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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Optical Simulation Tool [duplicate]

I am a student and trying to design an aperture from which a light will pass will project on a sensor. I tried to find some software simulation tool for this purpose where i can draw the aperture ...
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How does a microscopes optics expose defects in the users vision?

I've got cataracts in both eyes. My vision is correctable to 20/30, so the cataracts are essentially a non-issue in daily living. But when I use a microscope, which I do daily, (binocular, zoom ...
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Focused beam of light

I'm trying to understand what happens to photons when a beam of light is focused down to its waist. In the image attached, do photons take the path 1 or 2. That is, do the photons cross or just get ...
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How is the width of a slit related to the intensity of light passing through it?

Here's a question I got in my final exam this morning. "If in a Young's double slit experiment setup, the ratio of intensity of the bright spot to the dark spot is 25:9, what is the ratio of the width ...
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324 views

Infinity Corrected Microscope - Building from Scratch

I took an optics course a few years back, and am trying to figure out how to build an infinity-corrected microscope from discrete optical components which are listed in references [2] (lenses) and [3] ...
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Is TRUE invisibility possible?

First off, this question may seem highly stupid at first, but it arose from past cartoon memories. In the cartoon Tom & Jerry from the 1940s, there was already hypothesizing over cream that, when ...
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350 views

Optics - Faraday Rotator using waveplates

I'm trying to replicate the effect of a 45° Faraday rotator using a series of waveplates instead. I've encountered some difficulties using the jones matrix notation, the main book I'm using is: ...
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238 views

Cylindrical Fresnel Lens Focus Problem

How to focus beam from the fresnel lens on a flat surface. In my case, instead of producing the light beam, I am receiving the light beam. So, the beam comes from the right and then focuses at a ...
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114 views

Deriving and gaining intuition for the equation for the index of refraction $n = \sqrt{\mu_r\epsilon_r}$

I've come across the equation in the title. It relates the index of refraction of a substance to the square root of the product of the relative permittivity and the relative permeability at whatever ...
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36 views

Query regarding interference

In Young's Double Slit experiment, why is it that two waves vibrating perpendicular to each other doesn't show interference? I know that for interference to happen, the waves must be coherent ( i.e., ...
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Does a mirror help a near-sighted persion see at a distance clearer?

A near-sighted person without eye-glasses can not clearly see things at distance. If he takes a photo of the things at distance, he can see the things from the photo much clearer, because he can ...
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375 views

Magnification in compound microscope

I was studying about compound microscope here I don't see why we multiply linear magnification of objective with angular magnification of eyepiece. Shouldn't it be both angular or both linear? Can ...
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121 views

Help in understanding the derivation for Fresnel Distance?

An Aperture of size $a$ illuminated by a parallel beam sends diffracted beam (the central maxima) in angular width approximately $λ/a$. Travelling a distance $z$, it aquires the width $zλ/a$ due to ...
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Optical absorption — what are the common ranges and mechanisms?

So let's say you do some reflection/transmission spectroscopy of a material. It's clear that it's absorbing in some range. What would be your first step in identifying the source of the absorption? ...
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1answer
121 views

What really is reflection? [duplicate]

What really is reflection? Is it just the reemission of EMR? I asked my teacher, he said in quantum sense, it is true. But when I read something about emissivity in Stefan Boltzmann's equation, it ...
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Optical Bloch Oscillation

I have a doubt about how the optical Bloch oscillations happen in a 1D photonic crystal. I try to explain: in a photonic crystal with discrete translational symmetry in one direction I superimpose a ...
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2answers
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Can we solve California's drought crisis by pointing parabolic mirrors at the ocean?

If you concentrated sunlight to points in the ocean, could you make the water evaporate significantly faster to induce a substantial amount of rain? Assuming you could do that, could you use silver ...
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184 views

Can you replace the backlight of a thin film transistor (TFT) with a mirror?

I basically know how TFT' displays work. They have on both sides a polarizing foil, in 90 degrees with the crystals in the middle modifying which light particles should pass through or not. The light ...
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2answers
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what is the best way to collimate light emitted by a led?

I'm new to this forum. This is half a question, half a challenge. And it's more engineering then physics but I thought I might get good insights from a physics forum. I would like to cure a UV ...
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3answers
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Divergent thin lens producing real images

The question is as in the title, can a divergent lens produce a real image, when backed by a convergent lens? Which are the conditions to be respected? This was a homework and I have received the ...
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Fermat's principle to prove the law of reflection

Fermat's principle tells that a light ray will follow a path from point $A$ to point $B$ so that the optical path length of this path is an extremum over neighboring paths. I wanted to use this ...
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1answer
93 views

Identifying an optics equation in a code refactoring project

I apologise if this a somewhat naive post. My knowledge of optics is limited, and I am learning on the job, so to speak. I'm a computational biologist, dabbling in a bit of physics. I'm currently ...
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184 views

What are the current experimental limits on the polarizability of the vacuum?

Many (all?) materials are polarizable at some level; meaning that when we apply an electric field across the material, there is an induced dipole moment $$ \vec{p}=\alpha(\omega)\vec{E}, $$ where ...
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Is 'color' characteristics of a body or characteristics of light?

In situation when body exposed by light, is 'color' characteristics of a body or characteristics of light? Is there any difference on macro/micro levels? Will exist such term as 'color' in parallel ...
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171 views

If photons don't have mass, how can they accelerate objects? [duplicate]

As far as I know photons don't have mass but they do have momentum ($p=mv$). Scientists say that if we put a shiny (reflective) shield of large radius in the vacuum of space, then light from sun will ...
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223 views

How to compensate ray displacement caused by refraction in glass slab

I need a nudge in the right direction, i guess (this is not a homework question). I want to calculate the total length of a ray from an emitter to a target which passes through a slab with known ...
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How much light can pass through a point?

Analogy: an infinite number of lines can pass through a point. Is there a limit on the number of lasers that can pass through a point? Obviously, with lasers the “point” would be a sphere with the ...
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Relection of light [duplicate]

If I recall my physics correctly, and it was a long time ago, when a photon strikes a reflecting surface that specific photon is not what is reflected--rather the photon excites an electron which ...
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53 views

Rotation speed measurment

Could anyone please explain with simply how we can measure the rotation speed of an object using the Sagnac Interferometer ?
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1answer
96 views

What Material for reflective surface of a solar grill/barbecue? [closed]

I have been planning on building a solar grill for quite a time now, and the one problem, which is also the biggest - I need to shape a mirror into a paraboloid, so it bundles solar energy ...
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1answer
258 views

Apparent depth and the viewing angle [closed]

Does the viewing angle of a person observing a coin placed in a bucket of water affect the apparent depth in any way?
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185 views

Why is a rainbow curved in shape?

Why is a rainbow curved in shape? When dispersion of light takes place, light splits into seven colors, but when rainbow is formed it appear to be bent. Why does this happen even though light travels ...
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148 views

Pfund's method for refractive index

I wish to obtain the refractive index of a smooth surface using only a laser of given wavelength and a light sensor. I thought of using the Pfund method (attached), but I can't understand how the ...
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107 views

The velocity of light changes from one medium to another, but does its energy change?

Does energy of light change when a light travels from a medium to another of different optical density?
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97 views

Can a full image be made in mirror if we change the distance between object and mirror?

To see the full height of man, the height of mirror should be half of the height of the man. What happens when we decrease the distance between mirror and man?
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Can zinc nitride be used as light emitting material?

I cannot manage to find any journal papers about the applicability of zinc nitride as active layer of an light emitting diode (LED). But certain papers got mention that zinc nitride with a direct ...
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Optics Brewster's Angle Reflection Intensity

An incident unpolarised light beam of intensity $I_{0}$ strikes glass plate B at Brewster's Angle. The reflected light travels vertically and strikes a second glass plate A, again at Brewster's Angle. ...
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3answers
183 views

Clear vs black in terms of light reflection?

I've heard that clear things such as the gaseous components of the atmosphere or water reflect no light, and that is why they are clear. I've also heard that black things such as asphalt are such ...
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26 views

Equivalent temperature: laser and cell containing Rb

What's the meaning of "equivalent temperature" related to a cell containing rubidium and crossed by laser?
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1answer
48 views

Practical hardware question regarding optical source for an array of fiber bragg gratings [closed]

I have a single 1 meter array of 5 fiber bragg gratings that has FC/APC connectors on both ends. I will be embedding the array in a material and want to be able to do a quick check that the array is ...
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2answers
129 views

What really makes a rainbow happen?

Yes, a rainbow is formed when a raindrop refracts light, but why then does the whole sky not become a huge rainbow when it rains? Would the light not be dispersed into ordinary 'white' light? What ...
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Diffraction problem - How do I interpret

Here is a problem on diffraction - Diffraction pattern of single slit of width 0.5 cm is formed by a lens of focal length of 40 cm. calculate the distance between first dark and next bright fringe ...
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100 views

Characteristic quantities in Fiber optics

I'm having trouble finding typical quantities in fiber optic communication. In particular, what kind of powers are generally used (or what is the minimum that fiber optics receivers can detect ...
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96 views

Simple Experimental Laser Characterization Parameters Ideas?

I have 2 months to do a project on characterization of a laser parameter. We have typical optics lab equipment (DFB Lasers, oscilloscopes, random number generator, etc.). I was told to choose a laser ...
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Microscopic origin of optical transmission

When light interacts with matter, it is abosrbed, reflected and transmitted. With repect to the UV-Vis range, electronic abosrptions occur, where if the incident photon mode matches the energy ...
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What causes multiple colored patches on a wet road?

I was going to school (after a rainy hour) when I saw some patches of shiny colours lying on road. Some small children surrounded that area and thought that it's a rainbow falling on the Earth. (For ...
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Does optical fiber preserve the angles of incoming light?

I am reading up on optical fibers and there's one thing I haven't understood yet: Does an optical fiber preserve the angles of incoming light? For example, if we light two LEDs in front of an ...
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2answers
158 views

Why does a picture of a person seem to be looking in the same direction irrespective of the angle of observation? [closed]

If you observe a picture of a person hanging on a wall who seems to be looking directly towards you always seems to be looking at you even though you change your angle of observation to the extremes. ...
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1answer
33 views

Isotropic systems and homogeneity

In isotropic systems, the atomic arrangement is homogeneous in all directions. In the case of glass, which has the atomic structure of a liquid and, therefore, a random atomic structure that is ...
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What type of interferometry set up do I need to image a small structure at a distance?

Please forgive me, optics isn't my forte. I'm trying to work out how to image the surface structure of an object at a distance. Considerations are: Monochromatic light- it must be imaged in the ...