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How to identify Lasers?

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FelipeRibas

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May 13, 2013
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Hi, i've searched a lot but no good results untill now. It's a simple question:

how do I see the difference between Diode Lasers and DPSS Lasers? I'm about to buy some diode lasers from ebay but there is all kinds of color and power. How can I know if its DPSS or a simple diode?
 





It generally depends on what you are looking for. For example, right now 99% of green lasers you will buy on ebay are DPSS. Just about any other color is a solid state/diode laser. There are different sized diodes as well so make sure you get the correct size for whatever you are building. Same goes for DPSS modules.
 
405, 445, 450, 515, 520, 635, 650, 660 are all diodes and 532, 473, 589 and some other exotic wavelengths are DPSS lasers
 
Also diodes look like diodes.... :na: while a DPSS is a module and looks more or less like a copper cylinder....
 
Thanks for replies. I was not sure about that because once I read that high power lasers were all DPSS. So its not true? I see now in ebay some diode lasers of high power like this one:

http://www.ebay.com/itm/650nm-660nm...698?pt=LH_DefaultDomain_0&hash=item3cce8454ba

and I started to think whether it is DPSS or not. I need to buy a true laser diode because i need fast response. As far as i've read, diode laser takes about 0,5ns to rise. Do high power lasers take much longer than that?

Anyway, I was afraid of buying some lasers and those be DPSS. Any chance of a red laser (650nm) be DPSS? Isn't there anyway I could identify it only by looking at the package?
 
Taking into consideration that I need a fast response laser (priority) with largest possible range, does it lead me to some specific laser type? Or a simple red diode laser of 50mW/100mW will already do the trick?
 
Yep, a standard red diode will do the trick. mW for mW the "range" is the same. Brightness is determined by the response curve of our eyes; 100mW green has the same range as 100mW red (Rayleigh scattering aside).
 
three remaining questions:

-im not sure i follow you. 100mW red laser will reach more far objects than 20mW or 50mW red lasers, right? But is this difference huge?
-does a 100mW red laser have the same rising time (0.5ns aprox) of a 5mW red laser?
-still the first question: can I always visually see any difference from laser diode to DPSS laser? Or its not possible only by looking at it?
 
FelipeRibas said:
three remaining questions:

-im not sure i follow you. 100mW red laser will reach more far objects than 20mW or 50mW red lasers, right? But is this difference huge?
Click to expand...

Range also depends on divergence and beam characteristics, as well as atmospherics, but if all variables are the same the difference is linear.

-does a 100mW red laser have the same rising time (0.5ns aprox) of a 5mW red laser?
Click to expand...
It doesn't depend on output power. Rise time is a characteristic of the diode itself (junction capacitance is a main part of it). You need datasheets and they're generally not available to hobbyists.

-still the first question: can I always visually see any difference from laser diode to DPSS laser? Or its not possible only by looking at it?
Click to expand...

I'm not sure what you're asking, do you mean visually identify by looking at the laser or by the light from the laser?

The best way is by wavelength. If you know the wavelength many of us vets can tell you what kind of laser makes it.
 
Thanks Sigurthr.

As for the last question:

yes, i mean identify the laser phisically by looking at the package type, not by looking at the laser beam. Is it possible?
 
This is an example of a laser diode.

En6nsHR.jpg


DPPS lasers incorporate a laser diode (infrared) and a set of frequency changing crystals. Most (green) DPSS modules are housed in a metal casing.


images
 
Thanks!

Yea.. as I suspected. But once I searched google for this difference and I've found this web site:

DPSS Laser Kits (Pantotek Technology, China (Mainland))

where he says:

"DPSS Laser Kits Model No: DPSS LASER Kits Provide dpss laser kits in low cost, including: 1.808nm laser diode:200mw,500mw,1w,2w,3w, to9, to18 and c-block package 2. Crystal: Glude crystal(nd ... "

and the picture:

DPSS_Laser_Kits.jpg


As you said this would be a diode laser, not a DPSS. From what i've understood, those are IR diode lasers (pump) and all the rest is to change wavelength. Which means ALL together would be the DPSS. Is that correct?

Is it so simple to change a radiation wavelength?
 
Last edited:
yes. in this case you have a Diode which Pumps photons @ 808nm into an nd yag crystal which converts the photons to 1064nm these photons then are doubled with another crystal to produce 532nm photons. precise alignment is needed to accomplish this magic ;-)
 
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