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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27 views

What is the angular divergence of sun-rays?

I just want to find a number and I could not. Does anyone has it or can calculate it easily? Just in geometric optics, without diffraction, atmospheric effects and etc. Update: I think for me will be ...
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0answers
7 views

What is the ray diagram for Schuster's focussing?

I haven't been able to find it online. Our course book also doesn't provide a ray diagram for this particular phenomenon. I feel like it's difficult to understand the process without the ray diagram.
2
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2answers
72 views

What is the optimal distance to sit from a TV? [on hold]

I was wondering how to calculate the optimal distance to sit away from a TV. I don't quite know the full set of parameters it will depend on, I would suspect it to include the following: Size of the ...
1
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0answers
25 views

Analytical calculation for focus deviation [on hold]

How can I analytically calculate the deviation in focus or focal length variation in a situation as shown in figure. When the Sensor is parallel to the face of the lens/ light; its easy to calculate. ...
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2answers
60 views

Can we take photo of a mirage? [closed]

I do know that mirages are optical illusions . I know the phenomenon of its formation just tell me if we can ?
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0answers
21 views

Difference between linear magnification, axial magnification and aerial magnification (w.r.t. mirrors)? [closed]

Please explain how the three types are different from each other using pictures (preferably) or diagrams. And if possible, an explanation regarding how each would be different for mirrors and lenses ...
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1answer
39 views

Question about Fermat's principle

Why when deriving the law of reflection from Fermat's principle of least time do I set $dL/dx = 0$? I am a 12 grade student with a little notions of maxima and mimima in one variable calculus.
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23 views

What is the purpose of condenser lenses in the slide projector shown below? [duplicate]

I searched a lot on internet about this.I could not find the working of these condenser lenses in detail. Some websites say that condenser lenses make the light rays parallel and to pass through ...
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3answers
68 views

what is the purpose of condenser lens in a slide projector?

What if we don't use any condenser lens? can't we use a single convex lens as a condenser? what difference will it make? kindly explain it in detail.
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15 views

opaque to transparent based on distance of object?

If we look through a transparent glass window of an apartment, from a distance in day light, we can’t see what or who is inside. All the light is reflected off the surface of the transparent glass ...
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0answers
15 views

How to converge two independent point light sources with a single biconvex lens (20D)

I need to take an image of fundus of an eye. So I'm using a 20D lens to see the fundus. Camera is kept in the same axis and eye is illuminated by two 3v LED's. The LED's are placed just at the edges ...
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1answer
41 views

why can't we see our image on a simple brick wall?

We can see our image in a mirror due to the reflection of light. We also know that a red color brick wall also reflects light. So, why can't we see our image there?
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35 views

Does the curvature of the IMAX screen improve the view of 3D video projections in any way for viewers not sitting in the “sweet spot”?

When I think about a simple 2D projection on a screen with vertical-cylinder curvature and of viewing positions away from the "sweet spot" it seems to me pretty obvious that there would be geometrical ...
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0answers
30 views

What is the angular dispersion of an optical surface grating and why does the textbook answer seem to violate reciprocity?

The behavior of a surface grating can be described by the grating equation $m\lambda=d(\textrm{sin }\theta_i+\textrm{sin }\theta_d)$ [1] with $m$: diffraction order, $\lambda$: wavelength of the ...
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2answers
52 views

Lensmaker's equation and Imaging properties

In the textbook, usually the following construction (see the figure below) is used to determine the relative size of the image and the object. I understand that a ray parallel to the optical axis ...
2
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2answers
56 views

Why don't reflector telescopes place their reflectors at an angle?

To avoid placing a secondary mirror in front of the objective mirror, why not tilt the objective and design the eyepiece in such a way that comatic aberration is minimized?
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0answers
14 views

Refraction in solutions [duplicate]

What is significance of dn/dc change in refractive index over change in concentration of the graph of refractive index against concentration of a solution
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0answers
25 views

How is the Rayleigh criterion connected to the Abbe limit

I am interrested whether one can derive a formula for the point resolution (like Abbe did) of an optical system from the Rayleigh criterion (without the use of small angle approximation i.e. $\rm{sin}(...
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0answers
9 views

Coordinate Equation of a curve which bends all the parallel incoming rays from infinity towards a single point

How should i proceed on to find the coordinate equation of a curve such that it bends all the parallel rays coming from infinity towards a single point. Yes I know that it would be a 2nd degree ...
3
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1answer
39 views

Relationship between angular magnification and how much bigger the image appears

How is the angular magnification of a magnifying glass related with how much bigger the image appears to the user? Is it simply the same? If yes, why? (Let's assume that the object is placed in the ...
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1answer
40 views

If I placed a converging lens in water, would its surface power change?

If I placed a converging lens in water, would its surface power change ? The first case when the lens is in air then placed in water; does the surface power change or remain the same?
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1answer
64 views

Why should the image screen be placed at fourth focal plane in 4f setup?

They call it the 4f setup. But when the image coming from the second lens is anyway collimated, why is it necessary to place the image screen at the fourth focal plane?
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0answers
32 views

Sun light collimation

Is it possible to make sun light collimated in such a way, to increase energy density and keep it more less parallel? like on the Earth we have intensity of sun approximately 1300 watt/m2. If we use ...
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2answers
50 views

Explanation of ray caustics in E&M

My understanding (now) of a real caustic is that it is envelope of curves or ray-paths that arise due to reflection or refraction from the medium/manifold. My main question is, I am seeing the term "...
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0answers
19 views

addition of two lenses with a finite separation in between

Suppose there are two lenses with focal length $f_1$ and $f_2$ respectively. The effective focal length $f$ when they are combined is $1/f=1/f_1+1/f_2$, but this formula assumes the separation between ...
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1answer
41 views

Which shape focusses rays to a single point?

Which shape after refraction concentrates monochromatic light rays parallel to a single focal point at origin inside a denser medium like glass?
13
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1answer
787 views

Reflection of light rays

A set of light rays emitted from a point of an orange hits a smooth and flat surface. My question is: The angles of incidence are different, light rays are reflected towards different directions, why ...
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1answer
29 views

Actual spot size = geometric spot size + diffraction spot size?

I read in [1] that for a camera obscura the total spot diameter is equal to the diameter of the spot produced concerning geometric optics only plus the diameter of the spot concerning only diffraction....
2
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0answers
62 views

Breakdown of Snell [closed]

I have reason to believe the following: If we are using an accurately formed thin prism, with an apical angle of let's say 2 degrees, and direct a monochromatic source beam thru a slit onto the ...
2
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2answers
43 views

How does change in medium affect object distance/image distance?

Say,we have a container filled with a liquid of refractive index $7/5$ upto a height up $H$. There exists a plane glass mirror at the bottom of the container. Now if a fish were placed at a height of ...
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1answer
38 views

Focal Length Calculation [closed]

Although I research in the internet, I couldn't find detailed answer. I have a question and I want to make sure from the answer. The ligth is coming from a fiber laser source and focused on a ...
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1answer
96 views

Does this picture look wrong to anyone else? [closed]

There is a typo. One which obfuscates the main point and makes it difficult for anyone unfamiliar with the problem to deduce the answer.
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1answer
23 views

Minimum deviation of prism

Is it right to say angle of minimum deviation of a prism is an arithmetic mean of incident angle and emergent angle?
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2answers
52 views

Definition of a ray?

The typical definition of a ray and the one that I was initially taught was that a ray was a line perpendicular to the wave front. However, when reading up on birefringence it seems as though there ...
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1answer
18 views

Power distribution in a defocused focal plane

Given an optical system of focal length $EFL$ and f number $f/n$, if the focal plane is defocused in a way that the defocused plane distance from the focused plane is $d$, assuming we have a point ...
3
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2answers
58 views

Optics to correct focal distance across a plane

I have a laser beam which is focused to a point at a certain distance. I'm then going to use a galvanometer to scan that beam across a plane. Obviously, as the beam scans across the plane, the ...
2
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1answer
69 views

Would the moon be brighter if it were completely spherical?

I remember reading Galileo's 'Dialogue Concerning the Two Chief World Systems' where Salviati and Sagredo explain how the moon would be almost entirely dark if it were a perfect sphere but after ...
3
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0answers
30 views

Where do rays that are not marginal or principal get stopped?

The picture is from an MIT lecture but the concepts are explained in many optical texts. The chief/principal rays go through the center of the aperture stop, hit the edge of the field stop, and the ...
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0answers
20 views

Geometric optics, the size of the image

I have the following question from Snell's Law, I calculated the apparent location of the light source by: X = 20/1.47 = 13.6 So, this should be the apparent location of the light source. ...
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0answers
283 views

What is the physical meaning of magnifying power of a telescope?

So the following question was given in the JEE Mains 2016 conducted throughout India on 3rd April. An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To ...
2
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0answers
37 views

Is it possible to use a tapered fiber to collimate a single-mode light beam?

I would like to collimate a light beam stemming from a single-mode LED source. As the source is pretty big (a few millimeters), collimation with a single lens gives a bad result, i.e. a quite ...
1
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1answer
71 views

Why does a specific static image “move” when moving my head? (glass user)

I am a daily PC user. As most users, I have a taskbar (using Windows) that shows icons of programs. My two screens are big (24") and I'm at ~60cm distance from them, so fairly often I need to turn my ...
0
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1answer
44 views

Attenuation of light through a simple lens, and is it important?

I have an object with incident light rays traveling away from this object. Some of these rays are traveling from the left-hand side through a simple lens (say, a double-convex converging lens). As ...
2
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2answers
105 views

Why is this laser beam being scattered(and not)?

I was shining a laser beam through a liquid filled test tube(an ester particularly),and I found this phenomenon rather intriguing.Have a look. Now when I passed the laser straight through the ...
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2answers
87 views

What is exactly an ‘virtual object’ ? ( From the point of view of lens maker’s formula )

Here’s an image from my textbook It shows, how an image is obtained from a convex lens. The second and the third images, shows in depth , that how a convex lens behaves. They say, that suppose (...
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1answer
26 views

Why should the ray become parallel to base in a triangular prism at minimum deviation?

In the case of minimum deviation, the refracting angles at two surfaces are equal. Then the ray inside the prism should be parallel to the base only if it is isosceles triangular prism. But everywhere ...
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2answers
70 views

Magnification vs Magnifying Power [closed]

I've read it a lot of times. But I've not been able to get around magnifying power and magnification of a simple microscope and the difference between them. Can someone explain?
1
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1answer
52 views

Deep confusion with conventions and signs in geometric optics

This is an equation given in my book. The question is why have they used a negative sign on the LHS? Now, if you try to derive the mirror equation with simple geometry, you get 1/v +1/u =1/f . ...
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24 views

Plotting EM fields

I am currently studying transformation optics and learning about electromagnetic cloaking. To plot my results(Electric and magnetic fields) i have to solve maxwell's equations given the permeability ...
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3answers
24 views

What is the meaning of size of the image?

Say I am standing at a distance of $20m$ from a plane mirror and looking at it. My image in it as I see it is smaller than how I perceive myself. Why then does my physics textbook tell me that in a ...