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Advertised laser power in mW

Coragem

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Hello everyone,

Sometime ago a friend showed me a website (I think it was wickedlasers.com) that sold high power laser pointers. So I went and bought a 35mW laser pointer which was awesome! It was small, used 2 AAA's, and the green beam was very visible. Well, after a lot of use, that laser broke. :(

So recently a friend and I wanted to buy other lasers like that, so we went to Yourlasers.com and we bought this one:

SD-301 Focusable 200mW 532nm Green Laser Pen Pointer with Battery Set (1*18650) - Free Shipping

It's 200mW, so we thought it'd be almost 6 times more powerful than the one I had! Well, sadly, it was just like my old one as far as the visible beam.

So we started researching, and we found out 2 things: One is that they lie a lot about those lasers' power. And two is that power doesn't mean visible beam. A lot of invisible infrared light is also emitted by the laser, and that is also counted in the advertised power. I'm not sure which was our case. But if you look on the photos inside the link above (first photo), the sticker has 3 pretty nasty spelling errors: "APER TURE", "DRIECT" and "PEODUCT". We just went "oh wow..." on those. I mean, it's printed on a final product, geez... But that asside, the beam was not bright at all, and the burning power wasn't that great either. Takes a few seconds to light a match, and burning black surfaces takes quite some pacience. My old 35mW laser could do these just as fast.

Anyways, we thought we'd come ask the experts for help, because it's very clear to us that this takes knowledge and experience. We really don't care for burning power. We're really looking for a bright beam. But we're not sure what we should look for among the specs, since my old 35mW laser was just as bright as this new 200mW.

Also, we kept finding 200mW green lasers at very different prices, even on the same websites. So we should've noticed that mW wasn't really the whole deal. But most sites we looked (specially Yourlasers.com) pretty much only advertised that one parameter (mW) as far as the laser's intensity.

Anyone have any recommendation or advice?
Thanks in advance!
 

madog

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I think the more important question you should be asking is, "Who should I buy a laser from".
This is not an easy question to answer as there are a few good companies to choose from.
Since this is your first post you should go to the welcome section and introduce yourself. After that aquaint yourself with the search function and the answers will come.
 

Isoleucine

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Advice in my opinion.

Typically, a laser from chinese websites, such as yourlasers, DX(didn't DX move to Yourlasers), DinoDirect, KaiDomain and a lot of other chinese websites are typically a gamble for your mWattage. You will most likely obtain a laser of roughly 1/3 to 3/4 power of its advertised value. It is somewhat rare ~10-20% that you will get a laser that has a power output HIGHER than its advertised value. Some websites, such as Wicked Lasers may not look chinese, but with a bit of research, they end up chinese. Do not buy from them.

Most users here bypass that issue by making our own lasers... and thus, it is what fuels the laser hobby. We calibrate and hand fabricate our own lasers to our liking, and with a lot of research, you can make your own decent laser.

Most things I said above can be found in the forums on old posts. You can utilize the search bar to the point of abuse, and you will find all the information you need.
 

Coragem

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Well, what I find strange is: I removed the 3.7V Li-ion battery and plugged a lab power supply set to 3.7V in place. Powering the laser, the power supply will report 0.63A comming out. Then, just to confirm, I've also put a multimeter set to read DC current in series with the laser, and it also read 0.63A passing thru when the beam is on. Since P=VI (for DC), that gives me 2.331 Watts of DC power consumption. Let's assume the beam is actually 200mW as advertised. Where's the rest of the power going to? Heat generation? It doesn't heat much at all, but then again 2.131 Watts dissipated across it's aluminum casing shouldn't cause it to heat a lot.

Still, is that common for a... lets say 50mW laser (as it appears to be in actual visible light output - just a n00b guess btw) to actually drain 2.331 Watts of DC power?
 

Misanthrop

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Well, what I find strange is: I removed the 3.7V Li-ion battery and plugged a lab power supply set to 3.7V in place. Powering the laser, the power supply will report 0.63A comming out. Then, just to confirm, I've also put a multimeter set to read DC current in series with the laser, and it also read 0.63A passing thru when the beam is on. Since P=VI (for DC), that gives me 2.331 Watts of DC power consumption. Let's assume the beam is actually 200mW as advertised. Where's the rest of the power going to? Heat generation? It doesn't heat much at all, but then again 2.131 Watts dissipated across it's aluminum casing shouldn't cause it to heat a lot.

Still, is that common for a... lets say 50mW laser (as it appears to be in actual visible light output - just a n00b guess btw) to actually drain 2.331 Watts of DC power?
It's probably a 600mW Pump diode.. or 700mW.. = Roughly the equivalent of your reading of 600mA

Not sure if you understand lasers but that IR diode (pump diode) "shines" into a crystal which "shines" directly into another one to produce the 532 wavelength...

It is then collimated through a series of lens which also loses power in the process.

A lot of power is lost in this procedure... Hence the low readings... but with poor crystal quality which I'm sure DX are guilty of, you will have even less output.
 

icecruncher

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If you really are going to get into lasers

Get a good Laser Power meter in order to get a powr reading. Thats the only way you will know for sure. The rest is just guessing.

But a decent one will run a a lot more than the laser you bought!
 

madog

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May 14, 2010
Messages
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Advice in my opinion.

Typically, a laser from chinese websites, such as yourlasers, DX(didn't DX move to Yourlasers), DinoDirect, KaiDomain and a lot of other chinese websites are typically a gamble for your mWattage. You will most likely obtain a laser of roughly 1/3 to 3/4 power of its advertised value. It is somewhat rare ~10-20% that you will get a laser that has a power output HIGHER than its advertised value. Some websites, such as Wicked Lasers may not look chinese, but with a bit of research, they end up chinese. Do not buy from them.

Most users here bypass that issue by making our own lasers... and thus, it is what fuels the laser hobby. We calibrate and hand fabricate our own lasers to our liking, and with a lot of research, you can make your own decent laser.

Most things I said above can be found in the forums on old posts. You can utilize the search bar to the point of abuse, and you will find all the information you need.
I'm not sure I like how you used the word "chinese" as derogatory. I can think of a couple "chinese" companies that are more than adequate. JetLasers has a good product with exceptional customer service. CNI is also a good company, though I have no experience with them.
 

Coragem

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If you really are going to get into lasers

Get a good Laser Power meter in order to get a powr reading. Thats the only way you will know for sure. The rest is just guessing.

But a decent one will run a a lot more than the laser you bought!
But just for reference, lets say I've also measured the current drained by my old 35mW laser that apparently had some nice optics (again a n00b observation). Should I also expect something like 600mA?
 

Coragem

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Well, I did measure it and it was 570mA, so... i guess my 200mW laser is more like 50mW.
 




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