Which laser color is the brightest at night ?

[rigormortis]

sorry if i asked a stupid question. when i saw the first laser pointer at DX i was shocked it was 5 mw and green of course. After there was red and blue and so on. Now there are so many types. Now i am thinking about buying one around 200 dolars, which one do you advice ?

Thanks and regards !

 

[CurtisOliver]

Green is the brightest colour all round.
During bright daylight 555nm is brightest per mW but at night your eyes shift to become more sensitive to 507nm. As your typical DPSS greens are 532nm, they sit quite comfortably near the middle of the two peaks so are very bright regardless of lighting conditions.
As for blue and red lasers. Blue is dim during daylight but is brighter in the dark. Red is the opposite. As you approach the peaks the wavelengths get brighter. So your typical red laser at 650nm would appear dim at night, but if you get a 635nm it will appear brighter than the 650nm. That's the basic idea of luminous efficacy.

As you are after brightness rather than raw power I would suggest you look into green lasers of either DPSS 532nm or diode 520nm.

 

[steve001]

555.5 nm light has the highest apparent brightness.

 

[smallfreak]

Now i am thinking about buying one around 200 dolars

Well, any of the "greens" will get you most visibility per mW, as stated before. On the other hand, it might depend on your application for the Laser.

What do you want to achieve with it? Nowadays you get almost every color as bright as you might need. Bright enough to blind you instantly, if not handled carefully. So there might be a "maximum useful brightness" too for which you should think about.

If you are calculating "the most visible brightness for the money", you might be better off with a blue one. Despite blue is not perceived as bright as green when you compare the same mW, the blue Laser diodes on the market offer more power than comparably priced green ones.

So, if you think about buying something like that one with a 2W 445nm blue Laser, you might still outshine every green one.

And you should always think about the fact, that this "toy" is a dangerous, long range weapon that can fry someones (your) eyeballs much quicker than you can say "oops".

Btw.: the red pointers where first on the market. It took a couple of years to achieve green with the optical trick of frequency doubling an infrared YAG. Blue ones where next, followed by green direct lasers and Violet ones. The yellow tones ones are still missing in direct diode, but are available in "frequency doubling" (DPSS).

 

[Gazen]

This calculator might be useful for you:

Relative Laser Beam Brightness Calculator: (445nm 2000mw) vs. (532nm 198.51mw)

You can see that 200mW of 532 green is equal to 2W of 445 blue. 532 or 520 are your best options. Sanwu and jetlasers have some high quality options. For $200 jetlasers will be better, as sanwu is relatively expensive.

$200 700mW 520 PLE-pro- equal to over 6W of 445nm (https://www.jetlasers.org/pl-e-pro/13-pl-e-pro-520nm-diode-green-laser.html)
- more stable than dpss 532
- worse divergence and beam specs than 532

$180 200mW 532 PLE-pro- equal to over 2W of 445nm (https://www.jetlasers.org/pl-e-pro/...m_expander-no/90-ac_adapter-no/49-goggles-no_)
- better divergence
- less stable and more sensitive to temperature and shock


Jetlasers is one of the highest quality with an internal focus and high quality machining, you can't go wrong with one. Just keep in mind shipping will add around $40 to the total.

 

[CurtisOliver]

Yep. ^^^

 

[RA_pierce]

which one do you advice ?
Thanks and regards !

Hi, and welcome.
If you want to play with a laser outdoors without worrying about being very conspicuous, 50-100mW of any green wavelength will be just right.

A custom built 505nm laser will be able to produce about that much power and will work within your budget of $200. The color is pretty nice, too.

 

[CurtisOliver]

505nm is a lovely wavelength, and is also pretty much on the scotopic peak. So would be nice and bright at night.
Just don't expect too much power from these diodes.
It would be very different from the common 532nm pointers. Nice suggestion RA_pierce.
For the money however you are more likely to get a brighter pointer with 532nm.

 

[paul1598419]

I have a 502nm laser that outputs more than 100 mW. It was a low wavelength of the first 505nm diodes released by Sharp. You can still buy these diodes except they are all case positive now. Mine is case neutral. Being case positive makes putting it into a handheld more complicated. You are pretty much stuck with using the SL Blitz Linear driver and two Li-ion batteries.

 

[Benm]

Don't overthink it too much - both 532 and 510 would be fine.

Neither are actually exactly on the maximum sensitivity of scotopic or photopic vision, but they are pretty close. It may look 10 or 20 percent less bright for the power given, but other properties could be more important.

The 532 nm dpss often struggle a bit in hot or cold temperatures, whereas the direct diode 510 nm ones are a lot more thermally stable. If you don't need a huge amount of power a single mode 510 nm diode could be a perfectly acceptable solution.

The higher power ones are often multimode and have a pretty terrible beam pattern. This can be acceptable for laser shows and other short range things (like setting stuff on fire) but if you wan't a clear tight beam go for single mode diodes, or 532 dpss if thermal problems are not an issue.

 

[smallfreak]

This calculator might be useful for you:

Relative Laser Beam Brightness Calculator: (445nm 2000mw) vs. (532nm 198.51mw)

It's always interesting to learn something new. This calculator lead me to "ISO/CIE 10527 (1991) CIE Standard Colorimetric Observers definition", via the "spectral luminous efficiency function V(λ)"

[up to here], where all these eye sensitivity numbers are available in 0.1 nm steps. Meticulously measured by analyzing the actual absorption of light in the retina throughout the visible spectrum.

Very interesting stuff. Thank you.

So you are totally right. The sensitivity of the eye drops to 50% just ~50nm up and down the maximum sensitivity wavelength at 555nm. 100 nm off the center we are at ~10%.

I was not aware that the peak is that sharp. Must be quite tricky for the brain to balance the colors in a way that the world does not look all green.

 

[steve001]

It's always interesting to learn something new. This calculator lead me to "ISO/CIE 10527 (1991) CIE Standard Colorimetric Observers definition", via the "spectral luminous efficiency function V(λ)"

[up to here], where all these eye sensitivity numbers are available in 0.1 nm steps. Meticulously measured by analyzing the actual absorption of light in the retina throughout the visible spectrum.

Very interesting stuff. Thank you.

So you are totally right. The sensitivity of the eye drops to 50% just ~50nm up and down the maximum sensitivity wavelength at 555nm. 100 nm off the center we are at ~10%.

I was not aware that the peak is that sharp. Must be quite tricky for the brain to balance the colors in a way that the world does not look all green.

What is more curious is none of this text is yellow.

 

[cistercian]

Beam quality can be important depending on what you want to do. The more complex, fragile, and temperature sensitive 532 nm greens can have fantastic beam quality with very low divergence.
A diode green will have a fast and slow axis which generally speaking makes for more divergence, especially with a simple lens system.

I own 2 jetlaser 1 Watt 520nm green lasers...and they are freaking epic!!!
But I built a 515nm pointer that is about 80mw that is more fun to play with
since it does not light stuff on fire as quick as the jetlaser 1 watt lasers do.

Best beams come from my 532 nm DPSS lasers. They produce tiny in cross section beams with excellent divergence too.

I find myself playing with the lower power direct diode greens the most FWIW.
I recommend the eagle pair eyewear as well.

ALL of my greens look bright at night. The 1 watt ones are ridiculously bright.

 

[kecked]

565nm yellow green is the closest to peak eye sensitivity but the closest and cheapest is the green 532nm dpss laser pointer. 5.00
My low power 565nm is even visible in daylight at 30mw. 50mw 532nm should be same or better.

 

[hakzaw1]

Lots of good posts and advice. ^^^^
Thanks for the mention of your JETLASERS laser.

hak

 

[Unown (WILD)]

Two years ago Hak. Check dates before posting gee wiz...