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Pros/Cons of Common wavelengths

Trevor

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Well I said crystal quality because eBay pens go dim then bright constantly. While the higher-End 532s like my old NOVA pen would stay the same power if it was cold or hot.
There far more in play when you build a DPSS laser than the "quality" of the crystal.

Similarly, there's more to a laser driver than the "quality" of the components. ;)

And when will NOVALasers start selling again? I want to replace the one my idiot friend broke.
If I were a betting man... never.

Trevor
 

BShanahan14rulz

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optical feedback stabilizes lasers.

Wavelength does not contribute to stability. Wavelength describes an aspect of EM radiation. Like the name implies, it is the length of a wave.

405nm never changes color. 405nm is 405nm. You can't say 405nm = 600nm. You could say that some white surfaces that have been treated with whitening agents will emit blue light when pumped with 405nm radiation.

Really, if this is to help people decide what wavelength they want, just ask them what color laser they want?
 

Trevor

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Hello all, Alex here. I remember seeing in a thread a few days back a thread on what are some of the Pros & Cons about "Common" Wavelengths.

I haven't seen any post on this so I decided to take a crack at this, hope you enjoy :beer:

405nm
Picture:100mW-405nm-Violet-Purple-Blue-Laser-Module-Focused-Dot-M405D10031670_1 | Flickr - Photo Sharing!

Pro's
- Is a stable wavelength, which means you do not have to worry about temperature affecting performance as much as 532nm
- Laser diodes are stable. 405nm as a wavelength is not "stable." Because the emission comes directly from a laser diode, the output tends to be stable despite temperature changes.
- Only wavelength which somewhat "Changes Color", if 405nm is aimed on white surfaces it turns blue.
- It's called fluorescence. If you're going to write a "guide" you NEED to know that.
- Can be used to write on Glow-in-the-dark materials
- GITD materials are "charged" by UV. Because 405nm photons are near UV, they have enough photon energy to work.

Con's
- This wavelength being at the end of the spectrum will not appear BRIGHT AT ALL
- Brightness also has dependence on power. Holding power constant, 405nm will be much less visible than wavelengths closer to the center of the visible spectrum.
- Cannot be had in huge amounts of powers, MAX 2W.
- Yes it can. It's just very expensive. That is a very important distinction.

445nm
Picture:445nm | Flickr - Photo Sharing!

Pro's:
- Can be had at incredible amounts of power for cheap
- This depends on someone's concept of "incredible." Perhaps mentioning that up to over 3W can be had for just a few hundred dollars would work better.
- Is the best wavelength for burning/lighting combustible materials
- 405nm is the best commonly available wavelength to burn with, holding power constant. This is due to the photon energy inherent to shorter wavelengths. Similarly, 355nm would "burn" better than 405nm, holding power constant. Additionally, materials don't have to be strictly "combustible" to be marked by lasers.
- Have beautiful beams
- That's kind of subjective, isn't it?

Con's:
- (Even thought not noticeable) have an ugly rectangular aperture beam

532nm
Picture:1mW-532nm-Green-Laser-Module-Single-DotM532D131660_1 | Flickr - Photo Sharing!

Pro's:
- Brightest wavelength out of them all
- Brightest wavelength than others in this guide (holding power constant), yes. But not of the whole spectrum.
- Easiest wavelength to observe a beam at
- That may not be true depending on the power. This is another "holding power constant" statement that can be misleading.
- Has a nice, clear circular dot
- That depends on the quality of the laser. Cheap Chinese pointers often have messy dots that change shape as different transverse modes come and go. By saying this, you might lead a newcomer to buy a laser that will disappoint them, because the dot does not live up to "circular."

Con's
- Can be highly unstable, temperature will easily affect power output
- If not thermally stabilized, yes.
- Can easily be damaged
- Due to the fragility of the alignment. Might want to mention that.
- Price rapidly climbs as output of unit increases $$$$
- It starts climbing earlier. Every wavelength has a power at which the price starts to skyrocket.


650nm
Picture:red-laser-module-5mw-focusable-650nm-dot-798974-Gallay | Flickr - Photo Sharing!

Pro's:
- Most readily available wavelength for purchase(can be found everywhere)
- Indeed!
- Can be had at high powers for cheap
- This depends entirely on your concept of high power. This needs clarification.
- Highly stable
- Laser diodes are stable. 650nm is not inherently stable. There are DPSS options for 650nm that invalidate this statement.

Con's:
- Worst wavelength for burning/lighting(Some materials)
- Of this list, perhaps. It is not the "worst" of all wavelengths...


Thank you for reading, this is just a quick, fast easy thread for new users who may be deciding on which wavelength is best for them.

Like always, it all depends on what you will be using you're laser for, different wavelengths will excel in different domains.

Like always, if you feel this need any re-adjustments, please do not hesitate to write a post below and I will get to it as quickly as possible :beer:
I added some notes.

Without clarification or some additional notes, this "guide" is the blind leading the blind...

Trevor
 
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Hap

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Thank you Trevor,

Will get working on it ASAP!
 
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I gotta go with Trevor. Almost posted something VERY similar. It's great your trying to help but you've posted like 4 things like this and ALL of them could probably be found elsewhere. Next time compile it and gather a lot of information before posting. All these threads that are guide like always end in like 40 people giving you things to add. Rant over. How's the collection going?
 

chipdouglas

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I'd like to throw in something...

if you find any cons about any laser color, then lasers shouldn't be your hobby.

Now pros and cons for industry, research, or anything similar... obviously there are lasers for suited purposes.

Michael.
 
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Here we go again, the oldbies beating up on the newbies.

This thread is a really good idea, although you have made some generalizations about
wavelength which confuse it with the process being used to produce the light, among other
things, as Trevor has so pointedly pointed out.

Pro's
- Is a stable wavelength, which means you do not have to worry about temperature affecting performance as much as 532nm
Yes, if by "performance" you mean a nice TEM00 mode. But this is only because it is
being produced directly by the diode, not something inherent to this (or any) particular
wavelength. But a diode's wavelength will drift with temperature, so in that respect it is not
at all "temperature stable." A 532nm DPSS laser on the other hand will be 532nm at any
sane temperature because it is a function of neodymium transitions.

- Only wavelength which somewhat "Changes Color", if 405nm is aimed on white surfaces it turns blue.
Trev covered this well. Nice use of colors, BTW.

- Is the best wavelength for burning/lighting combustible materials
Actually, watt for watt, 405nm burns better. I suspect a 375nm would burn even better
than that. It all depends on what you're trying to burn and how well that material absorbs
the light. 445nm is just more known for burning because of the lower cost per watt and the
high volumes of 3W 445nm diodes on the market.

- (Even thought not noticeable) have an ugly rectangular aperture beam
An aperture is an opening, like a hole.

532nm
Picture:1mW-532nm-Green-Laser-Module-Single-DotM532D131660_1 | Flickr - Photo Sharing!

Pro's:
- Brightest wavelength out of them all
- Easiest wavelength to observe a beam at
The sensitivity of our eyes peaks at 550nm. A 550nm laser, if one exists, would appear
even brighter at equal wattage.

- Has a nice, clear circular dot
Again, this has nothing to do with the wavelength. It has everything to do with the cavity
producing it.

I don't consider a $400 diode cheap. (Price has gone down from $425, yay!) :drool:

The rest is fairly true.
 

ZRaffleticket

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Here we go again, the oldbies beating up on the newbies.
No. It's the people with knowledge correcting the people who lack it. Looks like I'm going to correct you here too. It just so happens I'm an older member myself. Deal with it.

Edit: this seems very malicious... Not intended, but I do take offense to people saying "the vets are jerks". So I do apologize for that, though my statement is still valid there ^

Yes, if by "performance" you mean a nice TEM00 mode. But this is only because it is
being produced directly by the diode, not something inherent to this (or any) particular
wavelength. But a diode's wavelength will drift with temperature, so in that respect it is not
at all "temperature stable." A 532nm DPSS laser on the other hand will be 532nm at any
sane temperature because it is a function of neodymium transitions.
Once again, nope. Power can be considered performance, power is GREATLY affected by temperature.

Null and void. See below.
Also, note temperature affects DPSS as well, just at most within the +/-1nm range. Pretty stable, but it's wrong to say it doesn't change at all.
Though it does very slightly change.... :p

Actually, watt for watt, 405nm burns better. I suspect a 375nm would burn even better
than that. It all depends on what you're trying to burn and how well that material absorbs
the light. 445nm is just more known for burning because of the lower cost per watt and the
high volumes of 3W 445nm diodes on the market.
Let's end this "better burner" discussion once and for all. 405nm photons have more energy than 445nm photons. HOWEVER, that is taken into account in powers. It's all about transfer of power. Material that will absorb 1W of power will absorb 1W of power. It's all relative to wavelengths and colors of the material you're burning.

405nm has an advantage due to a shorter focal length.

The sensitivity of our eyes peaks at 550nm. A 550nm laser, if one exists, would appear
even brighter at equal wattage.
Nope. Roughly 555nm.

I don't consider a $400 diode cheap. (Price has gone down from $425, yay!) :drool:
Aaaand what..? What the hell do you consider high powered? 200mW is not low powered by any means my friend.

_______________

@greenlander
not all white surfaces "change color" as you call it
445nm also readily causes objects to fluoresce. Even 532nm can make some fluoresce.

The Greenlander said:
- Have beautiful beams
- That's kind of subjective, isn't it?
Don't discuss with yourself in an informational post... even if it's directly copied from trevor.

The Greenlander said:
- Cannot be had in huge amounts of powers, MAX 2W.
- Yes it can. It's just very expensive. That is a very important distinction.
These are all over your first post. Please just fix these contradictions... It's extremely confusing.
 
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532nm can charge some GITD as well.

I have one of those bright GITD squares for emergency purposes on my closet door. It can be charged with 532nm, I did this with the 800mW CNI lasers. However, the GITD duct tape I have on my wall will not, even for the 1W green that went through my possession,

Not sure why one did, and the other didn't. Simply putting it out there :)
 

ZRaffleticket

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Some GITD materials readily charge themselves and others don't. Much like some can be "erased" with 650nm and others cannot.
 

ARG

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Also, note temperature affects DPSS as well, just at most within the +/-1nm range. Pretty stable, but it's wrong to say it doesn't change at all.
Do you have a temperature vs wavelength charge for a common DPSS crystal combo? Would be interested to see.

I've never encountered a DPSS laser off its wavelength spec. usually it just stops lasing at high/low temperatures because the diode wavelength changed with temperature. :p
 

ZRaffleticket

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I can make a video next time I get home... maybe the 27th :p

Found a video by atomicrox using IR. Same results :p

Edit:

That's all based from research I did for the theoretical chart. I'll dig around and find some graphs somewhere.

Some are more sensitive than others.

edit 2:
Still no graphs found... but for handhelds you're absolutely right. If that pump diode shifts too much it's game over :p

I remember the article focused on changing the temps of Nd: crystals affecting output wavelengths. If I remember correctly they upshifted 1064nm to 1067nm...

Edit 3:
Wait, why am I posting about this then. This is only doable in temperature controlled modules...

Edit 4:
Found a PDF... with graphs!

Though.. it's not nearly as dramatic as I remembered... Just scratch the wavelength thing. Unless someone's sticking the crystals into boiling water you won't have a noticeable change...
http://hal.inria.fr/docs/00/60/44/24/PDF/00604424.pdf

I swear though, someone somewhere got Nd:YAG doing 1067nm.
 
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Hap

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I gotta go with Trevor. Almost posted something VERY similar. It's great your trying to help but you've posted like 4 things like this and ALL of them could probably be found elsewhere. Next time compile it and gather a lot of information before posting. All these threads that are guide like always end in like 40 people giving you things to add. Rant over. How's the collection going?
Collection is going great, I received the tracking # today for the 635nm and should be arriving on:

Scheduled Delivery:
Monday, 11/18/2013, By End of Day
Last Location:
Concord, ON, Canada, Monday, 11/11/2013
 




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