445nm correction

[kiyoukan]

Okay so i have been playing with these lenses i got from dave.
I am getting some amazing results with using the 2mmFL lenses plus the 6x setup.
Granted there is alot of space between the diode lens and the c-lenses but i just burt my hand at over 50ft the dot is still a rectangle starts at about 4 by 1.5mm still setting up my far feild test but seeing as i came in from the shop felt like ill post this now.
Along with some pics of my red setup im putting it together tonight.
Got a PL member stopping by to come see it in person.
Alot of fun tonight.


So i adjusted it till i got it at 4mm at aperture and at 25ft it was 9.61 so a mRad of 0.736
Not bad kinda close to the 635nm if you pin hole the red down to 4mm

[taggalucci]

Interesting... Do you have any data on the transmission performance of these lenses with the 445nm diode?

[swamidog]

interesting... can you show a pic of the 445 spot?

Okay so i have been playing with these lenses i got from dave.
I am getting some amazing results with using the 2mmFL lenses plus the 6x setup.
Granted there is alot of space between the diode lens and the c-lenses but i just burt my hand at over 50ft the dot is still a rectangle starts at about 4 by 1.5mm still setting up my far feild test but seeing as i came in from the shop felt like ill post this now.
Along with some pics of my red setup im putting it together tonight.
Got a PL member stopping by to come see it in person.
Alot of fun tonight.


So i adjusted it till i got it at 4mm at aperture and at 25ft it was 9.61 so a mRad of 0.736
Not bad kinda close to the 635nm if you pin hole the red down to 4mm

[Solarfire]

It really makes no sense using a shorter FL lens with the 445nm diode (or any other diode with similar specs); the beam corrected results will always be the same @ ≈ 3.5mm diameter and 0.8mrad divergence (405-G-2 with drlave cylinders). As you see with your setup giving ≈ 4mm and 0.74mrad. If a lens captures the entire beam the laws of physics apply, beam divergence is revers proportional to beam diameter. Using a shorter FL lens will only result in a larger divergence to correct, not to mention that diode centering becomes much more critical. A 4mm FL lens with 4 x tele correction will bring ≈ the same results as a 2mm FL with 8 x tele correction. The initial divergence of the diode determines what beam specs can be achieved (divergence, diameter).

Larger distances between optics will make the setup more susceptible to beam drift due to thermal expansion and contraction which is proportional to the factor distance increase/decrease.

[-bart-]

Also, using short f lenses will introduce more spherical abberation.
Even aspheres have their limits.
Most important is that the NA of the lens matches or exceeds the divergence of the raw diode.

[logsquared]

I did a quick test the other day with different lenses on a 445. Basically just set the power supply to ~.5A and tested each lens with out any further power supply adjustments.

O-like blue: 499mW
optima 4mm: 547mW
Daves 2mm: 528mW
405-g-2: 583mW

[taggalucci]

Thanks Woody

It would be good to get some beam specs of the 445nm diode with Dave's 2mm FL lenses with no correction. Do you have this data?

Cheers,
Tony

I did a quick test the other day with different lenses on a 445. Basically just set the power supply to ~.5A and tested each lens with out any further power supply adjustments.

O-like blue: 499mW
optima 4mm: 547mW
Daves 2mm: 528mW
405-g-2: 583mW

[logsquared]

I didn't measure the aperture sizes I had a 445 on the bench and all the lenses with in reach so just did a quick test on power and far field spot size.

here is the spot size at 72 feet:

O-like blue: 1.62 X .19 inches
optima 4mm: 3.36 X .34
Daves 2mm: 7 X .6
405-g-2: 3.25 X .2

I also did a test with the optima 8mm but I fumbled with the lens when putting it in the holder and may have gotten a finger print on it Here are the results anyway.

optima 8mm: 472mW 1.58 X .136

These were just quick measurements so don't take as gospel

[alessandrotnt]

Nice to meet you. I'm new to the forum and i'm going to build a RGB laser but i have some problems to correct the divergence of the A140 445nm diode. I discovered that i have to use a bi-concave lens with a plano convex lens, can someone tell me more about this? Forgive my bad english, i'm italian!
p.s my 445nm laser mount a G-2 lens, i've tried to put a normal 3 element glass and at 3 meters distance the lenght of the output with a G-2 is about 11mm and with the 3 element glass is about 6mm..

[taggalucci]

Nice to meet you. I'm new to the forum and i'm going to build a RGB laser but i have some problems to correct the divergence of the A140 445nm diode. I discovered that i have to use a bi-concave lens with a plano convex lens, can someone tell me more about this? Forgive my bad english, i'm italian!
p.s my 445nm laser mount a G-2 lens, i've tried to put a normal 3 element glass and at 3 meters distance the lenght of the output with a G-2 is about 11mm and with the 3 element glass is about 6mm..

Welcome!

3 Options:

1: don't use any correction and just de-focus the lens until the stripe becomes square. The far field beam will be larger.
2: use anamorphic prism correction (search "anamorphic prisms") and use those to reduce the far field beam size and de-focus the lens (a bit less) to get a square.
3: use cylindrical lens correction (search this forum for "cylindrical lenses" or "dr lava lenses") and do as above.

There's plenty of information already on this forum so please try searching. Some good searches would be "445 collimation", "445 correction" and the ones I've mentioned above.

Good luck!