All Questions
321
questions
15
votes
2
answers
2k
views
Eye Floaters Optics
Eye floaters are these annoying objects floating in someones eye, usually seen by someone experiencing them as squiggly lines and dots buzzing around, either dark or partially transparent (I ...
- 153
-4
votes
1
answer
86
views
Why does a ventilator appear to run leftwise and rightwise and back when spinning up?
My university professor, a friend of mine, asked me: "Do you know why, when a ventilator starts and during the process up to final speed, it runs clockwise and anticlockwise and back again to ...
- 125
1
vote
1
answer
39
views
Is it possible to see thermal columns?
The most common way gliders gain altitude is to circle in a thermal. Thermals are often found below cumulus clouds, or above dark areas on the ground. Without these signs, they are harder to find and ...
- 111
2
votes
3
answers
224
views
What is the apparent location of a real image formed by a lens? [duplicate]
Let's say I place a tennis ball 1 m in front of a plane mirror. The mirror will form a virtual image of the tennis ball, and if I look in the mirror, it appears to me that there is a tennis ball ...
- 8,343
1
vote
1
answer
45
views
Why do we see objects with a given color?
I'm currently studying Electromagnetic Optics, and I don't quite understand the (classical) process through which we perceive an object with a given color. From my understanding, I'd make a ...
- 1,616
7
votes
6
answers
4k
views
Why does white light appear white?
When I think of white light, I'm imagining a combination of all 7 colors of light but I believe that since light has wave nature I can say that at some point that the probability density of red light ...
- 93
0
votes
2
answers
129
views
Why do I seem to see more depth in images when closing one eye?
I remember that when researching and learning about vanishing points and vantage points of art pieces, that by closing one eye and viewing a painting from an exact point in space, it would give this ...
- 103
0
votes
0
answers
24
views
Effects of chromatic aberration in the human eye
Due to metamerism, many different light spectra can be used to show a white colour.
If I understand it correctly, it is even possible to make white light by combining only two monochromatic light ...
3
votes
2
answers
232
views
How could RGB color system compose a violet color?
In the GRB system, we combine the three primary colors, red, green, and blue, to make some new colors.
It's easy to understand the production of yellow because the wavelength of yellow is between red ...
- 141
0
votes
1
answer
83
views
How to explain interference pattern in our eye?
Suppose we got a Lamp L that emits some light. The light afterwards hits a diffraction Grating G at a distance a. Now if you were to look through the grating with your Eye E, you were to see the ...
- 462
-1
votes
2
answers
58
views
How do dark color varies from people when seeing the back of their eyelids?
Depending on the light source, the back of people's eyelids either be black or dark gray depending on what lit environment they're in? the how does eyes function when people have the back of their ...
3
votes
2
answers
949
views
Would the "FFT" of a light source be a reliable indicator of perceived color?
Paraphrasing from here:
A purely monochromatic 575nm wavelength light would be "perceived" as yellow, as would a light that has equal components in red and green (but no yellow). However, ...
- 139
-4
votes
1
answer
84
views
What's a safe, easily executable experiment to confirm that quantization of light occurs directly to the retina? [closed]
What's a safe, easily executable experiment to confirm that quantization of light occurs directly to the retina.
We know that light is quantized when projected on to a surface, or on to an inanimate ...
1
vote
0
answers
71
views
Does our sense of color depend on frequency of source or the wavelength of light?
I was taught that the colors we see are results of the corresponding wavelength, but each wavelength also has a distinct frequency since speed of light is fixed for a specific medium (same goes for ...
- 169
0
votes
0
answers
44
views
Why would an object disappear when switching from monocular to binocular vision?
I have just used a compound binocular microscope which has an ‘eyepiece graticule’ (ruler in arbitrary units) in the right eyepiece lens.
If you close your left eye (or occlude the left lens), the ...
0
votes
0
answers
37
views
How exactly can the eye detect electromagentic waves? [duplicate]
From my understanding, EM waves are traveling disturbances in the electric and magnetic fields. They travel at the speed of light, since Maxwell's equation imply
$$\nabla^2 \mathbf{B} = \frac{1}{c^2} \...
- 101
17
votes
3
answers
3k
views
Why is the visible light spectrum different to a hue wheel?
The following problem has bugged me for a while, ever since I noticed it. On the Visible Spectrum Wikipedia, the following is the visible spectrum:
Now, in Photoshop, or really any colour picker, the ...
6
votes
8
answers
516
views
Why specifically is looking through a telescope at the sun more dangerous than the naked eye?
At first this seems like a stupid question: "Have you never used a magnifying glass on a sunny day?!"
But any lens will only ever make the focused image as intense as the target or weaker. ...
3
votes
2
answers
120
views
Is “imperfect black”, (anything other than a black hole or vacuum), actually a color?
Is “imperfect black”, (anything other than a black hole or vacuum), actually a color?
Nothing absorbs all light except for a black whole, or a vacuum which doesn’t reflect light. If we consider black ...
- 31
1
vote
2
answers
164
views
How do our eyes perceive a parallel beam?
So if our eye is considered a lens, a parallel beam (sort of like collimated light from a flash light) should converge to a single point, the focal point. So does that mean our eye will see a finite ...
- 313
0
votes
2
answers
60
views
How do we see the picture of an object as a whole thing in spherical mirrors?
When we see an object in a spherical mirror, the different parts of the object has different pictures which are also at different locations compared to each other.
The lights that go from the tip of ...
- 402
2
votes
0
answers
70
views
Why are circular polarized 3D glasses for cinemas so cheap and working for a range of wavelengths?
Does anyone know how the filters in circular polarized 3D glasses for cinemas work (meaning how the filter on a micro-scale works, which material they use...)? Because in the lab we use of course ...
- 1,803
0
votes
1
answer
72
views
Is it possible to design a wheel without the wagon-wheel effect?
Wagon-wheel effect is a well-known optical illusion due to the persistence of vision. It happens when the spoke of a wheel rotates to a certain position after the duration of persistent vision. ...
- 3,701
0
votes
2
answers
100
views
Does intense, cyclically-pulsed light appear brighter than its average?
Background
The Wikipedia article on the Talbot-Plateau law mentions:
If a light flickers so rapidly that it appears as continuous, then its perceived brightness will be determined by the relative ...
- 101
1
vote
0
answers
51
views
Why is each of these spectacle lenses creating two distinct refraction patterns? [closed]
Each of the spectacle lenses in this image cause two separate refraction patterns:
The patterns are different between the lenses because each eye is different, obviously, but why are there two ...
- 5,148
-7
votes
1
answer
191
views
Insides of eyelids and light
People commonly see the insides of their eyelids and see a little amount of light and no amount of light of the insides of their eyelids depending on what environment they're in, What's the difference ...
1
vote
1
answer
165
views
Strain on eyes when seeing a mirror [closed]
Suppose; The strain on my eyes when seeing an object at distance x is a.
The strain on my eyes when seeing an object at distance ...
- 23
8
votes
6
answers
1k
views
Why does the focus point of the eye does not burn the retina?
To see an object, its light rays have to meet on the retina in the focal point. But the focal point is a small white dot. Basically nothing would be distinguishable and the retina would burn because ...
- 737
0
votes
1
answer
226
views
Is it correct to say that light makes things visible but light itself is invisible?
Why some books write light itself is invisible but makes things visible for us. I mean if a laser beam is passing just parallel to our eyes in a dust free environment we can't see it but the reason ...
- 1,357
1
vote
1
answer
46
views
Horizon related question [closed]
I'm a student taking an undergrad course in physics and we were discussing light and how it works in relation to vision. This question stumped us. What altitude would you need to reach on the globe ...
- 11
1
vote
2
answers
144
views
Why rays of light from different points don't form an image?
I'm asking a clarification about this questions:
Why does an image only form where light rays coming from a single point get reflected or refracted and converge to a common point?
I want to know if ...
- 338
2
votes
2
answers
231
views
Farsightedness glasses beyond focal length
As I understand, farsightedness glasses use convex lenses to create virtual image that is farther than the object (and thus past the near point of the user). However, this only happens if the object ...
- 307
1
vote
1
answer
84
views
Is color perception linear? [duplicate]
I'm learning about the trichromatic theory of color perception. Say a receptor detects a wavelength $\lambda\in\mathbb{R}$ and responds with $f(\lambda) = (r,g,b) \in \mathbb{R}^3$. This system is ...
- 13
0
votes
2
answers
204
views
How do we see with glasses or contact lenses if the image formed by them occurs behind the eye?
Apologies for the poor wording of the question, I'm sure I'm gravely misunderstanding something here but not sure exactly what.
Suppose we have some point light source. We can see it because the rays ...
- 103
0
votes
1
answer
84
views
Do prescription swimming goggles have a gap between the lens and the goggles?
The lens-maker's equation for a given biconvex lens assumes that the refractive index of the medium either side of the lens is the same.
But in the case of prescription swimming goggles, this wouldn't ...
- 103
0
votes
0
answers
85
views
How does the human eye form an image of a certain size at a certain distance?
In looking at how geometric optics works and how an eye rebuilds an image of a certain size at a certain distance, some questions came to me:
Let's take a look at the first picture for example; the ...
- 941
1
vote
3
answers
222
views
How do you simulate astigmatism and other zernike aberrations of an image?
If I have a perfectly clear image, how do I simulate what this image would look like if there had been some sort of aberrations during image capture, specified by zernike polynomials?
For example how ...
- 1,325
13
votes
7
answers
5k
views
Are human eyes interferometers?
It seems like 2 eyes is enough “wetware” to do interferometry inside brain. Can you definitely see some reason why this could not be happening, or some way to test if it does happen?
- 605
0
votes
1
answer
47
views
Does any colour appear white to our eyes if its emitted power is extremely large?
let's consider an ideal monocromatic source (for instance red) and let's assume you can regulate its emitted power without compromising its spectral "finesse".
Start from 0 emitted W/sr. It ...
- 1,319
2
votes
0
answers
192
views
Why are actual prescription lenses for myopia almost plano concave with the curvier face near the eye?
In a recent revision of the chapter on spherical aberrations in lenses, I found that the lens with minimum aberration will be the one in which the curvier side faces the incident ray.
This is shown in ...
- 677
0
votes
0
answers
129
views
What do the Optometrist eyeglass prescription numbers mean?
I want to know what the numbers mean in my eye glasses prescription. The top 50 google hits give overly simplistic answers.
For example
...
- 174
-1
votes
2
answers
572
views
Which is the real reason for why we don't see light interference patterns?
There are many questions like mine in the web, but think I cannot fully understand it.
Let's look at this question. The first answer states that we cannot see light interference patterns because most ...
- 1,319
0
votes
2
answers
239
views
How does RGB really work with subpixels?
first off, I’d really appreciate any help. I have googled relentlessly to try to understand this, but I’m too stupid to fathom it. Please attempt to explain this to me in plain English if you can.
I ...
- 477
1
vote
0
answers
75
views
How is it possible for a human eye to see the entire reticle in a reflector sight?
Reflector sights such as used on fighter planes project an image of a reticle "focused at infinity", that is, whose rays are parallel, onto a semi transparent window. How is it possible for ...
- 79
1
vote
1
answer
144
views
Why does the boundary shows different colors between black and white regions on a projector screen?
Original Question:
My friend took a picture of his screen from an angle (please see the attached picture) and found that the colors of the boundaries from white to black and ones from black to white ...
- 11
0
votes
8
answers
980
views
How we can distinguish objects separately, even if light rays from them are getting mixed up in space surrounding them?
I am a high school student and I am very confused in one thing in optics (ray optics) which I think is the most basic thing but didn't find any answer on internet, before I ask let me present one ...
- 470
0
votes
1
answer
199
views
How does curvature of our eye affect our perception of the world? [closed]
The front part of the eye which can allow light to enter is a bit curved, so shouldn't this cause us to see a curved distorted version of reality when it is really not there? Is there any way to ...
- 7,980
0
votes
0
answers
227
views
Why do eyeglasses use meniscus lenses?
Any eyeglasses prescription could be filled exactly with "symmetrically-shaped" lenses.
E.g., a far-sighted person could use a symmetric biconvex lens (i.e., the normal "magnifying ...
- 1,016
0
votes
0
answers
83
views
How to calculate Distance $D$ to object from a camera with known $H$?
I am using algorithm to draw a bounding box around object when they appear in camera as shown in attached image. The main confusion is that i consider the object closer to camera when the Distance $D$ ...
- 101
3
votes
2
answers
197
views
Does this work to reduce eyes strain? Enlarge the PC monitor with a lens
I have an idea to reduce eyes strain, but don't know if it works.
I work by looking at PC monitor all day long and I believe my myopia condition is getting worse and eyes strain occurs are due to ...
- 208