Questions tagged [optics]
21 questions
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Why does black and yellow indicate danger?
It is a well-known fact that combination of black and yellow indicates danger or poisonousness.
In western society it seems obvious this comes from bees and wasps, but it seems like many tropical frogs use yellow and black. Black and yellow also…
Probably
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9
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Why does my eyes see a red spot when over exposed to light?
When I looked into my projector when it was on the blue screen it left a red spot in my vision. I should not have tried it but all the colors left a red spot. Why not a blue or yellow spot was left?
Muze
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4
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What is the minimal focal length of the human eye?
What is the minimum length to which the focal length of our eye can go, even when considering the blurred images too.
Ashish Ranjan
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3
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Why do the eyes of this cat have different colours when viewed from different angles?
Why do the eyes of this cat have different colours when viewed from different angles?
Both of the eyes of this cat appear yellow when looking straight at the camera.
However, when the cat looks at an angle to the camera one eye appears green.…
trinitrotoluene
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Eye Optics/Emmert's law: Where to place scaled copies of an object so they have identical images on the retina?
I read that the center of projection of the human eye is the entrance pupil. So given a light ray which intersects the objects position and the center of the aperture stop, all copies of said object when placed along that line should cover the exact…
InteractiveCube
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How would our vision be improved if our photoreceptors were not backwards?
I'm curious to how much better human eyesight would be if the nerves from our rods and cones were correctly placed behind the receptors?
Are there any Animal Models with correctly placed photoreceptors that we can use as a benchmark?
Gabriel Fair
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Do different microscopes and attached cameras differ in crop factor between each other?
I analyzed a bunch of microphotographs recently and used "% of image area" to describe the area of structures (chorionic villi, had to show their density in placenta). However my professor suggested I should have used mm2. There is no problem in…
Gogent
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Why does white light viewed through optical chopper appear purple/blue?
I looked at a light like the one shown here through a fidget spinner (I believe I was observing near where the "blades" meet the inner portion) and noticed that it appeared purple/blue, particularly when viewed for a prolonged period (I looked at…
Julien
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Neurophotonics vs. Optogenetics
What is the difference between the two? I see them frequently listed together in conference descriptions but can't seem to find anything that clearly explains the difference.
Diio
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Can the retina emit light?
The retina is light sensor, which converts light to an electrical signal. LEDs can both emit and receive light. Similarly, is it possible to apply electricity to retina to generate light?
Simply put, in theory, can humans emit electromagnetic waves…
Thaina
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Why do humans see exactly one octave of light?
The visible spectrum of light is often defined as 350nm to 700nm. On Wikipedia, it says 380nm to 750nm. Either way, the upper bound is very close to double the lower bound. This means humans can see exactly one octave of the EM-Spectrum. (By octave,…
Lycodo
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Does the Rayleigh formula apply to electron microscopes or only light microscopes?
I am asked to determine the resolving power of both a TEM (transmission electron microscope) and a SEM (scanning electron microscope) and given the Rayleigh formula below.
$$Resolution=\frac{0.61\lambda}{N.A.}$$
Where $\lambda=0.0039$nm since the…
jack
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Which organism can point us to the evolution of sight?
I'm trying to identify the basic biological mechanisms for sight.
Could you help me with identifying any organism that has the most basic ability to see objects?
Most importantly, creatures like dogs, cats, insects are able to not just see…
Nav
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Are brown eyes healthier than blue eyes?
I have read somewhere brown eyes have more melanin than blue eyes and as melanin protects our body from cancers, I thought that brown eyes are more healthier.
AScientist
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Is the human eye supposed to see the lense effect?
Just as the GoPro cameras, we need lenses to be able to focus. Nevertheless, we can see the "fisheye effect" on the shots taken by GoPros. I am talking about this:
Is it possible to notice the "fish eye effect"? Or does the brain somehow eliminate…
Probably
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