Laser pointer discussion. Read/write reviews of laser pointers and laser pointer companies. Learn about all types of laser pointers and lasers





Welcome to Laser Pointer Forums! If you are looking for a laser pointer or want to compare different laser pointer companies, you may want to check out the LPF Laser Pointer Company Database. The link will open in a new window for your convenience.








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes
Laser Technology Laser Pointer Parts Lasers by Wavelength
Top 10 Laser Pointer Companies Laser Pointer Company Database Visible Beam Laser Pointers


One laser store meets all your needs

























Go Back   Laser Pointer Forums - Discuss Laser Pointers > Lasers > Science & Lasers



LPF List of Laser Pointer Companies (link opens new window)



Reply
 
LinkBack Thread Tools Display Modes
Old 06-01-2010, 01:45 PM #1
Junior Member
 
Join Date: May 2010
Posts: 9
Rep Power: 0
ewolfe3 is on a distinguished road
ewolfe3 ewolfe3 is offline
Junior Member
 
Join Date: May 2010
Posts: 9
Rep Power: 0
ewolfe3 is on a distinguished road
Question Simple Explanation of Second Harmonic Generation

I realize that SHG is just frequency doubling, but how?

Specifically, I've been told by my professor that when two beams meet at a pinhole in our optics setup and are in phase, that we will be able to see blue light? Is this due to wavelength?

Points for keeping the explanation simple.


ewolfe3 is offline   Reply With Quote







LPF List of Laser Pointer Companies (link opens new window)







Old 06-01-2010, 01:51 PM #2
bobhaha's Avatar
Class 3B Laser
 
Join Date: May 2009
Location: Sydney, Australia
Posts: 3,256
Rep Power: 360
bobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond repute
bobhaha bobhaha is offline
Class 3B Laser
bobhaha's Avatar
 
Join Date: May 2009
Location: Sydney, Australia
Posts: 3,256
Rep Power: 360
bobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

Not too sure, but I have a feeling that this would be due to harmonic excitation of the material, rather then the properties of light. I know superposition of waves increases amplitude (intensity), but I do not understand how that could cause a shift in wavelength, other then for the reason I just mentioned. In any case the effect would be shifting the wavelength to the shorter wavelengths (assuming your information is correct) and thus pushing it into the blue section of the spectrum. Like wise if the waves were perfectly out of phase, it would do the opposite and shift to the red side of the spectrum (again assuming your information is correct).

Hopefully some one can fill in the blanks.... -Adrian
__________________
Lasers!
10.6um - >40W CO2 Laser - 25W RF excited CO2 Laser*
685nm - Being built!
660nm - 250mW LOC PowerLight B50 Host - 100mW WL pulsar
635nm - 430mW C6 Host*
632.8nm - Red He-Ne laser ~1mW
593.5nm - Regal 5
542.8nm - Green He-Ne laser ~2.5mW
532nm - 620mW+ lasersman Firedragon III* - 100mW PGL-III-M from JETLASERS* - 70mW Rayfoss Host*
~~~ - 175mW Rayfoss Host - <5mW WL Core - 55mW DinoDirect review laser*

488nm - On the hoist
473nm - 2x CNI lab lasers ~40mW
445nm - 3W Big Boyz Laser - >1.1W Cree C6 Host - 650mW WL Arctic
405nm - 65mW GLP-405 Aquarius host - 160mW 6x Blu-ray MXDL Host
Total: 71,868.5 mW

Goggles!
Laser glow LSG-532-Sport protective eye goggles OD 7+ 190-532nm HIGHLY RECOMMENDED!!
Jetlasers wrap around 190-540nm OD4+ goggles*
Eagle Pair Red OD4+ goggles
Scopeguy20 Blublockers for 405nm lasers!

* indicates a review has been done, on this item.

Check out my How to Build a Selectable Dummy Load Thread!

Last edited by bobhaha; 06-01-2010 at 01:54 PM.
bobhaha is offline   Reply With Quote
Old 06-01-2010, 01:55 PM #3
Junior Member
 
Join Date: May 2010
Posts: 9
Rep Power: 0
ewolfe3 is on a distinguished road
ewolfe3 ewolfe3 is offline
Junior Member
 
Join Date: May 2010
Posts: 9
Rep Power: 0
ewolfe3 is on a distinguished road
Default Re: Simple Explanation of Second Harmonic Generation

A point of clarity. Our laser will be at around 800nm wavelength. This beam will be split into a main beam and a probing beam, that will then converge at this pinhole. This will result in blue light... somehow?

Last edited by ewolfe3; 06-01-2010 at 01:57 PM.
ewolfe3 is offline   Reply With Quote
Old 06-01-2010, 01:55 PM #4
Class 4 Laser
 
Join Date: Nov 2008
Posts: 5,728
Rep Power: 547
ElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond repute
ElektroFreak ElektroFreak is offline
Class 4 Laser
 
Join Date: Nov 2008
Posts: 5,728
Rep Power: 547
ElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

To explain the full SHG process is not a simple affair, but the following link explains things about as simply as possible:

Encyclopedia of Laser Physics and Technology - frequency doubling, frequency-doubled laser, second-harmonic generation, SHG, design, physical mechanism, pulses

But basically two photons with lower energy are combined to form one photon with twice as much energy, and thus twice the frequency.. but the process is quite a bit more complex in reality and has little to do with the photons themselves, instead it has to do with incoming waves and their frequencies.
__________________
Laser Resources (for n00bs and veterans alike!)

Sam's Laser FAQ (The Laser Bible)

http://www.repairfaq.org/sam/laserfaq.htm

RP Photonics Encyclopedia of Laser Physics and Technology

http://www.rp-photonics.com/encyclopedia.html

ULTIMATE DIY PROJECTOR REFERENCE

http://nqlasers.com/scannerreference...itle=Main_Page

SUCCESS is the best revenge.
ElektroFreak is offline   Reply With Quote
Old 06-01-2010, 01:58 PM #5
bobhaha's Avatar
Class 3B Laser
 
Join Date: May 2009
Location: Sydney, Australia
Posts: 3,256
Rep Power: 360
bobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond repute
bobhaha bobhaha is offline
Class 3B Laser
bobhaha's Avatar
 
Join Date: May 2009
Location: Sydney, Australia
Posts: 3,256
Rep Power: 360
bobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

ok... I'm obviously wrong.... ohh well gave it a shot
__________________
Lasers!
10.6um - >40W CO2 Laser - 25W RF excited CO2 Laser*
685nm - Being built!
660nm - 250mW LOC PowerLight B50 Host - 100mW WL pulsar
635nm - 430mW C6 Host*
632.8nm - Red He-Ne laser ~1mW
593.5nm - Regal 5
542.8nm - Green He-Ne laser ~2.5mW
532nm - 620mW+ lasersman Firedragon III* - 100mW PGL-III-M from JETLASERS* - 70mW Rayfoss Host*
~~~ - 175mW Rayfoss Host - <5mW WL Core - 55mW DinoDirect review laser*

488nm - On the hoist
473nm - 2x CNI lab lasers ~40mW
445nm - 3W Big Boyz Laser - >1.1W Cree C6 Host - 650mW WL Arctic
405nm - 65mW GLP-405 Aquarius host - 160mW 6x Blu-ray MXDL Host
Total: 71,868.5 mW

Goggles!
Laser glow LSG-532-Sport protective eye goggles OD 7+ 190-532nm HIGHLY RECOMMENDED!!
Jetlasers wrap around 190-540nm OD4+ goggles*
Eagle Pair Red OD4+ goggles
Scopeguy20 Blublockers for 405nm lasers!

* indicates a review has been done, on this item.

Check out my How to Build a Selectable Dummy Load Thread!
bobhaha is offline   Reply With Quote
Old 06-01-2010, 03:41 PM #6
Benm's Avatar
Class 4 Laser
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Benm Benm is online now
Class 4 Laser
Benm's Avatar
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

I doubt there is any sort of simple explanation.

First, you should look at how light travels through a medium: Something with a refractive index higher than vacuum interacts with light, which "causes" it to travel slower through such a medium. This interaction is between the incoming photon and the electrons in the material, and normally only results in the light travelling slower in the medium than it would trough free space.

In some materials, it is possible for 2 photons (of equal energy and phase) to interact with an electron at the same time, resulting in absorption of the photon and re-emission of a photon at double energy.

With other materials the reverse is also possible, but that would probably be to far to get into, and i'm not sure how much practical application it has.

... and this is as simple as i can put it, the actual physics involved are far from easy to understand
Benm is online now   Reply With Quote
Old 06-01-2010, 04:30 PM #7
pullbangdead's Avatar
Class 3R Laser
 
Join Date: Aug 2007
Posts: 2,045
Rep Power: 238
pullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond repute
pullbangdead pullbangdead is offline
Class 3R Laser
pullbangdead's Avatar
 
Join Date: Aug 2007
Posts: 2,045
Rep Power: 238
pullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond reputepullbangdead has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

Simply responding to your question about 2 beams at a pinhole: No, two 800nm beams meeting at a pinhole will not give you 400nm light.

Second harmonic generation happens inside a nonlinear crystal, and it is the crystal's interaction with the light that generates the second harmonic.
pullbangdead is offline   Reply With Quote
Old 06-02-2010, 01:24 AM #8
Benm's Avatar
Class 4 Laser
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Benm Benm is online now
Class 4 Laser
Benm's Avatar
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

Indeed, as far as i know free space doesnt allow frequency doubling using slits, pinpoints and such.

In air, this might be different because that does break down at a certain field gradient, usually resulting in a sprak rather than any doubling effect.
Benm is online now   Reply With Quote
Old 06-03-2010, 04:27 AM #9
ossumguywill's Avatar
Class 3R Laser
 
Join Date: Jul 2008
Posts: 2,138
Rep Power: 55
ossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond repute
Send a message via AIM to ossumguywill Send a message via Skype™ to ossumguywill
ossumguywill ossumguywill is offline
Class 3R Laser
ossumguywill's Avatar
 
Join Date: Jul 2008
Posts: 2,138
Rep Power: 55
ossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond repute
Send a message via AIM to ossumguywill Send a message via Skype™ to ossumguywill
Default Re: Simple Explanation of Second Harmonic Generation

BTW it's worth noting that you can't increase the amplitude of a photon without increasing the frequency. That's why it works, instead of just giving you a more powerful 800nm photon.
ossumguywill is offline   Reply With Quote
Old 06-03-2010, 11:01 AM #10
Benm's Avatar
Class 4 Laser
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Benm Benm is online now
Class 4 Laser
Benm's Avatar
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

I'd rather say 'energy' than 'amplitude' there... if its about light, amplitude would probably refer to intensity, or the number of photons (per unit of time).
Benm is online now   Reply With Quote
Old 06-03-2010, 06:15 PM #11
ossumguywill's Avatar
Class 3R Laser
 
Join Date: Jul 2008
Posts: 2,138
Rep Power: 55
ossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond repute
Send a message via AIM to ossumguywill Send a message via Skype™ to ossumguywill
ossumguywill ossumguywill is offline
Class 3R Laser
ossumguywill's Avatar
 
Join Date: Jul 2008
Posts: 2,138
Rep Power: 55
ossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond reputeossumguywill has a reputation beyond repute
Send a message via AIM to ossumguywill Send a message via Skype™ to ossumguywill
Default Re: Simple Explanation of Second Harmonic Generation

Quote:
Originally Posted by Benm View Post
I'd rather say 'energy' than 'amplitude' there... if its about light, amplitude would probably refer to intensity, or the number of photons (per unit of time).
That's a good point, when talking about light people usually use amplitude and intensity to refer to the same thing, because very rarely would you need to discuss the amplitude of a photon did you know that the first speedometers worked by shooting a helium laser at a very precise frequency at a moving car, and the energy of the impact with the car changed the reflected frequency enough to measure speed? Now they use interferometry, but I thought that was cool.
ossumguywill is offline   Reply With Quote
Old 06-07-2010, 03:07 PM #12
Benm's Avatar
Class 4 Laser
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Benm Benm is online now
Class 4 Laser
Benm's Avatar
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,439
Rep Power: 18210
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Default Re: Simple Explanation of Second Harmonic Generation

I suppose you mean they used doppler lidar to calculate the speed? Guess that would work fine as long as you can measure the reflected wavelength very precisely, since the shift would be that great... a speeding car is pretty slow compared to light speed
Benm is online now   Reply With Quote
Reply





Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On











Loading








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes






Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 02:15 PM.


Powered by: vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC