FAQ

[climbak]

So, TEM stands for Transverse Electromagnetic Mode. It describes the intensity pattern of the beam cross section, transverse, or perpendicular, to the direction of travel. The numbers tell you which mode the emitted light is. So for TEM00 you have a primary mode of the laser and its intensity pattern is more or less a 2-dimensional gaussian distribution, basically a single spot. Higher order modes such as TEM02 or TEM10, etc, have different patterns. Wikipedia has a few nice pictures to describe this visually.
http://en.wikipedia.org/wiki/Transverse_mode

 

[nikokapo]

awesome, chad please if you'd like to rewrite what i said about removing the IR filter


even though we said "no wikipedia", the wikipedia article about TEM modes is VERY good...and the image is also very nice, we should make an exception here.. (IMHO!!)

 

[climbak]

We could always ask wikipedia if we can use the images in the forum faq and get rid of the wikimiddle man

 

[Chad]

Well, we can use the image without asking. It's under the GNU FDL, so we don't have to worry about copyright infringement.

I've got a lot of homework to do, but I should have these fully written up by thursday.

 

[bobobob121]

We could always ask wikipedia if we can use the images in the forum faq and get rid of the wikimiddle man

judging from your last couple of posts, i can you are one of the smartest people on this forum. and your picture on here reminds me a little bit of tom from myspace. lol +1 rep

 

[climbak]

judging from your last couple of posts, i can you are one of the smartest people on this forum. and your picture on here reminds me a little bit of tom from myspace. lol +1 rep  

Why thank you sir! [smiley=thumbsup.gif] i hadnt noticed before but it reminds me of that too haha. nothing like working on physics hw into the wee hours of the night.

 

[nikokapo]

HAHAHAHAA CLIMBAK YOU ARE TOM!!!

loolololol

 

[climbak]

hahaha, wow. i wonder if he's my long lost twin? someone should message him and see if he likes lasers ;D

 

[Murudai]

even though we said "no wikipedia", the wikipedia article about TEM modes is VERY good...and the image is also very nice, we should make an exception here.. (IMHO!!)

Why no wikipedia? In the thousands of articles I've read on there (many of scientific nature, though more chemistry related than lasers and optics) I've yet to see any information that didn't look correct.

I mean, I've gone straight out of lectures and into wikipedia just to see what they have on spectroscopy or something, and it turns out wikipedia are spot on

They've just got a bit of a bad rep because of the fact that anyone can edit it and some people have hijacked it, but in reality it is very well moderated and the talk about wikipedia being unreliable is unfounded.

 

[nikokapo]

[quote author=nikokapo link=1208133995/15#17 date=1209598736]
even though we said "no wikipedia", the wikipedia article about TEM modes is VERY good...and the image is also very nice, we should make an exception here.. (IMHO!!)

Why no wikipedia? In the thousands of articles I've read on there (many of scientific nature, though more chemistry related than lasers and optics) I've yet to see any information that didn't look correct.

I mean, I've gone straight out of lectures and into wikipedia just to see what they have on spectroscopy or something, and it turns out wikipedia are spot on

They've just got a bit of a bad rep because of the fact that anyone can edit it and some people have hijacked it, but in reality it is very well moderated and the talk about wikipedia being unreliable is unfounded.
[/quote]


i always support wikipedia, i think almost everything there is better than the old books, the word of the street is better adapted....everything is controlled, dunno why some people dont allow wikipedia on student projects

 

[nikokapo]

i thought of some new things
like

"What is CNI?" "Are they better than non-CNI lasers?"

and the one i came up with in another thread: "Why do I keep getting different versions of the same laser when I order from DX?"

 

[IgorT]

and the one i came up with in another thread: "Why do I keep getting different versions of the same laser when I order from DX?"

From the way these lasers are built, i doubt even the manufacturer knows the answer to this..

 

[nikokapo]

erm...there IS an answer, they just keep modifying them

 

[VillageIdiot]

what about stuff like

What is OD? What OD glasses should I get?

Why are 'red' glasses a blue colour?

What is a box type laser? Are they any good?

What's a heatsink and what's it do?

Also in your abbreviations section you can encode some links to the sites eg:

WL = Wicked Lasers, one of the first companies to sell high powered lasers in pen size. Does not have a good reputation around here because they are known to send out underspec units.
LG = LaserGlow, a company that sells a wide variety of lasers.

and so on.

 

[nikokapo]

i approve it.
let the defining and answering begin!

volunteers?


What is a heatsink and what does it do?

It is a piece of metal, generally shaped according to the body of a product which is in contact with the components which generate the most heat. This way, the metal dissipates as much heat as it can.
Aluminum has good heat dissipation capabilities and is somewhat cheap compared to copper heatsinks (which are more expensive but are able to dissipate more heat with the same size compared to an aluminum one).
Lasers tend to use their metal casing as their heatsink. [Expand this].

 

[Chad]

I don't think we'll need to explain what a heatsink is, unless we get a lot of 8-year olds visiting.  

What does OD mean? OD means Optical Density. Basically, the higher the OD rating on the goggles, the less light will be allowed to pass through. OD3+ goggles are fine for lasers up to 125mWs. Further than that, you'll need goggles with progressively higher OD ratings.  

Why laser goggles are colored the way they are Looking at the color wheel, you can see what colors are opposites of each other - IE, green is the opposite of red, and orange is the opposite of blue. If your laser is green, the opposite color (Red) will absorb more of the laser's light than any other color. Since the object is to reduce the amount of light reaching your eyes, the laser's light needs to be absorbed by the goggles. So, protective goggles for green lasers are red, goggles for blue lasers are usually orange (Because the wavelengths for green and blue are so similar, many goggles are simply orange - these serve very well at protecting from both wavelengths) and goggles for red lasers are either blue or dark green.

Box lasers What the crap? all this refers to is the shape of the laser. No need to get excited about that.  :-?

CNI In answer to the question posed before, there's no real answer to that. It all lies in the manufacturer. CNI makes lasers, tests them, and sends them out to the various companies - THEY, in turn, decide how to market the lasers. I've seen CNI's that have been just as crappy as stuff from DX and WL. See above paragraph.

Different stuff from DX Again, does this matter? They remain essentially the same. And I actually haven't seen this asked at all before, let alone frequently.


If there are any messed up parts in there, I'm terribly sorry.  :-/  It's all straight from Chad's-Brain-Ipedia. I haven't really read about these in a few years.