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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New focal point of converging light through a concave lens

Suppose I pass rays of already converging light through a concave lens. The rays are equally centered on the lens such that the original focal point is through the lens and centered on the lens axis. ...
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1answer
42 views

Color of macroscopic objects on molecular level

Macroscopic objects either reflect, or transmit, or absorbs electromagnetic waves. Assume now we have, say, a red apple exposed to the usual white light. The red light is apparently reflected from ...
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1answer
82 views

Is glass considered as a linear optical medium?

My research, which is mainly related to communication, involves the use of optical sources (mainly lasers). However, my background in photonics and optics is not yet solid, so my question might be a ...
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1answer
172 views

Relationship between Polarizability and Conductivity

I've seen in the literature the relation: $\sigma (q,\omega) = \frac{i e^2 \omega}{q^2}\chi(q,\omega)$ where $\sigma$ is the conductivity and $\chi$ the polarizability. However my attempt to derive ...
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1answer
95 views

What is the amplifying medium in a laser diode?

I know it seems like a trivial question, but I can't seem to find the answer anywhere. So - what is the amplifying medium in a laser diode? Meaning: In a classical laser resonator, there a substance ...
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1answer
96 views

Black holes: Behaviour of light near an event horizon

Electromagnetic waves travel mostly in vacuum medium, in outer space, but sometimes in gaseous media, such as in gaseous atmospheres involved in nebulae. If electromagnetic-waves come anywhere in the ...
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0answers
55 views

What happens when a polarized light get reflected by a rough dielectric material?

I have a polarized light (lets say p polarized) which happens to undergo scattering when it is obstructed by a rough opaque dielectric material. What will happen to polarization? Will some part of it ...
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0answers
36 views

Do plasmons depend on the ambient EM field?

Imagine a situation: There's an illuminated metal slab in vacuum. Normally, there are some plasmons created running all over the slab. What would happen if we had turned a giant magnet near the slab? ...
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2answers
50 views

What is light localisation?

Reading about plasmonic nanoparticles I faced the term "localised light". How can one localise light? What are applications of it?
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70 views

Are all fluorophores dipoles?

Lately I'm reading about surface enhanced fluorescence. In many articles I can see that fluorophores are called "dipoles". Is it because that they can be modelled by a vibrating electric dipole? Or ...
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2answers
180 views

Is a Perfect/Lossless Mirror possible?

In traditional mirrors, some of the input light is absorbed by atoms in the mirrors surface and are 'lost' as heat, degrading the quality of the reflected image. Could this loss be compensated by an ...
5
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1answer
111 views

Optical mode leakage through a layer of gold

The geometry of my semiconductor device is given below. The blue regions are gold, the grey ones - gallium arsenide (n-doped to $2.9 \times 10^{15} \mathrm{cm^{-3}}$). The dimensions are μm, i.e. it ...
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2answers
133 views

Distance between two light rays of a beam in a material.

Why is it that the distance between two light rays changes as they pass from one material to another? It must have something to do with the change in refractive index, but to me it seems the ...
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1answer
64 views

How should we put two lens?

How should we put two converging lens in order for parallel rays passing between both lens to remain parallel?
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1answer
77 views

Topological phase in Laguerre-Gaussian transverse mode

Why is the topological phase in a Laguerre-Gaussian transverse mode is the sum of orbital angular momenta per photon, and why is it quantized?
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3answers
123 views

Duality behavior of light and effect of system scale on its behavior [closed]

Does an electromagnetic wave that makes by antenna behaves purely as wave for all the times? or it can change its behavior as photon? and does the scale of system effect on behaving as EM wave or ...
3
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2answers
133 views

What makes a material a good lens for CO2 lasers?

I read on Wikipedia that zinc selenide and germanium make good lenses for $\mathrm{CO}_2$ lasers. My question is, Why?
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3answers
143 views

In what applications are lasers necessary vs. just convenient?

I’m trying to understand, given the wide array of current laser applications: Which applications actually require laser characteristics, as opposed to just use lasers because they are the most ...
3
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1answer
176 views

Help calculating field of view for ball lens I just bought

I have a 5 mm (diameter) solid ball lens that I intend to place in front of a 36mm X 24mm camera sensor (I have already made preparations for the image to be focused and for the sensor to not be ...
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1answer
44 views

Learning material on optical computing

I'm looking for guidance to choose material for a self-study of photonics, biased towards optical computing recent advances. My background is of undergraduate level electrodynamics, quantum ...
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7answers
15k views

How does light bend around my finger tip?

When I close one eye and put the tip of my finger near my open eye, it seems as if the light from the background image bends around my finger slightly, warping the image near the edges of my blurry ...
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2answers
336 views

Anodized aluminium reflectivity at 10.6 um

I wonder how I can model anodized aluminium reflectivity in ray tracing-based optical simulation. I know that the parts my company is using are anodized to get covered with a ~20 um (as specified) ...
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2answers
440 views

Why does sunset over a body of water cause a path of light stretching towards the horizon?

Have you ever notice the sunset's image in the sea? It's like long light path to the end of the horizon! I've attached a sample of this: How can we explain this? I know that it can happen even in ...
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1answer
100 views

Yet another Young Double Slit Experiment

If I have a laser light incident on the double slit at an angle O < 90 what kind of interference pattern will I see? Will i see the same with less intensity or different pattern?
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3answers
2k views

What happens to the index of refraction of a lens if placed in water?

What happens to the index of refraction and focal length of a lens that is initially in air that is then placed in water?
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1answer
343 views

Diver view of refraction

I'm studying the refraction in optics. If a red light monocromatic beam of red light (700 nm) passes from air to water it becomes with a wavelenght of aprox 526 nm. So, my question is: How is going ...
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1answer
41 views

optics biconvex and plano convex

What is the resultant focal length If a biconvex lens is cut into half and then the resulting 2 plano-convex lens arranged in such a way that the plane surface of one faces the curved surface of the ...
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2answers
79 views

Correlation between color of light visible to us and the intensity of transmitted light by the material

I wanted to know if there is any relation between the color of light observed by the eye and the intensity of light transmitted by a material. Let us assume that I have a table of intensities of light ...
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0answers
57 views

Beamsplitter and Dielectric Mirror

Among two optical components. One is a Nd:YAG Laser 50/50 Beamsplitter and the second one is a Dielectric Mirror see pictures. Both of them almost looks like the same. If the specification is not ...
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2answers
207 views

Spatial and Temporal Coherence

How is it possible to achieve waves which are spatially, but not temporally, coherent? Can this be done with a bandpass filter? Conversely, how is it possible to achieve waves which are temporally, ...
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2answers
64 views

Fate of light ray

This question has been on my mind since I first learned optics. Where will the light ray go? First, I thought of it taking a U turn. But, I don't think that will happen. Now I have studied a bit ...
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2answers
88 views

How am I able to tell whether it is dark or not while eyes closed? [closed]

How am I able to tell whether there is a light on in front of me even with my eyes closed? The usual darkness whilst eyes closed transforms into a not so bright glow when my closed eyes are in front ...
3
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2answers
154 views

Plano-convex lenses

When the spherical side of a planoconvex lens is towards the source we will see reduced aberrations normally we use it for the beam collimation. When we use two planoconvex lenses configuration why we ...
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2answers
120 views

Layer thickness measurement

I am interested to measure the thickness of the coating on a mirror (e.g. in the picture below). What are the available and best way of measuring it? What will be the solution in case of multiple ...
2
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1answer
89 views

What is $\epsilon_\infty$ in this equation and why can it be neglected in the IR?

I'm reading this paper (warning, PDF) and they mention that the complex permittivity $\epsilon$ and complex conductivity $\sigma$ are related through the equation $$\epsilon - \epsilon_\infty = (4\pi ...
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1answer
46 views

Does bragg diffraction affect intensity of transmitted light?

Is it possible to measure the plane spacing in a crystal by measuring the angle at which transmitted light intensity dips?
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831 views

Why use lasers for intense, localized heat instead of some other light source?

Lasers are used in various industrial processes that need intense, localised, heat (3d printers and laser cutters come to mind). My question is: why use lasers? There are many other (cheaper, ...
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2answers
503 views

Passing Polarized light through multiple polarizers in series

This is a question that has been troubling me from many days: Suppose we pass a linearly polarized light through a system of 3 successive polarizers. The 1st polarizer is offset 30$^{\circ}$ from the ...
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1answer
128 views

simple question about collimating lens

Let me preface this by saying that I have a very limited knowledge of optics -- basically, I know enough to be dangerous. So I have a square Fresnel lens that measures about 10.5 inches on a side. The ...
2
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1answer
52 views

How is “Band Intensity” related to absorption coefficient

I am interested in the linear absorption of 762nm light near a transition of molecular oxygen. I need to find some experimental numbers that will tell us how far the 762nm light will propagate before ...
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0answers
334 views

What is clock or phase adjustment in projectors? Why its proper setting eliminates strange behaviour of 1px lines/ [closed]

I'm doing experiments that require using a big, thin, contrast grid, for example 1 black pixel and then 1 white pixel alternately. I've met with a few DLP projectors and in each of them I had to ...
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0answers
61 views

How do RGB colors work? [duplicate]

They say that all colors can be formed by mixing Red, Green, and Blue appropriately. Is it true? Isn't the Fourier basis infinite dimensional? Or does it turn out to be the case that only three ...
0
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1answer
358 views

Fraunhofer Diffraction using lenses [duplicate]

I've come across a question that I don't know how to tackle: An alternative way of observing Fraunhofer diffraction uses lenses to provide appropriate conditions. Sketch an optical configuration ...
2
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1answer
118 views

Why exactly are images formed by lenses/mirrors?

I just don't get the concept behind why a lens or a mirror forms a reproduction of the object at present. Is it to do with the object blocking parts of the light source? I just don't understand why an ...
4
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1answer
210 views

Reconciling total internal reflection and the evanescent Wave

I understand that light is guided in a dielectric waveguide via total internal reflection. My question is regarding the origin of power contained in the evanescent field traveling along the direction ...
2
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3answers
220 views

Why can colors be mixed? [duplicate]

We can combine colored light, creating other colors, at least in terms of visual perception. But how it the result physically "a different color" - if it is at all? Or is all this not a physical ...
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0answers
13 views

Can a $TEM_{00}$ beam incident on a confocal cavity along its optical axis excite modes other than $TEM_{00}$ in the cavity?

Can a $TEM_{00}$ beam incident on a confocal cavity along its optical axis excite modes other than $TEM_{00}$ in the cavity? If not, is the FSR of the confocal cavity $\frac{c}{2L}$ in this case, ...
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0answers
255 views

What is the effect of total internal reflection on polarized light [closed]

Total Internal Reflection causes phase change of a light beam. I searched for effect on a polarized light beam by Total Internal Reflection but could not find much. I am assuming polarization does not ...
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2answers
1k views

How car headlight works?

There are two headlight of car. One having a light bulb between two concave mirrors (one mirror behind and other infront of bulb), and the other type of light only have one concave mirror behind the ...
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1answer
1k views

Why do we see laser beams?

A laser produces a coherent beam of photons with particular $\mathbf{k}$ and $\mathbf{\omega}$. So, if there is no particular $\mathbf{k}_0$ directed toward our eyes, why do we see laser beams? I ...