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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2answers
98 views

Can focused light be treated as a point source?

Imagine there is a uniform, collimated beam coming from a distant light source. This beam passes through a lens and is focused to a point at the focal length. Can this "point" be treated as a point ...
0
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0answers
69 views

Derivation of the formula related to number of images?

I have read in my book that if two mirrors are inclined at an angle $\theta$, if 360/$\theta$ is even , the number of images is given by (360/$\theta$) -1 What is the derivation of this formula? I ...
-1
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1answer
25 views

Light and Visibility [duplicate]

It is difficult to see through a closed glass window from the inside of a well lighted room, when it is dark outside. However it becomes relatively easy to see outside, when the light in the room are ...
1
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0answers
66 views

Which Method for finding velocity of an object in the mirror is correct? [closed]

My Professor asked a question, "A person is seen jogging in a rear view mirror of focal length $1$m. He is at a distance $39$m from the mirror. His jogging speed is given to be $5 \frac{m}{s}$. ...
2
votes
1answer
89 views

How to determine the radius of curvature of a convex lens?

Suppose there is an equi-convex lens made of glass which has a focal length ($f$) of 30cm. Then, can we not say that the radius of curvature, $R$ of the lens is twice the focal length, i.e. $R = ...
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4answers
39 views

What is the distinction between a “ray” and a “wave” in optics?

What is the distinction between a ray and a wave in optics? From what I can gather, the only discernible difference is in nomenclature, where a ray simply refers to an EM wave with short wavelengths. ...
0
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0answers
16 views

The image of an object through a curved surface

We have a curved surface, separating two different medium, with refractive index n1 and n2. We know the radius R of the curve,then how can we find the position v of the image? I read that the ...
41
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6answers
6k views

Do people wearing glasses have different field of view than those who don't?

There is one thing I sometimes wonder about ever since I was a child. Do people who wear eye glasses see objects in different size than those who don't?(Technically different size means different ...
2
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0answers
44 views

Rings of light around a jet [duplicate]

When an obstacle is put in the path of a liquid jet, some standing waves are created upstream of the obstacle (see the pic) or we can say a similar form like this for them ( the wavelength of ...
1
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0answers
38 views

Prismatic shaped rear view mirrors

To reduce the intensity of the incident light, prismatically shaped rear view mirrors are used in cars with a day-night switch which changes the angle such that instead of the polished surface ...
0
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0answers
69 views

Lens formula and Lens maker's formula

When we derive the formula for lens and lens maker's formula using the formula for refraction at spherical interface $$\mu_2/v - \mu_1/u = (\mu_2-\mu_1)/R$$ we put $u$ to be $-u$ as it is on the left ...
8
votes
3answers
576 views

What determines the sharpness of a shadow?

What are the factors that affect the sharpness of a shadow? I would think that the distance between the light source and the object, the distance between the object and the shadow, and the size of ...
1
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2answers
149 views

Why doesn't a Gaussian beam converge to a point?

No matter what lens is put in the beam path of a Gaussian beam, it will always go through a waist of non-zero width. Why not just a point? I know the maths, I'm wondering whether there is any ...
0
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0answers
38 views

Refracting telescope image formation

I'm having some trouble understanding how a refracting telescope forms a magnified image for an object that is not assumed to be infinitely far away. I drew this ray diagram: And as you can see, a ...
0
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0answers
148 views

Image formed by a Prism

A series of questions that came in my mind after I saw a question So here it goes first the questions that have made me confused : 1) How image is formed by the prism? 2) When we take different ...
0
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2answers
68 views

Are these reflected rays really parallel?

I have read that if an object is placed on the focus of a concave mirror (assume that the object is a vertical line placed on the focus), then the image will be formed at infinity. Here’s a diagram. ...
1
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1answer
45 views

pinhole in projector screen

Consider a conventional slide projector projecting a properly focussed static image from a photographic slide onto a conventional screen, with a second screen placed a short distance behind that one. ...
1
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1answer
30 views

Do all thermal radiators have the same surface brightness?

Imagine I heat a piece of metal to 1000K. It will be red hot and will emit black body radiation corresponding to this temperature. But what about the brightness? Assuming the bulk is opaque, does it ...
18
votes
1answer
530 views

Do light waves precisely follow null geodesic paths in General Relativity?

In special relativity one may show that a plane wave solution of Maxwell's equations (in a vacuum), of the form $A^a=C^a\mathrm{e}^{\mathrm{i}\psi}$ has the following properties: The normal ...
1
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1answer
532 views

Rayleigh-Plateau instability and optic [closed]

Let a liquid jet fall onto a surface. If the contact point is illuminated by a lase beam, rings of light around the jet can be observed . (pic.1) and we know it that the reason of this phenomenon is ...
2
votes
2answers
156 views

Experiment to find the circle of least confusion (optics)

I want to conduct an experiment where the circle of least confusion (wiki ref) occurs for a lens. Suppose that I shine white light onto the lens and I know the lens EFL is lets say 100 mm, in order to ...
3
votes
1answer
55 views

100x magnifying optics system for short laser pulse

I am now designing an experiment that consists of a 400 nm short pulse (~300 fs). In the experiment, we need to magnify the transverse profile of the pulse by 100x. That's the problem. I was ...
0
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0answers
37 views

Balance lens tilt aberration

Given a doublet (singlet in reference figure), if the rays enter at an angle with respect to the origin axis, we would see a shift of focal length for blue and red. A known optical jitter How could ...
-3
votes
1answer
133 views

Combination of mirror and lenses [closed]

I am a keen learner of physics, but I am unable to solve problems involving lenses and mirrors together. please can anybody tell me the method to solve these problems? for instance let us take a ...
1
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2answers
50 views

Let's suppose I am to display the letter R on mirror as well water , will I get the same images?

As far as my practical experience goes both look quiet the same when an image of any object is formed on them, yet I wanted to be ascertained is there any actual visible differences between both the ...
0
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1answer
33 views

Encoding multiple images in 1 beam

I am doing some research involving geometric optics. I need to reduce an image in size so it fits a rotating mirror we are using. I came up with the idea of projecting the focal plane on the mirror, ...
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0answers
15 views

Why to use the sign convention while solving problems as the mirror-formula itself is derived using the sign convention? [duplicate]

When we derive the mirror equation of concave mirror, i.e.,$\frac{1}{u}+\frac{1}{v}=\frac{1}{f},$ we've already used the sign conventions. Then why to use the sign conventions again while solving a ...
0
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0answers
110 views

Velocity of image formed by a spherical mirror in Y axis

If an object is moving with velocity $v_0$ along the positive Y axis in front of a convex mirror of focal length $f$ at a horizontal distance $u$ from the mirror's pole, what will be the velocity of ...
3
votes
1answer
429 views

Why doesn't a backward wave exist? [duplicate]

Huygens principle says every point of wavefront emit wavelet in all directions. Then why does a back ward wave not exist? Can any expert tell real answer? On different sites I get different and ...
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0answers
30 views

Effect of introducing lens on Fringe width

Suppose I have a light source of wavelength 400 nm. The slits are placed at a distance 1 mm apart. The distance between the slit plane and the screen is 50 cm. So that makes the fringe width, $\beta ...
0
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0answers
40 views

How to collimate a wide-field from a classical Cassegrain telescope?

I have a 0.25 degree field-of-view Cassegrain telescope (see below) that I'm trying to collimate, i.e. make the diverging beam afocal, not collimate in the sense of aligning M1-M2. I can do this with ...
2
votes
0answers
44 views

Aquarium/refractive indices/detector

Quick question: I'm currently fiddling around with this homework of mine and I seem to be lacking some basic optics knowledge apparently. An aquarium is filled with a fluid as seen in the figure ...
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0answers
199 views

A small object faces the convex spherical glass window of a small water tank, find the final image?

I was hoping you guys could look over my solution to this question. A small object faces the convex spherical glass window of a small water tank. The radius of curvature of the window is 5cm. The ...
0
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0answers
48 views

Trapping force in optical tweezer

I am reading a paper on theory of optical tweezers in ray optics regime by A. Ashkin. For reference "click here". It is given that Gradient force $F_g$ is directed perpendicular to the light ray and ...
1
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0answers
25 views

Method of Transformed Impedances

So I am taking an advanced optics class at the moment, using the book Lasers and Electro-Optics by Chris Davis. At one point, while explaining the concept of impedance, he mentions something called ...
3
votes
4answers
208 views

Shining a laser onto a mirror

Theoretically, if I shined a laser at a mirror at an angle of 0 degrees so that the light was perfectly reflected back to the light source, then I should not be able to see the light because it is not ...
0
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1answer
44 views

Ray optics : Circular mirror with reflecting surface on the inside

A light ray enters through an infintely small hole and gets reflected as shown. After how many reflections will it emerge out again? (It can come out in any orientation). Will it emerge out for any ...
3
votes
2answers
81 views

What makes a lens a lens?

I am asking about the way that a convex lens works. All the lenses I have ever seen were solid glass or solid plastic. If I have a convex sheet of clear glass or of clear plastic, shaped into a ...
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0answers
59 views

Source of a parabolic wavefront

The Huygens-Fresnel diffraction integral has been formulated for incident spherical waves. A source of a spherical wave is kind of intuitive, since the perpendicular rays of the sphere converge into a ...
1
vote
2answers
60 views

Can we trap living cells in optical tweezers?

I read that optical tweezers work on the principle of radiation pressure caused due to momentum change of incident light due to refraction from a spherical object. For refraction to happen the object ...
1
vote
1answer
174 views

Path of a light ray in a medium of varying refractive index [closed]

How do we get the equation for the path of a light ray in a medium of varying refractive index. I can draw a rough sketch, but don't know how do we get the exact curve. I encountered this while ...
5
votes
4answers
341 views

Infinite total internal reflection

Suppose that I have a block of some transparent material, glass, for instance, with a certain index of refraction. Suppose that the transparent material is placed in air or in any other transparent ...
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0answers
91 views

Why isn't the magnifying power in a compound microscope zero when image is formed at infinity?

I think, in a compound microscope, angular magnification and lateral(or linear) magnification is given by the same formula for both image at infinity and near point(D) And the formula is ...
1
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0answers
55 views

Optimization of transfer matrix method for quarter wave stack

Does anyone have any tips for Matlab optimization algorithms to use with a 2x2 Transfer Matrix Method Program? I have written a Matlab function that takes a series of refractive index values and ...
2
votes
1answer
71 views

Why does in the definition of 'optical path', only spatial phase change is taken into consideration & not that of time?

In Concepts of Physics by H.C.Verma, I got the definition of optical path. However, one thing that I couldn't understand is why only the spatial phase change is considered in its definition. As he ...
3
votes
2answers
268 views

How does Huygens Principle incorporate the unidirectional property of a traveling wave?

I was reading French's Vibrations & Waves where he discusses Huygens-Frensel Principle. The principle talks about how secondary sources give rise to secondary wavelets to form the displaced ...
1
vote
1answer
36 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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0answers
89 views

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

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 ...
0
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1answer
235 views

How to calculate the diameter of a thin lense?

A photo produced with a single thin lense is provided. Only based on the photo I should calculate the diameter of the lense. The photo shows a ruler in the foreground and a point source of light in ...
0
votes
1answer
814 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 ...