What's the different between 637nm and 638nm?

[bridge]

The information we received before or in most people’s knowing, 637nm laser means good beam and divergence; 638nm laser means bad beam and divergence. Why most people have this kind cognition? If the real situation is really like this? First, viewing from the theory of lighting, 637nm and 638nm are the same semiconductor light-emitting material, that is, they are the same laser. As for semiconductor laser, there is a deviation of ±5nm from the central wavelength. Speaking from lighting essence, there is no difference between 637nm and 638nm. In fact, the central wavelength of 637nm and 638nm is roughly accordance, so the idea of 637nm’s wavelength is short & brighter, but 638nm’s wavelength is long & dim is wrong.
Viewing from appearance, why 637nm is actually brighter than 638nm? The reason is that, in current market, 637nm laser diodes are all single-mode diode, through simple facular-shaping can reach to original beam with low divergence, brightness is concentrated, in other word, the density of power is higher. However, 635nm and 638nm are multi-mode diode, simple facular-shaping can’t reach to beam with good divergence. In the circumstance of only adding lens shaping, the beam size of 638nm is still big with high divergence, brightness dispersing. Through long distance transmission, the power density of 500 mW 638nm is far smaller than 170 mW 637nm, so 637nm seems brighter.
Besides, at the point of light combination, the beam size of 637nm is similar with the beam size of green and blue laser, so almost red light is all used effectively. But as for 638nm, its beam size is much bigger than green and blue lasers, so only small part red light is effectively used, the left red light is not only waste, but form a very big red halo outside of RGB light, so the result of final combined RGB is not very good, especially, the RGB projector is used for cartoon, it seems terrible.
So if 638nm can’t reach to the good beam just like 637nm? The answer is wrong. The beam of 638nm can be produced as good as 637nm’s beam. If you pay attention to this point, in the parameters table of one famous company, red laser is 638nm other than 637nm with the divergence ＜１mrad. We also referred above, there is no difference of lighting between 637nm and 638nm in nature, just because 673nm is single-mode, 638nm is multi-mode. 638nm can’t reach to good beam via simple optical shaping. The difference is at if you have the ability to make the 638nm laser’s beam good. It’s easy for 637nm, a collimation mirror can make it, this point can’t indicate a company’s ability of optical designing, 638nm is different, in order to get good beam size and low divergence, 638nm needs reasonable design. Beam of 638nm is good or bad indicate the ability of a company’s optical designing. In the long period of researching and improvement, Laserwave found the good solution to improve 638nm’s beam. Making suer the near beam size point, we can make the divergence of 638nm is same with 637nm. At the same time, because 638nm is multi-mode laser, the power of one diode is much higher than 637nm, this reduce the complexity when using multi diodes to getting a high power 637nm, improving efficiency, saving cost, therefore, compared with 637nm’s price, 638’s price has much advantage. It also avoids laser’s beam separates when working for long time like 637nm is combined with multi diodes. At present, blue lasers are mainly 445nm and 462nm, green lasers convert from 532nm to 520nm. Green and blue lasers are square beam, in the combination of RGB, the square beam of 638 can cover green and blue beam very well, the efficiency is much better than the round beam of 637nm. Therefore, viewing from aspect of price, efficiency, stability, and difficulty of repairing, 638nm is absolutely your better choice.
Below Pictures one is 4W 638nm, one is 4W 637nm, can you see which one is which?

[swamidog]

please show a picture of the spots on the wall.

The information we received before or in most people’s knowing, 637nm laser means good beam and divergence; 638nm laser means bad beam and divergence. Why most people have this kind cognition? If the real situation is really like this? First, viewing from the theory of lighting, 637nm and 638nm are the same semiconductor light-emitting material, that is, they are the same laser. As for semiconductor laser, there is a deviation of ±5nm from the central wavelength. Speaking from lighting essence, there is no difference between 637nm and 638nm. In fact, the central wavelength of 637nm and 638nm is roughly accordance, so the idea of 637nm’s wavelength is short & brighter, but 638nm’s wavelength is long & dim is wrong.
Viewing from appearance, why 637nm is actually brighter than 638nm? The reason is that, in current market, 637nm laser diodes are all single-mode diode, through simple facular-shaping can reach to original beam with low divergence, brightness is concentrated, in other word, the density of power is higher. However, 635nm and 638nm are multi-mode diode, simple facular-shaping can’t reach to beam with good divergence. In the circumstance of only adding lens shaping, the beam size of 638nm is still big with high divergence, brightness dispersing. Through long distance transmission, the power density of 500 mW 638nm is far smaller than 170 mW 637nm, so 637nm seems brighter.
Besides, at the point of light combination, the beam size of 637nm is similar with the beam size of green and blue laser, so almost red light is all used effectively. But as for 638nm, its beam size is much bigger than green and blue lasers, so only small part red light is effectively used, the left red light is not only waste, but form a very big red halo outside of RGB light, so the result of final combined RGB is not very good, especially, the RGB projector is used for cartoon, it seems terrible.
So if 638nm can’t reach to the good beam just like 637nm? The answer is wrong. The beam of 638nm can be produced as good as 637nm’s beam. If you pay attention to this point, in the parameters table of one famous company, red laser is 638nm other than 637nm with the divergence ＜１mrad. We also referred above, there is no difference of lighting between 637nm and 638nm in nature, just because 673nm is single-mode, 638nm is multi-mode. 638nm can’t reach to good beam via simple optical shaping. The difference is at if you have the ability to make the 638nm laser’s beam good. It’s easy for 637nm, a collimation mirror can make it, this point can’t indicate a company’s ability of optical designing, 638nm is different, in order to get good beam size and low divergence, 638nm needs reasonable design. Beam of 638nm is good or bad indicate the ability of a company’s optical designing. In the long period of researching and improvement, Laserwave found the good solution to improve 638nm’s beam. Making suer the near beam size point, we can make the divergence of 638nm is same with 637nm. At the same time, because 638nm is multi-mode laser, the power of one diode is much higher than 637nm, this reduce the complexity when using multi diodes to getting a high power 637nm, improving efficiency, saving cost, therefore, compared with 637nm’s price, 638’s price has much advantage. It also avoids laser’s beam separates when working for long time like 637nm is combined with multi diodes. At present, blue lasers are mainly 445nm and 462nm, green lasers convert from 532nm to 520nm. Green and blue lasers are square beam, in the combination of RGB, the square beam of 638 can cover green and blue beam very well, the efficiency is much better than the round beam of 637nm. Therefore, viewing from aspect of price, efficiency, stability, and difficulty of repairing, 638nm is absolutely your better choice.
Below Pictures one is 4W 638nm, one is 4W 637nm, can you see which one is which?

[dnar]

What's the difference between good punctuation and none?

[danielbriggs]

Not all 638nm lasers are multi-mode.
As you correctly stated, you can not tell the performance of a laser from the wavelength alone.

Not aimed at Laserwave, a general comment:
I wish manufacturers would measure the beam parameter product and M² for each of their lasers, as this, if measured correctly to standards, would cut the crap of "ours is better than theirs, look at the dot on a wall, "I'll slip in half-angle divergences, no one will know".

But proper test equipment is expensive, so few care for it.

[bridge]

near and far beam compare.
the last picture is take photo using goggles.

[Bradfo69]

So... I'll guess and say that in your first photo in the first post that the 637 is on the right and, in your down range pics showing the spot that it's the one on the left. I figure I have a 50/50 shot at getting this right.

[jors]

Please beam size (mm) at aperture on 638?
How many P73 do you combine for 4w out?
thanks

[bridge]

637nm is left, 638nm is right

So... I'll guess and say that in your first photo in the first post that the 637 is on the right and, in your down range pics showing the spot that it's the one on the left. I figure I have a 50/50 shot at getting this right.

- - - Updated - - -

PM me your email, thanks

Please beam size (mm) at aperture on 638?
How many P73 do you combine for 4w out?
thanks

[Humphry]

I received an email from laserwave a while ago with the same drift... "Our 637nm is as good... " have been sceptical at best about this - I assume they are just correcting mitsubishi multimodes? I thought the laws of physics prevented this, if both modules given the same quality of workmanship?

[jors]

I get 3w out on my mitsu quad 4,5mm beam (teced at 18ºC)..less when spatially filtered...and it is nicely tuned. So 638 4w out is only possible on octo p73/oclaro but with 8-9mm beam out IMO. This is along with F2+correction (Dave's cyls) for less than 1mrad on both cases...
With no correction, yes, you can knife llll+pbs+llll for 5x5mm beam waist and up to 5W out...but don't look at FF torch "spot"