The subfield of optics in which light propagation is approximated in terms of rays. It mainly includes reflection and refraction on surfaces.

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Plano convex lens with one silvered surface

For the derivation of the focal length of a planoconvex lens with one surface silvered, we consider the phenomenon taking place in three steps: Refraction through first surface Reflection ...
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556 views

Is there any optical component that uniformizes the incoming light?

Is there any optical component in existence that uniformizes randomly pointing rays?
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177 views

Is it possible to focus the sun in such way?

Imagine the sliding part of the mirror is controlled by computer and opens on intervals. Is it possible to increase the power of the beam by making it bounce between the mirrors thus going through ...
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187 views

Why would the reflection of a lamp by a bowl look like a heart?

I have this bowl roughly the shape of a circular truncated cone, and the lamp shines on the bowl at an angle. The reflected lamp light hit the bottom of the bowl and created a light ring that looks ...
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63 views

Determine whether the light will reach certain points or not [closed]

I've got an interesting question which goes like that: suppose we have a long cylindrical rod made of a transparent material (see illustration below). A point source $O$ which sits on rod's axis emits ...
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Fresnel distance and Geometrical limit

I read about the geometrical limit of wave theory. The source from where I read had a slightly different explanation to provide than here(The more rigorous answer is too complicated for me to ...
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90 views

Are images of three-dimensional objects also three-dimensional?

Suppose that I produce an image of a dog using a converging lens. I can draw ray diagrams for the nose of the dog as well as the back leg. These are definitely longitudinal points, not transverse. ...
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What's the local law of propagation of disturbances

In Vladimir I. Arnold's Lectures on Partial Differential Equations, Chapter 3 Huygens' Principle in the Theory of Wave Propagation, which is devoted to the proof of Huygens principle (original one by ...
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87 views

Is it possible to build an optical system that increases the perceived surface brightness?

So is it possbile to build a system from lenses and mirrors that can make faint gas nebulas brighter or can be used as nightvision? If you increase the size of the aperture of a telescope it will ...
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318 views

Image formed in a compound light microscope

I am trying to understand whether the image formed in a compound light microscope is at infinity or not. I get conflicting answers everywhere I look.
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594 views

Reflections in Rearview Mirror

In the rear view mirror of your vehicle, the driver in the car behind is on the driver's side and the passenger is on the passenger's side. When they raise their left arms they are on the same side as ...
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120 views

Why is there no dark band below a rainbow?

I've read articles about Descartes' theory of the rainbow and I can understand why there is a dark band of about 8 degrees (Alexander's band) between the primary and secondary bows: for all the water ...
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681 views

how does the mirror equation works and what lead to using of sign convention?

EVERYTHING HERE IS FOR CONCAVE MIRROR Everywhere I see the derivation of the mirror equation is given by placing an object before the focus and then proving similarity of the triangles to get to the ...
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384 views

How to determine if a optical system is afocal?

I have to come up with a method to measure the focal length of a concave lens that's not in my lab guidebook. So I decide that I will build an afocal system with a convex lens and a concave lens and ...
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234 views

Infinite Mirror Face to Face With Infinite Two Way Mirror

If you are in deep space, and there is an infinite plane mirror, and in front of it there is another infinite mirror that is two way, with the see through side towards you, what do you see? Is it the ...
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264 views

Refraction of light in medium

Given that the plane $y=0$ separates the vacuum ($y>0$) from the optical medium ($y<0$), I would like to calculate the trajectory of a light ray starting at the point $(x_1,y_1)$ and ending in ...
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Why Does Passing Light Through a Slit Make it Coherent?

Related: Why incoherent source of waves have to be passed though a single slit for double slit interference pattern to occur? If you have a an incoherent light source, why does passing it through a ...
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309 views

Optical Waveguide's “Base Bandwidth”

Consider a dielectric slab waveguide (lossless, isotropic) illuminated transversally from the vacuum (with coherent, monochromatic light). We define the base bandwidth of a waveguide (or optical ...
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161 views

How is Fermat's least time principle proven?

How is Fermat's least time principle proven? Or it is what usually is observed and is basis for the theories?
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Analytic solution for angle of minimum deviation?

Consider a simple prism with a prism angle $A$, angle of incidence $\theta_1$, angle of emergence $\theta_4$ and the first and second angle of refraction as $\theta_2,\theta_3$. the refractive index ...
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722 views

Refraction Vector (Ray tracing)

I am doing ray tracing and I do the refraction of the ray using the following relation (I got it from PDF called "Reflections and Refractions in Ray Tracing"): But I have seen it in another PDF as ...
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Lenses and Magnification [closed]

A $2.05\text{ cm}$ tall object is placed $30.0 \text{ cm}$ to the left of a converging lens with a focal length $f_1 = 21.0\text{ cm}$ . A diverging lens, with a focal length $f_2 = -42.5\text{ cm}$ , ...
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189 views

Good explanation of a real image?

Okay well I've started to study phys chem in school recently and I honestly can't get my head around what a real image actually is I've asked my teacher to demonstrated it but she's quite lazy, and ...
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325 views

Calculate the polarization vector on reflection or refraction from a dielectric interface

I am interested in ray-tracing polarized photons. I have code that works very well for unpolarized light. When a ray hits a dielectric interface the photon is either reflected or refracted by ...
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278 views

Change of hue near shadows

My brother is an artist and he told me his paintings look more natural when he slightly change the hue (color) of the surface near the transition between shadow and light. Here's three examples: (1) ...
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Why do powers of lenses get added?

In our physics class, we were told that a power of a lens is defined as the reciprocal of its focal length. Also, the powers of multiple lenses get added up. But I didn't understand why this is. I ...
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449 views

How mirror equation can explain farsightedness correction?

I have a friend who has just show me his medical prescription for hyperopia (farsightedness) correction and he needs glasses with 4,25 diopters for that, which seemed to be weird for me because I had ...
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864 views

Wave theory limit of geometric optics? [duplicate]

Why is geometric optics the low wavelength limit of the wave theory of light? I can't seem to grasp why either a low or high wavelength limit would be necessary.
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334 views

Refraction of light in water

Here's a question in a paper based on refraction of light. I can't seem to solve it for some reason. A man looks down at a fish length of 20 cm. His eye is 2m above the surface of the water ...
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Converting indices of refraction

If I know that the index of refraction of a given substance is 1.4 for the average wavelength (say 550 nm), and I would like to know what is the index of refraction with a wavelength of 832 nm, how ...
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434 views

Finding the illuminance from a triangular light source

Since most light sources in games are point-like, it's pretty difficult to approximate area light sources with point sources. As triangles are a universal form to represent 3D models (thus area light ...
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Simulating an Optical Lens

An optical lens focuses the light according to a rule (due to its special shape) and we know that rule. Now, instead of making bigger and bigger lenses, can we use an array of optical sensors and the ...
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861 views

Two different mediums can have equal index of refraction?

In other words: given a certain medium, is light's phase velocity unique?
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46 views

How close do two wavelengths of light need to be to produce a metamer?

Suppose I have two wavelengths of light ($r_1$, $r_2$) coming from a source. These rays are then reflected specularly on a surface. What is the minimum distance required for the two wave trains of ...
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249 views

Formation on image on screen?

When we first learn elementary geometrical optics, the first thing taught to us is the two broad divisions of the type of reflection.-Regular and Irregular or Diffused. The difference in cause for ...
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Seeing the image as explained by Geometrical optics?

I was thinking about how the human visual system perceives the position of an object. I assume it essentially does this by focussing the incoming rays onto the retina and then judging from the power ...
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186 views

Perfectly focusing refractive surface

On reading Feynman's lecture on physics, in the geometrical optics section he said that a curve which focuses all the rays coming from a point to another fixed point beyond the refracting surface ...
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108 views

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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3answers
689 views

Light Ray Reflection from concave mirror

Suppose a ray of light hits a concave mirror and is parallel to the principal axis but far away from it such that it doesn't follow paraxial ray approximation. Will it pass through focus or between ...
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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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440 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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Can virtual image be photographed

Is there any instrument that can photograph a virtal image? How would such a device work?
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639 views

How does the eye perceive a real image?

Okay, so I'm trying to grasp how the human eye will perceive the real image created for example by a convex lens. Take the upper image in this picture for example. If you were to place a screen at ...
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449 views

Why don't you see multiple images of an object?

Consider the ray model of light. Let's say an object such as a pencil is illuminated, and consider one point on that pencil. Since there could be many rays of light bouncing off the same point on the ...
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706 views

Sign convention of the lens formula and its application

Why is the sign convention used in the derivation of the lens formula and yet used again when it is applied in numerical problems? Won't the whole idea of sign convention be eliminated if it is used ...
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272 views

Which fraction of light is refracted from a source of light under a lake?

I was trying to solve this problem: "A punctiform source of light is standing inside a lake, at a height h of the surface. f is the fraction of the total of energy emitted that escapes directly from ...
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219 views

Proof that a spherical lens is stigmatic

In geometric optics, we generally allow that, for example in the case of a convex lens, rays coming from a particular point get refracted towards another particular point on the opposite side of the ...
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644 views

What does it mean that a wavevector is null?

I have derived geometric optics for gravitational waves and I am trying to interpret one of the results. I have \begin{equation} k_{\rho}k^{\rho}=0 \end{equation} for the wavevector. For the case ...
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4answers
403 views

What does the wave principle of light actually represent?

Light has a dual nature, one of photons and the other of waves. But energy doesn't really travel in waves. So what do the wave represent?
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Image formation [duplicate]

What is the real cause behind the formation of an image? It is explained as" when rays of light focus at a point image is formed." So here we have two events, one focusing of light and another ...