# Tagged Questions

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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### 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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### 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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### 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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### 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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### 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 ...
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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### 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 ...
366 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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### 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 ...
223 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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### 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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### 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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### 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 ...
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### 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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### 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 ...
393 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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 ...
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### 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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### 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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### 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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### 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 ...
133 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 ...
43 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 ...
225 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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### 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 ?
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### Object inside the eye

What will be the image seen to us if an object is placed in between the focus and pole of our eye lens ? I guess no image will be formed.
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### how can a lens combination take virtual object to the second lens?

When two lenses are in combination. what logic is it to take the image of first lens (which is not formed in real) as a virtual object to the second lens ?
213 views

### Geometric optics question

This question appeared on this site Q17: here A concave mirror is broken into two parts and these parts are separated by a distance if 1 cm. The focal length of the mirror is 10 cm. Find the ...
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### Using aluminium foil as a reflection for UV at 240nm [closed]

Will aluminium foil or sheeting reflect UV light at 240nm being used as a disinfection cell for bacteria in water.
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### Issue on sign convention with optics

I have a problem understanding the sign conventions used in the equations that describe the imaging properties of mirrors - in particular, when and why should I use a positive or negative number for ...
282 views

### Interferometers and Earth's motion relative to the Aether

Why was the Michelson and not the Fabry-Perot interferometer used to detect the motion of Earth relative to the Aether? Maybe the Fabry-Perot was used but we all know that the most famous experiment ...
329 views

### Ray diagram of infinity well

An infinity well works on the principle that when two plane mirrors are placed in front of each other an infinite number of images are produced thus creating an illusion.I am a bit confused about it's ...
426 views

### Good resource for geometric optics

I'm looking for a good resource (preferably a book) on geometric optics. I am thorough with the basics (the mirror formula, lensmaker's formula, thin lens formula, etc). What I want is something that ...
176 views

### Why isn't Zemax showing a tilt on the wavefront on my telescope design?

Attached is a Zemax file Zemax File for an afocal telescope system. When i tilt the field by an angle of 2 degrees (In green) I would expect a wavefront tilt at the "Image " plane, however when I ...
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### Increasing the volume of a object in a photograph

I have two images which look like this --- These images are two views of a calibration object --- the white die that you see hanging in the middle. The problem is that, the die is too small and ...
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### Two thin lenses in contact [closed]

Two thin lenses with same focal length are in contact. what is the resultant focal length? Options a) f b) 2f c) f/4 d) 4f My Answer By both plotting the light ...
294 views

### light ray undergoing total internal reflection thrice inside a prism

Can it ever be possible that a light ray going inside a triangular prism of refractive index n having refracting angle A undergo total internal reflection thrice before emerging out? Note:I know it "...
210 views

### Wavefront sensor specifications Shack-Hartmann

Why is the dynamic range of Shack-Hartmann wave-front sensors (As seen in the first image below) quoted in wavelengths and not in angles? I thought that one of the most important aspects of the ...
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### Can multiple lasers be concentrated in a circular area using some optical arrangements?

Can multiple lasers be concentrated in a circular area using some optical arrangements such as using a paraboloid surface? If yes, why do in high laser power systems do they use only 2D arrays of ...
212 views

### Changing light beam direction

I'm using a rotating mirror to reflect a beam of light like that: where A is the beam source, B is the projection of the reflected beam on a surface at a distance y from the mirror, x is the ...
453 views

### Shack-Hartmann wavefront sensor concepts, pupil conjugate planes?

I am just starting to looking at the application of wavefront abberommtery to measure abberations in the human eye. I am confused over the pupil conjugate planes, do you use relay lenses to image the ...
130 views

### Fresnel Rhomb Retarder specifications

In my homework I have a Fresnel rhomb retarder and I am asked to calculate the retardance. I have the refractive index in terms of the wavelength(dispersion equation) and the phase difference incurred ...