Optics is the study of light, and its interaction with matter. It includes topics such as imaging systems, fiber optics, lasers, quantum optics, and more.

learn more… | top users | synonyms

0
votes
0answers
16 views

Frequency dependence of refractive index $ n $ considering electron oscillator using Electromagnetic Theory

First and foremost, I am referring to Hecht, Zajac E. Optics 4th edition. I am reading the dependence of refractive index on frequency, and it goes well until Hecht jumped on his equation. First we ...
-2
votes
0answers
40 views

Can we use the electricity produced by lightning? [on hold]

I HAVE SEARCHED THE WEB FOR 'ABOUT LIGHTNING', HOW IT HAPPENS AND NOW I AM SEARCHING FOR HOW ELECTRICITY CAN BE PRODUCED FROM LIGHTNING.
1
vote
2answers
29 views

Transfer matrices - drift distances

I have a question regarding transfer matrices in optics. For thin lenses, the thickness of the lense is not taken into the calculation because it is very small compared to the dimensions of the rest ...
0
votes
1answer
18 views

Mie theory “upper limit”?

I have read most often that objects experimented with in Mie theory are on a scale not much larger than the incident wavelength (usually a fiber of diameter $5$ microns with an incident wavelength of ...
1
vote
0answers
29 views

Silicon/silicon dioxide interface

Suppose we have an interface of silicon/silicondioxide. If we shine light on the top surface electron-hole pairs are generated in silicon. since there is always a field directing from surface to bulk ...
0
votes
2answers
38 views

How to define a convex surface in case of refraction?

In an exam at high school level, it was said, "ray goes from optically denser to rarer medium through a convex surface. It forms a real image...." this was a part of the question. Now I thought that ...
0
votes
2answers
58 views

Light-Matter Interaction and Object's Appearance

I am taking a course in Computer Graphics, and the teacher said we could put materials in there main categories: mirror like glossy or specular diffuse He suggested that the law of reflection is ...
2
votes
1answer
59 views

How to calculate the refracted light path when refraction index continuously increasing?

Suppose an incident light from vacuum ($n_1=1.0$) into some media ($n_2=n_1+\mu\; x^2$) as in the figure below. How to calculate the refracted light path curve in closed form? Update: Try to set ...
0
votes
0answers
35 views

Calculating M squared [closed]

I have a laser beam which has a wavelength of 1064nm. The beam quality is 12 mm mrad (SPP). The diameter of the beam is 10 mm. I was told to calculate: $$M^2$$ I used this formula: ...
0
votes
0answers
67 views

Is the image formed at the retina messy?

The following passage has been extracted from Newton's book Opticks: ...So if PR [in Fig.at the top] represent any Object without Doors, and AB be a Lens placed at a hole in the Window-shut ...
2
votes
1answer
70 views

A mirror in the sky to look at past Earth

Earth reflects light from Sun into Space; are there any "mirror like" objects which reflect back to Earth this light? Has anyone been able to use this method to recover some information on how was the ...
-1
votes
1answer
34 views

Can we multiply an electromagnetic field?

can we multiply light by a sequence of reflections in a closed vessel? also, is light a part of EM wave? can we multiply the radio wave or EM wave from a transformer?
1
vote
1answer
17 views

The lineshape of a 2D photonic crystal dispersion diagram

Using simulation software (CST Studio), I calculated the dispersion of the eigenmodes of a photonic crystal, that is frequency vs wavenumber for the desired propagation direction. I wonder what kind ...
3
votes
2answers
98 views

Refractive index of dielectric in different frames of reference

The setup A transparent isotropic dielectric medium moving in the negative $x'$ direction at speed $v$ in frame $S'$ is stationary in frame $S$, where it has refractive index $n$. In other words, ...
1
vote
0answers
57 views

Sum of 2 Light sources

When we have 2 sinusoidal waves with slightly different wavelengths and the same amplitude, the resulting wave has a changing amplitude (amplitude = intensity) which varies from 2*Amplitude to 0 ...
1
vote
0answers
32 views

Angular magnification of a two-lens system

Suppose an object is a distance $d_o$ from a first lens (which has a focal length $f_1$), where $d_o>f_1$. Behind the first lens is a second lens with a focal length $f_2$, such as to produce a ...
0
votes
0answers
31 views

Microscope Objective / NA, F/#, Exit aperture - when are they non-intuitive?

Numerical aperture (NA) $= sin(\theta)$ where $\theta$ is the half-angle (see: http://en.wikipedia.org/wiki/Numerical_aperture) F/# $= \frac{f}{D}$ (same reference as above) where F/# is the ...
1
vote
1answer
48 views

What happens to light at sharp points? [closed]

At the tip of the sharp point shown, what will happen to light incident on it. This curiosity was invoked by a friend and also my childhood of watching shiny pointed swords in cartoons. Original ...
0
votes
0answers
16 views

Lens parameters / Principal Planes vs. Entrance and Exit Pupil

Under what conditions are the Principal Planes not the entrance and exit pupil? For the definition of Principal Planes see: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/priplan.html ...
2
votes
1answer
58 views

A beam of light, traveling around a planet

Some time ago, I happened to have found one problem: The refractive index of the planet's atmosphere decreases with height above the surface under the following law: $$n=n_0-\alpha h$$ ...
1
vote
1answer
102 views

Magnification of an astronomical telescope not in normal adjustment?

I am stuck on this question: A telescope consists of two thin converging lenses of focal lengths 100cm and 10cm respectively. It is used to view an object 2000cm from the objective. What is the ...
5
votes
1answer
77 views

Why is optical orbital angular momentum (OAM) called “topological charge”?

The terminology "topological charge" is frequent in lots of research papers related to optical vortex or optical OAM, it is used to represent the optical OAM. Why? How to comprehend it?
2
votes
1answer
51 views

Effect of water on an image

I am stuck on this question: "consider the image above, P is an opaque disc (lying in a glass beaker) illuminated from bellow by a source S. A converging lens L forms an image of this at Q. Explain ...
2
votes
2answers
71 views

Optical absorption in a semiconductor for $E<E_g$ [duplicate]

Quoting from Solid State Electronic Devices (by Ben G. Streetman and Sanjay Banerjee): A photon with energy less than $E_g$ is unable to excite an electron from the valence band to the ...
2
votes
2answers
44 views

does the positon of the virtual image change when I change position?

I placed a box in front of a plane mirror I looked at the image and smudged a bit of Vaseline on the mirror as a mark to indicate where I thought where the virtual image was. After that, I ...
1
vote
1answer
36 views

Increase contrast on the image taken by CCD camera

I project a pattern on a reflecting object and I capture the reflected pattern (reflected via the object) using a CCD camera. However, the reflected pattern has a very low contrast (due to volume ...
2
votes
1answer
332 views

why does the optical media have different refractive indices?

Optical density is a measure of the refracting power of a medium. In other words, the higher the optical density, the more the light will be refracted or slowed down as it moves through the medium. ...
1
vote
0answers
22 views

What are the current size limitations of NIR spectroscopes? [closed]

So few days ago I came across this new tool for smart phones http://www.consumerphysics.com/myscio/. It says it uses NIR spectroscopy, which I don't know lot about. My question is: Is it possible for ...
2
votes
1answer
39 views

Optical signal filters

Are there any optical filters which filter the signal's frequency and not based on the wavelength of the light? So what I mean is, if I have a modulated/pulsating light signal riding on a large DC ...
-2
votes
0answers
49 views
1
vote
2answers
76 views

Speed of light and distance

Our measure of distance (the meter) is defined in terms of how far light in a vacuum travels in a specific time. When light travels through another medium, we say it travels at a different speed. Why ...
0
votes
1answer
38 views

Drawing Ray diagrams

When drawing ray diagrams for concave mirrors, I was advised to : draw a ray that is parallel to the principle axis, the reflected ray will pass through the focus Draw a ray through the center (C), ...
0
votes
1answer
40 views

How to understand “the speed of propagation of the condition of constant phase”?

I still can't understand that the phase can be a constant until now. If the phase is constant, from the $$y(x,t) = a \times \sin(phase)$$ the shape of wave will be a line parallel to x-axis.But I ...
2
votes
1answer
78 views

Making fire using a filled water bottle

I have seen videos where a fire was started using a water bottle filled with water. I guess the bottle acts like a convex lens that converges light to a focal point to start a fire. But why does water ...
2
votes
1answer
79 views

Why aren't train headlights brighter? [closed]

I suspect a valid scientific, physics answer for this question, because I'd venture that train, insurance companies would've calculated and contemplated this question. Yet the train headlights at ...
0
votes
2answers
35 views

Resolution of the Eye-Light Rays and Diffraction

Please look at the problem. The problem is solved for me. However, I don't understand why the angle alpha is considered to stay constant when the rays go through the lens. The ray along the distance s ...
0
votes
0answers
22 views

What are some good resources for learning photonics?

Including the generation, transmission, modulation, signal processing, amplification, and detection/sensing of light, I am interested in getting a good understanding of photonics. Does anyone have any ...
0
votes
0answers
36 views

What is a good textbook to learn how to ray trace light through an optics system in 3d?

I can do 2d problems easily, but I need to learn more to do a 3D ray trace. Can you guys point me towards a textbook? I'm having trouble dealing with the normal and incident rays in 3D
0
votes
1answer
48 views

Why do we observe opposite motion of trees (nearer) and trees (distant) when seen from a moving frame? [duplicate]

If you are in a moving train or in a bus, what you observe is that the trees which are nearer to you move opposite to the direction of your motion. But the trees which are very far away from you, ...
1
vote
2answers
55 views

Some objects seem to have the same color whether the light that we perceive is emitted or reflected

Is color only a property of perception, considering these two examples: The glass used in a green traffic light looks green no matter how it is illuminated, either by a white light bulb behind it or ...
3
votes
1answer
29 views

Can a Chemical's Opacity be Deduced Mathematically?

all. I have tried Googling but have had no luck. My question is simple (although, I presume the answer is not): If one knows the chemical structure of, well, a chemical, could its optical properties ...
2
votes
1answer
26 views

Can a painting be used as a current generator via absorption of photons in the paint?

What happens to absorbed photons in a painting? Heat of course except for the free electrons. Could paint compounds (the dark, non-reflective) be embedded with reactive and conductive materials to ...
0
votes
1answer
35 views

Highly diminished image of an Object placed at Infinity

Consider an object at infinity. The rays coming from it are parallel to each other. Let one of the parallel rays pass through the focus $F_1$ of a thin lens, and let a second ray pass through the ...
1
vote
1answer
18 views

Calculate transparency from Beer-Lambert Law

I want to calculate a transparency parameter for a superposition of several volumes containing media using the Beer-Lambert Law, which states that $$I/I_0=exp(-\tau)$$ where $I$ is the transmitted ...
1
vote
2answers
56 views

How is photon time of flight/range over sub-millimeter distances measured?

I was reading a paper that described how the force a low-thrust torsion pendulum was measured. In it, the paper states a laser is bounced off a mirror and the displacement is "...based upon the beam ...
10
votes
4answers
887 views

Why are objects opaque?

I have been searching the internet for answers to this question, but haven't found a convincing one. I would appreciate any response. I understand why objects are opaque/black. For example when ...
3
votes
1answer
58 views

Optical absorption in multilayer structure

Assume a hypothetical 3 media/ 1 layer structure with the following indices of refraction: $$n_1 = 2, n_2 = 2+i0.5, n_3 = 1$$ where the thickness of the layer is 100 nm and wavelength = 1000 nm. ...
-1
votes
1answer
40 views

Interferometer problem about periodic fringe patterns [closed]

Please,kindly help me; my teacher assigned me problem set, and she never went over anything about interferometers in class. Also, there is almost no information about about how to solve interferometer ...
2
votes
0answers
20 views

How absorption coefficient determines which material is used to make solar cells?

Does the knowledge of the material absorption coefficients aids engineers in determining which material to use in their solar cell designs? If yes, how?
0
votes
0answers
21 views

Refractive index variation with colors [duplicate]

To explain the spectrum formation in the prism, my teacher said that different colors have different speeds in a medium, so, refractive index is different for all. So, angle is different. But I don't ...