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.
Questions tagged [optics]
7654 questions
29
votes
9 answers
Why can you have shiny black objects?
Knowing black is supposed to be the "color" (I don't want to get into the color/hue/shade debate, please) that absorbs light. how does one manage to have shiny black surfaces? I know about "gloss black" versus "matte black" finishes, but shouldn't…
user172
22
votes
8 answers
Does a mirror help a near-sighted persion see at a distance clearer?
A near-sighted person without eye-glasses can not clearly see things at distance.
If he takes a photo of the things at distance, he can see the things from the photo much clearer, because he can place the photo much closer to his eyes.
If he turns…
Tim
- 571
17
votes
4 answers
What causes multiple colored patches on a wet road?
I was going to school (after a rainy hour) when I saw some patches of shiny colours lying on road. Some small children surrounded that area and thought that it's a rainbow falling on the Earth. (For some 5-6 year old children it is a serious…
Mukul Kumar
- 599
15
votes
2 answers
Why do thin films need to be thin?
No matter what thickness a piece of glass is wouldn't its optical thickness be close to an integer multiple of a wavelength such that it could create interference effects? I feel like I am missing something here.
sTr8_Struggin
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12
votes
1 answer
Optical microscope magnification limits?
Optical microscopes are quoted as having a maximum magnification of 1500x to 2000x - what is this calculated from?
Rupert Maximum
- 123
11
votes
2 answers
Why can't virtual images form on a screen?
Part of the definition of a virtual image is that it cannot be formed on a screen. I understand this is the case when the screen is right next to the image, since there are no physical rays that can hit the screen. But what I don't understand is why…
Denn
- 167
10
votes
1 answer
The principle behind door peepholes
Hotels usually install peepholes in their doors so that a person inside a suite can see who is at the door without having to open it.
I understand that there should be a convex lens within the peephole so that the person inside can easily see the…
user172
10
votes
1 answer
Wouldn't any structured beam of light be expected to travel slower than a plane wave?
There aren't many new, actual bona-fide discoveries in classical optics these days.
I saw this news item in Phys.org: Observation of twisted optical beam traveling slower than the speed of light
The researchers first noticed the slow speed of…
uhoh
- 6,308
10
votes
3 answers
Usefulness of half-shade in Laurent half-shade polarimeter
In the Laurent half-shade polarimeter, if the half-shade weren't there, what difference would it make? The light after being polarized by the Nicol polarizer,could have entered the tube containing the optically active solution and then the rotated…
Wonder
- 754
10
votes
2 answers
Pinhole camera: How "How to See Without Your Glasses" works?
If you see through small enough aperture, you can see things without glasses.
How does this trick work?
Pratik Deoghare
- 5,609
9
votes
2 answers
How does Fraunhofer diffraction depend on the orientation of the sides of a lens?
Matt in his answer on What does a hexagonal sun tell us about the camera lens/sensor? mentions
Incidentally the number of (distinct)
points to the star is equal to double
the total number of unique
orientations* in the sides of the
aperture…
Lazer
- 836
9
votes
4 answers
What are the various kinds of Cassegrain telescopes, and what benefits and drawbacks does each have?
Many hobby or amateur telescopes are of the Newtonian design, but most of the professional telescopes that I know about are some kind of Cassegrain (a very specific kind, I believe).
In general, what types of Cassegrain telescopes are there, and…
voithos
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9
votes
1 answer
Why does the chief ray not bend like other rays at the optical axis but goes straight?
1
pg
In this picture the chief ray is not bending which is going through the optical axis. It passes straight while other rays from the same object are refracted because they change the medium.
Anusha
- 101
8
votes
3 answers
How to delay visible light
I want to delay visible light (~450nm-600nm) by 10ns. One way would just be to have it travel about 10ft since the speed of light is about 1ft/ns. Could I reduce that length by sending it through some high index of refraction material? Dispersion is…
cpc333
- 1,137
8
votes
1 answer
Negative radiation pressure from negative refractive index?
I see this claim being originally made by Vesselago (the discoverer of the principles of metamaterials) and indeed in contemporary papers. It means that such a metamaterial would be pulled towards its illuminating light source. Why does this not…
Andrew Palfreyman
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