Optical Definition and 640 Threads

Why is it that we are able to use a laser beam with optical fiber but not with a white light source?

In order to produce coherent laser light is it necessary that the length of optical cavity between the mirrors is a multiple of the wavelength of laser light? I cannot see how otherwise the laser been could bee coherent. On the other hand I don't see how it is possible to place the mirrors with...

[SOLVED] Optical absorption in Semiconductors Homework Statement I'm doing a lab report on the optical absorption of semiconductors. More specifically it was to determine the bandgap values of the semiconductor samples. This is the experimental setup...

1.A rectangular loop and a Circular loop are moving out of a uniform magnetic field to a field free region with a constant velocity V.In which loop the induced e.m.f is constant during the motion of the loop. 2.Name two Physical quantifies other than velocity,wavelength and C,associated with...

Hi Everyone! I was wondering if someone could help me with Optical Depth, I read some articles about it but since my English isn't that good I couldn't Get it well! I have some views about the Opacity But when it comes to optical depth I'll get lost :D help!

Can anyone solve me these questions, please 1. A convergent lens has one 8 cm focal length. One places a 2 cm height object at 4 cm of his optical center. Find the various characteristics of the image obtained. 2. A divergent lens has one 8 cm focal length. One places a 2 cm height object...

I can't find any useful page which explains in detail how to calculate the equivalent resolution of an optical interferometric telescope. I found out, after LONG search, the formula to calculate standard-telescope resolution: Resolution (Km) = 5,5680 * 10^-4 * Distance (Km) / diameter (mm)...

Homework Statement Multipath dispersion of a pulse of light in an optical fiber. How is this problem solved?

Help Needed! Optical extinction Homework Statement Spherical cloud (gas to dust ratio 100) with mass = 1 M(sun), diameter = 1pc. Radial density can be described by power law (see below). Determine the maximum optical extinction, ie. the function A_{v}(\alpha). Homework Equations Power...

I am doing some research on atomic clocks. From what I have read, I understand that in Rb atomic clocks you: -optically pump a cell of Rb, so that the electrons are all in a single hyperfine state -subject the cell to microwaves of appropriate frequency, so that the electrons will be...

Why do all rays coming from far off distance from a source(may be planar)... converging at a point need to travel the same Optical Path Length(OPL)

Now I can obviously just search the internet for information about what these areas of physics are about, but what I want to know is more specific information about these areas that I can't find. Like what areas of Physics are used in Optical physics or maybe more specifically Quantum...

I saw an article http://www.washingtonpost.com/wp-dyn/content/article/2007/01/18/AR2007011801683.html which is talking about how creating a device that slows down light would be necessary to make optical computers. My question is is there already a way to slow down electricity because...

Hello, I have been given an assignment to design an optical communication system. A 12 MHz LED (laser diode would be too easy) signal has to be sent 45km via optic fibre and read at the other end. Simple enough, you may think. however I have been told that I have to use multimodal cable...

Why is the outermost ring of an optical encoder the least significant bit? Is this somehow related to frequency?

Basically, I have a project involving thermally tunable photonic crystals and part of the essay in the run up to the experiment work I want to write a bit on the thermo optical effect, but I have searched in vain for a resource for this. Can anyone suggest a textbook or something online? Thanks.

Hello! I have a problem - a non-physics student has asked: "Why do I see my face upside down on one side of a spoon, while it is O.K. on the other side?" How to explain it? The only method I thought of was geometrical optics. Is it possible to clarify this phenomenon without drawing...

Homework Statement "figure 3" (below) shows an optical fibre bent in a curve. The diameter of the fibre is 4mm. If light is not to escape, calculate the smallest radius of R of the curve round which the fibre can be bent. Assume that the fibre is surrounded by air (refractive index 1) and...

I'm currently working towards a masters in mechanical engineering, however I plan to focus in physics once this is complete. Which Mechanical Eng class would be most relevant towards a future in physics? - Kinematics and Mechanisms - Traditional Kinematics of mechanisms, joints...

Hello All, this is my first post, and while I'm a newb to the forums I'm not a newb to Optics. However, I have a very light background in low level electromagnetics, I'm more of a network design person. I'm working on a very very long term personal project to understand optics better and I've...

Hello, Supose you have an U tube, in which the inner walls are made absolutelly reflective. Now, put a termical state (temperature T) for the radiation field inside the tube and close it with reflective discs which can slide without friction. Supose further that de diameter of the tube in its...

Hi guys, can anyone help me with this question?- An optical fiber has a loss of 0.8dB/km at a wavelength of 1250nm. If 120uW of power is injected into the fibre at the transmitter, how much power would be lost at a distance of 20km down the fibre, also calculate the energy loss over a 24hr...

I thought optical phonons only existed in crystals with two or more types of atoms in a unit cell. But I keep reading references of optical phonons in single atom crystals, like silicon. What's the deal here?

Okay, I'm writing about optical spectrum analysers as part of my AS coursework, but I've been having some problems finding more in depth information on how they work. Can anyone explain to me how they work? Or link me to a website that can tell me? Thanks,

For the molecule \textrm{Ni}\left(\textrm{OH}\right)_{2}\textrm{Cl}\left(\textrm{NH}_{3}\right)_{3}, how do you determine the number of geometric and optical isomers? I first drew the molecule with a central \textrm{Cl} bonded to three \textrm{NH}_{3} molecules and a \textrm{Ni}; the...

Hi, I am curious to know what is a typical numerical value for the attenuation coefficient of common optical fibre. Please don't include anything strange in the units like dB since I am new to that. Thanks.

Homework Statement Explain why there is no optical phonon in the dispersion curve for the one-dimensional monatomic chain of atoms. The Attempt at a Solution I am completely confused. I know that optical phonons get their name because when an array of 2 atoms of different charge...

You are taking pictures of the beach at sunset. Before the Sun sets, a shutter speed of 1/125 s at f/11 produces a properly exposed picture. Shortly after the Sun sets, however, your light meter indicates that the scene is only one third as bright as before. (a) If you don't change the...

What is "optical coupling" ?? This may problem may sound stupied, but what is "optical coupling" ?? I did surf the net to find some information, but I can't find the definition of optical coupling, and I can't even find it in "Encyclopedia of Modern Optics". Could someone please tell...

why is it impossible to generate a purely optical standing wave? thanks in advance

Try it, its creepy. Its probably best to click "Maximize" at the top right of the video before playing. http://emuse.ebaumsworld.com/watch/5850

hi do anyone of you know optical tweezers... these are used in manipulating nanoparticles... any of u if ur working or familiar in nanotechnology or optical tweezers.. it would greatly help me... please reply thanks in advance

Homework Statement Needan optical sensor to detect a dot sequence on widgets passing 50cm away from the sensor. Want each dot to exactly cover the sensor. If the dots are 10mm in diameter and the sensor is 40mm in diameter, what is the position and focal length of the lens to do the...

hye.. i want some theoratical detail on optical model of nuclear reactions.. no hard mathematical detail. just theoratical explanation of things ... thanx...:smile:

Hi, I have to do a rediometric analysis on an optical system , basically calculate how much radiant power goes through an optical system from the target to the detector, passing through multiple lenses and prisms then to the detector. I am having some problem with radiance and irradiance...

Hi. I'm asked the following question: What isomers does the complex [\text{Fe}(\text{H}_2\text{O})_6] give rise to? Is it optically active? My answer to the first question would be 'none': The 6 identical H2O molecules are arranged in an octahedral fashion around the central Fe-atom, so...

Snapped this pic the other day. At first, I was drawn by the subtlety of the central tip of the cloud, which is illuminated by reflected light from the sunlit mound of cloud between it and us, but I was wowed by these fanlike structures in the sky above the cloud. Those are not digital...

hey guys, For those of you who use optical mouses, have you noticed any kind of weird behaviour like the cursor crawling up the screen diagonally? This happens especially when you don't do anything and just leave the mouse by itself...I was wondering does anyone know why this happens and...

When an optical field is written as: E=A_1e^{i(\vec{k}\vec{r}-\omega t)}+A_2e^{i(\vec{k}\vec{r}-\omega t)}+c.c what does the c.c. for?

Hi to everyone... I had a silly question to ask... I know that the light in a fiber travels faster than a electromagnetic signal in a wire. I was wondering how photodetectors work because we all know that they convert the ligh to electromagnetic signals. But if the light travels faster than the...

Are topics on Optical Engineering also included in this subforum?

If you have two photons traveling in opposite directions, that destructivly interfere witheachother, is energy conserverd0? Is the E, in E=hf a vector quantity, that will take in account the directions in which they are travelling? I believe the answer has something to do with treating the light...

Hi, I need to do an experiment to calculate Planck's constant from LEDs. Basically what I'm intending to do is a fairly simple variable dc supply->voltmeter->LED->spectrometer->diffraction grating->my eye type setup. I know how to do that, but the trouble is I'll need to track down a...

I read the instruction on how to make a hologram at http://www.3dimagenery.com and it says that you need optical table in order to make a hologram but the optical table is quite expensive for me . So, I want to ask that can I make the hologram as in the 3dimagenery website without using a...

We are all familiar with the illusion of the wheels on a car on television appearing to spin backwards when the car is traveling forward, this being caused by a mismatch of the picture frequency and the wheel's rotational speed. However I have also observed this phenomenon in the real world...

Can anyone tell me the reason why an enatiomer rotates the plane of polarised light? Or at least tell me where i can read more on the reason why some compounds exibit optical activity. Thanx Saurya

The group velocity is always negative except k=0 and k=Pi/a in the optical mode, is there a reason from the general picture of crystal vibration? Well, it seems to me that optical mode describes the situation that different atoms in a unit cell have opposite motions. Also, in the optical...

How optical mouse to work? What's principle of the physics? thanks b4

How does an optical computer mouse know which way it is moving?

Hi do u know what phase velocity is>? I have found it a boot for optical fibers vp=1/(srqt(em) m denotes greek m letter