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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why interference pattern changes with given relation when the source slit changes?

Why for interference condition to be seen the dependence relation should be like $${\frac{s}{S}}<{\frac{\lambda}{d}}$$.Where $s$ is width of source slit and $S$ is the distance between the source ...
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0answers
40 views

Why is window glass only transparent from one directional axis?

If you look through a pane of common window glass the way it was meant to be looked through, it's clear. But if you look at it from the side it's not very clear at all, but a dark green color. One ...
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8 views

How is the Rayleigh criterion connected to the Abbe limit

I am interrested whether one can derive a formula for the point resolution (like Abbe did) of an optical system from the Rayleigh criterion (without the use of small angle approximation i.e. ...
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1answer
22 views

How do I find the constants in Cauchys equation for index of refraction for different wavelengths?

Im trying to find the indexes of refraction for my Dispersion of a Glass Prism lab. Specifically I need to use Cauchy's equation to find the index of refraction for different wavelengths. $$ ...
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4answers
3k views

How do those T-shirts that change color in the sun work?

When I was a kid, I asked my dad about them and he said (not in so many words) that it was because sunlight and artificial light have different spectrums and they picked colors that reflect only the ...
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1answer
124 views

Maxwell Stress Tensor at material boundaries

I am trying to grasp the meaning of the Maxwell Stress tensor $T_i^j$ at material boundaries. Concretely, I am trying to calculate the force between two waveguides. The results are given in an article ...
3
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1answer
30 views

Relationship between angular magnification and how much bigger the image appears

How is the angular magnification of a magnifying glass related with how much bigger the image appears to the user? Is it simply the same? If yes, why? (Let's assume that the object is placed in the ...
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2answers
33 views

How do you calculate the intensity of the $m$'th fringe in a Young's slits diffraction pattern? [on hold]

I'm preparing for an exam on wave optics and am struggling with part d) of this question: c) A beam of coherent monochromatic light (wavelength=500nm) is incident normally of a plane of two slits ...
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16 views

Diffractive peak for high-frequency scattering from a sphere with small index of refraction?

How does a transparent sphere's shadow fade as $n\to 1$? Consider radiation of wavenumber $k$ incident on a transparent sphere of radius $a$ and index of refraction $n$ in the limit $ka \gg 1$. ...
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19 views

What's the conductivity of graphene nanostructres (nanoribbon, nanomesh)?

As we know, the conductivity of graphene can be expressed with Kubo formula,including intra transition and inter transition. But does graphene nanoribbon or graphene nanomesh have the same ...
3
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1answer
108 views

Why one should follow Snell's law for shortest time?

whenever two media and two velocities are involved, one must follow Snell's law if one wants to take the shortest time. Why snells law must be followed to travel diffrent media in shortest time? ...
2
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2answers
145 views

What will be the effect of placing a light source very close to a photodiode?

What will be the effect of placing a photodiode really close to a laser source and what should be the appropriate distance between a light source and photodiode to get maximum output current?
5
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1answer
42 views

Optical Retroreflectors: How Are the Faces So Accurately Righted?

This question is about Optical Retroreflectors (corner cubes) and how the extreme precision in their manufacturing is achieved. I suspect there is interesting basic physics involved, which is why the ...
9
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1answer
336 views

What's the size of the smallest possible CCD/CMOS pixel size?

For a given wavelength $\lambda$, is there a limit on the size of the sensor pixel, regardless of the optical equipment attached to the sensor?
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2answers
41 views

Refractive index of red and blue light

if $\frac{\sin(I)}{n}=\sin(r)$ where $n$ is the refractive index, $I$ is angle of incidence and $r$ is angle of refraction (these are relative to the normal). How come blue light refracts at a ...
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0answers
19 views

Distance between objective lens and eyepiece in a compound microscope

why does the total distance between the objective lens and the eyepiece in a compound microscope needs to be greater than the sum of the focal length of objective lens and focal length of ...
2
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4answers
517 views

Why does light bend?

I have just read about dispersion of light by a prism and the thing which i donnot understand is that WHY does the light bend at all? Through prisms and slabs? I came to know that red light has the ...
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1answer
49 views

Why should the image screen be placed at fourth focal plane in 4f setup?

They call it the 4f setup. But when the image coming from the second lens is anyway collimated, why is it necessary to place the image screen at the fourth focal plane?
2
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3answers
271 views

What makes a rainbow happen?

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 causes it ...
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1answer
203 views

How is Fermat's least time principle proven?

How is Fermat's least time principle proven? Or it is what usually is observed and is basis for the theories?
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1answer
214 views

How would we see the earth if refraction of light was significantly stronger?

On worldbuilding.SE there is a question about the cosmological consequences of a world with super-high refraction and atmosphere opaqueness. I'm assuming the easiest way to minimally change the laws ...
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0answers
41 views

Add optical filter to discriminate between coherent and incoherent light to commercial airliner cockpit windows [on hold]

I read about Planar's Transparent Displays yesterday morning on Slashdot.org, We will use them to replace each of the 4 quadrants of a Boeing 767 cockpit window for the objective of 4 independent ...
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0answers
41 views

Why does light propagate rectilinearly? [on hold]

I found a question: Light propagates rectilinearly because of its: a. Frequency b. Velocity c. Wavelength d. Wave nature. Now the answer given in the reference is wave ...
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2answers
163 views

Why (infra-)red light is not used in diagnostics?

I noticed that human body conducts red visible light quite well. A hand placed over a powerful red lamp seems to be semi-transparent while over any other color it does not. Possibly the light ...
2
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1answer
354 views

Solar energy and optical fiber

I'm not really good at science or physics, just wanted to ask about the idea (doesn't have an opportunity to test this). Will this scheme work and what can be its efficiency?(The goal is to make ...
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2answers
42 views

Explanation of ray caustics in E&M

My understanding (now) of a real caustic is that it is envelope of curves or ray-paths that arise due to reflection or refraction from the medium/manifold. My main question is, I am seeing the term ...
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1answer
22 views

Calculating f-stop with given focal length and desired depth of field?

I have a varifocal zoom lens set to a desired focal length and at known distance from the subject. I also have a desired depth of field. Given this information, can I calculate a theoretical f-number ...
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30 views

What is the explanation of the glory (optical phenomenon)?

Yesterday, I took the following picture. I was looking downwards from within an aircraft and I saw the 'glory' around the shadow of the plane on the clouds below. Wikipedia has an entry on the ...
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3answers
352 views

Why don't the colors in an oil slick change as I walk past?

After it rains, I often see bands of color on the asphalt roads. This is usually explained as an thin film interference. Wikipedia has a picture of it which looks by inspection to be the same ...
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2answers
32 views

Will these two coherent electromagnetic waves be in phase?

My question is how will I know if two coherent electromagnetic waves are in phase based on their phase difference. I just solved a problem which stated... Two coherent sources A & B send ...
7
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1answer
11k views

What is the difference between the words transparent and translucent?

Merriam Webster defines transparent as: Having the property of transmitting light without appreciable scattering so that bodies lying beyond are seen clearly. And translucent as: ...
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0answers
14 views

Electric field calculation [closed]

An intensity of a light is given which is Gaussian respect to time. I would like to drive its electric field but have no idea how? Any idea?
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2answers
223 views

How do they derive the apparent-real depth formula?

We know that the refractive index of water to air is 4/3 . So, n=4/3 which should be n = 4/3 = n2/n1 , but my book says, 4/3= real depth/apparent depth. How have they put the “depths” in the ...
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2answers
117 views

What's the meaning of partial derivative for radiance?

The definition of radiance is: $$L\equiv\frac {\partial^2 \Phi}{\partial A\,\partial\omega\,\cos\theta}$$ where: $\Phi$ is the radiant flux $\omega$ is the solid angle $A\cos\theta$ is the ...
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1answer
113 views

Single Slit Diffraction

I am trying to derive the intensity variation function for a single slit diffraction. Sorry for the poor diagram... So I decided to take the amplitudes of the waves originating from the slit on the ...
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25 views

Gaussian beam interference

The superposition of a gaussian beam and a plane wave generates a pattern of rings whose phase shift before and after the focal plane (of the gaussian beam) is $\pi$. This means that if you measure ...
0
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1answer
22 views

Within what range of defocus from the object/image plane does the Fraunhoffer approximation hold?

The Fraunhoffer apporximation of diffraction is said to hold for an image "at infinity," or to be quantitative, for any observation point $R >> \frac{a^2}{\lambda}$. But it is said that, ...
2
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1answer
75 views

how can interference occur within diffraction?

My book says : The number of interference fringes occuring in the broad diffraction peak depends on the ratio d/a that is the ratio of the distance between the two slits to the width of a slit. In ...
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1answer
59 views

what do we mean by speed of light dependent on direction?

I have a statement in textbook saying "When the speed of light is independent of direction,the secondary waves are spherical". Can someone tell when it is dependent on direction and how the secondary ...
2
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2answers
3k views

Radius of curvature and focal length

Is the radius of curvature of a convex or concave lens longer than the focal length of the lens? Does the center or curvature affect the focal point in a lens?
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1answer
30 views

Calculating angle of min deviation of prism [closed]

Two rays incident with angle 40 and 60 on one face of equilateral triangular prism the angle of deviation are equal .find angle of minimum deviation?
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2answers
150 views

Michelson interfermetory point source types of fringes?

When we illuminate a Michelson interferometer with a point source with the mirrors at $0$ separation and with an angle between them, I have read we get linear fringes at infinity. Is it also true ...
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0answers
31 views

What happens if we stand in the centre of a sphere inside covered with as a mirror? [duplicate]

What happens if we stand inside a sphere covered with as a mirror? That is when we are at the centre of a spherical mirror, how the image of us is formed?
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0answers
19 views

addition of two lenses with a finite separation in between

Suppose there are two lenses with focal length $f_1$ and $f_2$ respectively. The effective focal length $f$ when they are combined is $1/f=1/f_1+1/f_2$, but this formula assumes the separation between ...
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2answers
51 views

Creating nanosecond pulses from a CW laser source

Experimental setup question. If anyone aware of a technique to create pulses of several nanoseconds at a around 10Hz repetition rate from a CW laser source?
5
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1answer
52 views

Laser resonator analytic formula for sum of modes

For a sum of N modes in a resonator with identical phases, find an analytic formula for the pulse shape in the limit of many modes. Use the analytic expression for the sum of a geometric series. ...
1
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1answer
50 views

What are the right signs? [closed]

This is a question provided in my book: An object of height $2\ \mathrm{cm}$ is placed at a distance of $2.5f$ from a concave mirror where $f$ is the focal length. Find the height of the image. ...
3
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1answer
81 views

How far apart can the slits be in a double-slit experiment using direct sunlight?

In a normal double slit experiment, I'm told that sunlight doesn't produce a visible interference pattern because there is no stable phase relationship between the two slits. However, sunlight ...
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1answer
36 views

Can I use an optical long-pass filter as a short-pass filter if I just collect the reflected light?

The transmission spectrum filter of long-pass filters are often better shaped than short-pass filters because long-pass filters are often specified for use in a very broad region from 200nm to 2200nm. ...
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1answer
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Apparent depth is supposed to be independent of viewing angle but this seems inconsistent with critical angle diffraction

When rays from the object at some depth are draw so as to be incident at the critical angle (or some angle just lower) the ray is refracted along the surface. Retracing this line would give you an ...