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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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
333 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?
4
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1answer
453 views

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 ...
2
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1answer
73 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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0answers
63 views

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
849 views

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
82 views

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
404 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 ...
4
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2answers
335 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
58 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 ...
3
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2answers
155 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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1answer
312 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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3answers
1k views

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
112 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
154 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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0answers
130 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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1answer
788 views

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 ...
2
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2answers
135 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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0answers
78 views

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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3answers
2k 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 ...
11
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1answer
2k 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?
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5answers
3k views

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 ?
4
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2answers
213 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
212 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
1k views

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 ...
4
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0answers
158 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 ...
3
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1answer
459 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 ...
3
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1answer
2k views

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. ...
3
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2answers
77 views

Adaptive Optics Capability in the Visible Range

Telescopes with adaptive optics (AO) have been in use for several decades. To my knowledge, the lowest wavelengths utilized are in the near-infrared. It's known that Fried parameters are smaller for ...
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2answers
292 views

Optical Tunneling

Is there light tunneling taking place in optically transparent mediums like glass? wherein light travels a larger path in these mediums without interacting with atoms and without any change in ...
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2answers
3k views

If blue light has a higher energy than red light, why does it scatter more?

As $E=hf=\frac{hc}{\lambda}$, blue light - with a smaller wavelength - should have a higher energy. However, it is the case that blue light scatters the most. Why is it that higher energy rays scatter ...
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1answer
427 views

How does the Fraunhofer irradiance distribution look for a double slit aperture of different lengths?

How does the Fraunhofer irradiance distribution look for a double slit aperture with $d$ = integer multiples of $b$?
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0answers
233 views

What are Jones matrices and how to derive them?

I'm coding a software for an optics lab I'm working in and I need to know how to derive expressions for Jones matrices for various polarizes. What does a Jones matrix represent and how would you ...
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4answers
2k views

Optics of the eye - do we see Fourier transforms?

I've recently been learning about Fourier optics, specifically, that a thin lens can produce the Fourier transform of an object on a screen located in the focal plane. With this in mind, does the ...
6
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2answers
626 views

High school double lens optics question

This is a first year high school homework question (in the Finnish high school), and I'm having serious trouble solving it. I apologize for possible non-standard terms: I'm doing the translation from ...
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2answers
455 views

Human perception of distance

When we see things around us, distant objects look smaller to our eyes than nearby objects do. Is there any physics-related reason why our eyes or brain perceive things like this? Or if this is ...
4
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2answers
309 views

Effect of a wavefront deformation on the far-field diffraction pattern of a TEM00

By performing Matlab simulations on a TEM00 mode (approximated by a gaussian intensity profile with a flat wavefront), I got the impression that applying wavefront deformations (such as a single ...
2
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1answer
130 views

Why the color motion picture film appears as black?

Why the color motion picture film, or a color photographic slide, appears as black? The film appears black but when the light from the projector lamp hit it then you can see all the colors.
6
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2answers
92 views

How would you figure some of the methods (in order of importance) to take a picture of the supersonic bullet with the wave it produce in 1888?

It would still be almost impossible for me in 21th century to take this picture: (image courtesy of wikipedia) How would you figure some of the methods (in order of importance) to take a picture ...
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2answers
277 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?
3
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1answer
256 views

Fermat principle: which index of refraction?

I am somewhat puzzled by a common formulation of the Fermat principle (light travel time), because it contains index of refraction related to phase velocity while light travel time through a slab of ...
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2answers
156 views

Bolometer calibration - voltage and intensity

I am interested in possible hazards due to high intensy infrared light sources. Therefore I want to use the "PASCO TD-8553 radiation sensor" (website) to measure the intensity of the radiation of an ...
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5answers
190 views

Light refraction and causality

One way how to look at refraction by a dielectric medium like water or glass is that (phase) velocity of light decreases because it is the wavelength rather than the frequency of the light which ...
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1answer
783 views

Find the dispersion of the slab?

I've been having trouble with this for a few days and already used up all my tries on the homework for it, but have the final is coming next week. Thus I would like to know how do this, however I ...
7
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0answers
99 views

Third-order susceptibilities of metals?

Can anyone point me to a source for measurements of the third-order nonlinear electric susceptibilities $\chi^{(3)}$ of various metals? Specifically in relation to the AC Kerr effect, so measurements ...
2
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2answers
3k views

How does Newton's 2-prism experiment help to explain why light does not get dispersed into 7-colors in a parallel glass slab?

In a real parallel glass slide(with two prisms imagined to be touching each other to form a parallel glass slide), The ray of light should pass through the Z in between without any dispersion or ...
4
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6answers
3k views

Is it possible to witness a circular rainbow?

What conditions would make it possible to see a naturally occurring fully 360° circular rainbow? Would it even be possible?
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1answer
154 views

Rear Projection 3d figures?

From the wikipedia page on a now prominent 3d virtual idol "From 'Things often confused with holograms' on the Wikipedia page linked above: 'In 2010, there was a series of concerts ... which included ...
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1answer
269 views

Number of Images from pair of plain mirrors?

Basically not exactly a homework, but I came across this problem. I have two plain mirrors angled at 60 degree angle. An object is placed in between symmetrically. What will be the number of total ...
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2answers
7k views

3d holograms - How are they created?

How do 3d holograms work exactly? I read that there is a laser in use, but how are the multiple perspectives generated and how is the light trapped? in a certain area to create the effect? ...