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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85 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
64 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 ...
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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 ...
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1answer
184 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 ...
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4answers
354 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
94 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 $$M=m=m_om_e$...
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0answers
58 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
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1answer
72 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 ...
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2answers
286 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 ...
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1answer
38 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 ...
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1answer
247 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 ...
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1answer
865 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 ...
2
votes
2answers
161 views

What is really a light ray? [duplicate]

I've been studying geometric optics and I'm still a little confused with this idea of light ray. In the book I'm studying everything is being done starting from Fermat's principle which states that ...
40
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5answers
5k views

If a lens focuses all incoming light to a point, how do we get 2D images?

How do lenses produce 2-dimensional images, if a lens bends all incoming rays of light to intersect at the focal point? Shouldn't this produce a single dot of light on a screen placed at the focal ...
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3answers
3k views

Calculating light's lateral shift in a glass slab

I have tried to compute light's lateral shift after passing through a glass slab In terms of the incidence angle $\theta_1$, the slab thickness $d$ and the refraction index $n$, I have found that ...
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2answers
102 views

How can one prove the equation for a system of lenses? [closed]

Let's say we have a system of 2 lenses which are placed in a non-negligible distance $L$ from eachother. How can I prove without using geometrical construction and principal planes that $$\frac 1f =...
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1answer
78 views

In geometric optics we treat light as a collection of particles?

I've been reading the book "Geometric Mechancis" by Darryl Holm and the in the first chapter he treats geometric optics. There the author talks about light rays and those light rays looks like ...
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2answers
29 views

Principle of fibre optic cable coating

I was reading about fibre optic cables and it was mentioned that ,the individual "light pipes" are coated with a material whose refractive index is less than that of that of the glass. My question is ...
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1answer
717 views

Question about lens maker's formula

I am trying to follow the derivation of lens maker's formula from the textbook "University Physics", p.1133 (https://books.google.com.hk/books?id=nQZyAgAAQBAJ&pg=PA1133#v=onepage&q&f=false)...
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2answers
74 views

How to estimate if an image is in focus

I am building a test measurement (optics) to look a rectangular slit opening (1mm x 15 microns). The slit opening is illuminated by a white LED and using a microscope objective to magnify it to 10X on ...
0
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1answer
61 views

What's the difference between two types of diaphragms?

What's the principal difference between aperture iris diaphragm and field iris diaphragm?
0
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1answer
47 views

Does “converge” mean intersecting and producing image when we are taking about convex lenses?

After reading the chapter on convex lens, I saw several places where "converge" is used. In the very beginning of the chapter, my book says "converging lenses bring light together". So I thought ...
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3answers
213 views

What is the total internal reflection?

From what I read, it sounds like when a light ray passes from one medium to the other, if the critical angle is reached so that the refractive ray is at 90 degree with the normal, the light ray does ...
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5answers
1k views

Why does an image form at the intersection of light rays?

If image is simply what we see, then why, when light rays bend in the atmosphere, enabling us to see the sun, is there no intersection of rays? The concept is strange. I can not relate it to anything ...
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0answers
139 views

When to use lateral magnification vs angular magnification?

What is the essential difference between lateral and angular magnification (like why do we need to use both and when do we use which)? Also, is there a relationship between the two magnifications?
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0answers
171 views

General proof of formulas of geometric optics?

In most lf textbooks formulas of geometric optics like lens maker formula and base formula for that are proven (or rather verified from my point of view) by taking specific case (ray diagram) and ...
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1answer
75 views

Bragg's interference

This may be a little of a stupid question. But I was looking at a diagram describing Bragg's Law of Diffraction. and I was like...how can an interference happen if wave beam C and wave beam C' are ...
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1answer
198 views

Why are mediums always represented as straight and parallel lines in Ray optics?

I have been reading Ray Optics lately and I always see that the interface between mediums are always represented as Straight lines in ray diagrams. There is no mention that they are considering an ...
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1answer
382 views

Inside a spherical mirror

imagine standing inside a sphere composed entirely of mirror surface; what does this look like? inside is lit by an invisible light source if each point encounters a reflection of itself, what is ...
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0answers
35 views

Why would longer distance between collimated lenses improve coupling efficiency?

Im coupling 1550nm output from a single-mode lensed optical fiber to a standard SMF using a pair of collimating lenses, matched to the NA of the respective fibers. However, I find that by increasing ...
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1answer
87 views

Can QED explain this or do I have revert to the classical model of light?

I want to know can QED can explain this image,like why there are someplaces with low light (shadows) like behind the chair, and why there are some places that are bright(rest of the floor). I know ...
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0answers
32 views

How can line be parallel to Pricipal Axis after following Paraxial Ray Approximation?

I Studied In my previous Standards that Light Parallel to principal axis passes through focus always in Concave Mirror. But Now In one Book I read that there is a condition which should be followed ...
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1answer
127 views

What is Retracing in context of this Question?

My textbook Question is Two Mirrors are inclined at an acute angle theta.Light ray is incident parallel to one of the mirrors. Light will start retracing its path after third reflection if angle ...
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2answers
881 views

How second image is brightest here?

One of my Textbook's Multiple Choice Question is- A Thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the- First Second Last Fourth ...
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1answer
60 views

Determining path of light through a nanolens

In the case of light passing through stacked liquids, we can use a ray approximation of the path of light to determine the path taken through each layer of liquid using Snell's law. From all the ...
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0answers
165 views

Re-reflecting in HUD optics

Simple HUD optics design can be described with below image. (source : http://www.mikesflightdeck.com/hud/head_up_displays.html) As you can see, if combiner and colimating lens(after fold mirror) ...
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0answers
105 views

False sunset and false sunrise time estimation

False sunset and false sunrise are described . Here is a sample day rise and set time according to AccuWheather site and calculated value of sunrise and sunset in my country. Could you please help ...
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1answer
66 views

Geometry confusion with incident E field

My geometry is very rusty and I'm having trouble understanding why for the incident E field the X component is multiplied by cos and the -Z component is multiplied by sin instead of the other way ...
0
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1answer
72 views

Why does some light escape when in a fiber taper?

I am working with fiber tapers and i noticed that some light escapes from the tapering region and i am quite curious. I am using a 500 micron plastic optical fiber and i managed to stretch the ...
2
votes
1answer
251 views

If I wear contact lens and spectacles of same power, is it same wearing thick spectacles of twice the lens power?

Assume I have a contact lens of power -1 and a spectacles of +1. Will they cancel out their effect? is it same as my normal eye sight?
0
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1answer
261 views

combination of mirror and lens [closed]

a convex lens forms a real image of a point object at a distance of 50 cm from convex lens. a concave lens is placed 10 cm behind convex lens on image side. on placing a plane mirror on the image side ...
1
vote
1answer
78 views

Position dependent refractive index [duplicate]

How to determine the angle of refraction when the medium has position dependent refraction index? Lets say that the angle of incidence on the glassy slab is $\theta_1$ and the ray goes through the ...
0
votes
1answer
161 views

Determining the path of a light ray

Let's consider a ray in the plane $xy$. Let the refractive index be defined in any point of the plane with the function $n(x,y)$. In time $t=0$ the ray is located in coordinates $(x_0, y_0)$ and its ...
0
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1answer
225 views

How is angle measured by telescope in spectrometer is twice the prism angle [closed]

While measuring the angle of the prism with the help of telescope in a spectrometer (see figure below), the observed angle is twice the angle of the prism. Can someone prove it geometrically? Edit : ...
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1answer
81 views

Why the image is being formed at the surface?

Last week I encountered a very cool optical phenomenon. A photo was sandwiched between the two glass plate to make the paperweight. The cool part is the picture seems to have been pasted on the top ...
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0answers
68 views

How does light manage to change its course at the boundary of two media of different optical densities?

This is a conceptual question. I already know the law of refraction but I need something like an idea of the Physical process from both particle and wave theory standpoints. Why does a ray of light ...
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0answers
128 views

About Powell lens

I am a Post graduation student and I am doing a project on the conversion of a Gaussian beam into a flat top beam using optical components. I have found that the best component to do the same is a ...
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0answers
76 views

Rayleigh length determination for Laguerre-Gaussian Modes

Recently I have measured the Rayleigh length of a Gaussian electron beam probe in a scanning electron microscope, using the function: $$w(z) = w_0 \times \sqrt{1 + (z/z_r)^2}$$ Where $w$ is beam ...
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1answer
225 views

Refraction of light marching band analogy

When trying to understand the refraction of light when it hits a slower medium, lots of people seem to be enlightened by the 'marching band' or 'marching soldiers' analogy, which 'explains' that when ...