
The Lorentz oscillator seems a good way to model material characteristics.
Yet in introductions to eg. X-Ray Crystallography, we ...
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Size of metal domain needed to reflect light ; are small graphene sheets shiny?
I remembered that shininess of a material is because of reflection, ie surface current responding to light. Mathematically, one can solve Maxwell equations under a relevant boundary condition, with ...
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What is difference between Electromagnetically induced transparency (EIT) and Coherent population trapping (CPT)?
EIT: Electromagnetically induced transparency
CPT: Coherent population trapping
When two resonant light fields (probe field and strong coupling field) are incident on an opaque material whose atoms ...
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Difference between seed and pump in chirped pulse amplifier
What is the difference between to seed an optical amplifier (such as Chirped Pulse Amplifier) and to pump it with a laser source?
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How to calculate lens sag due to gravity for the largest LSST lens?
I saw some articles about the LSST recently and remembered that glass lenses generally aren't made that big due to gravity induced sag as well as other issues. I did some research and found that the ...
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Ideal surface for a perfect lens
in this physics lecture, on slide 15-16, it is found that the ideal surface for a perfect lens (which maps a plane wavefront into a perfect spherical wavefront, i.e. which makes focus all input ...
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Brewster's angle for Metal?
As metal has a high refraction index, it is possible to have Brewster's Angle for Metal when the light incident from the air? Is it possible to derive from any formula?
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Why does non-linearity come into picture only at a large intensity of optical fields?
I have read that for sufficiently large intensities of optical fields (of the order of $10^8$), we can actually observe a non-linear relationship between the polarization and the field, given as
$$\...
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What are good materials to diffuse/scatter 850nm infrared light?
I want to properly light up a room with an IR Illuminator, but most illuminators lack diffusion, therefore shadows are especially sharp and bold. Since IR rays don't behave like visible light rays, it'...
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Why do efficient blue emitters (LEDs,OLEDs, quantum dots) take much longer to discover than red and green emitters?
For example, it took over 3 decades to create efficient blue LEDs in the lab after the red and green leds were discovered. For OLED displays as well, the red and green pixels are phosphorescent oleds ...
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Does the front of a light wave always propagate at $c$ in media
Consider light moving along one dimension at the classical level. I am interested in the situation where a wave front impacts a material with some generic index of refraction $n(\omega)$, and ...
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How does reflectance change with wavelength? [duplicate]
Sorry if this is an easy question, I am new to physics and this field.
I have a question about reflectance which i believe to be "effectiveness of reflecting radiating energy"
My goal is to ...
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How to figure out TM and TE modes based on dispersion relation?
According to this paper (https://doi.org/10.1063/1.5128679), the dispersion relation of hyperbolic materials is as follows:
then it is said, that he first term in brackets in the equation describes a ...
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Why do some anti-reflective (or anti-glare) lenses use layers of materials with alternately very high and very low refractive indices?
Some specials lenses like this (or coatings on them) try to minimize the refractive index, or the change thereof, or at least make the change very gradual.
But others apparently do the exact opposite, ...
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Non-dispersive mediums for light
Apart from the vacuum are there other mediums for which light velocity does not depend on frequency?
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Reflection of light on a colorless material. What happens on atomic level?
I try to understand reflection explained with photons that are interacting with molecules on atomic level.
For this I would like to start with an example and ask the question based on this:
Say I have ...
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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 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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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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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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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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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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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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