B&W Tek BWB-10-OEM - 473nm 10mW

[wby300]

Got ya qumefox, I am fairly new to lasers so I was unsure about the head. As far as the UV lasers are concerned, you guys are right and they are expensive. I have an idea for a cnc engraver/router and would like the laser for that, since a uv laser of less power is stronger than a ir laser with more power. I am getting quite a collection, I didnt even mention I have 2-40w fiber coupled lasers also for the above mentioned project. I have also been buying up some 10 of the 650nm 6x14 mini diodes for a seperate project. I want to make bore sight laser cartridges, only I plan to put the diodes into an actual cartridge for the firearm intended. I have wanted some of these for my weapons and they are expensive, I would like to make a cheaper alternative for people. I would also like to make some weapon sights in different wavelengths than the normal red and now some green. All lasers purchased to use in any comercial products will be kept at or below the 5mw power. For my personal use, I dont think so:shhh:

 

[Sigurthr]

My BW Tek 473 labby started up at what looked like 5mW in a strange mode; TEM02 the other day. I opened her up and tried to realign her again, hoping to rotate the nonlinear crystal by 180degrees, but when I got to it after removing the plastic IR blocking cover over the crystal I noticed that the screws which hold the copper crystal module to the aluminum plate were soldered in place to the copper plate. So, I just realigned the aluminum plate, as I had tried to do last time. It didn't appear to have shifted from my last alignment though. This time it is about 1/2 a millimeter away from the previous location, and it is lasing bright in a mixed mode, kinda half between TEM00 and TEM02. The upper (main) vertical lobe is dominant and the lower lobe is just barely visible as a slight semicircular thin blob below the main lobe. All the splash effects have been removed from the beam though, and it appears to be slightly brighter to the eye. Also, the head is running a LOT cooler now. I guess there must have been some internal IR reflections heating things up.

 

[Bionic-Badger]

For your CNC, you should just stick with those CO2 lasers as they're cheap for their power, are absorbed by most materials, and widely available.

 

[wby300]

Yea, I know. I have actually got a very good deal on both 40w lasers anyway. I just seem to have the laser bug, I have always been into them just never built my own.

 

[laserlink]

Just listened to it again.. its just very peculiar. I only hear it when the top cover is off. Its soft, but it can't be anything like a little temperature 'creak' of any kind. It just sounds like white noise, with a bit of a hiss. Maybe my ears are just sensitive to the UHF waves from space now?

This sounds like what is called "Mode Beating". There is a very good article from Melles Griot on this effect at http://www.cvimellesgriot.com/produ...uide/Frequency_and_Amplitude_Fluctuations.pdf

If the link doesn't work just google Melles Griot mode beating and look for the pdf link.

 

[wby300]

Well after taking one of mine apart the wire that mounts to the diode C-mount has broke loose. I managed to solder it back but I am thinking about getting a higher watt diode now, might go with a 2 watt or so, I even sawa 15w but it is a little expensive. I may also tweak the lenses to see if I can get it focused instead of difused.

 

[wby300]

Just out of curiousity, what other frequencies do you guys think these crystals will double? The diode has to be 946nm to be 473, I would like to try 808 or maybe down into the very high 700's to get this laser down into the high UV?

 

[HaloBlu]

The coatings on the crystals will only allow 473. The IR diode is 808 which is converted to 946 by Nd:YAG. The DPSS Primer...

 

[wby300]

Frequency doubling is actually cutting the nm in half, 473 is half of 946 and in that article it states this. 808 would be 404. Fact is that most crystals, lenses and eye protection cover a certain "area" and sometimes even a couple at different nm's completely. So I was curious about what the average range of a set of these crystals was to see if different ir diodes would be worthwhile. If the crystals cover a good range, you could go from right around 500nm down to 400nm with different diodes.

 

[HaloBlu]

Took the opportunity to hack up an image. :san:

That 1064 should be 946...
Coatings: AR=anti-reflective, HT=high transmission, HR=high reflective. OC=output coupler, TEC=thermoelectric cooler/peltier.
Please ignore the green color of the resulting beam.
~edit~ There are no output optics on the BWB-10-OEM since it was originally fiber coupled. Other 473nm DPSS lasers should have some optic there. There is also a optical feedback after the IR filter which is not in this image.

You can see the actual OC in a BWB-10-OEM attached on the right side.

Picture by GBD I believe (flipped)

Even with different coatings, whether its doubled, tripled or combined, crystals can only produce certain frequencies.

 

[Sigurthr]

Hmm, are the output optics inside the rectangular cavity of the head with the rest of the guts or are they between the head cavity and the aperture?

There's nothing after the nonlinear assembly on the TEC in my head.

 

[HaloBlu]

Opps, There are no output optics on the BWB-10-OEM at all. Forgot to remove them from the image. Just a IR filter & optical feedback.

Here are examples of Crystals & OCs with different coatings.

 

[Sigurthr]

Ahh, ok made me wonder, lol. Mine is 9mRad before external correction, thought I might have finally found why.

My nonlinear assembly doesn't have any aluminum around it like in the photo either if that is signifigant.

 

[HaloBlu]

My nonlinear assembly doesn't have any aluminum around it like in the photo either if that is signifigant.

What aluminum is missing? Care to take a pic perhaps?

 

[Sigurthr]

You know what? My memory is failing me in my old age, haha! I was wrong, the aluminum structure the nonlinear assembly is on is intact and as represented in the photo above.

There doesn't seem to be the outer most lens there though, unless it is recessed in and small. I suspect that if it is the OC, then it must be there on mine, but very small and recessed. I can see the spanner wrench holes and the ring to adjust the lens, but the lens isn't protruding or visible like in your photo.

I tried getting a picture, but my camera won't macro that close. My camera won't macro at all actually, 10 inches is the minimum distance.

 

[HaloBlu]

You know what else? I can't be sure thats the OC! Others have identified it as such but on cheap greens at least the OC isn't separate & is just done with coatings on the crystals.