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.

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How to find focal length of a single convex lens?

I need help finding the focal length of a single convex lens. The radius of curvature is 200mm. left side is air and the glass has a index of 1.5. I search on google but there was only formulas for ...
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Why does your reflection stay the same size when you move further away from the mirror?

This was an experiment I saw in my son's workbook. It said to mark out the top of your forehead and the bottom of your chin on a mirror using a whiteboard marker. Then slowly move backwards, and ...
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How to make the projected image smaller by adding one ore more lenses in front of the built in projector lense?

I have a projector that creates a large image, even if the distance to the screen is short. The device is very small, approximateley 10x10 cm if you look from above. The height is only 3 cm. I ...
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920 views

What are these rays that appear in photograph of sun?

In many images of light emitting objects we see such rays. Why do they appear ? What is the math behind their number and direction?
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108 views

Photonics: Slab As a Lens [closed]

The question can be found here: http://gyazo.com/fc4d26cd35e6ce368ad2a8ed504f1dcc The refractive index it references can be found here: http://gyazo.com/94fd2f3b5ea7da9226c3acd56b0024c1 I'm not ...
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419 views

Intensity of the diffraction pattern of the double slit

I am trying another approach for my last unanswered question. (Bounty still on for 3 days. Anyone? Please?) Note that this is not the same question but a greatly simplified version concerning a much ...
3
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1answer
498 views

Is there a simple model explaining Faraday effect?

I find magneto-optical effects fascinating, and especially the Faraday effect. But most sources only give a phenomenological description, while I want a deeper explanation of its mechanism. Is there a ...
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1answer
750 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? ...
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524 views

Conservation of energy with Huygens-Fresnel principle

I am currently experimenting with Huygens-Fresnel principle. I am trying to simulate the propagation of a beam, emerging from an aperture slot of width w. I assume the slot to be long and therefore ...
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535 views

Why do rainbows have distinct colors?

When I searched on the Internet for the reason of formation of rainbows, I got many explanations like this one & this. All the explanations consider only one spherical water droplet (like this ...
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3answers
492 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 ...
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2k views

Reflection of Electromagnetic Waves

Visible light - Being an Electromagnetic wave is reflected by glass (take mirror). Would all other waves in the electromagnetic spectrum be reflected in the same way by our simple mirror... For highly ...
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360 views

Why does heterodyne laser Doppler vibrometry require a modulating frequency shift?

On the wikipedia article (and other texts such as Optical Inspections of Microsystems) for laser Doppler vibrometry, it states that a modulating frequency must be added such that the detector can ...
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116 views

Filming light in motion?

Regarding this video http://www.youtube.com/watch?v=Y_9vd4HWlVA, which claims to "film" light in its motion. Is it not an absolute nonsense? Even if photons could even be "seen" (meaning, returning ...
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482 views

Huygens-Fresnel principle

Huygens principle states that 1) Every point on a given wavefront may be considered as a source of secondary wavelets which spread out with the speed of light in that medium. 2) The new wavefront is ...
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2answers
401 views

How can I estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of a material?

I am attempting to estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of $\mathrm{TiO}_2$ and $\mathrm{ZrO}_2$, where $p_{11}$ and $p_{12}$ refer to the elements of a strain-optic tensor ...
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2answers
161 views

Dimensions of obstacle needed to block light?

How many dimensions are required minimum for an object to block light? in 1d I doubt it's possible. in 2d I think it could do it if only the light was limited to a dimension perpendicular to the ...
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1answer
161 views

Optical waveguide that can displace a 4D light field

Has anyone invented an optical waveguide that can "pipe" a scene from one place to another unaltered? More precisely, I want to displace (and/or rotate) a 4D light field. An optical waveguide is an ...
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2answers
571 views

Does a fluid's temperature affect the way light passes through it?

For example, if I were to supercool water would it's refractive index still be 1.33 or would it be 1.31, the same as water-based ice even though it's still in liquid form?
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What are the properties of the partially polarized light on refraction?

When a ray of ordinary light is passed on the surface of the water the reflected light will be completely polarized( vibrations in one plane). My question is what will be plane of vibration in the ...
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1answer
439 views

If light diverges, how can there be a virtual image?

I have seen this question: Why can you see virtual images? but answers evade the question. Light needs to hit the retina in order, what is the meaning of "dashed" lines in most visualizations that ...
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3answers
354 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?
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416 views

Reflectance of Titanium as Function of Thin Film Thickness

As far as I know, transmittance equals $e^{-\alpha x}$, where $\alpha$ is absorption coefficient and $x$ is thin film thickness($100-300\,nm$). My team and I have engineered a way to find absorption. ...
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4answers
673 views

Why does a photograph of a face look like it is always watching you?

Imagine a photo that is taken of someone looking straight at the camera. Why when we look at the photo now from any direction it looks as if the person is looking straight at us?
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1answer
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How does a holographic object change perspective when the image is rotated?

Fundamentally i want to know: How do holograms work? The problem with that question is that normally you will end up with pages and pages talking about: a laser a beam splitter a diffuser the ...
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1answer
92 views

In electro-optic material, what is happening to the structure of the material for the index of refraction to change?

I apologize if electro-optic material is not the correct word. As I understand it, when an electric field is applied to an electro-optic material, the index of refraction changes in proportion to the ...
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A problem concerning the change of temperature and spectrum of a filament

The spectrum of a filament has been given before, the left one having the lowest temperature, the middle with a medium temperature and the right one with the highest. My question is this: Why does ...
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1answer
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How do Anamorphic images work? [closed]

I found the following anamorphic image on this site Can anyone explain the physics behind the working of such images? Can we create our own anamorphic images? If so how? Thanks in advance.
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2answers
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limits on a gauss box of light

Consider a wall defined by $w(x,y,z) = \Theta(x-L)$ which is nonzero in the infinite semi-space of $x \ge L$, as well as a coherent planar standing EM wave travelling in the $z$ plane given by its ...
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2answers
586 views

Mean free path of UV photon

I was wondering if there's a simple way to compute the mean free path of UV photons in a optically thick medium with density n. I've looked up at the literature ...
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2answers
599 views

Optical Drive Physics

I have been recently wondering how is data stored on and retrieved from optical devices like CDs, DVDs, and Bluray. What makes these different storage types different from each other?
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1answer
69 views

Does a FTS work on the same principle as a michelson (amplitude division) interferometer?

As far as I can tell within an Fourier Transform Spectrometer the spectral information is gained from changing the path length along one arm, this sounds very similar to a michelson interferometer but ...
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2answers
291 views

Liquid crystal polarizes light reflection question

I was hoping someone could help me with understanding why a row of polarizes reflects a light wave when the whole row is the same length as the wavelength of the light. I pretty much get the ...
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625 views

Speed of light is not fixed? [closed]

In my research, I found that the speed of light is not fixed. IS it true? Namely, We know that light refracts when the medium it travels through changes. Actually, light travels in the same medium ...
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formula for transparency of very thin film of metal

Is there formula that gives transparency of very thin film of given metal (tens of nanometers) to the visible light/light of given wavelength ? Which properties of metals are needed for the formula ? ...
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1answer
134 views

How to estimate number of Laue Spot

Why are "Laue Spots" spots instead of rings? Or is there an effective way to estimate the number of Laue spots? I can't find any formulas or theory concerning this issue. Thanks for your attention!
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1answer
183 views

Physics of Fireworks

This evening I saw the 4th July classic Fireworks in San Diego, and I was wondering about the most physical picture of what was happening. Does anyone have a good way to explain the detailed physical ...
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170 views

Why are subjects upside down when I look through my door peephole?

There is a convex lens 3/4" on the outside and 1 1/2" convex lens on the inside. Each lens has one flat side facing out and one convex side facing in. What can be done to correct this image?
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Rotation of parabola

I'm designing a parabolic solar concentrator and am doing ray-tracing on Matlab from scratch. I'm beginning to look into compound concentrators and would need to have an equation for a parabola ...
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2answers
156 views

May molecules of ideal gases have an inner structure?

The following question is probably very elementary: whether molecules of ideal gases may have optic properties? As far as I understand, when one discusses optic properties, one assumes that molecules ...
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polarization - quantum point of view

polarization could be easily imagined in classical model: direction of E vector. is there any simple image for polarization of single photon?
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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 ...
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1answer
6k views

Why does paper become translucent 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 translucent; but when I attempt the same with water it doesn't as much. Why?
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How to bend light?

As we all know that light travels in rectilinear motion. But can we bend light in parabolic path? If not practically then is it possible in paper? Has anyone succeeded in doing that practically ?
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2answers
250 views

Why do we stop using optics for photons above a certain energy?

I'm reading about how the soon-to-be-launched NuSTAR is on the cutting edge of focusing x-rays, which captures 5 to 80 keV radiation by focusing them with optics that have a 10.15 meter focal length ...
3
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1answer
305 views

What is the optical power level of common fiber optics lasers?

In the book Nonlinear Optics, it is stated that the nonlinear effects start to become a problem in WDM systems (around 1550 nm) after about 1 mW of optical power. However, I measured the optical power ...
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2answers
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Make a semi transparent mirror with copper

The question: How would you make a semi transparent mirror (50% reflection, 50% transmission) with glass with a layer of copper. For light $\lambda$ = 500nm Try to be as realistic as possible What ...
7
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1answer
297 views

Are cylindrical mirror telescopes possible?

Is it possible to use a set of cylindrical mirrors and software correction to build an optical reflector telescope, instead of using a paraboloid reflector? By 'cylindrical' I actually mean a planar ...
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1answer
661 views

Why do polarized sunglasses remove (most) reflections on car windows?

Why do polarized sunglasses remove (most) reflections on car windows? I know that both lenses of polarized sunglasses are polarized in the same direction and I can see that reflections in my own ...
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2answers
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How does the grid on the microwave oven window prevent microwave radiation from coming out?

If I look through the microwave window I can see through, which means visible radiation can get out. We know also that there is a mesh on the microwave window which prevents microwave from coming out. ...