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"Naturally" bad collimation for 473nm blues?

Schrecken_Licht

Schrecken_Licht

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This is a question for anyone who has a blue DPSS laser, pen or lab-style (or someone who knows a decent bit about them). Anyway, I have a 130mw lab-style blue laser and it has (for a visible light laser) pretty bad collimation + it is multi-mode. Now I remember on LC that those few people who had the Spyder BX noted that those were Tem 02 (I think that's right - anyway there were three beams). I don't recall anyone saying much about collimation, other than that there was no way they could burn anything (or try - those weren't anywhere near 130mw, maybe around 35 or 40mw....) with out a lens.

My laser splits off into 3 beams at about 14 feet or so; and at about 25 feet the beam is the size of a half-dollar! Also, I need a lens to light a match as well, though it will sting my skin at a couple feet from the aperture unfocused.
73a.jpg


So, is is this (multi-mode and poor collimation) characteristic of 473nm DPSS lasers? If you have a blue, is it like this?
 





Razako

Razako

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My blue rpl has "decent" divergence. It isn't great but it isn't bad enough to complain about either.
At 40 feet my Blue RPL30 produces a spot that is about the size of a penny. The beam does stay Tem00 at a distance and the spot looks decent.

I think you need a refund on your lab blue if it splits into 3 beams.
 
scopeguy20

scopeguy20

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My Aquarius -10 is going back and forth in modes: Tem 00 or nearly so, and Tem 01 (through a magnifier, easy to see a double dot).  I have been thinking of getting an RA# to send it to LaserGlow, if I send it, I will miss it terrably, but in the long run, maybe I'd be getting more output power and a better quality beam, and if you have to send it back, I would much prefer it be to LG!
 
andy_con

andy_con

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my lasever 100mw 473nm blue module, is multi, but after 15mins when its warmed up its back to 00.

and it got an amazing beam on it, very veyr small even at distance
 
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pseudonomen137

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Shrecken, when it warms up do you still have the multi-modal problem? The warm up time is supposed to be 15 minutes. At 25 feet its understandable that the spot could be around 7-15mm. With blooming from that much power, it may be possible it appears half dollar size (off the top of my head, isn't a half dollar something like 30mm?) It could also be a side-effect of the mode problem, or the collimator got jiggled out of place (I adjusted the divergence to make surewas decent before I sent the unit to you).

But no, blue lasers aren't inherently worse. In fact, a 473nm DPSS should be marginally better than a 532nm DPSS in terms of beam specs. Since the DPSS process for blue is a bit more finnicky though, you tend to find more multi-moding units there.

Anyway, try letting it sit warming up for 15 minutes and let me know how the modal situation is. Also then try measuring diameter on a very dark black matte surface from a far distance (well over 25 feet, 100+ if possible). If the problem persists, we can ge in touch about a possible solution.
 
Schrecken_Licht

Schrecken_Licht

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pseudonomen137 said:
Shrecken, when it warms up do you still have the multi-modal problem? The warm up time is supposed to be 15 minutes. At 25 feet its understandable that the spot could be around 7-15mm. With blooming from that much power, it may be possible it appears half dollar size (off the top of my head, isn't a half dollar something like 30mm?) It could also be a side-effect of the mode problem, or the collimator got jiggled out of place (I adjusted the divergence to make surewas decent before I sent the unit to you).

But no, blue lasers aren't inherently worse. In fact, a 473nm DPSS should be marginally better than a 532nm DPSS in terms of beam specs. Since the DPSS process for blue is a bit more finnicky though, you tend to find more multi-moding units there.

Anyway, try letting it sit warming up for 15 minutes and let me know how the modal situation is. Also then try measuring diameter on a very dark black matte surface from a far distance (well over 25 feet, 100+ if possible). If the problem persists, we can ge in touch about a possible solution.
Click to expand...


I fired it up and left it on for about a half hour tonight (the laser head got quite warm to the touch) and at first it was single mode (I didn't measure it but it was almost as big as a dime at about 20 feet) but then after a few minutes it went into multimode. I took a photo of the mode that it settled into and stayed in - I'll have to see how big the beam is further away than that when I take it out into my garage tomorrow and point it out into the yard.

725.jpg
 
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steve001

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andy_con said:
my dot at 16 metres

DSCN7707.jpg
Click to expand...

never measure the spot size against a white surface for obvious reasons. Do so against a black surface or through a piece of flat glass like picture frame glass.
 
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darklandz

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my viasho 20mw blue needs to warm up for a few minutes before it gets really bright and looks a clean TEM00 beam even at a distance, tho i wish the divergence was bit better. after 50 meters at night with ambient lighting i cant see the dot unless its pointed on a white background.
this laser sure kicks ass tho :D
 
Razako

Razako

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darklandz said:
my viasho 20mw blue needs to warm up for a few minutes before it gets really bright and looks a clean TEM00 beam even at a distance, tho i wish the divergence was bit better. after 50 meters at night with ambient lighting i cant see the dot unless its pointed on a white background.
this laser sure kicks ass tho :D
Click to expand...
That's odd. My blue RPL can put a visible dot on stuff over a mile away easily. The beam is great at night. It produces a clearly visible blue beam that is comparable to a 10mw green at least.
 
murrat

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My viasho 5mW has also a very good divergence. Better than my old fusion.
And it is tem 00 all the time. ;)
 
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darklandz

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im not sure but this unit may have a 2W diode compared to a 2.5 in yours.
mine wasnt bought from opto direct, and that extra 10mw may make a big difference.
 
andy_con

andy_con

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steve001 said:
[quote author=andy_con link=1205294469/0#6 date=1205352964]my dot at 16 metres

DSCN7707.jpg
Click to expand...

never measure the spot size against a white surface for obvious reasons. Do so against a black surface or through a piece of flat glass like picture frame glass. [/quote]


really?! LOL

i wasnt measuring the size, it was just for the purposes of this thread
 
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Things

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Yeah, mesure the dot when its shining on something black, otherwise the dot will look much bigger than it actually is because of the scattering.
 
Chicxulub

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My 8mw 473 blue laser has a roughly 2mm dot at the aperture, and at 50 feet the dot's about 9 mm. Not too shabby me thinks. :) Also, it does have a VERY TEM 00 dot. It did arrive with a cracked lens, but that is going to be covered by the warranty so I'm not worried.
 
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bluephoton

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The multi mode of this appears to be a problematic batch of optical glue in China. Some of the optics are and have been seperating at the crystal junction in the past due to thermal expansion. I would investigate a warranty repair. Unless you have a chamber to regas the optics housing and re-seal it.........
 
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