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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What is the effect of a flat mirror's surface flatness as a function of beam wavelength
Mirror surface flatness is specified as a multiple of $\lambda$, where $\lambda$ is the wavelength at which the surface flatness was tested, and is typically $\sim 632\ nm$. A $4\lambda$ surface ...
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Refracted rays and reflected rays intensity change [closed]
When light enters medium A to medium B some light is refracted while some reflected.
How we can derive their relative brightness?
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Dielectric wave guides vs metallic wave guides
I have a couples of questions regarding wave guides. First of all, why are dielectric wave guides better than metallic wave guides for wavelengths in the visible spectrum? Also, for non-ideal metallic ...
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Roll, Pitch, and Yaw in Micro-Ring Optical Resonators
I'll remind those who answer that I am neither a physicist nor a physics student. I'm just that (58-year-old) kid who keeps asking, "Why?" Though formulas and equations are welcome, they’re ...
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Hologram recording photography [closed]
Considering holograms are (I may oversimplify) complex interference patterns created from the ref beam and object’s beam , is it possible to record hologram using a large format traditional camera (...
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Can X-rays travel quicker than visible light in a medium?
I have seen while reading a few books that the refractive index depends on lambda as follows by the Cauchy equation.
$${\displaystyle \eta(\lambda )=A+{\frac {B}{\lambda ^{2}}}}$$
From this, the book ...
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Min spot size for light collimated from an optical fiber?
We are currently setting up an experiment in which we need to pipe laser light from one optical table to another. One way we were thinking of doing this was by coupling into an optical fiber, running ...
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Homodyne and heterodyne detection for light statistics
I'm learning about homodyne and heterodyne detection in quantum optics, but I'm having some trouble understanding how these two detection schemes are used in practice to measure the statistics of your ...
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Fabry-Perot Finesse vs Ring Resonator
Why is the finesse of a fabry-perot resonator given by $2\pi/\text{RTL}$ while the finesse of a ring resonator is given by $\pi/\text{RTL}$?
The finesse of a fabry-perot resonator is given by $F = 2\...
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Astronauts in spacecraft, they have to circle the earth many times a day, do they also have the illusion of the moon?
Astronauts in spacecraft, they have to circle the earth many times a day, do they also have the illusion of the moon? I don't think they have, because according to the theory, the illusion of the moon ...
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What causes this fluorescence-like effect?
I have a New Year's garland that emits blue light:
When I turn it on and turn off all other lights in the room, almost all objects in the room would be colored in different shades of blue - as I ...
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Light doppler effect to low velocity [closed]
Show that for low speeds the Doppler effect of light can be written in the following approximate form: $$\frac{\Delta \lambda}{\lambda} = \frac{v}{c}.$$
I don't have many ideas. Can anyone help me?
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How do dark color varies from people when seeing the back of their eyelids?
Depending on the light source, the back of people's eyelids either be black or dark gray depending on what lit environment they're in? the how does eyes function when people have the back of their ...
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Are Fresnel equations valid in conductors?
The derivation of Fresnel equations assume no surface charge density or current density is present at the interface, hence making the normal and tangential components of D and H continuous, ...
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Fresnel's Equation - Area Terms in Power Expression
I have a lecture note about Fresnel Equations and related power ratios of the reflected and refracted rays. But I cannot understand how the area on the boundary is related to the areas of the rays, e....
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Why does the focusing efficiency drop with numerical aperture for a microscope objective?
I am doing the following experiment in my lab. I have a collimated laser beam, which is focused by a lens. Then the light is collected by a microscope objective. Also, I use two lenses (L1 and L2) to ...
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How does rotating a beam splitter (cube) affect the output angles?
Normally, you would want to place a beam splitter at 45 degrees with respect to the input beam. This way, it splits the light 50/50 and the output beams are aligned for sure. Like this:
Now, I want ...
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Minimum intensity fringes are not perfectly dark in diffraction pattern?
I am studying Interference and Diffraction and everywhere I look it is written that "In an interference pattern,the minima are usually perfectly dark while in a diffraction pattern they are not ...
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Working principle of Shack-Hartmann Wavefront Sensor
(Image source: https://www.thorlabs.de/newgrouppage9.cfm?objectgroup_id=5287)
In the Shack-Hartmann wavefront sensor, the local slope of the incident beam's wavefront is measured as a displacement of ...
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Why doesn't sun go all the way to the horizon during sunset?
This is a very silly question and I really don't know the answer to it but curious to know.
Everytime I see the pics of suset on beaches the sun appear to go all the way down to the surface of the ...
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Phase shift in reflection
Does every day-to-day life reflection cause a phase shift of pi? Or does this occur only in thin-film interferences?
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About Snell's law and Fresnel equation
I'm currently studying optics with Hecht's book.
I got some questions about Snell's law and Fresnel equation.
When $\theta_i = \theta_p$(the polarization angle), as $\theta_p+\theta_t=\frac\pi2$, by ...
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Silvering of lenses and their focal length
For a silvered biconvex lens the equivalent power is give by $P_{eqv.}=P_{lens}+P_{mirror}+P_{lens}$. Here we put power of lens as negative since it behaves as a concave mirror overall.
Reasoning for ...
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Blurred vision clearer with use of 2 mirrors
I have been having trouble with my vision. blurry and shadows. I realized that when I use a hand held mirror to see the back of my hair that is being reflected by another mirror behind my back I can ...
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Is it possible to have a medium rarer than vacuum? [duplicate]
I was wondering whether it is possible to have a medium rarer than vacuum. If that is possible then we can increase the speed of light beyond $c$. Might sound like a weird question.
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Wavelength of "complementary colours"?
In physics/chemistry/the life sciences there's a common experimental method of determining the concentration of a sample using spectrophotometers. We can measure the absorbance of the sample at a ...
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Superposition v/s Superimposition
What is the difference between 'superposition of waves' and 'superimposition of waves'?
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Why does Near Infrared (NIR) light allow deeper imaging in biological tissue in Multiphoton Microscopy?
I have been reading this paper on multiphoton microscopy (https://www.nature.com/articles/nphoton.an.2010.2) and I am very confused about something. Here is a quote from the paper:
"The NIR ...
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How effective are privacy screens at blocking blue light in the presence of other protective measures? [closed]
For quite a while, I've been using privacy screens, which not only increase... well, privacy, but also purportedly block blue light. However, web search results generally yield very broad statements ...
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What happens if I send light from two light sources through a single slit?
I have two identical point light sources A & B emitting the same frequency. They are equidistant from the single slit and from the line passing perpendicularly through the middle of the slit ...
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Conflicting lensmaker's equation representation
I keep finding these two conflicting forms of the lensmaker's equation. I understand that (n2-n1)/n1 is the same as (n-1) if referring to a lens in air, but I can not make sense of why the reciprical ...
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Justification of the relationship $s/S<\lambda/d$ for interference fringes to be seen
[My book] (NCERT Class 12 Physics text; Chapter no.:10 - Wave Optics)
(https://www.google.co.in/url?sa=t&source=web&rct=j&opi=89978449&url=https://ncert.nic.in/ncerts/l/leph202.pdf&...
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Relationship between the power of a convex lens and the refractive index of a medium
According to the Lensmaker's formula,
$$\frac{1}{f} = (μ-1)\left(\frac{1}{R_1} - \frac{1}{R_2}\right)$$
Apparently, focal length $f$ is inversely proportional to the refractive index of the medium $μ$....
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Why are diffraction spikes from bright light sources longer with larger pupil than with smaller?
In photography, it's well known that reducing the aperture leads to the starburst effect, like in the following photo:
(source)
This happens due to diffraction on the aperture, which has a polygonal ...
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How to begin my journey into simulating light-matter interactions?
I am interested in simulating how light interacts with matter. For example, I want to create a 3D heatmap describing how light might scatter in some heterogenous material. But the more I dig into this ...
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How close to reality is my handwaving argument about Fabry Perot interferometers?
Under this answer to https://astronomy.stackexchange.com/q/55437/7982 I wrote a comment where propose the uncertainty inequality roughly written1 as $\Delta E \Delta t \ge h$ or for photons $\Delta \...
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Why doesn't a lens after a diffraction grating affect the optical path difference?
When observing interference fringes one often uses a lens after the diffraction grating to focus the fringes on a screen like this:
At first sight, one might think that after the lens the path ...
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How does the reflection coefficient change with scattering and absorption?
My professor of Biomedical Optics course asked us to think upon the evolution of the reflection coefficient with the absorption coefficient $\mu_a$, the reduced scattering coefficient $\mu_s'$ and the ...
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Explanation of formation of Newton's rings
I was asked to do a lab report in my University about Newton's rings experiment that we made in lab. I understand that the aim of the experiment is to measure the wavelength of a light after the ...
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Does using thinner glasses have any effect on how the eye look?
My daughter asked me to buy thin glasses for her eyes. So the power of the lenses are the same, but the glasses are thinner because the glasses use plastic with higher refraction index.
Latter I found ...
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Is reflection from pockel cell normal?
We are trying to align a laser for a 2-photon microscope and we noticed a reflection from the pockel cell. The reflection can be caught on the edge of the waveplate or the iris that are before the ...
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Choice of Unit Cell on Band Diagram (Brillouin Zone Folding)
I am looking at photonic band diagrams specifically, but my question relates to band diagrams in general.
For a honeycomb lattice, I can pick a (primitive) rhombic unit cell or a hexagonal unit cell. ...
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Need help with experimental setup to measure Birefringence [closed]
First message here, sorry if this is scrappy:
I am looking to measure the birefringence of multiple crystalline structures (calcite, ice, etc), and came across this methodology:
Shine a laser at ...
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Two-qutrit preparation using linear optics
How can I prepare a two-qutrit product state (let's say $\frac{1}{\sqrt{2}}|0\rangle|0+2\rangle$ using optics? Do I need a BBO crystal (as I know BBO crystal produces an entangled state), or can I use ...
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What would I see if I looked through the double slits?
The double slit experiments all talk about the photons hitting a screen. What if I replaced the screen with my own eyes? What would I see? For example, they talk of the quantum (photon) being a ...
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The use of Corner reflector and beams to find the distance between moon and earth and light Divergence?
I am about to start college and my knowledge regarding both beams and retroreflectors is close to nonexistent ,
but from what I read a corner reflector is a device that reflects waves back to its ...
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Can a system of lenses or compound lens have a higher numerical aperture than a single element in the system?
I am attempting to create a simple Abbe condenser for a microscope, which typically consists of two converging lenses.
Ideally, I would like to achieve a numerical aperture for the condenser of ...
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Interference using three slits
Lets say there is a Young double slit interference apparatus, but with three slits placed at $y= - d$, $0$, $d$, and where the screen is at $X = D$ parallel to the $y$ axis. Can there be any areas on ...
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Why transparent object altering only the phase of light but not the frequency or amplitude? Is there exception?
I have learned the fascinating phase contrast microscope from Eugene's textbook optics that made transparent object become visible.
From page 647, he said that
In contradistinction, it is often ...
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Irradiance and current
Is there a relationship between Ir-radiance of an LED and the forward current supplied to it? I am designing a photo-therapy device for neonatal jaundice treatment. The required quantity is Ir-...
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