Questions tagged [optics]

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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Blazed grating question

In blazed gratings it is possible to have one order with higher diffraction efficiency. How to make a blaze grating that has max diffraction efficiency in 1 order? How to make a blaze grating that ...
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The velocity of a shadow on a wall [on hold]

A point source of light is at a distance 2 m from a vertical screen AB. An opaque object of height 0.5 m moves translationally at a constant speed of 10 cm/s starting at / 0 from O towards the screen ...
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Why photodiode measures random phase superpositions on continuous-wave (10kHz) white light?

I measured a 10 kHz modulated white light using a photodiode (Thorlabs PDA10A): Unexpectedly, the photodiode output sensitively depends on the orientation and position of the photodiode. For two ...
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Why does the shadow of Io on Jupiter look so big?

It has been reported this week[0] that the following image by Kevin Gill is the shadow of Io crossing Jupiter. Why is the shadow so large? My intuition is that Io is much smaller than Jupiter so ...
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Error propagation in sine

Having little experience teaching uncertainties and error propagation to high school students I am learning a lot of new things this year. One thing in the textbook we use states that the uncertainty ...
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1answer
37 views

Unable to follow Feynman Lectures reading on opacity

Feynman is explaining the phenomenon of opacity in terms of classical electrodynamics. Let us first ask: “What is an opaque screen?” Suppose we have a completely opaque screen between a source S ...
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2answers
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Fermat's Principle: no first-order change in time?

I was reading the chapter on Fermat's principle in the Feynman lecture series. The principle is stated along these lines: "The correct statement is the following: a ray going in a certain ...
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Deriving Fresnel Equations for parallel polarization using Maxwell's boundary conditions

I'd first like to preface this post with the "right answer" per wikipedia (I've seen the same answer elsewhere on more reputable websites) The thing I find trouble some is the cross terms such as $...
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4answers
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How exactly is white light a combination of several wavelengths? [duplicate]

I have read that light is an electromagnetic wave. Every ray of light has a specific wavelength. The colour perceived by any observer is dependent upon the wavelength of the incident light. What I ...
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1answer
46 views

Satellite image anomaly

This is a satellite image of somewhere in West Texas: See the localized Red-Green-Blue feature on the road? What could have caused this?
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1answer
57 views

Explaining phase shift from a half-silvered mirror

I am trying to understand why light undergoes a phase shift when reflecting off one side of a half-silvered mirror, but not the other side. This Wikipedia page and this answer both give the following ...
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33 views

What lens should I use to converge collimated light beck to a point without losing image quality?

I made a simple shadowgraph using 2 aspherical biconvex lenses(identical lenses) to collimate and converge an LED's light into a camera. The camera came with a lens(not sure what kind) that does a ...
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2answers
37 views

Physical meaning of angular spectrum

I have been going through the paper Diffraction from an irregular screen with applications to ionospheric problems. H.G. Booker, J.A. Ratcliffe and D.H. Shinn. Philos. Trans. Royal Soc. A 242, 579 ...
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3answers
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How do we see virtual images?

Here in the diagram rays coming from B' point falls on two different places on retina of eye.So we should see B' at two different places. But it doesn't happen like that in reality. Is my logic wrong? ...
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1answer
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How do sharp objects deflect radio waves?

This technology is used in stealth aircraft.The pointed nose of aircraft deflect those incident waves but not reflect back.Also speculate in case of rounded object with those waves.
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Does the Rayleigh formula apply to electron microscopes or only light microscopes?

I am asked to determine the resolving power of both a TEM (transmission electron microscope) and a SEM (scanning electron microscope) and given the Rayleigh formula below. $$\mathrm{Resolution}=\...
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1answer
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Are Fresnel Equations with Complex Indices and Angles always valid?

This question-answer pair came after i was asked the following question and realized i had to do some research of my own to answer it fully, and to be sure that the answer is „yes“, in the sense ...
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1answer
45 views

Focal plane of ideal thin lenses and spherical mirrors

Recently I was studying about optical instruments and in my book I came across a point which stated that When non axial parallel rays are incident on an ideal spherical mirror at a small angle or a ...
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21 views

How do I calculate the resulting field of a 2f-arrangement?

I've been trying to proof that the 2f-arrangement for lenses causes a fourier-transform of the original field. After some research I found a hint how to pull it (see page 15), but all my calculations ...
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Calculating Laser Beam Intensity Absorbtion

This question pertains to the ability to calculate the laser beam intensity , at a particular point in time when using lasers for the purposes of Cutting and Engraving Materials. The parameters at ...
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1answer
20 views

Calculation of emergent angle of prism

Is there a way to calculate emergent angle of an equilateral prism (non-experimentally) ? I know that one equation that might be helpful is $$\angle D + \angle A = \angle i + \angle e$$ But a single ...
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1answer
35 views

Fermat's principle in classical mechanics?

I do know the principle of least action, but is it possible to formulate classical mechanics based on the principle of least time? That is, if we know the initial state $(x_i,p_i)$ of the particle and ...
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1answer
36 views

Refraction in oil and plastic

Can some one help me in understanding this picture. I came across this interesting picture in wikipedia on Refractive index. when green light is refracted in plastic it looks like reddish orange and ...
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25 views

Velocity of image

Suppose i have an object placed in front of a convex lens at a distance twice its focal length.Then an image is also obtained at twice its focal length to the right of the lens.Suppose it is not a ...
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Reflection coefficient phase using Kramers Kronig, formula equivalence

Why are the following two formulas for the phase of the reflection coefficient equivalent (according e.g. to [1])? \begin{align} \Theta(\omega_0) & = - \frac{\omega_0}{\pi}P\int_{0}^{\infty}\frac{...
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87 views

Effect of metal disks on diffraction of light [closed]

Recently, I started to go deeper into physics. I don't speak English well, so I'm sorry. This experiment was carried out in Hungary 25 years ago. The measurement results were not accepted by the ...
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What are some good physics project for college students? [closed]

Any project that involves physical principles, from mechanics, waves, electrodynamics, etc
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1answer
38 views

What does it mean that the polarization plane “rotates”?

Following description are quoted from Wikipedia. "Optical rotation or optical activity (sometimes referred to as rotary polarization) is the rotation of the orientation of the plane of polarization ...
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Focal length of a payload orbiting at 800 km LEO [closed]

What is the focal length of a payload given these parameters Orbital height = 800 km. GSD = 5m Wavelength = 800 nm Only these parameters are available. Is it possible to calculate the f?
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1answer
24 views

The change of focal distance as a result of adding a substance

I have a given focal distance between lens and an image sensor (in air). Now I add a protective glass with a known refractive index and width between the lens and the sensor. How can I calculate the ...
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2answers
225 views

Rayleigh scattering light intensity

Assume a single ray of unpolarized light propagating through an opaque medium (water). Due to absorption and Rayleigh scattering the intensity decreases and light gets scattered/diffused before hiting ...
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1answer
23 views

Geometric optics in the (early) far infrared

I'm looking into thermal radiation from hot glass, in particular I'd like to compute the angular and spectral distribution of radiation from borosilicate glass as a function of its temperature. I am ...
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34 views

What is the spin angular momentum of an elliptically polarized photon quantitatively?

The answers to a similar question Is a single photon always circularly polarized? suggest that the angular momentum of the elliptically polarized photon can be known depending on the probability ...
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44 views

electron double slit experiment manipulating interference pattern

Let us suppose we can change the magnetic field and the charge on the interference surface like shown in the picture. Would it be possible to move our interference pattern along the y-axis by changing ...
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2answers
63 views

Factor of 3 in Photon Diffusion coefficient

From definition of Diffusion coefficient: $$D = c/3(\mu_a+\mu_s),$$ where $c$ is the speed of light front, $\mu_a$ is absorption coefficient and $\mu_s$ is scattering coefficient. I wonder where does ...
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Born approximation of scattering field

So I am trying to solve the Born approximation of the scattering field for an incoming plane wave $E_0 e^{i K x}$ for a Kramers-Kronig permittivity profile which is given as $$\alpha (x)=\frac{i-x}{...
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2answers
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Question about zooming out with optical lens

I need some help. I am working on a project and I am wondering if it is possible to make an object to look 100 times far away than it is actually using lens (or more than one lens). The lens (or ...
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1answer
32 views

Simulating Gaussian beam through lens

After spending some time in the lab and finding out how frustrating it is to align optical elements, I have decided to go and adapt a numerical solver that I wrote to simulate the propagation of a ...
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2answers
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Some digital watches display digits in black on a white background and in the dark the backlight is reversed. How is this possible? [closed]

Some digital watches display digits in black on a white background and in the dark the backlight is reversed, blue on a black background. How is this possible? Here is an example: https://images-na....
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How to modify the entrance pupil of a system (in Zemax)?

I have a very specific question. I need to perform some aberration analysis and I'm using Zemax OpticStudio. In particular I need to trace several raysets to different surfaces of my system using the ...
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1answer
56 views

Reflection of an under-water-object

I saw a photograph of a polar bear who is under the water surface. I would like to receive an explanation about the reflection of the polar bear on the water surface, which creates a second image.
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Littrow Configuration Spectrometer

I have been studying the design of a spectrometer using a transmission diffraction grating. I stumbled upon this link, https://ibsen.com/technology/spectrometer-design-guide/. It explains a ...
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1answer
32 views

What would be the intensity of light if polarizer is additionally absorbing some percent of light? [closed]

I came across one question that said the polarizers are additionally absorbing 10% of light. So, can I write (I/2)(9/10) or (I)(4/10) as final intensity of light where I is initial intensity. ...
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Creating some sort of optical transistor

Is there a way to create an optical transistor that runs using a cheap laser and made using mirrors and lenses? My point of using that is to make an optical logic gates, but there is another problem ...
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Scattering of light rays off a corrugated surface

I am currently facing the following problem: Suppose I describe the shape of a corrugated surface with a certain function: \begin{equation} y_\mathrm{surf}=A\sin(kx); \qquad x\in(-\infty,\infty) \...
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45 views

Estimating focal length using light

I am considering how to estimate the focal length of a dynamic lens (such as biological lenses) non-invasionally, i.e., without harming the animal. The mammal lens changes its shape depending on ...
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Polarizing beam splitter operated in reverse direction

Let us consider a polarizing beam splitter. A light beam enters at $E$ and is split into a vertically polarized beam exiting at $V$ and a horizontally polarized beam exiting at $H$ (or, more precisely,...
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How does light pass through any glass? [duplicate]

This might be a very stupid question for Science students, but I had this doubt always, since childhood. I still don't understand even when I'm adult because I didn't read science in detail. When I ...
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2answers
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Do the Fresnel equations of reflection apply to monochromatic light?

I have a monochromatic light source (wavelength ~ 420 nm), which will be incident on the interface of two different media. Could someone please explain if the Fresnel equations applies with ...
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Quantum Electrodynamics explanation for refraction [duplicate]

I am trying to understand the fundamentals of Quantum Electrodynamics through the simple example of refraction. Let's start with a plane wave coherent state (or a number state) impinging on a boundary ...