Which diode for maximum beampoint intensity (mW) at 50-100 meters?

[cncyana]

There seems to be no forum Table showing maximum beampoint intensity (mW) at longer distances, regardless of beam color. In other words, minimum divergence. I see posts stating that beam divergence is a function of wavelength (this number is easy to get) and beam diameter (this number is not easy to get). The larger the wavelength number, the larger and worse the divergence. The larger the beam diameter, the lesser and better the divergence.

Also, some higher power diodes, especially in the blue colors, tends to have large divergences. So getting a higher power diode does not necessarily get you higher beam intensity at long distances due to worse divergence at those distances.

Anyway, is there any way to figure out what diode to get for highest beam intensity at longer distances? This question is regardless of beam color, I am only interested in beam shape with highest intensity at longer distances.

I am also assuming that a beam expander will improve divergence of any beam so getting the best beam without the expander and then adding the expander will get me an even better beam, ultimately.

Maybe this info is somewhere on this forum but I don't see it.

For starters, any suggestions on which diodes I might consider will be helpful.

Thank you for your help and input.

 

[brendon7358]

Pretty sure your best bet would be either a 500mW 405nm (don't remember which diode). Or a high power dpss (such as 532nm). An 800mW that usually runs at 1W can be purchased from jetlasers for $460. Whichever you choose, a beam expander will make it even better.

Also beam intensity doesn't exist, what you want is just power (mW) and lowest divergence.

 

[ZRaffleticket]

The 405 referenced in the above post would be the BDR-209.

What is your application? Budget? Do you care if it's visible or not? All this will help get a better answer as there are many options

 

[paul1598419]

Divergence is more a product of the emitter geometry. Actually, a larger beam, beam expanded, gives you better divergence specs. The 405nm diodes are so close to UV that they are hardly visible at all. They do make for some great single mode burners though.

 

[RedCowboy]

I have a 505nm direct ( case positive ) that has very low divergence, it's only doing about 30mw but in daylight I can set it on the shady part of a big tree 100's of meters away and with my telescope I can see the spot and I can actually see it with my naked eye at dusk also dpss 532nm lasers with their Gaussian beams can produce very tight spots at distance........I love the way modern directs like my 505nm and some of my 520's can make a very nice beam/spot over distance, I use a DTR G8 on my PL520 and run it @ 215ma which gives me about 90mw, I use it in a continuous run build.

 

[RA_pierce]

As you have read, beam divergence and beam diameter are inversely related. This means that you can obtain lower divergence by increasing beam diameter. However, the problem gets more complex when you consider that the beam waist increases with increasing distance and with increasing wavelength. You may also consider scattering in the atmosphere, which is more of an issue with short wavelengths.

If cost and form factor is not important, a 532 nm DPSS laser is probably going to be better than any diode available. A good unit will produce much better beam characteristics than any diode and will work well with beam expanders. This wavelength (532 nm) is also very good in terms of its power/price ratio and is very stable compared to other common and affordable DPSS lasers.
My second choice would be a BDR-209 405 nm diode. This diode produces a good beam with low divergence. The low wavelength makes possible a smaller beam waist and lower divergence than with longer wavelength lasers but suffers from more scattering in the atmosphere.
The main advantages of DPSS include high power, and very good beam quality compared to direct diode lasers.

If you are building your own setup, consider using aspheric optics to collimate the laser beam. Aspheric lenses are better at focusing rays across the surface of the lens to a single point. In contrast, spherical optics may result in rays that enter the lens at the edges coming into focus at a different point than rays entering the center of the lens. In other words, rays that enter a spherical lens do not all converge at a common point, resulting in an unfocused, "blurry" beam. There are numerous online resources that explain this concept simply with diagrams.

BUT...
We can be of much more help if you explain what you are trying to accomplish.

 

[cncyana]

A big thanks to all who answered my question. I never considered the 405nm or the 505nm before.
I just found this video comparing balloon popping abilities between a 1W 405nm vs 2W 445nm. The 1W 405nm won (BDR-209 module from DTR).

 

[cncyana]

DTR has three 405nm diodes of which the highest power is the BDR-209 but has the smallest overall can size and cheapest. I am wondering if the smaller size means it may burn out easier, assuming it is running at recommended current of 500mA. The other two 405nm diodes appear to be housed in a larger can but at lower power. The Sharp GH04W10A2GC 350mW/1.1W(Pulse) has greater divergence than the BDR-209 but is more expensive. What does 1.1W 350mW/1.1W(Pulse) mean?

 

[Mosc007]

The GH04W10A2GC is capable of a much higer output than the BDR 209. It can reach over 2 Watts if you have a good one. The one I have is set to 1600mw. Have a look at DTR's review. https://laserpointerforums.com/threads/sharp-gh04w10a2gc-350mw-405nm.104348/