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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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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45 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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44 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
31 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 ...
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15 views

Chief ray in two thin lenses optical system [duplicate]

I have an optical system made by two thin lenses with a stop between them. How can I find the chief ray in this optical system? Obviously I find a parameteric method assuming: $f_1:$ focal length of ...
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24 views

Rayleigh Criterion and Resolvability

If I want to resolve two close but different wavelengths $\lambda_{1}$ and $\lambda_{2}$ to the second order in my experiment using a grating of spacing $d$, is the size of the grating ($D = Nd$) I ...
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21 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 ...
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1answer
45 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?
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34 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 ...
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1answer
36 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 ...
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1answer
76 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 ...
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1answer
45 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
61 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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50 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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42 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
20 views

Is the focal length of a thin convex lens always less than the radius of curvature?

For a convex lens, would the focal length always be less than the radius of curvature? How does the focal length vary as a function of the refractive index of the lens and the radius of curvature?
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43 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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37 views

geometric ray tracing

I'm using matlab for tracing rays in 3D through an optical system. I have a 3D prism which its yz cross section is a parabola, and its xz cross section is flat. It has non negligible thickness. I know ...
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1answer
85 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 ...
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67 views

Light absorption for different liquid

when I was working on a cylindrical glassy bottle that filled with water, I found that the initial light intensity is less than the final light intensity. (It's clear but I experiment this) This is ...
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24 views

Fresnel coefficient

I dont think I have enough backgrounds for optics. I am sorry for asking this elementary question. I am reading a paper Phyc Rev A, Vol 59 # 6, 1999 they introduces discontinuity matrix ...
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1answer
44 views

Can a virtual image created by a mirror have position in front of the mirror?

I dont think so, because then the rays will intersect and the image will be real. Please let me know if you know a case in which a virtual image is formed in front of the mirror.
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124 views

How to calculate desired light path in continuous medium with gradient refraction index

See the Figure below. $O:(0,0)$ is the disk center of light source $\odot{O}$ with radius $3$. Then the profile light rays of disk $O$ from the view point $B:(-14,0)$ is defined by segments $DB$ ...
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76 views

Interpreting Seidel Aberration coefficients

I am trying to model a simple system in Zemax (though I think the question is general and is not limited to Zemax app), but the ray-tracing does not seem to be consistent with the analysis of the ...
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1k views

How many times can light revolve around a black hole?

Take a light ray approaching a black hole from infinity which goes out again to infinity. What is the maximum finite rotation it can describe? (I know it can loop around indefinitely in the ...
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37 views

Microscopy: aperture matching and Huygen's principle

I have repeatedly read that the maximum spatial resolution of a microscope occurs when the aperture of the objective and condenser are the same. However, I don't understand why. The resolution is ...
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2answers
117 views

Examples in which the light maximizes the optical path length

I posted a similar question about geodesics on Math.SE. Many sources (Wikibooks for instance) claim that the light could maximize the optical path length in some cases. But I don't think it's actually ...
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1answer
71 views

Why grating is an essential part of a monochromator?

From looking at these two images, it appears that the dispersed "rays" of the reflected light could be manipulated just as well if the reflecting mirror would be turned to a fixed angle. So why is ...
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1answer
93 views

geometrical optics

I doing an experiment now. My structure has 700nm periodicity. The surface of the unit structure is sloped at 45 degrees from the normal incidence angle. My laser is 500 nm. I can expect there ...
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103 views

Options to correct rectangular laser beam profile?

We recently switched to a 405 nm laser diode which has a terrible beam profile -- it is a well-defined rectangle with an aspect ratio of about 10:1. The image below shows the collimated beam which ...
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1answer
111 views

Reflection in a cylindrical mirror

Suppose I have a completely cylindrical surface which is silvered on the inside. I want to know what type of reflection takes place when an object is placed inside the ring. Does infinite reflections ...
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14 views

Hildring - Influence of vertical temperature gradient on light beam curvature

In special atmospheric condition it is possible to see coastline that normally is behind the horizon. It is apparently lifted to become visible. In Scandinavian the phenomenon is called 'hildring', a ...
2
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1answer
315 views

Huygens' Principle During Reflection: comparing wavelets from before reflection with wavelets from during reflection

I was recently reviewing geometric optics, during which I read about Huygens' Principle and how it could be used to prove the Law of Reflection from the "light is a wave" viewpoint. I'll quote what I ...
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1answer
108 views

Can a polarizing beam splitter cube be used to replace two polarizers?

I have a design for a setup to look at the light reflecting off the back of the human retina. I would like to remove any specular reflection that occurs at the cornea. At the moment the idea is to use ...
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1answer
91 views

What does the equation of a refracted ray trace mean?

I am doing a ray trace to a refracted vector. I read in some PDF files that: vector($\mathbf{t}$) is the refracted ray, vector($\mathbf{i}$) is the incident ray, the angle $\theta_t$ is the refraction ...
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1answer
179 views

Apparent depth and virtual image position

Why does the virtual image appear right on top of the object and not a little to the right, for example? Is it explained by some formula or just symmetry of the geometry?
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3answers
108 views

How to improve the visibility of light without increasing the brightness?

I am not sure whether or not this is the right SE site to post this question on but I'm sure someone will inform me of my mistake soon enough if it is wrong. Basically I am an Electronic Engineer and ...
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1answer
75 views

Problem with Beam Splitter Refraction

I made a beam splitter for a simple test, as shown in the images below: This was my expected ray trace: But it instead refracted light like this: Why did the splitter cause light to ...
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1answer
66 views

What are the common points between physical optics and geometric optics? [closed]

I am trying to write a paper about light, I want to discuss the two way of studying light, the physical/wave optics and the geometric/ray optics, but I want to write a general introduction about them, ...
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52 views

Does the anisotropic Fermat eikonal equation predict the extraordinary ray direction given by Poynting vector?

Does the anisotropic Fermat eikonal equation predict the extraordinary ray direction given by Poynting vector?
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2answers
102 views

how to trace light after refraction by a camera lens?

I am a programmer and I am doing a camera simulation, I am stuck in a matter of how to know where arrives every ray of light after traveling through the lens and being refracted. Every point of the ...
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2answers
292 views

Why do we assume that rays from infinity are parallel?

If light rays are parallel to each other , if they are from infinity, they are not gonna make an image because they won't intersect with each other. So we are not gonna see the image. Does that means ...
108
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2answers
6k views

Why do sunbeams diverge even though the sun is much more than a few kilometers away?

Consider this picture of sun beams streaming onto the valley through the clouds. Given that the valley is only (at a guess) 3km wide, with simple trigonometry and the angles of the beams, this ...
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3answers
79 views

Does polarization remove any of the fields completely?

A light is made up of electric and magnetic fields oriented perpendicular to each other. Can polarization lead to the removal of any of the fields completely?
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1answer
267 views

Ways to measure the focal length of a convex lens with only natural sun light [closed]

What are the common ways to measure the focal length of a convex lens with only natural sun light?
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2answers
116 views

Gaussian beam modelling, location of the beam waist?

In reference to the specifications of a laser diode below: http://www.thorlabs.de/thorcat/11900/L780P010-SpecSheet.pdf I wish to be able to model it as a gaussian laser beam. I understand there is a ...
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1answer
58 views

Does the distortion of an image depend on the location of the object with respect to the mirror?

A mobile phone lies along the principal axis of a concave mirror with its distorted image, as shown in Fig. How do we actually figure out the formation of such images? The answer says: "The image ...
2
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0answers
33 views

Ray tracing a three-way intersection

I've been studying ray tracing in media with linear velocity-depth functions. One of the key concepts I've come across is the ray parameter, and in particular the idea that the ray parameter is ...
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0answers
79 views

Gaze tracking with the pupil-glint response how does the geometry work?

I am struggling to understand the geometry behind the pupil glint response (see above) (With only one light source). I understand that you use the glint to find the corneal centre (Centre of corneal ...
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23 views

Does dispersion take place in our eyes? [duplicate]

What do we see if a single ray of white light falls in to our eyes ? Doesn't it undergo dispersion ?