3
votes
1answer
42 views

Can zinc nitride be used as light emitting material?

I cannot manage to find any journal papers about the applicability of zinc nitride as active layer of an light emitting diode (LED). But certain papers got mention that zinc nitride with a direct ...
0
votes
1answer
24 views

Microscopic origin of optical transmission

When light interacts with matter, it is abosrbed, reflected and transmitted. With repect to the UV-Vis range, electronic abosrptions occur, where if the incident photon mode matches the energy ...
1
vote
1answer
90 views

Is it possible for a material to shift the frequency of all light reflected off of it by a specific and constant value

Without reducing the energy more than necessary due to the frequency decrease? And if this happens/works, is there an index of such materials and their optic properties?
5
votes
1answer
148 views

Why Negative refractive index is negative

$n=\sqrt{\epsilon \mu }$ Negative refractive index happens when permittivity ($\epsilon $) and permeability ($\mu $)of a material is negative. My question is, if permittivity and permeabilitity of a ...
3
votes
3answers
195 views

Effects of surface roughness on specularity

Say you have a piece of glass, which looks specular if propery cut/polished. But if you sand the surface using say sand paper, it will look hazy and glossy. I'm wondering how much surface roughness ...
1
vote
3answers
78 views

Trapping EM radiation [duplicate]

Is there a material which can allow light (or any other EM radiation) to pass through from one side as if it is transparent but its other side reflects light like a mirror?
1
vote
2answers
57 views

Optical refocusing efficiency

What is the material for optical focusing that produces the less diffraction losses? Suppose one have a sequence of serial optical elements $R$ that keep refocusing a beam of collimated light, each a ...
0
votes
3answers
756 views

Liquid crystal shutter with >90% transmission?

Today's liquid crystal shutter glasses, when in the "transparent" state, exhibit only 40% light transmission. They work using two polarizer layers, one which is liquid crystal and goes {vertical ...
0
votes
1answer
361 views

Are silicone polymers transparent to infrared light?

I know that silicon and even black plastic bags are transparent to infrared light. What about light-colored silicone polymers (take white or green colors)? Are they transparent to infrared light too? ...
2
votes
3answers
343 views

Is there a simple approximation to calculate the index of refraction of water?

A very rough approximation from first principles, from the elementary charge and hbar, would suffice. But is there such an approximation at all? (Alternatively, if water is too difficult: is there ...
2
votes
3answers
203 views

Electrial Conductivity of Thin Metal Films

What is the best way to find specific/electric conductivity which is dependent of very thin film thickness?
34
votes
3answers
2k views

Why wet is dark?

When something gets wet, it usually appears darker. This can be observed with soil, sand, cloth, paper, concrete, bricks ... What is the reason for this? How does water soaking into the material ...
11
votes
1answer
2k views

Why does paper become transparent when smeared with oil but not (so much) with water?

When I smear oil onto a scrap of paper and rub it in, the paper becomes quite transparent; but when I attempt the same with water it doesn't as much. Why?
0
votes
2answers
278 views

What is the difference between Sapphire and BK7?

What is the difference between Sapphire and BK7 in optics (lenses), is it only about quality?
7
votes
2answers
460 views

How does infrared light 'erase' phosphorescence on zinc sulfide?

I found some sheets of zinc sulfide in my basement that phosphoresce green for up to 24 hours or so after exposure to bright light in the violet range or shorter. One of the first things I tried was ...
13
votes
3answers
1k views

Is one way glass possible?

I am not talking about mirrors, just a plain window made of glass like material. Would it be possible to allow light pass only in one direction but not the other?
1
vote
2answers
268 views

What material can a lens be made from?

I need to make a camera lens that can easily withstand temperatures of about 1000 Fahrenheit. What should I make the lens out of?
1
vote
1answer
208 views

Nonlinear absorption coefficient and the band gap

How does the nonlinear absorption coefficient depend on the band gap? How can that coefficient be calculated theoretically? (Preferably with an example)
1
vote
0answers
901 views

What properties of certain plastics make them x-ray transparent? [closed]

I was blown away by the abundance of good info here, and I thought maybe you could help me out with this query. I am in the process of developing a product, and I need to find a clear plastic resin ...
12
votes
3answers
715 views

Can the speed of light become complex inside a metamaterial?

The speed of light in a material is defined as $c = \frac{1}{\sqrt{\epsilon \mu}}$. There are metamaterials with negative permittivity $\epsilon < 0$ and permeability $\mu < 0$ at the same time. ...
2
votes
3answers
218 views

Material resistency to lasers beam

Keeping the average power constant, why some materials are more eager to be damaged by pulsed laser with respect of C.W. lasers, or viceversa? When i talk about pulsed lasers i think for examples of ...