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help: mixed 470nm laser with 445nm laser in white RGB laser module

laserlands

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I have sold one RGB white laser, the specification is as follows:

green 532nm 30mw (808nm ld)
blue 470nm-473nm 80mw
red 650nm 100mw
total output: 200mw

a buyer bought one from me and I confirms that it is 470-473nm laser for the blue. it is not 445-450nm.
when the buyer received it, he insists that it is a 450nm laser ld. he uses this way to caculate it:

Green 532nm is used as the standard because it is a DPSS, diode pumped solid state, laser. It doubles the frequency of an infrared laser at 1064nm to 532nm using a KTP crystal. Measuring the diffraction distance, the ratio of diffraction could be found and thus the wavelengths of the blue and red lasers. If the blue laser had a wavelength of 473nm, which is also made by the DPSS principle, the diffraction distance would be measured to be 35.30cm not 34.00cm as measured which infers a 455nm laser. A difference of 1.30cm is significant enough. This proves that the laser sent was not a 473nm DPSS as said but a 455nm blue diode laser.

I replied it that:
the green laser is 808nm ld, not 1064nm.

but buyer still does not trust me.
so that I introduced him to this platforum. I think there must be some one more professional than me and can offer some middle suggestion and advise.

thank you guys and happy new year to everyone.

Merry
 



Apocalypse

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Hello all,

This is the unit in question, a 200mW white laser unit.

200mw RGB White Laser Module Beam Combined 532nm Green + Blue 473nm + Red 650nm | eBay

Laserlands claim that the laser they gave me uses a 473nm DPSS laser. I specifically asked whether it is a 473nm DPSS laser or a 450nm diode laser prior to purchase.

Me:

Hello,

I want to confirm that this laser uses 473nm DPSS for the blue and not the 450nm diodes.

Thanks.

Reply:

thank you for your interesting in our product.
I confirm that white laser less than 500mw uses 473nm laser. white laser over 500mw we use 450nm laser
hope my answer is helpful. if you have any question please feel free to let me know
with best regards
Merry

This said, I received the laser a couple of days ago. I turned it on and split the white light with a diffraction grating. However, I found that the blue light is the same color as the 445nm diode I got from DTR. Therefore, I measured the amount each color is diffracted by and recorded them. I used the 532nm as a standard because it has the narrowest spectral width and the wavelength varies little with change in temperature (unlike the red diodes).

Here's what I did below.



I think this method even though crude, would be able to differentiate between 445nm and 473nm since the blue dot should be at least 1cm closer to the green if it was indeed 473nm.

I also opened the laser up and found this:



So... Either laserlands has perfected the art of making the world's smallest DPSS 473nm laser (with all the crystal sets) or it is a 450nm diode.

I will also note that the total current through the device is 0.38A at 12V. I think that a 473nm DPSS laser alone would need approximately this current.

So all I want is a refund.

What do you guys think?

I agree that I was a little greedy in thinking that this 1 hundred dollar thing would come with a 80mW 473nm DPSS laser but I took the chance.

Thanks for reading!

Note: The green 532nm is pumpted by a 808nm IR diode but that isn't important. The important part is that the 808nm IR light is converted to 1064nm by neodymium atoms in the crystal. The 1064nm IR photons are then combined (frequency doubled) to 532nm, giving it a very narrow spectral width characteristic to most DPSS units.
 
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bennett326

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its a diode for sure, not 473nm. but at 100$ its actually a pretty damn good deal for a rgb unit. i think you deserve a refund if you want it, but i would keep the module it is a good deal IMO and the fact that it came with what seems to be quite good alignment is also pretty lucky. :shrug:
 

Apocalypse

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Yeah, the unit is fairly well aligned. However I'm already building a projector which can do the same thing but is around 1.5W. (650nm and 635nm reds, 532nm green and 445nm blue). What I'm looking for is a more exotic wavelength 473nm. I don't really care how powerful the 473nm is to be honest. I bought this unit quite impulsively :na:.
 
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bennett326

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Yeah, the unit is fairly well aligned. However I'm already building a projector which can do the same thing but is around 1.5W. (650nm and 635nm reds, 532nm green and 445nm blue). What I'm looking for is a more exotic wavelength 473nm. I don't really care how powerful the 473nm is to be honest. I bought this unit quite impulsively :na:.
lpf scanner thread - Imgur im building a RGB projector too :D there is an imgur album with some pics. i only have 445 and 532 in right know about 1.3 whats in total and whn i get red it should be 1.8-2W
 

Apocalypse

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I don't need a wavelength meter. Unless you tell me you can make a 473nm DPSS that small... The diffraction ratio and the visual of the blue unit alone is enough to say that it is a 450nm blue diode.

Okay, if you're saying 808nm is GREEN, 808nm is IR NOT GREEN.

Btw bennett, that's a sweet projector :). I got all the parts on mine but need some spare time to assemble it :p
 
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laserlands

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dear
I confirm the wavelenth is 470-473nm. I have never confirmed it is a DPSS laser. I have received a lot of message to ask for the dpss or not, I never tell anyone it is a dpss laser. pls reread the message again. since the misunderstanding, I have added the note in the description right now.
we have sold 473nm DPSS laser as well. you can see that the price is triple or may five time more expensive than this RGB white laser.
 

laserlands

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it seems that you are not familiar with laser
green laser = 808nm ld + crystal
there is only one green laser ld now. the manufacture is OSRAM and the wavelength is 520nm. the price is about 500usd each.
 

Bionic-Badger

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laserland: diffraction ratio/distance aside, a DPSS 473nm laser is going to be at least the same size as the 532nm laser in that module. They're built in nearly the same way and I wouldn't be surprised if the 473nm module would be larger. They're not small single diode-size lasers like a 445nm laser.

Also, there are no cheap 473nm single laser diodes in production now. If you had them, you certainly wouldn't be selling them for $99 in a device such as this. Look at the price of this 20mW 473nm laser diode; it is almost $3000. Nor are there small 808nm lasers + crystals for 473nm lasers that would fit into the little metal block on the left; if they did they would be extremely unstable, and certainly would not reach 80mW.

The eBay product listing is incorrect, and you should amend it to show 445nm instead of 473nm so this doesn't happen again. Then allow Apocalypse to return the laser for a refund if he desires. Maybe he can even verify whether the laser is single mode so you can advertise that in the listing, but as a 445nm laser, not 473nm.

On another note, I agree with bennett326 that the complete system is pretty nice for $99. So maybe this whole incident will result in more sales for laserland anyway. No such thing as bad advertising.
 
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laserlands

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dear Bionic-Badger
thank you for your reply
I know how expensive a DPSS 473nm laser is. in our store. a 50mw DPSS 473nm laser is 288usd --shipping not included.
the RGB white laser is a new product. so that it is not a DPSS one. it uses laser LD in side.
you know there are only a few laser ld manufacturer can produce 470nm laser ld. we use this kind of ld inside. it is quite different with the DPSS 473nm. so that we got the cheap price. the wavelength is 470-473nm. but it cannot be 445nm blue one. 445nm laser ld is stable. we use it for higher output rgb laser.
we agreed to return and refund--do not worry about it. we have 3+3 warranty.
the issue we discussed is about the wavelength.
and thank you so much for your kind understanding.
we may sell some 470nm laser ld. people may know more about it. :) it is new and fantastic.
 

Bionic-Badger

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I'm still quite skeptical. Still, the entire RGB rig looks like a decent price for what it is.

By the way, your ebay listing shows two delivery date ranges, an ePacket Delivery, and an Expedited delivery, both with the same price. How does this work, and what is the actual delivery time?
 

Apocalypse

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it seems that you are not familiar with laser
green laser = 808nm ld + crystal
there is only one green laser ld now. the manufacture is OSRAM and the wavelength is 520nm. the price is about 500usd each.
Um... so you just repeated what I said? What do you mean by "you are not familiar with laser"?

Here's a diagram of how DPSS lasers work. Specifically the 532nm green if you still don't know what I'm talking about. http://upload.wikimedia.org/wikipedia/commons/5/5f/Green-laser-pointer-dpss-diagrams.jpg

Also I'd like to see the 470nm diodes you claim to have. Where do you have it for sale and how much? If you really have a 470nm diode which can output 80mW for around $100, there will be a lot of people here interested in them.
 
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Bionic-Badger

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If you happen to have a dichro and a meter, you could reflect away enough power from your other 445nm laser so that the power levels match, and do a 1:1 comparison.
 

lasersbee

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Or you can send it to a member that has a Spectrometer...
But a side by side "LL blue" and a 445nm through a diffraction
grating may also show if they are the same wavelength or
not.

Either way Laserland said they would refund you....
BTW... it was quite obvious that there was no 473nm DPSS
Laser in that $99 module no matter what the seller said...:rolleyes:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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