445nm lensing options - discuss them all here!

[taggalucci]

please tell what you used to get divergence of 1.6mrad

...and what initial beam diameter was obtained

[Stoney3K]

Has anyone considered the option of using a PBS to turn this thing into something more symmetrical?

Either use two (one on its side) and combine, or chop a single beam in half, waveplate it, and combine.

The first option would probably be cheaper and give you more headroom in power, or reduce cooling requirements.

[taggalucci]

Has anyone considered the option of using a PBS to turn this thing into something more symmetrical?

Either use two (one on its side) and combine, or chop a single beam in half, waveplate it, and combine.

The first option would probably be cheaper and give you more headroom in power, or reduce cooling requirements.

Please correct me if I'm wrong, but I think option one would result in the fast axis being replicated 90 degrees perpendicular to the other, resulting in potentially similar divergence in two axes however, it is the fast axis which is th problem here. Unless you then used a telescope to tame the divergence and were happy to deal with a larger beam diameter, I'm not sure this is desirable (unless you clipped the edges of the elongated sides of each beam prior to, or after, combining).

Your second option sounds interesting. Say the beam shape was twice the width of the height and one were to split the beam mid-way resulting in two beams of equal width and height (at that point), could you rotate the polarisation using a waveplate and recombine via PBS to obtain a more desirable beam? I see a lot of alignment and components required here, as well as loss through optics. Would the gain from doing this outweigh the cost? And would this effectively reduce the divergence in the fast axis?

[Stoney3K]

Please correct me if I'm wrong, but I think option one would result in the fast axis being replicated 90 degrees perpendicular to the other, resulting in potentially similar divergence in two axes however, it is the fast axis which is th problem here. Unless you then used a telescope to tame the divergence and were happy to deal with a larger beam diameter, I'm not sure this is desirable (unless you clipped the edges of the elongated sides of each beam prior to, or after, combining).

The way I see it, we got plenty of power for practically nothing. So we can get away with beam clipping with little trouble. Less divergence is better than a smaller beam in that case, because who needs 2W of blue in a pinpoint-sized beam anyway, unless you want to burn stuff?

You could even think of a setup with an adjustable (controlled) aperture, which you can put wide open for beam shows, and dial it down to a pin-point if you wan to do graphics.

[stanwax]

I have just used the laserwave uncoated lens that comes with the diode module kit and I can get a clean beam which as has been seen elsewhere focuses the beam to a line (dont ask me what the lens spec is). I then placed a prism pair in front of this and get correction that makes it into a square. I have not attempted to measure the divergence but the beam looks almost identical to the beam from the 445nm lasers I have used from RGB laser systems.
will take some pix later of tomorrow if I get a chance. I will be happy with this beam

Rob

[allthatwhichis]

I have just used the laserwave uncoated lens that comes with the diode module kit and I can get a clean beam which as has been seen elsewhere focuses the beam to a line (dont ask me what the lens spec is). I then placed a prism pair in front of this and get correction that makes it into a square. I have not attempted to measure the divergence but the beam looks almost identical to the beam from the 445nm lasers I have used from RGB laser systems.
will take some pix later of tomorrow if I get a chance. I will be happy with this beam

Rob

..............

[stanwax]

here are the results
focussing the beam over a distance of about 20m and then directing it at my screen 3m away I get what you see below. On the left is a 7mm stripe from the beam just passed through the laser-wave lens. On the right pretty square beam after a prism pair - I will at some point hook up a RGB 445 module and run alongside for comparison - just not possible tonight.
Now I really must go and kill one of these diodes.....

Rob

[mccarrot]

Very nice. , when do you take that baby outside for a diergence test

[stanwax]

not tonight!
May do it tomorrow but now I need to set about building some laser projectors plus I wanna get more of these lasers running and combined. Finally as stated above I wanna do a destructo test but will have to butcher the driver off one of my lasers to acheive that - fun fun fun! (the diode for this is already earmarked)
I am also dying to put this laser in with my 556nm laser (baby bunk) to see how sexy the white will be - its sexy as fcuk with 473nm and I am guessing it will look even better with 445nm
Dont anyone mention the 'ch' word or I will stick the remains of the casio where the sun dont shine!

Rob

[mccarrot]

Last evening I did some quick test with the High quality collimator from my webstore.

Out of the aperture there is a clean 3mm beam, after 30 meters I ended up with a line of 8mm wide and 80mm long

this give me a fast axis divergence of less than 0,2mRad full angle, and aprox 2,6mRad at the slow axis full angle (or 0,1 x 1,3mRad half angle like Kvant like to rate there lasers: eek

For beamshows it's good usable without any correcting optics, at least it's way better than a 635nm flashlight. For graphics you should add correction optics like a cylindrical lenses to shape the slow axis.