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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104 views

Using a laser to overhear a room conversation

Movies with science based tricks and gimmicks are generally silly and sometimes even annoying. The science based trick that I don't know enough about to judge is the following (and I have seen it in a ...
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2answers
33 views

Reflection during refraction

I have observed in a book (one that is different from the one that I study with in school) that a light ray reflects during refraction, which is a partial reflection, but when does that occur? Is it ...
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1answer
46 views

Can one detect a single photon through measuring its impulse/momentum on a mirror?

Can one detect a single photon through measuring its impulse/momentum on a mirror? If the answer if YES or theoretically possible, photon path and interference fringes can be detected simultaneously ...
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0answers
22 views

Which wave works best?

I heard that gamma waves have the highest amount of penetrability, being able to penetrate even lead. On the other hand, my brother told me that super low frequency radio waves are used to communicate ...
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1answer
21 views

Experiment to test flatness of prism

I have a Prism glued to a prism plate. Let's say the method of using optical glue is good enough, and minimal human error is tolerated. What experiment would be a good to check if the prism is not ...
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1answer
25 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?
2
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1answer
31 views

Derivation of relativistic mean free path

I am working through a short derivation found in Abramowicz 1991 regarding the mean free path of a photon. We have a fluid moving in a particular direction with velocity $v$ and in an inertial rest ...
2
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2answers
51 views

How is the virtual image reconstructed from a hologram?

To make a hologram a film is exposed to an incident plane wave and wave from the object to record the interference pattern on the film. The principle is commonly explained in a way like that in p.1212 ...
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0answers
18 views

In Fermat's Principle of Least Time, how do we know that light is able to reach the end point?

From my understanding of Fermat's Principle, you decide a start point and an end point for a light ray to travel between, and the light 'chooses' whichever path takes the least time (or technically ...
3
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2answers
43 views

Why array of telescope is used?

To increase the resolution of an instrument, smaller wavelength and larger aperture is desirable. It is mentioned in some textbooks that the "effective" diameter of a telescope can be increased by ...
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2answers
34 views

x-ray diffraction of crystals

In explaining x-ray diffraction of crystals, usually the approach is to consider the atoms absorb radiation and scatter it, at some angles constructive interference occur and bright spots can be ...
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0answers
14 views

Question about dark fringe in diffraction

In finding the angle for the mth dark fringe of single slit diffraction using Huygen's principle, they usually split the slit into equal portions. For example, to find the first dark fringe the slit ...
0
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1answer
9 views

Dissolving photoconductor (TiOPc) from Laser Printer drum possible?

When I was thinking of a Lab-On-a Chip Application which combines a lensless microscope and an optical tweezers I saw the ...
0
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1answer
31 views

Light (Laser) operated optical switch

I have searched the web and found that optical switches are activated either through mechanical or electro/magnetics. Making them sort of Optomechanical or optoelectronic switches. Lets exclude ...
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1answer
17 views

Is it possible to “change the focal plane” of a 2d image?

Can we apply some type of transformation to 2D image in such a way that when a person looks at it directly (i.e. focuses on the paper or the computer screen which displays the image), it is blurry; ...
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0answers
33 views

Can a person with bad vision see a blurry picture clearly? [duplicate]

I was just thinking to myself how weird it must be to have bad vision. Then I thought, I wonder if you could print a picture that would appear clear to someone with bad vision. That seemed unlikely to ...
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0answers
25 views

How to measure the diameter of a Glass tube? [on hold]

I'm working on something and I need to find the diameter of a glass tube. I wanted to use diffraction pattern to find the diameter of my tube. but the problem is that my tube is transparent. Anybody ...
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0answers
10 views

Limitation of Rytov approximation for turbulence

I have been working through the textbook "Laser Beam Propagation through Random Media" by Andrews and Phillips and have arrived at an interesting dilemma. For a second-order perturbation in the Born ...
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0answers
10 views

optical fibre numerical problems [on hold]

(a) What is the need for a cladding layer on the core of an optical fiber other than mechanical strength? (b) Assuming a fiber that is kept stra ight and is of length L, find the ...
21
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7answers
4k views

How do we see? Where do the photons disappear?

I know that the light is reflected from a object to my eyes, but I don't understand exactly how. The photons appear from the light source and disappear in my eye! Can someone explain the phenomenon of ...
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2answers
46 views

Why railroad tracks seem to converge?

I stand up and i look at two parallel railroad tracks.I find that converge away from me.Why? Can someone explain me why parallel lines seem to converge,please?
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1answer
30 views

Effect of the refractive index of a transparent layer coating a particle?

I am modelling a cell as a particle coated by a layer of a material whose refraction index might change. This layer is to resemble the membrane. The purpose of the model is to simulate what happens ...
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0answers
14 views

How can I determine spatial resolution from an Airy disk diffraction pattern?

From introductory optics, the angular resolution of a lens (in radians) can be described by the Rayleigh criterion: \begin{align*} \theta = 1.220 \frac{\lambda}{d} \end{align*} This has its ...
2
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1answer
23 views

Absorption Magnification

I'm working on an optical project about the absorption of glass sheet and I need to measure the intensity of laser beam that has passed the glass sheet and compare that with the intensity of laser ...
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2answers
31 views

Slit width in single-slit diffraction

In Born's Atomic physics, he makes the comment on the single slit diffraction that For diffraction patterns to show themselves, it is necessary that the width of the slit employed should be of ...
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0answers
33 views

How to calculate the Refractive index of a glass sheet

My question is how to find the $n$ of a glass sheet with just aiming a laser beam to that. I've got lot of ways that let me find the $n$ ( Refractive index ) but I need the whole part of the ...
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2answers
43 views

Light Absorption of a glass

I've the $n$ (refractive index of the glass sheet ) and $t$ (the thickness of the glass sheet) with this information, how can I find the amount light absorption of the glass sheet?
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0answers
26 views

Can I calculate the size of a real object from a picture taken by a Camera placed a 45 degree angle from object [duplicate]

I am trying to get actual width of a object looking thru a camera real time. i would get the image distance from camera and i know focal length of camera so getting object distance 1/f-1/i=i/u. Since ...
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0answers
32 views

Optical properties of a glass [closed]

What are the optical properties of a glass? let's look at this properties! Glass Properties Properties of a glass Can we measure them by a laser pointer?
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1answer
32 views

Focal length problem

Let we have an biconvex lens with equal radii, that means the two radii of curvature are equal. We know that from lens equation, For biconvex lens, $r_1= r$ and the opposite radius $r_1= -r$, we ...
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2answers
36 views

Optics of perceived shadows on LCD monitor

After changing my desktop wallpaper on my LED-lit LCD monitor to one with a dark corner, I started seeing shadows on where the clock widget is while looking sideways at the screen. These shadows move ...
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2answers
46 views

Which photons pass through a circular annulus?

Passing light through a circular sieve: Well, actually, let’s think about radar or microwaves with a wavelength of order a centimeter or two, so you can tailor your aperture, say by etching a silver ...
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1answer
25 views

The Thomson scattering optical depth for a photon ar radius r

I am looking to understand some more about the physics of gamma ray bursts. In particular I am looking at the origin of the "prompt emission". Some of the energy associated with this prompt emission ...
1
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1answer
41 views

Spherical and chromatic aberration correction

I have some spherical lenses which are 5mm, 1mm and 0,5 mm in diameter, having 100x, 350x and 1000x magnification respectively. While looking at blood samples, I'm having big problems with spherical ...
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2answers
85 views

Thought experiment on light accumulation

Consider an object which is a spherical one-way mirror, and let's call it the "Sphere". For the needs of the thought experiment, suppose that: the Sphere is perfectly spherical the mirror is ...
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2answers
44 views

Can we measure speed of light in a non-transparent material

As I think even photons are absorbed by a non-transparent material, they aren't absorbed exactly at the same time. Light does propagate though a (sufficiently thin) opaque material. So can we measure ...
4
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3answers
145 views

Why does shining a laser into an iPhone camera create these shapes?

When I shine a laser light into an iPhone 6 camera I get these weird shapes: The shapes are in no way in the background behind the laser. What causes these to appear? I know about typical lense ...
2
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1answer
42 views

Interference of LED Lights

I have read that colored LED lights are nearly monochromatic. Does this mean that they could be used in double slit interference?
40
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2answers
5k views

Why are gold mirrors yellow?

Why are golden mirrors yellow? Do they add a yellow component to the spectrum or absorb non-yellow components? If they absorb, then why are they used in telescopes being imperfect? If they add a ...
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2answers
37 views

Is it possible to calculate the dimensions of ANY object in a picture having at some known distance an object on know dimensions?

Is it possible to calculate the dimensions of ANY object in a picture having at some known distance an object on know dimensions? I'm thinking about the scenario where someone is holding a smartphone ...
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0answers
24 views

Converging rail tracks

When we look at parallel rail tracks, it appears to converge at a certain angle. Let us say the width of the tracks is d and the height of the eye is h. Assuming one stands in the middle of the ...
2
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0answers
15 views

Lens-Mirror systems and conservation of specific intensity

This came out of a discussion I started yesterday and a related discussion I found. I'll recap the problem quickly: Consider two blackbodies, with surface areas $A_1$ and $A_2$ and temperatures $T_1$ ...
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11 views

Thickness of glass sheet with Michelson's interferometer

I've got a question, are we able to calculate the thickness of a glass sheet by using Michelson interferometer experiment ?
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1answer
71 views

Way of measuring thickness of a glass [closed]

Imagine you have a laser pointer and a glass. You don't know the refractive index of the glass and you just have Wavelength of laser! How can you measure the thickness of glass? (I have some idea but ...
2
votes
2answers
69 views

Appartus for Young's double slit?

I am wanting a full description of an apparatus used for Young's double slit (not necessarily the one that Young himself used though), which takes monochromatic light (though not laser light) and ...
0
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2answers
79 views

Video of light passing through water

How is this possible? https://www.youtube.com/watch?v=EtsXgODHMWk Video shows beam of light travelling through water. I was under impression that Einstein's equations showed that light speed is ...
2
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1answer
65 views

Why does circularly polarized light break time-reversal symmetry?

I've encountered some interesting paper on 2D materials where authors use circularly polarized light to break time-reversal symmetry to split energy levels. Here you can find the paper: ...
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0answers
13 views

What is micropulsing in optics?

I've seen this in a presentation, but I am not quite sure what it means. Is it simply emitting light in a sequence of very short pulses?
2
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2answers
61 views

What is really a light ray? [duplicate]

I've been studying geometric optics and I'm still a little confused with this idea of light ray. In the book I'm studying everything is being done starting from Fermat's principle which states that ...
38
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5answers
4k views

If a lens focuses all incoming light to a point, how do we get 2D images?

How do lenses produce 2-dimensional images, if a lens bends all incoming rays of light to intersect at the focal point? Shouldn't this produce a single dot of light on a screen placed at the focal ...