Laser Definition and 1000 Threads

Let's suppose i want to send a message over really big (interplanetary, maybe out of the solar system) distances. I read the Rayleigh formula, but i also read the a telescope array can give even better angular resolution. Does that also means, instead of one giant laser focusing mirror...

I have a diode laser that emits multi-mode light. Two frequencies of this light are selected in an external cavity and reflected back into the laser diode. The laser diode's gain medium then resonate at these two frequencies and emits dual mode light. The laser operates in the 1550nm region...

I just saw an article regarding NASA's Lunar Probe that will use lasers to communicate high resolution images and data from the Earth to the probe for faster comms. My question is...in Outer Space with no atmospheric influence, at what distance would laser communications like this remain...

I can't figure this out. Say 2 frames are in relative motion. When the origins at at the same place, 2 lasers shoot up the positive x-axis and negative x axis. Let's call the 2 frames F and F'. F says the lasers will always hit simultaneous events along the x-axis. Then by the relativity of...

For some reason, can't delete this thread... thank you, UltrafastPED, the below video was very helpful!

Hello, I have to conduct a literature review in regards to Laser Doppler Anemometry and Impinging Air Jet. I am doing a project and it is to compare real velocity data obtained from LDA to CFD data and was wondering if anyone had any good books they could recommend for me to read or good...

Hi, I'm trying to set up a microscope to have wide-field laser epi-illumination. This is to be used with an infinity-focused objective lens. My current plan has the laser expanded 4x using a Galilean beam expander (from 1mm to 4mm) and coupled into the back of the objective using a...

Does anyone know of an article that has a good in-depth, side by side comparison of DFB edge emitting lasers and VCSEL lasers? From my research it seems to me that the VCSEL papers are all trying to justify why laser production should shift towards VCSEL, and mostly list the advantages over an...

Hello, I was hoping someone might be able to help explain what the following are, I have found many articles but non which explain it in Lehman's terms: Probe Volume Bragg Cells Also can someone explain how the effect of varying beam angle is not under our control, but it can tell us...

Hello, this is my first post to this site. I had this idea a few nights ago, and I've been trying to wrap my head around it. Before I go ordering supplies to run some tests, I thought it would be worthwhile to gain some insight from you guys. Anyways, as you probably know, total internal...

Homework Statement So basically I'm given the distance to the moon (384,000,000 meters), and I need to find out how many degrees per second I'd need to move the laser for the spot touching the moon to move faster than the speed of light. Homework Equations w=\frac{v}{r} The Attempt...

In my lab I have a TEM00 laser, so there is no electric or magnetic field in the direction of propagation (call it z direction). However, I know that the intensity of the laser is greatest when my eye is along z direction...why? If there is no electric field along this direction, then what is...

Greeting PFers, I need to use the low pressure region inherent within the cross section of a laser beam for a project. However, I don't know how to calculate the necessary laser power to generate a sufficiently low pressure. The topic is briefly dicussed *here*, but I see no relevant...

I'm new to laser technology and learning it from some lecture videos and a textbook "Optics & Lasers". When I came to the light amplifier part, I got stuck in understanding the difference between "rapid decay" and "metastable state" -- what I can recite now is that "rapid decay" cannot...

Hi, I was wondering if someone could tell me what the best way would be to determine if a semiconductor laser is broken using a multimeter? I have a semiconductgor laser that is still emitting but the signal appears lower than expected and it is hard to tell if it is broken internally...

I wasn't sure where to post this question, so I posted it here. As the title suggests, I want to know how to calculate (at least roughly) the electric field induced by excitation and ionization of a material (such as a metal) using a high intensity laser. My final goal is to compare the...

Hey guys, I'm wondering how come if we're in a completely dark room and shine a laser beam at an object, we see the color of the laser beam (say it's red). How is this consistent with the the theory that objects appear a certain color since that is the frequency of light that they reflect? For...

i am just being curious about some details about how laser can induce charges inside a glass bulk? Does anyone else have more knowledge on this?

Homework Statement A circular cannister of some reflective liquid is spinning at some ω. The distance between the cannister and the surface is given by h(r) = h(0) + (ω2/2g)r2 Where g ≈ 9.82 and r is the distance to the axis of revolution. When we shine two parallell laser beams on the...

what is the source of the first photon in the laser ? i understand there is a burst of light or electricity that excites up the medium , but what is the source of the first photon ? is it the light source or is it one atom of the medium itself releasing photon as it gets de-excited * if...

I have a vertically linear polarized laser according to specs. "Polarization ratio 100:1; Vertical linear polarization". However, When I place a polarizer in front of the laser its maximum is at 132 deg. and minimum is at 42deg. Thats 90 degrees apart.. Placing two polariazer infront of...

Hi Please help me to know : if i have a laser beam with 5 millimeter diameter that reduced to 0.5 millimeter diameter with a lens, Can i reduced the 0.5 millimeter diameter beam to 0.05 or less that 0.5 with another the same lens...

Hello all, I'm a new Mechanical engineering graduate student who needs help using a photodiode. I'd like to rig up some kind of circuit that will let me measure the intensity of laser light. This is kind of a new area for me haven't really done anything like this before so forgive me if I come...

Hi, I am just about to go into my 3rd year of my Mechanical Engineering Degree and have decided to do a project with the following description: "Laser Doppler Anemometry (LDA) is a non-intrusive technique used to measure flow velocities and turbulence quantities in a fluid flow. The...

Hello, I am working on a system where a laser does something and then there is a lot of wasted laser radiation. I want to capture this waste radiation in a small array of solar cells then feed the resulting current back into the laser to make it more efficient. The output from the solar cells...

Hi I have a laser beam(engraving laser machine) and then use a lens for focus the beam but my lens has a crack on the center of lens and when i use my laser in high power the beam diameter will bigger and burning area zone is bigger so: 1- Does the crack doesn't let the maximum focus?in law or...

Many nations are developing hi-energy laser weapon. My question is, what if target is coated with mirror like coating? Can laser (since laser is still light) penetrate mirror? If it can then how is it possible? Regards

Good morning, Before all, I also posted a question to maths forum, but I am convienced that this is the forum I was more like looking for. Firstly, hello to this forum, secondly I want to apologize if this is not a place I would like to post a question like that, maybe in another thread ?; )...

Hello, I've been helping a graduate student out with his project which is planar laser-induced fluorescence. Part of the procedure involves generating a laser sheet with which to illuminate over the flame under study. Now, typically a usual procedure involves using a beam expander to...

Hi, I wanted to ask some questions about lasers. I'm pretty bored with school and want to work on a project for a while. I though of maybe trying to build a laser, mostly because it's really awesome, it sounds like a project that would be challenging but also teach me a lot, and it's sort of...

Hi there, I'm working on fiber lasers and I'm interested in getting up to speed with the topic of mode-locked fiber lasers. However, I can't seem to find resources suitable for me at this current stage, hope that you guys can help recommend a suitable review paper, book or anything that's...

Hello, As stated in the title, I've just completed a first year in physics and am interested in working in the field of laser science. Bear with me, as my questions may sound naive. Ideally, I would like to hear from those currently in the field, but any advice is welcome. 1.) Did you begin...

What is the best way to calculate the coherence length of a laser?

Hello, I need to figure out how to mathematically model via simulations a solar pump in space, or another type of laser that receives input from solar irradiation from the Sun. Amplifies it to the specified frequency i.e. 1064μm, and then transmits it to Earth. The problem is I'm just...

Fresnel biprism sorry if this is the wrong place. Does anyone know a supplier for a Fresnel biprism with apex angle approx 168° should be reasonably small (approx 2cm x 2cm). Looked everywhere but no joy.

I have a question that I haven't found any information elsewhere on how to approach. Just because yahoo answers seemed particularly keen to sniff out homework and mock those asking questions by it, just to clarify this is for my own knowledge not for any project for school or anything. Anyway, I...

Is the laser perfect monochromatic light source?

Homework Statement A transparent cube with index of refraction n = 1.6 and side length a = 4.0 cm is free to rotate about an axis passing through its center. A laser beam is aimed at the cube. After passing through the cube the beam hits a screen on the other side forming a spot. The spot is...

Hi, I was wondering what the diffraction pattern would be like if the suns light is diffracted through a pin hole or double slit diffraction grating compared to that of a laser beam? thanks.

Hi. I am interested in medical physics, but I also like to become a laser scientist. If I have a masters in medical physics can I go straight to laser physics Phd, if not what better option can I take after having master in medical physics.

Hi I'm a first year undergrad student studying Electronics. I am really interested in creating a working Laser Induced Breakdown Spectroscopy(LIBS) setup in my summer break which is June and July. I'm reading about it these days, although still scratching the surface. I'm confused whether I'll...

Homework Statement a narrow beam of laser light (i.e coherent monochromatic light) wavelength 630nm is incident on a grating having 300 lines per mm. a piece of paper is curved 180 degrees beyond the grating. calculate how many spots of red light should be seenHomework Equations...

Homework Statement A collimated laser beam of power P = 106 Watt illuminates a 100%-reflecting micromirror at an angle of incidence of θ=30 for duration of = 0.015 seconds. Prior to laser illumination, the mirror is at rest. What is the mass of the mirror m if it acquires velocity of 1...

Hi forums I really want to do some experiments with lasers and i was wondering if for the double slit experiment a 100mw green laser is so powerful and bright. also there is a 30mw laser, would that be better. another thing is that i wanted to make a laser "microscope" but i was worried that a...

Would you pay for this?

Lets say its the future your camera has an insanely fast shutter speed. You're standing on the ground watching a train travel past at just under the speed of light and the train driver is shining a laser pointer out the front window. With your insanely fast reflexes you take a take a picture of...

Hey everyone, hope this is the right place to ask this question so I'll just put it out here. I've been measuring the pulse duration of a mode locked Ti:Sa laser with an autocorrelator. For a central wavelength of λ_0 = 800 nm and the spectral bandwidth of the Ti:Sa Laser (FWHM) Δλ = 8 nm, the...

Hello there! I was brainstorming a lot when I took a walk today. Not that I posses any type of degree in communication, although I find it interesting of IT communication and they techniques we use for cellar communication. NOW to what I thought about. Let's have an example: If I were to...

Homework Statement I am doing a lab and need to understand how laser light from a HeNe laser goes into a Si photodiode connected to a lock in amplifier, which I believe is simply a device for measuring potential, works. Homework Equations The Attempt at a Solution This lab was...

A simple model of a laser (URGENT!) Homework Statement [SIZE="6"]Need to turn this in 2 hrs from now. Yes, I'm a slacker. (a) Suppose that N evolves much more quickly than n so that we can make the quasi-static approximation N ≈ 0. Given this approximation, re-write our equations as a 1-D...