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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Principle of Reflection on atomic level

The well observed phenomenon has besides several others has always been a fascination to me, we are well aware of several theories, experiments and practical applications of the well known phenomenon. ...
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1answer
111 views

counting refractive index of a plano convex lens [closed]

suppose that, there is a plano convex lens and its thickness is 5.00cm. If you watch it straight from the convex side, it seems that its of 4.4 cm. What is the refractive index of this lens?
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1answer
88 views

Can polarization effect the coherence length?

I'm taking an optics lab in which I'm required to construct an interferometer, and measure the wavelength of a laser, and the coherence length of the light emitted from a candle fire. Now, I've been ...
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1answer
198 views

Thin lens formula workout method (Query)

In order to workout the method for establishing the formula of thin lens, my teacher says that the optical path is: $PA + AQ = PS_1 + nS_1S_2 + S_2Q$ ($n$ is the refractive index of the ...
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1answer
105 views

Polarization of light

So for my experimental optics class, I had to create a device that would emit horizontally polarized light such that its intensity is independent of an incoming linearly polarized beam of arbitrary ...
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2answers
82 views

Are there any known, non-spectroscopic effects of EM directly on Light?

Photons have no charge. Light is a form of electromagnetic energy. All spectroscopic effects (to my knowledge) are due to changes in electron state, induced either through an interior or exterior EM ...
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1answer
174 views

Semiclassical description of EM waves reflection from metallic surfaces

Imagine an EM wave impinging on a metal. Fresnel's formulas tell us that no wave can propagate through the metal, or that the transmitted field is an evascent wave with some penetration depth ...
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3answers
614 views

How do 3D glasses work?

I am really curious as how do 3D glasses work. I know that they uses some kind of circular polarizers but how does this actually make the screen jump right out at you?
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2answers
176 views

Educational applications of a small Michelson interferometer?

The community college where I teach has some nice old Michelson interferometers. There appear to be a bunch of versions of these that used to be sold (may still be sold?) which were all probably ...
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3answers
905 views

What causes atoms to have their specific colors?

I understand that light (color) is part of the electromagnetic spectrum, and that it depends on what wavelengths are reflected/absorbed. Though what property of an individual atom gives it its color? ...
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4answers
206 views

Why can't we perfectly focus light-abberations aside

I don't understand why there is necessarily a diffraction limitation on optical systems. Where does this limitation in focusing light come from?
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5answers
606 views

Could the speed of light change outside our solar system

Theory: The speed of light changes when it enters or exits the solar system due to a difference in medium (dark matter possibly). Potential problem 1: refraction If there was a speed change at the ...
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1answer
42 views

Additive Trichromatic Color: Seeking Answer for a Fun Application

I'm not the brightest person and I was wondering if it was possible, in the same way that it's possible to make ink that's visible under UV light, if it's possible to make ink that requires a distinct ...
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2answers
867 views

Reflection formula for spherical surface from Fermat's principle (Query)

The snip shows a part of the method shown by my teacher, to describe the reflection formula for spherical surface. However I do not understand how the relation of AB and BI (which I have ...
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3answers
578 views

Beam splitters and Mach-Zender interferometers

I have a question (my very first here) related to 50/50 beam splitters as used in the Mach-Zehnder interferometers (see for example the Wikipedia page). Let's concentrate on the input beam splitter: ...
2
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0answers
322 views

Myopia / Hypermetropia eye glasses inverting image on retina

As far as I'm aware, the eye acts like a pinhole camera in that it inverts the image on the rentina. This makes sense as the rays converge and form a focal point that is upside down. Myopia ...
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2answers
5k views

Full Width Half Maximum (FWHM) of a transmission spectrum

I have a transmission spectrum of a material which has been fit to a Lorentzian. According to Wikipedia here and here, FWHM is the spectral width which is wavelength interval over which the ...
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2answers
1k views

Difference between propagating and evanescent waves

Currently I am reading about super lens and came across these two waves, propagating and evanescent. If a negative index material is used as a lens then both propagating and evanescent can be passed ...
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1answer
392 views

Speed of approach between image and object

A plane mirror image approaches the object at the same rate the object approaches the mirror. So the speed of approach is twice the speed at which the object approaches the mirror. If the object ...
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3answers
13k views

How fast does light travel through a fibre optic cable?

The principle behind a fibre optic cable is that light is reflected along the cable until it reaches the other side, like in this diagram: Although I know that the light is slowed down somewhat ...
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3answers
169 views

Law of refraction from Scalar Diffraction Theory

I am trying to figure out if Snell's Law for refraction can be derived from Scalar Diffraction Theory. The setup is this: light (plane wave, with wave vector $\vec k_i = (k_x, k_y, k_z)$ ) falls on ...
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1answer
338 views

Magnification for a concave mirror

Here is the question as given in my textbook: Find the distance of the object from a concave mirror of focal length 10 cm so that the image size is 4 times the size of the object. The solution ...
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3answers
2k views

Why is it difficult to differentiate between interference and diffraction?

Why is it difficult to differentiate between interference and diffraction? Is it because we don't clearly understand how both of these phenomenon takes place? My thoughts: From an answer to one of ...
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2answers
103 views

Paralel light conditions after passing from a sphere

Is it possible to get such result that light will be parallel after passing from the sphere? what is the total condition for such result if possible? Thanks for answers
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2answers
850 views

Do mirrors have a “resolution” quality to them?

I would like to know if mirrors have a quality of "resolution" to them like a regular photograph might, or like a JPEG does. For example, if you looked to closely, or magnified a photograph, you ...
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0answers
199 views

What are the values of effective mass approximation

For my research work i am trying to calculate band gap of zinc oxide theoratically and found this paper (Determination of the Particle Size Distribution of Quantum Nanocrystals from Absorbance ...
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1answer
277 views

Why Negative refractive index is negative

$n=\sqrt{\epsilon \mu }$ Negative refractive index happens when permittivity ($\epsilon $) and permeability ($\mu $)of a material is negative. My question is, if permittivity and permeabilitity of a ...
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2answers
136 views

Diffraction pattern when wavelength tends to zero

While studying about Fresnel and Fraunhofer diffraction, I came across a statement which says that the fringes disappears and the image would take on the limiting shape of the aperture when wavelength ...
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2answers
190 views

Is there any case of total transmission?

When light strikes the interface of two media some light is refracted and some is reflected. But, is there a case where no light is reflected i.e all the light gets passed through the given object. ...
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2answers
928 views

Does diffraction occur before interference?

In the double slit experiment, light passes through two slits and the waves interfere and form an interference pattern. A single slit is required for diffraction. So, I was thinking about whether ...
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0answers
112 views

Why an extra path difference of wavelength/2 is added when light reflects?

In my textbook it is given that in thin film interference a path difference of wavelength/2 is added up to the reflected light from the upper surface. But, how does that happen? No physics textbook of ...
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0answers
949 views

Simulating the Interference Pattern of Fraunhofer Diffraction by a Single Slit

I'm attempting to simulate the Fraunhofer diffraction pattern due to a single slit. We know that the intensity at an angle $\theta$ is $I(\theta)=I_0 \text{sinc} ^2(\beta)$ where ...
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7answers
5k views

Why does a laser beam diverge?

I was wondering why a laser beam diverges. If all the photons are in the same direction, I would imagine that it would stay that way over a long distance. I am aware that a perfectly collimated beam ...
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2answers
225 views

Light in fibre optic cables

Imagine a fibre optic cable stretching from London to New York (5571 km) carrying a data signal This data signal is split into two parts, red and blue light Both signals start travelling down the ...
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1answer
278 views

question about the focul length and the position of a convex lens [closed]

How can I determine the focal length and position of a lens mounted in an inaccessible position inside a tube by a laboratory experiment? Please help.
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3answers
312 views

Dark matter is electrically neutral

I would like to know how come if dark matter was electrically charged it would reflect light. What are the equations or the logic behind it?
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1answer
419 views

Why does burning things make them black?

It's not clear to me how burning process can transform a material which was previously capable both of absorbing and emitting photon to one which can only absorb them. I would like to hear an educated ...
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1answer
314 views

What happens if an already excited electron gets hit by another photon (lasers)?

Slightly vague title but it is the best I can do. My question stems from some interest in how 3 stage lasers function. A photon from the pumping source comes in and strikes a atom in the active ...
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4answers
12k views

Difference Between Fraunhofer and Fresnel Diffraction

What is the difference between Fraunhofer diffraction and Fresnel diffraction? I mean diffraction is just bending of light waves or waves in general around a point. So how can there be two types of ...
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6answers
11k views

Are Fresnel lenses widely used for solar electricity? If not, why not?

I was just wondering why Fresnel Lenses are not widely used in the production of solar electricity. Their use there would mean that you could produce heat within a fraction of a second, up to a few ...
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0answers
39 views

Law of reversibility of light and total internal reflection [duplicate]

When a light passes from a denser to a rarer medium at critical angle of incidence the light rays graces through the surface of the denser medium.According to the law of reversibility of light same ...
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4answers
1k views

How big should a lens of a telescope be so we can see the American flag on the Moon from the Earth's surface? [duplicate]

How big in diameter should the lens of the imaginary telescope to be so we can see the American flag from e.g. some observatory in Hawaii?
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1answer
71 views

How far can diffused undersea light travel and still be perceived by the human eye?

Example: If one SCUBA diver looks past another SCUBA diver horizontally into negative space, how far away is the most distant emission of 'blue' light waves? Consider the sight angle in question to ...
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0answers
57 views

Why is a $\pi$ phase added on reflection and why do things change with absorption? [duplicate]

Mathematically, how does a $\pi$ phase shift appear upon reflection of light off a optically denser medium? Why is it always $\pi$? If the medium is absorptive it is no longer $\pi$?
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0answers
227 views

Optical Raytracing by using Adiabatic Hamiltonian Method

I'm looking into raytracing a Lüneburg Lens which is a gradient index (GRIN) optical element with a radially varying refractive index: $$ n(\rho)=n_0\sqrt{2-\left(\frac{\rho}{R}\right)^2}, ...
3
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1answer
79 views

Why is the receiver of this solar tower cream-colored?

I wonder, why the receiver of this solar tower is not black? Wouldn't a black receiver be more efficient? If not, why is it not white then, but is an intermediate color? It seems that the receiver ...
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2answers
188 views

Good explanation of a real image?

Okay well I've started to study phys chem in school recently and I honestly can't get my head around what a real image actually is I've asked my teacher to demonstrated it but she's quite lazy, and ...
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1answer
2k views

How far can the human eye see? Any ending point or infinite?

How far can the naked human eye see if unobstructed? (straight ahead on perfectly flat land). Is there a stopping point or is it infinite when you look in the sky? Is there any situation that the ...
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1answer
132 views

Depolarisation of Light in Optical Fibre

I have a question for which I can't seem to find a solid answer in literature and wondered if anyone could offer advice or reliable references please: How does light depolarise in ...
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0answers
192 views

Maximum-Entropy Method deconvolution implementation?

I am looking for an implementation of the Maximum Entropy Method for image deconvolution, ideally in MATLAB or Mathematica. I'm trying to reconstruct an image from fringe visibilities, as is often ...