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Basic FAQ's... Read before posting!


New member
Jan 20, 2008
This is a list of frequently asked questions made by newer members of these forums. Please, before asking questions, read this list, and search the forum before posting. There is a very large chance your question has already been answered before, so search around before asking questions.

Everything that is this color is a link. Click on them. They're handy stuff.

Getting Started

What is a laser?
"Laser" is an acronym that stands for "Light Amplified by the Stimulated Emission of Radiation" For the technical stuff regarding lasers, read Sam's Laser FAQ for a good idea of what lasers are and how they work. Don't worry, you don't need to know all of the technical info to get started in the laser hobby.

What do "mW" and "nm" mean?
mW stands for milliwatt, a measure of energy. nm stands for nanometer, a measure of length. In lasers, mW is used as a unit to describe the power of lasers. Basically the higher the power, the brighter the dot and beam will be. Also, with more power comes more burning capability. nm refers to the wavelength of the laser. Wavelength can basically be thought of as a very specific color. Common wavelengths you will see here are 405nm (violet), 473nm (blue), 532nm (green), 593.5nm (orange/yellow), and 650-670nm (red). This is a good illustration of the visible spectrum.

Where can I find green diodes?
Green diodes are very rare and hard to find. The industry doesn't mass-produce them, as they're very expensive and hard to build. In addition, they're only capable of reaching a few mWs, with insane amounts of cooling.

I've heard that IR is really bad. Is it?
It can be, especially if you're not expecting it. Many green lasers that aren't sold by reputable companies don't have IR filters. Without a filter, there can be huge amounts of IR being output along with the 532nm light. Because many people don't know how DPSS lasers work, they don't expect the IR to be present, and therefore aren't prepared for it. Unfortunately, many people are blinded by excess IR.  Remember - it's still light, even if you can't see it.  

But why is there IR if it's a green laser?
Because, as previously mentioned, green DPSS lasers are built using an IR diode and crystals to convert it to green light, thus approximately 80% of the energy is absorbed by the crystals (poor quality ones absorb even more).  
As you might already know, no material is perfect and in consequence, some of the IR light goes through the crystals and is "fired" with the green light you see at the end of the laser. Despite the fact that you can't see IR doesn't mean you can't get hurt by it. Again, use safety glasses!  

What about red lasers?
Red lasers use a diode to produce red light, there's no wavelength conversion, so there's no IR. This doesn't mean that you shouldn't wear safety glasses either; if you're using a high-powered red laser you can get your eyes injured same as any other wavelength.

What are "open cans?"
"Open cans" are diodes which have, as it's name says, an open metal housing. On the other hand, closed cans have theirs enclosed, and thus the diode itself is smaller -  That's the reason why open can laser diodes can be pushed to higher powers than regular closed can ones without the diode blowing. For the technical details on where the actual diode chip is placed and where all of the parts are, see this great explanation on laser diodes.  

And blue lasers?
Blue lasers are built with the same concept as green lasers, but with more complex conversions and crystals. Subsequently they are a lot more expensive than red and green lasers (yellow/orange and other colors are even more expensive because they have even more complex building processes).

Can I make a laser out of a spotlight?
See the definition of "laser" and you'll understand why. You can collimate (focus) a spotlight to a certain extent, but it will never be a true laser.

What else can I do with a laser besides burning stuff?
Here are some great examples of other cool tricks you can do with lasers besides just burning stuff:

Liquid Sky
Time Tunnel
And this is just the beginning of what lasers can do!

Your First Lasers

I want to buy my first laser, what one should I get?
This is a difficult question. It depends on YOUR wants and needs, and chances are that we don't have a clue what those are. Basically, there are three well-known companies that are extremely reliable, and will never disappoint: Nova Lasers (www.novalasers.com ), Optotronics (www.optotronics.com ), and Laserglow (www.laserglow.com ). Between those three, you should be able to find what you need for a relatively low price.  
Keep in mind, though, that there are many more companies that can't be trusted to give you anywhere near what you pay for. The most common company is Wicked Lasers/TechLasers. They are infamous for selling overpriced, underspec lasers. They market to people who have no experience with lasers, and that tactic is what's kept them alive for so long.  
The Buy/Sell and Group Buy sections of the forum are also great places to get your first laser. Deals abound!
In addition, read over this topic. Many other questions are answered there.

Okay, I just got a laser, what batteries should I use?
For pen style units that take AAAs, alkaline batteries are at the bottom of the best batteries list. The voltage of them sags after little use, and they die quickly in a high power consuming unit like a laser. Rechargeable batteries usually work the best, Eneloop AAAs by Sanyo are arguably the best ones. For maximum performance from your laser, you also can buy expensive lithium AAA batteries, but after buying these for a while you will realize they do take a good chunk out of your laser budget!

For lithium batteries, especially rechargeables, make sure you only buy batteries from respected brands. Cheap knock-offs have been known to explode either in the charger or in the device that is using them, so invest a few extra dollars in good batteries when you buy them.

DealExtreme? NOTE: DX has STOPPED shipment to the USA due to legal restrictions. See the GB section or PM Sawt Al Hurriyah for details on getting one.
For a first laser, DealExtreme (DX for short) is a decent choice. The 30mW pen is their most popular unit, as it's generally the most stable of the bunch. The lasers at DX aren't anywhere near the best quality, but their cheap prices help make up for this a bit. There are some downright terrible lasers sold at DX though, read around the forum to see which ones they sell are "good" and which ones are bad.

But what's the deal with the "True" ones?
The "True" green laser pointers from DX are the ones which have a NewWish brand diode, which are known to be somewhat more reliable than the generic ones used on the standard laser pointers. This makes them more likely to perform up-to-spec... But that likelihood is still very small.

Where can I get an IR filter?
You can buy IR filters here.

What about Kaidomain?
KD for short, it's very similar to DX. Another decent choice if you're new to lasers.

DIY Laser Questions

DIY Lasers are a common interest around here, and there are many things you need to know before endeavoring to build one.

How do I build a burning red laser?
You need to buy a laser diode and build a driver to power your diode. A great driver you can make at home is found here.
Once you buy a diode and make a driver, this is a very good tutorial for slapping it all together.

I'm new to electronics, and I don't know how to make a driver. Help!
A member here made a great video walk through on making a driver. Check it out.

Where do I buy burning red laser diodes?
For burning red laser diodes, this is your best bet to start off with. Buy a couple of them, as you will find yourself making mistakes that could kill your first diode. It's always good to have backups. You can also buy a bunch of other parts you need to build laser with at that site, including DIY laser diode Driver kits, modules to heatsink and focus your laser diodes, and more.
You can also buy DVD burners, and salvage the diode from them. This option, although more expensive, is a good way to get more powerful diodes than the ones offered in the store above.

I saw KipKay's laser flashlight hack, can I have some help?
DO NOT follow KipKay's laser flashlight hack. In that video, KipKay hooks the laser diode directly up to the batteries with no current regulation at all. One of the biggest "no-nos" in the DIY laser hobby is too hook a laser diode directly up to batteries. This is why KipKay's laser hack doesn't work: there is a difference between light bulbs and Laser Diodes. Light bulbs are controlled by the the voltage, that's why the bulb itself is working so well directly on the supplied energy. Laser diodes, however, as well as other semiconductors, are controlled by the current. So, if you try to feed a LD directly with the batteries, there is nothing that controls that current. Let's say that the LD needs 3.0v, 200mA to operate and you hook it up to the batteries (3.0v), will it work? Yes it will, but with even the slightest change in temperature will make the LD require less voltage and a HUGE amount of current will flow through it, and kill it. See Ohm's Law.
In short, driver boards greatly reduce the risk of voltage spikes and current over-saturation.

I need a driver but I don't want to build my own. Where can I buy some?
The AMC7135 may be a good choice for you. It's small, cheap, and easy to use. The Lavadrives and Flexdrives are also very good choices - check the GB section periodically to get these.

Safety Questions

Do I really need eye protection?
Yes, technically for anything over 5mW you need goggles for. Goggles usually run around $50 a pair, but you have to realize that your eyes are worth more than whatever you pay for goggles. One unlucky hit in the eye with almost any laser and you will have a permanent blind spot. We have a saying, "You can only look into a high powered laser twice, once with each eye". This is because it only takes a tiny fraction of a second to blind yourself or severely damage your eyes.

Can I use sunglasses or Welding Goggles for at least some laser protection?
No. This is a common misconception. All sunglasses/welding masks will do is make your pupils dilate, which makes the potential for damage much greater. The amount of light reaching your eyes will be diminished, but still far more than what is needed to damage your eyes. Need a demonstration? Watch this short clip.

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. Specifically, the number is the power of ten reduction that the transmitted light of that wavelength is reduced. IE, OD3 passes 10[sup]-3[/sup] (1/1,000) times the incident light, and OD4 is 10[sup]-4[/sup] (1/10,000) times the incident light.

Why are 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.

Browsing the Forum

All of the abbreviations and terms are confusing me, what do they mean?
LD = Laser Diode
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.
NL or Nova = Nova Lasers, a branch of LaserGlow.
TL = Techlasers, a branch of Wicked Lasers.
SenKat Diode, or SenDiode = A laser diode equivalent to the red laser diode found in 16x DVD burners.
DX = DealExtreme, a company based in China that sells many, many gadgets at cheap prices. They sell mediocre green lasers at great prices.
KD = Kaidomain, a company that sells a wide variety of products, including cheap green lasers.
LC = Laser Community, a neo-communist forum operated by Wicked Lasers.
CNI = Changchung New Industries Optoelectronics Inc. A manufacturer of a bunch the lasers we use. Examples of CNI products are all of Nova Laser's and Laserglow's class IIIB portable lasers.

This FAQ was written/contributed to by Chad, climbak, styropyro, nikokapo, and FireMyLaser.


Well-known member
Sep 20, 2008
Agreed... I would like to be able to point New Members to this thread...
but it needs to be fixed so it looks right on the New vBulletin LPF...:cool:



New member
Oct 3, 2009
I'm not good at languages.
If the error Sorry.

Are on this page.
I spent over 3 hours to read all.
Not difficult to read.
I'm Translate with Google.
But! difficult to translate that understanding.
With Google.
I will try to understand
I will read all the forum slowly.
Perceptively. To progress.
And Thanks for basic knowledge. :drool:


New member
Oct 18, 2009
How could I know some abbreviations used by users of this forum?
In the General area, there is a Sticky: Acronyms for the Forum. Is that what you're looking for?



New member
Nov 2, 2009
I am new here, would you please tell me why i can not see the button of "post new thread"? i can only see this
Where is the button for post thread?


New member
Nov 2, 2009
Is there any one can help me? I have contact the admin, he also do not know why.


New member
May 26, 2009
Do you mean that you do not see the "post new thread" inside threads, like in this one, or that you do not see it in any place, included the forums ?

If you mean from inside a thread, it's just normal, you cannot post a thread inside another thread, just reply to the current one where you are.