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# Exact DPSS Outputs

#### hwang21

##### Well-known member
Does anyone know what the wavelength output of our DPSS lasers is? Like in more detail than just "532nm"... 532.1nm? 531.9nm?

And with 473nm, 589nm, 593.5nm? I know that the pump laser diode may not be exactly 808nm for example, but shouldn't the Nd:YAG or Nd:YVO4 put it pretty close to 1064nm? Or is that faulty thinking and the laser diode will throw off the final output wavelength because it may not output exactly 1064nm? And if that were so, what would the exact outputs be assuming the laser diode outputted exactly 808.000nm (in the case of a green laser)?

Thanks

#### NKO29

##### Active member
Like all diodes and such, i think we only state the proposed or average output. If the pump diode is off by 1nm, then that sets off a chain reaction in the dpss i assume. I think it would be fair to say there are variances in all lasers even if they are technically identical :thinking:

#### ZRaffleticket

##### Well-known member
Nope ^

There is a bell curve in wavelength usually .5-1.5nm wide (well, it's bigger but anything notable is in that range). Different processes have more or less variance...

Peaks do slightly depend on temperature and purity of the KTP or other frequency doubler. So stating a peak of a 532nm as "532.165nm" can also change to "531.869nm".

Long story short: Gas is safe to go with a lot of decimal numbers, DPSS is safe to go in increments of .5nm, and Diodes are safe to go in increments of 5nm.

A little thing how DPSS works-- your pump diode, ~808nm in most cases, pumps a crystal. Say that is Nd:YAG. Nd:YAG has ranges where the pump light is absorbed, and re-emitted by exicted atoms at specific transitions. 946nm, 1064nm, etc etc etc. Then those, pre-determined wavelengths go through SFG and presto you have your laser color.

Edit: regarding a diode at EXACTLY 808nm... uhh I don't think that has much effect... the light is absorbed and emitted at the transitions. I think the efficiency will just go up if anything.

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#### hwang21

##### Well-known member
So within +/- 1nm is a reasonably accurate range for a DPSS laser?

#### ZRaffleticket

##### Well-known member
Well, it's even safe to say +/- .5nm (for 593.5nm's sake), but yes that's the main idea of it.

Like I said, the bell curve mostly fits into that big range. It's still very reliable in the .5nm increments.

#### hwang21

##### Well-known member
Ah ok thanks for the info :beer:

By the way, is it just me or is my 488nm in my sig significantly bluer than the 488nm in your sig?? :thinking:

#### ZRaffleticket

##### Well-known member
Heh it is. I sat there side by side matching the color of the spot to the color on my screen.

Note that a lot of screens are calibrated differently, you might have yours right on your own screen too

#### ZRaffleticket

##### Well-known member
Nope! I don't trust that tool, 532nm and 520nm look nearly identical

I'll eyeball it, it looks better that way

#### hwang21

##### Well-known member
Orrrrr you could help make the tool better using your results

#### ZRaffleticket

##### Well-known member
If anything I'd need quite a few tunable lasers, and a better programming background.

In all seriousness, I'll get to my own tool over the summer probably.

#### hwang21

##### Well-known member
Or just a few more DPSS and gas lasers