Tagged Questions
3
votes
4answers
143 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
38 views
Trapping EM radiation
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?
0
votes
1answer
41 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
318 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
194 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
2answers
198 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
118 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?
19
votes
3answers
548 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 ...
9
votes
1answer
772 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
181 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?
5
votes
2answers
264 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 ...
11
votes
3answers
611 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
218 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?
0
votes
1answer
171 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
650 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 ...
2
votes
3answers
192 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 ...
