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 05-05-2009, 08:07 PM #1
Junior Member
 
Join Date: Nov 2008
Posts: 5
Rep Power: 0
sacapuntas is on a distinguished road
sacapuntas sacapuntas is offline
Junior Member
 
Join Date: Nov 2008
Posts: 5
Rep Power: 0
sacapuntas is on a distinguished road
Default Polarizer question. Help needed please.

When you polarize a laser beam, then polarize it again with a second polarizer - perpendicular to the first - no light comes through, right? But when you put a third polarizer in the lineup and adjust the angle, the beam reappears. Why is this? What makes it come back?


sacapuntas is offline   Reply With Quote







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







Old 05-06-2009, 01:17 AM #2
Banned
 
Join Date: Oct 2008
Posts: 245
Rep Power: 0
deam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the rough
deam_87 deam_87 is offline
Banned
 
Join Date: Oct 2008
Posts: 245
Rep Power: 0
deam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the rough
Default

where did you see this? was it by experimentation?..... and what do you mean by "adjusting the angle"??
deam_87 is offline   Reply With Quote
Old 05-06-2009, 02:38 AM #3
Junior Member
 
Join Date: Nov 2008
Posts: 5
Rep Power: 0
sacapuntas is on a distinguished road
sacapuntas sacapuntas is offline
Junior Member
 
Join Date: Nov 2008
Posts: 5
Rep Power: 0
sacapuntas is on a distinguished road
Default

Yes, I did it in a lab. Sorry, I didn't explain that very well did I? By adjusting the angle, I meant rotating the third polarizer to some angle other than that of the first and second. For example, the first would be adjusted to "0 degrees", the second would be perpendicular to that, "90 degrees", and the third would be anywhere in between those two. It was the weirdest thing. The first two completely blocked out the beam, which makes perfect sense, because putting two polarizers together, one perpendicular to the other, blocks all incoming light. But I can't figure out how adding a third polarizer makes the beam reappear (intensity of the beam is significantly less). Does that help?
sacapuntas is offline   Reply With Quote
Old 05-06-2009, 05:15 AM #4
Banned
 
Join Date: Oct 2008
Posts: 245
Rep Power: 0
deam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the rough
deam_87 deam_87 is offline
Banned
 
Join Date: Oct 2008
Posts: 245
Rep Power: 0
deam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the roughdeam_87 is a jewel in the rough
Default

.... no haha, ive never heard of that before, but ima research it...


Edit...
Seems pretty darn interesting, but there is quantum physics involved in the explanation ... here is a link that describes it at "our level" hahaha

http://alienryderflex.com/polarizer/

Last edited by deam_87; 05-06-2009 at 05:23 AM.
deam_87 is offline   Reply With Quote
Old 09-24-2009, 07:38 AM #5
rathat's Avatar
Class 1M Laser
 
Join Date: Jul 2008
Location: Philadelphia, PA
Posts: 143
Rep Power: 10
rathat is on a distinguished road
rathat rathat is offline
Class 1M Laser
rathat's Avatar
 
Join Date: Jul 2008
Location: Philadelphia, PA
Posts: 143
Rep Power: 10
rathat is on a distinguished road
Default Re: Polarizer question. Help needed please.

Because it doesn't just block light not polarized to the filter, but actually changes the angle of some of it, in a way. Its weird. Light closest to 0 degrees will go through and light at a further angle going through will come out with a lower magnitude. from 0 to 90 none will go through but from 0 to 45 lets say the light looses 50% of the magnitude and 45 more to 90 will loose another 50% now that is not 100% the light at the end will have 25% of the original magnitude.
rathat is offline   Reply With Quote
Old 09-24-2009, 10:46 AM #6
HIMNL9's Avatar
Class 4 Laser
 
Join Date: May 2009
Location: Lost somewhere in the EU mess ;)
Posts: 5,416
Rep Power: 404
HIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond repute
HIMNL9 HIMNL9 is offline
Class 4 Laser
HIMNL9's Avatar
 
Join Date: May 2009
Location: Lost somewhere in the EU mess ;)
Posts: 5,416
Rep Power: 404
HIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond reputeHIMNL9 has a reputation beyond repute
Question Re: Polarizer question. Help needed please.

Are you sure that the middle plate is still a polarizer ?

After all LCD works in this way (the liquid layer rotate 90 degrees the polarization of the passing light), so maybe also other substances can do this ..... just a thought
__________________
High Impulse Multipath Neutron Laser (mark 9 ) (LOL)
Dare mo mita koto no nai, kaze, kumo, suna, umi ..... Kokoro no hate no doko ka eien ga kagayaku.
HIMNL9 is offline   Reply With Quote
Old 09-24-2009, 04:39 PM #7
Benm's Avatar
Class 4 Laser
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,442
Rep Power: 19481
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: 7,442
Rep Power: 19481
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: Polarizer question. Help needed please.

It does work like this.

What a polarizer does, is take whatever fraction of the total amplitude of the incoming light is in its pass-orientation. This fraction of the light is then emitted from the other end - polarized in the pass direction.

If you have 2 polarizers at 90 degree angle to eachother, they will block all light.

If you add a third at 45 degree angle between the two, that will take half of the light of the first polarizer, and rotate it to 45 degrees. The final polarizer will be able to pass half of that, and emit it at a total rotation of 90 degrees.

Notice that while the beam does 'pass', it will have lost 75% intensity in the process.
Benm is online now   Reply With Quote
Old 09-25-2009, 01:22 PM #8
Class 3B Laser
 
Join Date: Jan 2009
Location: Spain, tarragona
Posts: 3,635
Rep Power: 219
Hallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond repute
Send a message via MSN to Hallucynogenyc
Hallucynogenyc Hallucynogenyc is offline
Class 3B Laser
 
Join Date: Jan 2009
Location: Spain, tarragona
Posts: 3,635
Rep Power: 219
Hallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond reputeHallucynogenyc has a reputation beyond repute
Send a message via MSN to Hallucynogenyc
Default Re: Polarizer question. Help needed please.

ahhh, the third one is put between the other 2! I thought you meant you added this last one at the end and that the light was just "appearing" lol
__________________
The difference between an ignorant and a wise is that the wise knows the limits of his knowledge while the ignorant ignores the limits of his ignorance.
Learn how to use Opera and tell me about your experience here!


Wicked Lasers Evolution Pro 130mW ------------------> Review
Rayfoss 150mW waterproof
Rayfoss 200mW focusable torch -----------------------> Review
Dealextreme 5mW true laser pointer
Dealextreme 50mW true laser pointer
Dealextreme 100mW true laser pointer
Laserlands 30mW disco laser --------------------------> Review
5mW pointers (many of them)
DX 200mW Red laser (Dilda) --------------------------> Review
120mW PHR custom build
200mW GGW custom build

Focalprice 7$ green&bluray laser goggles
Dealextreme tripod and clamp for laser holding -----> Review
DIY 3 motor Spirograph --------------------------------> Review
HLPM-2 laser power meter
Hallucynogenyc is offline   Reply With Quote
Old 09-25-2009, 11:44 PM #9
Benm's Avatar
Class 4 Laser
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,442
Rep Power: 19481
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: 7,442
Rep Power: 19481
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: Polarizer question. Help needed please.

That would have been very odd indeed.

A nice thing is that other materials affect optical rotation too. If you set up 2 polarizers in a row such that they block all light, you can see stress lines in pieces of (plexi)glass you put in between, appearing as rather pretty coloured shapes.
Benm is online now   Reply With Quote
Old 11-23-2009, 02:59 PM #10
Class 1 Laser
 
Join Date: Oct 2009
Posts: 57
Rep Power: 12
Helmholtz Watson is just really niceHelmholtz Watson is just really niceHelmholtz Watson is just really niceHelmholtz Watson is just really niceHelmholtz Watson is just really nice
Helmholtz Watson Helmholtz Watson is offline
Class 1 Laser
 
Join Date: Oct 2009
Posts: 57
Rep Power: 12
Helmholtz Watson is just really niceHelmholtz Watson is just really niceHelmholtz Watson is just really niceHelmholtz Watson is just really niceHelmholtz Watson is just really nice
Default Re: Polarizer question. Help needed please.

Quote:
Originally Posted by Hallucynogenyc View Post
ahhh, the third one is put between the other 2! I thought you meant you added this last one at the end and that the light was just "appearing" lol
This is what I thought too!

Everyone should have done this experiment in school: Optical Rotatory Dispersion: Polarized Light and Sucrose

Shows how polarization works including demonstration of rotation of poplar plane.
Helmholtz Watson is offline   Reply With Quote
Old 11-24-2009, 09:08 PM #11
LordKaramazov's Avatar
Class 2 Laser
 
Join Date: Nov 2009
Location: Coimbra/Lisboa, Portugal. Current location: Hannover, Deutschland
Posts: 271
Rep Power: 19
LordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud of
LordKaramazov LordKaramazov is offline
Class 2 Laser
LordKaramazov's Avatar
 
Join Date: Nov 2009
Location: Coimbra/Lisboa, Portugal. Current location: Hannover, Deutschland
Posts: 271
Rep Power: 19
LordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud ofLordKaramazov has much to be proud of
Default Re: Polarizer question. Help needed please.

i wasnt understanding it at first too...just like the light hopped from one place to another... and i was starting to think like the zeeman effect and the fact that u cant get one electron to have just one component (xy or z) of spin, was something similiar to this... but now that i know the 3rd polarizer goes in the middle it does make perfect sense. im just goin to repeat what someone said, just because i dont have anything better to do :P

we can look at this like vectors. if u have a given vector on a xy plane, and if u can project this vector on the xx axis, ull have a new vector with direction being the same as the xx axis. this was the 1st polarizer. now if u apply the second (90) polarizer, ull have to transform this last vector into its projection on the yy axis, which is, of course, 0.
But now lets assume u havent applied the 2nd polarizer yet, and get a 3rd (45) polarizer first. one can in fact project a vector that only has a xx component on vector that bisects the angle between both axis. This projection gives you a vector that has equal ammounts on both directions. if u now apply the yy polarizer, ull get only the yy of this last vector to pass.

This process really does cut the light energy, but it makes it look like for some people that the light is rotating xD
LordKaramazov is offline   Reply With Quote
Reply

Tags
polarize, polarized, polarizer





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 09:24 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