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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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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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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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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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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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}, ...
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77 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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169 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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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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117 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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162 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 ...
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Why are so many different types of objects white, yet appear gray when they are wet?

There are many things with different textures that appear white – salt, beer foam, paper, shaving cream, snow, talcum powder, white paint, etc. The most common answer is all of the frequencies must be ...
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94 views

Intensifying a light source using black body concept

Is it possible to intensify light by initially passing it through an apparatus like a perfectly black body and then through a colloidal solution? What kind of material can be used inside the ...
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637 views

Fresnel Diffraction at a circular aperture

In Fresnel Diffraction at a circular aperture the central image according to 'Optics' by brij lal and subramanyam will be bright if odd number of full half-period zones can be ...
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1answer
274 views

Fabry-Perot cavities and phase difference

I'm reading a paper which says The beam that reflects from a Fabry–Perot cavity is actually the coherent sum of two different beams: the 'promptly reflected beam', which bounces off the first ...
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1answer
865 views

Wavefront RMS errors, mirror surface roughness and Gaussian beam scattering

What I'm interested is in the scattered power of Gaussian beams reflected from mirrors with a given surface RMS. Usually the surface RMS $\sigma_{s}$ of a mirror translates in an error for the ...
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1answer
112 views

Increasing the maximum angle of laser scanners with optics?

With laser scanning devices, very roughly speaking, the maximum deflection angle seems to be inversly proportional to speed. So for example, while acousto-optic deflectors can steer the beam very ...
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352 views

Faster than light in plasma

Some plasmas have a refraction index of less than 1. In these plasmas the phase velocity of light can be faster than light-speed. But the phase itself won't transfer information, so no paradox occurs ...
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If a beam of light follows the path $y(x)=y_0\sin(x/y_0)$, what is the index of refraction?

An exam question that showed up while I was studying: A plane wave refracts and follows a ray given by the equation $y=y_0\sin(x/y_0)$ where $y_0$ is a constant. Find the refractive index $n(y)$ ...
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103 views

Time duration for pulse of single electron viewed as a wave

Electron as an example has a de Broglie wavelength and could diffract. If it has a single wavelength the time extent of the particle's pulse duration would be infinite .. If it carries a broadband ...
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207 views

Book on optics in curved space-time

As evidenced from my earlier questions on vision and curved space, I am struggling a little bit with visual perception in curved space-time. I would like a book recommendation on optics and vision in ...
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Is wearing 3D glasses from the cinema as sunglasses hurtful to the eyes?

I heard a few times that using them as sunglasses is hurting the eye since UV light is not filtered, but the pupil is wider than it would be w/o wearing them because the visible light is dimmed. I ...
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Does light loses its energy when it passes through denser medium

I know it does not because it emerges out of denser medium at 300,000 KM per second, but according to E=MC square and given that speed of light decreases inside denser medium with refractive index ...
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303 views

Calculate the polarization vector on reflection or refraction from a dielectric interface

I am interested in ray-tracing polarized photons. I have code that works very well for unpolarized light. When a ray hits a dielectric interface the photon is either reflected or refracted by ...
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2answers
1k views

What is optical confinement?

What is optical confinement? What is it intuitively? How does this 'optical confinement' affect the performance of a laser?
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115 views

When one can make telescope that can distuingish 1 mas?

When one can make telescope that can distuingish(angular resolution) 1 mas object by angular diameter? If already possible, tell the name of telescope/observatory. How to calculate angular resolution ...
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1answer
129 views

Energy conservation in plane wave

In plane wave the H and E are in phase. So the pointing vector disappears regularly every pi. How is energy conservation validated ? Is it through the uncertainty of energy and time ?
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170 views

Does gravitational lensing violate Fermat's Principle that light must travel in straight lines?

Does bending of light due to warping of space violate Fermat's Principle or is it that in the principle light goes in a straight line with respect to space (taking space as the reference) and in ...
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272 views

Why does a mirage disappear as you approach it?

Related: why do mirages only appear on hot day? The title says it all: why does a mirage disappear as you approach it? The related question does not answer this.
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A simple question [closed]

This is a simple question but it seems to me that both the explanations are acceptable. Let say the least distance of least distinguished vision is 25 cm. An object is placed 12.5 cm in front of a ...
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1answer
99 views

Input parameters for the reconstruction algorithm in Digital Holography

I've been browsing some Digital Holography papers these days, and have come across this fundamental question. When you reconstruct the complex amplitude for the object image, you use e.g. Fresnel ...
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Conceptual way of understanding what material 'does' at critical angle

I would like a conceptual way of understanding how a material behaves at the critical angle. So why does it all reflect? I can see why it reflects in the maths, but conceptually, it doesn't make ...
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246 views

Change of hue near shadows

My brother is an artist and he told me his paintings look more natural when he slightly change the hue (color) of the surface near the transition between shadow and light. Here's three examples: (1) ...
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3answers
505 views

Unpolarized light vs. randomly rotating polarized light?

I am confused with physical picture about unpolarized light. Is unpolarized light very fast rotating polarized light? or co-existing state of two orthogonal polarization? (or something else?) If ...
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255 views

computing wavefront deviations for off-axis mirrors

Suppose you have two off-axis aligned mirrors which are nearly planar, with small deformations such that a wavefront at plane $P_I$ at distance $-D$ from the mirrors, is refocused at distance $D$ at ...
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Transmittance of glass

Glass has low transmittance for infrared light. Does glass reflect or absorb infrared light? Greenhouses are able to reflect infrared as I understand it.
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Cylindrical lens aberration fixed by roll

I have two cylindrical lenses essentially forming a beam expander. The problem that I am having is that I am seeing a very strange aberration. The image becomes "squashed". Cylindrical lenses only ...
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1answer
495 views

Huygens wave theory not applicable to lasers or parallel beams of light?

According to Huygens wave theory, every point on a wavefront acts as a secondary source of waves. Using this principle we can never have pretty narrow parallel beams of light right? Like lasers? ...
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Optimal slit width in Young's double slit experiment

I'm trying to do Young's double slit experiment at home. Note that I don't have a laser, only a torch. I could get a bulb or use a candle though, if it helps I built the slits by cutting into a ...
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Why do powers of lenses get added?

In our physics class, we were told that a power of a lens is defined as the reciprocal of its focal length. Also, the powers of multiple lenses get added up. But I didn't understand why this is. I ...
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223 views

How far can you scatter light using a prism?

If I were to scatter light how far do you think it will disperse and what prism is the most effectively scatters light?
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1answer
433 views

time constant for typical fluorescent lights

For a typical flourescent light available in the United States on a a standard 120V 60Hz line, is there information available on the decay time of the light? For example, if I am running the light a ...
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75 views

Brewster angle with diffraction propagation?

Diffraction theory is scalar. How you deal with beam propagation in fourier optics that is sensitive to the to the polarization? If I have linearly polarized gaussian beam incident on glass surface, ...
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1answer
248 views

Distinction between Larmor frequency and Rabi frequency

Wikipedia said "In the context of a nuclear magnetic resonance experiment, the Rabi frequency is the nutation frequency of a sample's net nuclear magnetization vector about a radiofrequency field. ...
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233 views

Four questions on color

First, I apologize for being a mathematician and having no scientific background in physics. The following questions on color came up in a discussion at lunch and I would be very happy to get some ...
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1answer
689 views

Compound microscope vs astronomical telescope

In compound microscope, we take such an objective lens which has small focal length. While in astronomical telescope, we take such an objective lens which has large focal length. Why don't we use ...
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269 views

How to calculate the helicity of polarized light?

At first, I used to think that only circular polarized light has non-zero helicity, linear polarized light has zero helicity, because the linear polarization can be seperated as the superposition of ...
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1answer
403 views

How mirror equation can explain farsightedness correction?

I have a friend who has just show me his medical prescription for hyperopia (farsightedness) correction and he needs glasses with 4,25 diopters for that, which seemed to be weird for me because I had ...
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3answers
525 views

Why does light diffract only through slits?

We can see diffraction of light if we allow light to pass through a slit, but why doesn't diffraction occur if we obstruct light using some other object, say a block? Why are shadows formed? Why ...
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1answer
380 views

electric field of unpolarized light after reflect?

Reflection and transmission (Fresnel equation) of polarized light are treated in many optics or electromagnetism books. If $E_s$ and $E_p$ is incident electric field with s-polarization and ...
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Radius of curvature of lens: Newtons Ring method vs spherometer

I have to do an experiment to find out the radius of curvature of a lens using the Newtons ring method given that you know the wavelength of the monochromatic light used in the experiment. What the ...