635nm vs. 650nm

[Dingers]

Hi all,

as everyone knows a 635nm is much brighter than its 650nm brother.

However I, and I'm sure others too, have never quite understood how much brighter.

If anybody has any pictures comparing the two,
please post them up!

 

[Murudai]

Ah, good idea. I'd like to see that too

And also, if the 635 is noticeably more 'orange' than the 650

 

[Razako]

The best way to see the difference is to point a 5mw 650nm and a 5mw 635nm at a white wall and compare the two dots. The 635nm will look visibly brighter and will also be more vibrant/eye catching.
Here is a pic from the reviews section.

 

[styropyro]

From close up, you can barely tell the difference between the two colors. Over a distance is where you can tell the biggest difference. 635nm goes surprisingly far considering it is 5mW of red. You also can tell that 635nm is orangish from a distance, but it is still more red than anything. In fact, you can even barely see the beam from a 635nm at night.

If you need some pictures I can take some. I attached a picture of shining a 5mW 635nm module at a wallish thing.

 

[Dingers]

Thanks Styro and Razako,

how many mW's of 635 do you reckon you'd need to match the brightness and beam of a 5mW green?

Also, although probably irrelevant in this subforum,
how many mW of Blu-Ray 405nm would match the 5mw of an 532?

 

[andy_con]

with ratios -

650nm to 532nm its 4:1

635nm to 532nm its 2:1

so a fair bit brighter

 

[Dingers]

Thanks Andy,

any info on the blu-ray to green ratio

 

[andy_con]

LOL not sure probably something like 10:1

405nm is very very dark

 

[Benm]

If you want visibility ratios for various colors, why not look at the CIE data for the luminosity function:

http://www.cvrl.org/database/text/cmfs/ciexyz31.htm , in http://www.cvrl.org/database/data/cmfs/ciexyz31.txt the middle column gives relative visibility with 555 nm = 1.

532nm is almost as visible as it gets with about 0.9, 635 is at 0.32, and 660 at about 0.06.

I quote the 660 nm figure since that is what most dvd diode based pointers actually produce, despite claiming 650 nm. So 660 to 532 would be a factor of 15, 660 to 635 about 5, and 635 to 532 about 3.

For blu ray there is a problem with this dataset as it has been proved to be pretty far off reality for lower wavelenghts. If you use the stockman correction the ratio between 405 and 532 should be in the order of 200 times.

With the laser dot this is obviously much less apparent since it makes most materials flouresce and hence appears much brighter.

 

[Zom-B]

Hey this thread is a double post. My answer including CIE is already in this thread: http://www.laserpointerforums.com/forums/YaBB.pl?num=1210508946

 

[Ace82]

One of my first lasers was 635nm and I always thought of it as 'red-orange'. I paid $119 for a 5mW pen back in 1994. Is there some reason why 650nm has dominated over 635? Can you get high powered 635nm diodes (for reasonable costs)?

 

[Benm]

Didnt see the other answer about the CIE function yet, but i guess it all boils down to the same anyways.

650/660 nm diodes have a real world application, dvd players and writers, 635 nm do not, apart from laser pointers which is far from a big market.

Also producing lower wavelength diodes is more difficult (worse yields), which is probably why they chose 660 nm for the dvd - at 635 more information would fit on a disc.

 

[phenol]

One of my first lasers was 635nm and I always thought of it as 'red-orange'.  I paid $119 for a 5mW pen back in 1994.  Is there some reason why 650nm has dominated over 635?  Can you get high powered 635nm diodes (for reasonable costs)?

here are some 635nm high power LD cost examples :
60mW single mode - EUR320
100mW multimode, 9mm - EUR154
150mW multimode, TO3 - EUR180
300mW------------------- - EUR370
500mW------------------- - EUR444