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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Photo of reflection in magnifying mirror shows normal magnification. Why?
I just took a picture of myself in one of those magnifying shaving mirrors and in the photo I am unmagnified! Why is this?
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17 views
Heat deposition at optical focus in a clear medium
This is an applied physics question for an engineering problem. The well known experiment we have all done--burn paper and wood with a magnifying glass and the sun's rays. My question is, if one were ...
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28 views
Penetration of light in the atmosphere
While I was considering an answer to this question, I wondered how much light that enters the atmosphere reaches the ground without colliding with air molecules—if any. I've taken a good bit of ...
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1answer
28 views
Manufacturing Fresnel Lenses with Sound
I understand fresnel lenses are manufactured using CNC machines. I was wondering, if it would be possible to use sound to vibrate liquid silicon and then fast cool it into the standard form of a ...
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Optics alignment of scanning microscope
I am facing a challenge in my project regarding optical alignment.
See the figure:
The challenge is with the vertical optical system alignment. I considered placing a mirror and check back if the ...
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15 views
What's the equations for spacial charge distribution in COMSOL? [migrated]
I am now using COMSOL (RF model) to simulate the optical response of a given object (say, a Au sphere) when experiencing the incident plane wave. I wish to get the spacial charge distribution of this ...
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Physical Optics [closed]
Monochromatic light is used to illuminate a pair of narrow slits 0.3 mm apart and the interference pattern is observed on a source 0.91 mm away. The second dark band appears 3.0 mm from the center. ...
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129 views
What's the physical significance of using fourier transform for diffraction?
I am studying some basic idea of diffraction and there mention in far field, the diffraction pattern could be understood by Fourier transform. But I just don't understand what's the physical fact for ...
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Reflection of a polarised beam
The past days I've been trying to understand how AutoFocus(AF) works on photographic cameras. There is a statement that says AF systems are polarisation sensitive. This means that they can only work ...
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Liquid crystal physics, uniaxial nematics, do director and optical axis point in the same direction?
question relates to the physics of liquid crystals(tried to add liquid-crystal or soft matter physics tag but couldn't find one). Uniaxial nematics are a type of LC. It's easy and convenient to ...
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40 views
Reflectivity of a glowing-hot metal surface
When a polished piece of metal (or steel in particular) is heated to incandescence, how do its reflective properties change?
Given a mirror-like surface, would the object temporarily cease to act ...
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Hyperopia, Far Sightedness
With hyperopia, the focal point is behind the retina, shouldn't this mean that the image is flipped on the retina itself from what is usual?
I must be drawing my ray diagrams wrong.
A little ...
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Optics, lenses and our eyes
When we view an image, is the focal point of our eye on our retina? Shouldn't that hurt?
Also, if that is how our eye works, then why don't lenses put the focal point their equivalent retina? I was ...
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67 views
Mirror image at relativistic speeds
Imagine moving parallel to the surface of a very large flat mirror at relativistic speeds. What would be the effect of viewing yourself in the mirror? At non-relativistic speeds your image would be ...
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81 views
Is there a way to create a flickering frequency to be dependent on speed of the person looking at it?
Is there a way to make a screen or a road sign flash at different rates, depending on the velocity of the observer looking at it?
I would like to achieve a state where two observers going at ...
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1answer
38 views
State emitting from an extended thermal source
This calculation is for a double slit experiment setup which is experiencing a far field radiation from an extended monochromatic thermal source. I assume the source is 1-D and it's length is $b$. ...
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Non reciprocal light propagation
In search for some explanation in why magneto-optical materials (like the one used in the Faraday rotator and, consequently, in the "optical diode") act in such a "strange" way, I saw that this kind ...
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1answer
41 views
Apparent and real depth object in water [closed]
Did I get my formula right? Seems like the correct answer is $d_o = 1.33 \times d_i$ but I thought the formula I should use is $d_i = - \frac{n_2}{n_1} d_o$
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Physical explanation for why total internal reflection occurs
I have been trying to understand total internal reflection (and have read several posts on this site already). Mathematically, I feel that I understand how the evanescent wave decays exponentially as ...
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Keep the light beam in a closed room, is it possible? [duplicate]
I mean if I am in a room totally closed to light. If I switch on a torch for a second then switch it off. So will the inside of room be always bright?
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Is my textbook in error about this geometric optics relation?
Given a centered optical system (having an axis of rotational symmetry), let $H_1$ be the intersection of the optical axis and the "principal object plane" (I'm studying in French and have no idea how ...
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Infinite reflection of light and the conservation of energy / momentum
First off, I confess I'm no physicist, but I have been asking people with a more extensive knowledge this one question, without a definitive answer so far.
Basically, I'm playing around with the idea ...
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The weight of a cavity of radiation
A sealed cavity full of light weighs more than an empty one. So consider a cavity consisting of parallel mirrors, with a pair of beams bouncing between the mirrors. The question is whether that weight ...
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Concerning Scattering Intensity and Particle Concentration
I am trying to determine what governs my sensor output. I have an optical sensor that emits infrared radiation on a sample volume and gives me a voltage output from the scattering of (1 to 10 micron) ...
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Optimal telescope size?
Consider a diffraction-limited telescope with unobstructed aperture $D$. Such a scope is capable of yielding an angular resolution $\alpha$ that scales as $\lambda/D$, with $\lambda$ denoting the ...
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Why does the quantum eraser seem to violate energy and momentum conservation?
In the literature of the quantum eraser experiment it is argued that the change in statistics of the system from non-interference to interference is due to the erasing of "distinguishing information". ...
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Can a photon exhibit multiple frequencies?
Can a photon be a superposition of multiple frequency states? Kind of similar to how an electron can be a superposition of multiple spin states.
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Selectively visible laser beam with a controllable means
How can parts of a laser beam be made visible while others left invisible using something electronically controllable (for example, another laser beam crossing it, or a magnetic field, or heat, etc).
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152 views
Light Ray Reflection from concave mirror
Suppose a ray of light hits a concave mirror and is parallel to principle axis but far away from it such that it doesn't follow paraxial ray approximation. Will it pass through focus or between focus ...
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Why do focal lengths affect magnification?
For compound lenses, the image formed by first lens acts as the imaginaryobject for the second lens.
In telescopes, the objective lens projects an image on its focal point which works as the object ...
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Is light red shifted in optical tweezers?
This is a question I put to my supervisor during my PhD many years ago, and never really got a satisfactory answer to.
In an optical tweezers, assume that a beam of light is used to move a glass ...
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can you guys help me with image properties. how to do the calculations [closed]
A 10 cm tall perfume bottle is placed 100 cm in front of convex spherical mirror with a radius of curvature of 50 cm.
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Confusing mirror problem
A piece of thin spherical shell that has a radius of curvature of 106 cm is silvered on both sides. The concave side of the piece forms a real image 79.5 cm from the mirror. The piece is then turned ...
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67 views
Three polarizers, 45° apart
If light is passed through two polarizing filters before arriving at a target, and both of the filters are oriented at 90° to each other, then no light will be received at the target. If a third ...
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Determine the image properties by calculation [closed]
A 10 cm tall perfume bottle is placed 100 cm in front of a convex spherical mirror with a radius of curvature of 50 cm. Determine the image properties by calculation
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Young's double slit experiment viva question
My professor asked me (in my viva exam), "If, in the Fraunhofer single slit diffraction experiment, if we have 2 slits instead of one (at very short distances), What would happen?"
I answered with ...
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Can the choice of reflection angle for light can be derived from a minimality condition?
When the light hits on a surface, it reflects with the "same" angle as the one that hits the surface. I was wondering if this choice of angle can be explained by a minimality condition?
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Problem in geometrical optics [duplicate]
I was trying to solve a problem taken from an Physics Olympiad when I came across a curious and complex mathematical expression. I can not prove with what I know so far about mathematics, does could ...
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47 views
Trigonometry in the plane mirror [closed]
I was trying to solve a problem taken from an Physics Olympiad when I came across a curious and complex mathematical expression. I can not prove with what I know so far about mathematics, does could ...
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1answer
39 views
How can a Jones vector give linear polarization along an axis?
If we represent a Jones vector by two complex-valued exponentials, $J_1 = e^{i \phi_1}$ and $J_2 = e^{i \phi_2}$, how can this ever give a polarization along the x-axis? We write such a polarization ...
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How to create visible reflections in shallow water?
Assumption: The only lights I have are candle, table lamp, and sunlight.
What would I need to create visible reflection of an object in the shallow water contained in a 5 liter bucket? Is it even ...
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Speed and transparency of light
I have been puzzled with a fact that as an object moves faster, it ceases its property of opacity. I mean to say that as an object moves faster we can see right through it (more clearly than in a ...
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How does this trick with mirrors work?
Imagine two mirrors, set touching each other at right angles to one another. There is a 90 degree arc in which reflections can be seen, and a person standing in that arc can see himself reflected in ...
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79 views
Why can't we see real images?
When light from an object passes through a convex lense, it gets reconverged at a single real image. From there, the light rays presumabely begin diverging again, exactly as if there was a ...
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How much refraction occurs as a fraction of all reflection and refraction?
When light reaches a boundary between materials below the critical angle, some of it refracts and some of it reflects. For example, glass acts as a partial mirror with a dark background.
Assuming ...
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Direct Normal Insolation
I need a help please.I'm struggling to know how to convert from KWh/m2/day to a flux unit.
For example, if I have a Direct Normal Insolation (DNI) that is equal to 7.41 KWh/m2/day, how can I convert ...
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Can virtual image be photographed
Is there any instrument that can photograph the virtal image and by what principle it is working on ? ?
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48 views
How to calculate beam spread of a non-point light source via an aspheric lens
I need to determine the angle, or rate of divergence of light from a single aspheric lens when I place a non-point light source (e.g. LED array) at a given distance from the lens which is less than ...
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22 views
Why the mirror changes the sides [duplicate]
Why the mirror changes the left with the right side but not the top with the bottom? Go to the mirror and check this out.
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Definition of frequency domain coordinates
I am using the Fourier Transform in Optics to perform differentiation with a filter by making use of the relation
$\frac {\partial}{\partial x} f(x)=2\pi i \int^{\infty}_{-\infty} u F(u) \exp (2i\pi ...
