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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Variance of daylight over short periods of time?

I've searched various publication archives but I'm a signal processing engineer and not an applied physicist, so I might not be using the right terms. While I can find various average values for the ...
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2answers
603 views

Why does a single mode fibre have a cutoff wavelength?

I earlier had a doubt based on ray theory that light must reflect and so all wavelengths should propagate through SMF. This Q/A Single-mode fibers and ray-theory of light does specify that we have to ...
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2answers
116 views

Difference between single mode and multi mode optical fibres?

What is the difference between single mode and multi mode optical fibres? First off, I guess that by modes we mean the spatial modes of the electric (or magnetic?) field right? Now: what makes a ...
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1answer
74 views

Is a lens with a focal point that doesn't shift as sun shines from different angles possible? [closed]

My question: Is it possible to manufacture a lens whose focal point doesn't shift in any direction during the day when the sun shines from different angles? It is understood that the focused energy ...
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0answers
56 views

Expectation value for the time of a photon reflection

A photon is reflected by matter (by an electron in empty space). How long does the reflection take? (i.e. is there any infinitesimal time elapsing during the reflection process?), or more precisely, ...
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1answer
223 views

How does the color of fine dispersed metal particles change between silver and black?

Small dispersed particles of metals are often black, while a solid object of the same material would be some shade of silver. The most notable example is the use of metallic silver as the black color ...
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1answer
203 views

How is the imaginary part of angular frequency omega related to the imaginary part of the refractive index?

I'm trying to find the attenuation constant (leak rate) $\alpha$ from the imaginary part of the refractive index of a lossy material. I have the eigen frequency $\omega$ for my structure which has an ...
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1answer
722 views

Why do i see bright red hand when i place flashlight behind my hand?

When I place a working flashlight behind my hand, I see my hand bright red because of the light. So my question is, why do I only see red light after transmission even if incoming light from the ...
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1answer
85 views

Reducing the distortion of transmitted light through a prismatic array

I'm wondering if there is a way to reduce the distortion of light transmitted through a prismatic array (without touching the surface of the prisms). The obvious thing to try is a corresponding ...
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1answer
17 views

Light Focus Guider [closed]

How can I easily guide a focused light source to a different location without losing focused light intensity? If there is an item, where can I buy this? I heard about fiber cable, but I do not know ...
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1answer
613 views

Anti-reflective coating effect on total internal reflection?

If the surface of prism is coated with an anti-reflective coating, (specifically an index matching, refractive index gradient, or moth-eye structure), and light impinges at a greater than critical ...
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1answer
416 views

Experimentally measuring coherence length of laser

So I am trying to figure out the coherence length of my laser source. I am using a mach zehnder interferomter (image attached). I have theoretically calculated $L_c$ to be somewhere between 800-1200 ...
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1answer
94 views

How to calculate transmission of photonic band gap fiber?

How to calculate transmission of hollow core photonic fibers (multilayer fiber and 2D band gap fiber)? Which books/article you can recommend ? I see that comsol can do it, but is there a model that ...
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2answers
397 views

Seeing one's back on the event horizon

If we would hypothetically be exactly on the event horizon, we should see our own back, because of the circular motion of photons on the event horizon, right? But what would be the image size, or $-$ ...
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83 views

Absorption Spectrum

I just learnt what absorption and emission spectrum are. And our teacher introduced us to what Quantum Dots are. And showed us their absorption and emission spectra. And they look something like this ...
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3answers
581 views

Image formation (lenses) [closed]

I have a question regarding image formation by lenses. It is the following: A lense with a focal length of $-48.0cm$ forms an image $17.0cm$ to the right of the lense. Where is the object positioned? ...
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1answer
95 views

Usage of the terms Raman, Stokes and anti-Stokes scattering

I am confused over the correct usage of the terminology for "Raman scattering", "Stokes scattering", "anti-Stokes scattering", or even "Stokes-Raman scattering" and "anti-Stokes-Raman scattering". Is ...
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1answer
381 views

An optical system with image from a convex lens forming behind a concave lens

I am having a problem drawing optical ray lines for optical systems. Namely, one which have a formation of image of the first lens beyond the second lens. Take the picture below as an example: In ...
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2answers
150 views

Can a point source be located more accurately out-of-focus or in-focus?

Let's say I am taking a picture, and I know a priori that the image is of a single ideal point source of light at infinity. With a perfect imaging system in focus, the image shows an Airy disk. I ...
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2answers
968 views

What is the difference between surface plasmon and surface plasmon polariton?

I'm trying to understand this reading article linked below and I still don't know how to explain this simply, without need to derive everything mathematically. Can someone just write here how do SP's ...
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1answer
232 views

Determinant of ray transfer matrix

Quick question on the wikipedia entry for the ray transfer matrix, which is defined : where $x$ is the distance of a point from the optical axis and $\theta$ the angle that the beam profile at that ...
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2answers
3k views

Why does a mirror reverse polarization of circularly polarised light?

A glass mirror (with metal backing layer) will reverse the polarisation of circularly polarised light upon reflection. A polished piece of metal will also reverse the polarisation of circularly ...
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1answer
306 views

Can horizontally and vertically polarized light combine to become circularly/elliptically polarized light?

Well, we know that circularly/elliptically polarized light is made up from orthogonal components. So is it possible then to create circularly/elliptically polarized light by combining horizontally and ...
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8answers
14k views

Could Legolas actually see that far?

The video “How Far Can Legolas See?” by MinutePhysics recently went viral. The video states that although Legolas would in principle be able to count $105$ horsemen $24\text{ km}$ away, he shouldn't ...
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2answers
916 views

Is single photon perfectly monochromatic?

Now, we do have equipment to generate single photon at a time, and LASERs are nearly monochromatic. While typing the question, am realizing that successive photons in case of single photon ...
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224 views

Cut angle for BBO type I SPDC

I am using an old BBO crystal, which is not designed for spontaneous parametric down conversion, to see whether I can generate converted photons of 800nm from 400nm. I used a photon avalanche detector ...
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1answer
2k views

The physics behind Google Glass' “prism”

In writing a bachelor's thesis about applicable use cases for Google Glass in retail I also strive to explain the physics behind Glass' optics. So far I've come to the following conclusions: Glass ...
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1answer
156 views

Calculate minimum intensity of a point source visible to a camera

I have two cameras and know the specified minimum faceplate sensitivity for both: Camera 1: Minimum faceplate sensitivity 4 x 10-6 Lux Camera 2: Minimum faceplate sensitivity 2 x 10-7 lux I also ...
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1answer
94 views

light color and refraction

I'm a bit confused on the topic of refraction, some starting premises: 1) When light refracts from exiting a medium with a low n and entering a medium with high n the light bends. 2) The index of ...
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1answer
3k views

Problem with plane mirror focal length thoery: Is the focal length actually infinite?

We all learned that the focal length of plane mirrors is considered to be infinite, as the radius of curvature is infinite. However, imagine this scenario: You have a perfectly flat (no one get mad, ...
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36 views

What are the characteristics of fluorescence microscope that allow detection of living cells?

How can we see living cells underneath it?
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2answers
244 views

optical diffusion (scattering) versus refraction

When an electromagnetic wave meets an interface a part of it is reflected and part of it is refracted (and from the refractive index I can calculate the angles of propagation and the intensities using ...
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2answers
770 views

Why does light travel in a straight line through a liquid?

So I was reading a document that stated that when traveling through a material (I'll use a liquid here, maybe water), a photon actually always traveled at 300,000 km/s, it was just that it ...
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3answers
508 views

Will a prism widen a monochromatic beam?

The representation of the experiment which demonstrates that white light consists of many colors, invariably shows that the beam of white light is broadened inside the prism and is some what more ...
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807 views

Are the fast axes on Thorlabs quarter-waveplates mislabeled?

Some members of my lab are performing a polarization-sensitive experiment where they need to use a quarter-waveplate (QWP) with the fast axis in a specific direction. In the process of carefully ...
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79 views

Twinkling in sunlight reflections

A question that covers optics and possibly biology/physiology: looking out my window, I see the Sun reflecting off car windshields in a distant parking lot. The very bright reflections are distinctly ...
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2answers
600 views

Phase and amplitude information of an image

By applying Fourier Transform to an image we can get its magnitude as well as phase spectrum. A magnitude spectrum describes how various frequencies are attenuated and accentuated in that image but ...
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2answers
153 views

Can I use one convex lens to create a telescope?

Is it possible to create a telescope with only one convex lens? Specifically, is the image I drew below possible? (This was supposed to be rotated 90 degrees counterclockwise.) In this picture, ...
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1answer
395 views

Image Reconstruction:Phase vs. Magnitude

Figure 1.(c) shows the Test image reconstructed from MAGNITUDE spectrum only. We can say that the intensity values of LOW frequency pixels are comparatively more than HIGH frequency pixels. $$ ...
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159 views

At Interfaces Does Light Have to Accelerate?

First, I'm not sure if photons have to "get up to" the speed of light, or if they are thrown into existence at that speed. I know that they should just be generated moving at their speed, and I know ...
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2answers
97 views

Thin Lens Methods and Object Perceived vs Literal Size

When using the ray trace methodology to solve a given thin lens question, does the arrow (commonly used as the example object when tracing) represent the literal height of the object or the perceived ...
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105 views

Bandpass of diffraction grating - exit slit width?

I'm supposed to derive a relation for the range of wavelengths that's being transmitted by a spectrometer (bandpass) in terms of the dispersion, focal length and exit slit width. Given grating is ...
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1answer
79 views

Helicopter blades

Why do the propellers on helicopter appear to be so slow when the propellers is going at full speed? Can you please explain this particular optical illusion to me?
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19 views

Conjugated-Phase Matching

I am working on imaging applications of phase-conjugation in optics, in particular phase-conjugation imaging from recorded holograms. I have found several useful sources, but I cannot find a book ...
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1answer
60 views

Thin Film Interference in Fluid Dynamics: Many are welcome to throw ideas in here, Please!

It was a few days ago, and there was a very heavy storm(currents were flowing beside the sidewalks as normal). I became intrigued by a thin film of gasoline that got caught in one of the currents. The ...
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1answer
121 views

Is this a photograph of Surface Plasmon Resonance?

Does this photograph depict surface plasmon resonance? PHOTO 1 - Ellipsometric style photograph produces blue-green and purple resonance waves from nanogold-like tubule. PHOTO 1 was cropped from ...
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1answer
73 views

Placing a lens in front of ultraviolet femtosecond laser with 10e38 J in pulse makes it a gun that fires microscopic black holes at speed of light?

I calculated that in the focal spot of such a laser the critical energy density would be met. Will these black holes really move at the speed of light, just as the the photons that made them? The ...
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1answer
597 views

How to transform material permittivity tensor from Cartesian coordinates to another orthogonal coordinate system?

I have a material specified by a permittivity tensor written in Cartesian coordiantes: $$\begin{pmatrix} \epsilon_{xx} & \epsilon_{xy} & \epsilon_{xz}\\ \epsilon_{yx} &\epsilon_{yy} ...
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31 views

How to isolate and verify the source of optical absorption/effects?

This is similar to my other question, but not the same -- that one was about the energy ranges of various absorption mechanisms, and this one is more about experimental techniques to find them. Let's ...
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247 views

Determining diameter of effective image circle of large lens in a Camera Obscura

I am in the process of gathering materials and designing a large lensed Camera Obscura. I would like to estimate the approximate diameter of the image circle and the approximate field of view. in ...