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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Laser shone at liquid jet

When a liquid jet of water falls in laminar flow, it hits a surface. If this contact point, between the surface and the jet, is illuminated by a laser. Rings of light can be seen forming around the ...
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34 views

Optical Frequency Divider?

Is there an optical frequency divider that works to make 1064nm light from 532nm light? The opposite of KDP crystals?
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What is the meaning of size of the image?

Say I am standing at a distance of $20m$ from a plane mirror and looking at it. My image in it as I see it is smaller than how I perceive myself. Why then does my physics textbook tell me that in a ...
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38 views

Size of Fiber Optic? [closed]

I would like to know that why the size of fiber optic is important? What will happen if the size of the fiber optic is made large or small? EDIT: My question is simple. We all know that fiber optics ...
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54 views

Why are optical parametric oscillator so big?

Optical parametric oscillators have an optical resonant cavity. Why is this cavity so big when the wavelength of light is so small? What will happen if optical cavity length is shortened?
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52 views

Is it possible to save the light?

I am just thinking why can't we save the light (not a bulb). Lights normally get reflect by mirror, when source is off reflection is gone or absorbed or discharged by other object in room. Can't we ...
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1answer
38 views

Blue hues in Aluminum mirror

[][] When depositing Aluminium sometimes I end up with a bluish hue to my film especially when changing angle of view. I use a very high rate of deposition and low temperature. What would cause this?
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1answer
35 views

N-Body Simulation for Photons

For my undergrad optics class I am taking we have to select final projects to work on for second half of the semester. I have spent the last few weeks working on my own project which was a GPU ...
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1answer
45 views

How can one tell how much light is blocked by a secondary mirror in a reflecting telescope?

I've been reading about reflecting telescopes and I understand how the secondary mirror doesn't cause any obstruction to the image itself, but I've read that it does dim the image by blocking the ...
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3answers
59 views

Do white light generated by light bulb also have significant Infrared intensity?

I am planning to obtain near infrared light for a project. Instead of producing the infrared myself, I thought it might be easier to use something inexpensive and commercially available. That's why I ...
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1answer
13 views

What equation should I use to determine retinal image size generated by 10 micron DIA input beam?

If I plot the effective focal spot diameter (S) achieved by using the popular expression: S = (4L/pi)(F/D), where L is input beam wavelength, F is the focal length of the lens, and D is the input ...
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2answers
874 views

How does making “pyramid hologram projectors using smartphones” work?

The basis of this question is this video, where a 3D hologram like effect is achieved using a 4 sided hollow pyramid. I don't know if this is holography in the usual sense. Can some one explain this ...
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Spectroscopy: The trustworthiness of reflected, refracted, and “mixed” light sources

Spectroscopy: If spectral lines are used to determine the composition of an object, wouldn’t the reflected light (e.g., from a star) that allows us to see non-luminous objects (e.g., planets, bolides) ...
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32 views

When can the Poynting vector be reducible to an expression with just $|\mathbf{E}|^2?$

In the case of a single plane wave, it is clearly to me that the intensity should be proportional to $|\mathbf{E}|^2$. The derivation usually follows from the relation $E=cB$ and $S=\frac{1}{\mu}EB$ ...
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1answer
55 views

Converting Stokes Parameters to Jones Vector

How do you convert a Stokes vector into a Jones vector? I am only concerned about fully polarised light, and I need to convert the Stokes parameters (or the azimuth and ellipticity angles) as measured ...
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1answer
35 views

Ion beam optics software

I'm starting a new project that requires the simulation of a ion source test facility. I don't have much knowledge of beam optics so I want to find a beam optics software that is easy to learn/use. ...
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1answer
85 views

Does the complex conjugate of a vector have the same direction as the vector?

Looking at reflected and transmitted optic waves, the $\overset{\rightharpoonup }{E}_t$ vector is always perpendicular to $\overset{\rightharpoonup }{k}_t$ (as seen in the attached image). So ...
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40 views

What happened to the perfect mirror?

Back in 1998 an article was published in Science by JPL's Jon Dowling claiming a method for making a perfect dielectric mirror: "Mirror on the Wall: You're Omnidirectional After All?" Jonathan P. ...
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2answers
58 views

Shape of a mirror that focuses non-parallel light

If I am not mistaken, a parabola is the shape that a mirror has to be to focus ideal, parallel light rays to a single point. Real light sources are usually not actually parallel though, but are more ...
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37 views

Concave lens path of ray

What will be the path of ray passing through the first focal length of a biconcave thin lens kept in air? I know that a ray passing through focus or appearing to pass through focus of a thin lens ...
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1answer
55 views

Concentrating the Sun with mirrors facing each other

What will happen if the sun is concentrated by directing sunlight to mirrors that are facing each other? i know that mirrors absorb light and dont reflect 100% but will the efficiency increase due to ...
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1answer
46 views

Why do we have the absorption edge?

I am very puzzled by the discontinuity of any physical quantity. If the energy of the photon is smaller than the excitation energy of the atom, the absorption rate is zero; if the energy of the ...
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2answers
79 views

How come lenses alter the path of photons?

From what I know, photons are theorized particles and believed to be massless (just energy) and travel at the speed of light. How come a lens, which is an object made of atoms, can bend a light path? ...
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43 views

Does light influence transparency?

Let's consider this thought experiment: There is a sheet of a (more or less) transparent material. On one side of the sheet there are two light sources illuminating one spot on the sheet. The sources ...
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236 views

Why is my shadow deformed and not the shadow of the ceiling? [duplicate]

Look at these two photos of my shadow from sunlight. Case 1: My shadow is separated from the shadow of the ceiling and my head is round. Case 2: But when I walk a little more and the shadow of my ...
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48 views

How is the MTF determined of a telescope?

The Modulation Transfer Function (MTF) of an optical system if often determined with the use of a MTF chart (image) or something similar. This chart has to be in focus in order for it to be used. ...
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Multi-directional ether

In the Michelson-Morley experiment,the two beams of light should be directed at right angles in order to test the existence of ether, but that postulate is based on the prediction that ether has only ...
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Why can't an electron be observed?

I was watching a show on Netflix hosted by Neil Degrasse Tyson and he mentioned that one of the fundamental particles that we know of, the electron, is something we have never even observed directly. ...
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59 views

How does the distance between a light source and a lens affect the beam's intensity?

I have a system with a light source, a convex lens, and a light detector. The beam travels from the light source, through the lens (causing a divergence), and into the light detector. The light source ...
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2answers
42 views

Does refraction or diffraction cause rainbows?

The title is explicit. I just read several web pages about rainbows and all of them refers both to refraction and diffraction. Things are not really clear in my mind, and to fix this, I'd like to have ...
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1answer
21 views

Diffraction pattern in the image plane?

Consider the setup below: In all cases the relationship between $u_o(x_o)$ and $u_f(x_f)$ is given by a Fourier transform. My question is, when is the same true for the relationship between ...
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36 views

Collimation and the inverse square law

This is my understanding of how the inverse square law applies to collimated light, and specifically laser light, since AFAIK it's the only light that can be collimated with any accuracy thanks to ...
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2answers
55 views

The image of a wall clock is to be obtained on the opposite wall 2m away by the means of a convex lens. What is the minimum focal length required? [closed]

I'm in 10th grade and this question came in my physics test. Nobody was able to answer this question correctly except my physics teacher who says that the answer is 2m. My answer is that there should ...
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41 views

Plane waves intensity

Our professor said that a plane wave has the same intensity in the plane perpendicular to it's propagation. I can't really make sense of how that is possible. I mean, shouldn't the intensity decrease ...
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42 views

Calculate the laser heating on a crystal

Let's say I'm doing an optical experiment. I focus a laser on a crystal with a certain amount of power. The crystal's temperature is regulated to a certain temperature but it is localy heated by the ...
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1answer
48 views

Why does narrower slit give a wider diffraction pattern in single slit diffraction?

I was reading on this website and it said that one of the characteristic of single slit is narrower slit give a wider diffraction pattern but why? ...
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1answer
30 views

Polka dot beamsplitter. Is it good for gaussian beams

I am doing pump probe and I am looking for beam-splitter which will not affect beam polarization too much, as I intend to measure polarization dependencies. I have heard of polka-dot beam-splitters ...
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36 views

Wave optics physics

When does monochromatic beam of light incident on a reflective surface get completely transmitted.according to the question what exactly the word transmitted means? I'm little bit confused .could you ...
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Why does conservation of étendue matter when showing one cannot focus light to arbitrary temperatures?

The latest XKCD What-If post discusses how one cannot start a fire by focusing the light from the moon. The answer is no, for well-established reasons, but the explanation isn't watertight. Maybe ...
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Are the Rayleigh criterion and the Point Spread Function related to each other?

Reading this paper as of now, and at the very end of the appendices, it mentions that: However, assuming a highquality preparation, the limit of resolution for any application is always ...
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Seeing red color against violet

If you put a red dot and violet dot on a wall and move far away from them, after certain period/distance you will only be able to see the red light, then my teacher explained why/how this happens , ...
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Can a biconcave thick lens ever have a positive focus? I.e. if both sides have radius of curvature -/+R?

Since a thin biconcave lens has a negative focus, can a thick biconcave lens with a certain thickness have a positive focus if both sides have the same (magnitude) radius of curvature?
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53 views

Why don't eye lenses alter depth perception?

What it is going to do is bend the rays so that light from infinity "appears" as though it is coinciding with a person's far point. In doing so, it allows the person to see a clear image, without ...
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3answers
187 views

Single slit diffraction - choosing a wavelength?

For the classic experiment of determining the slit width of a single slit. If we assume the rough order of magnitude of the width is known. What factors determine the choice of wavelength? (Clearly ...
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1answer
51 views

What is the math behind the smartphone fish eye lenses

I found out information that these add-on fish eye lenses for smartphones have a focal length of about 2mm. I bought a lens and tried it with several different phones and it worked. I found out that ...
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1answer
41 views

How can I change the divergence angle of a single mode fiber

For my project I use the end of a single mode fiber as a "transmitter". I need to set the divergence to 20 micro radians. Is there an equation how to calculate the divergence and the necessary optics ...
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1answer
73 views

why do light bulbs explode when in contact with water?

Is it true that when water pours on a light bulb it will explode? If so does this apply to all light bulbs and how does that happen.
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102 views

How is refractive index related to the density of a medium (for example, air)?

I have a question regarding refractive index dependency on the density of a dielectric, specifically air. Background Let us start from Newton's second law form of driven harmonic oscillators ...
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67 views

Why does magnetic field and not electric field invert in a reflection? (related to another question)

When you are talking about an elctromagnetic wave that reflects on a surface (for example here), why do you say that the reflected magnetic field inverts and not the electric field? \begin{align} E_+ ...
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103 views

How far do we need to be removed from the earth to show the curvature with a viewing angle between 42 and 48 degrees? [duplicate]

I have seen already a couple of answers but none of them give an exact number of what should be the minimum height where we would be able to record the curvature of the earth All I could find is ...