Beam combining - effects of different wavelengths on resultant human perception.

[Arcygenical]

Well,

I don't see a 589nm beam in my near future, mainly because it's unlawful to import - and Frankly, I just don't want to deal with that right now.

I was considering metal-printing a mount to create a simple red+green combining module, throwing a dichro in, and calling it a day. Can still get it handheld as well, at the appropriate outputs.

But then I thought... We have all sorts of options for greens now, and a couple options for reds. Obviously summing two different, non-coherent and most certainly mis-phased, Mis-TEMed, wavelengths doesn't change the optical harmonics of two beams, which are already barely interacting with eachother... But, to the human eye... Does anyone know what the best combination of red+green diodes would be to achieve that 589nm yellow?

Or just an equation in general? Or, a concept in general? There are all sorts of interesting colours I'd like to make some small, weak pointers with... Not currently achievable with solid state diodes on the market, or at a reasonable price.

 

[Alaskan]

Look at this:

Chroma - a laser color blender

Having put a few more hours into this little project I feel it has reached a point where it might be worthy of its own thread. What is Chroma? Well, it is a tool for calculating the chromatic coordinates of mixtures of monochromatic light and displaying them in a CIE xy chromaticity diagram...

photonlexicon.com

If you find that program, please let me know how well it works out for you. Of course, what you will probably want to do is find two laser devices with similar red and green beam characteristics to combine that way and what you get, is what you get for an approximate color hue.



CDBEAM777 built a pointer using dichros for green and blue diodes to produce the perception of a cyan wavelength, search the forum for "cyan cannon" for more info on that.

 

[Encap]

Many people use "Wavelength" and "Color" interchangeably, when in fact they are apples and oranges different.
Wavelength is a physical property. Wavelength is not a description of a color you perceive/see. So asking about a combined red/green that makes 589nm is an imaginary question--there can be no such thing.
A wavelength is term independent of human observation -- a description of electromagnetic radiation.
You can't make a 589nm wavelength by combining red and green--all you get if do that is a visual illusion of the color yellow that is still just red and green wavelengths. You don't get any new wavelengths. Colors created by combining wavelengths still remain the wavelengths used-- if you split the created "yellow" apart with a prism you get the wavelengths used to create the illusion of yellow. It is not a single pure wave, and as such, it does not have a well defined `wavelength' like 589nm for example.

The properties of 'Light" are very different from the properties of the human visual system and are independent of it.
See: Properties of Light | PVEducation and here: https://en.wikipedia.org/wiki/Photon

Color is not a physical property; it is merely the brain’s interpretation of different wavelengths of light based on input signal from the eyes. Color names are words/symbols for that brain activity.
See: https://en.wikipedia.org/wiki/Visual_system

You can buy a cheap RGB laser module for about $50 and experiment with creating the illusion of many other colors by varying the amouns of each. R. G. and B.
If you want a cheap imaginary "yellow" get your feet wet creating the limited illusion of white laser and many other colors as well, one of the RGB modules module on eBay for around $50 are a good starting place. See: https://www.ebay.com/sch/i.html?_from=R40&_nkw=RGB+white+laser+module&_sacat=0&LH_TitleDesc=0&_sop=15

If you want a real handheld 589nm you can get a low cost and output pen for $249 here: https://www.dragonlasers.com/yellow-laser-pointers.html
O-like makes a low cost lab type red/green combiner at $89.99 see: http://www.o-like.com/index.php?main_page=product_info&cPath=72&products_id=385
If you want a handheld pointer that can create many color illusions including "white" the only commercially made one that exists, albeit not low cost, is a Sanwu u it see: https://www.sanwulasers.com/product/rgblaser

Here is a RGB handheld with printed housing and operational circuits designed by member ArcticDude and assembled by member Grainde which uses an OPT laser RGB module: https://laserpointerforums.com/threads/build-discussion.102481/page-22
It utilizes this high quality micro RGB module made by OPT: https://optlasers.com/rgb-modules/300mw-micro-rgb-laser-module

 

[Anthony P]

I have done a couple of RGB projects. While I do not have any formula for you, I can say that the red ratio must be much higher than the green.

 

[Alaskan]

You do however have different perceived hues of color using specific wavelengths when mixing them together. I was only meaning to refer to a perceived color hue. You probably are already aware of this, but light is always additive mixing, for paints, subtractive.

Subtractive color - Wikipedia

en.wikipedia.org

 

[Arcygenical]

Many people use "Wavelength" and "Color" interchangeably, when in fact they are apples and oranges different.
Wavelength is a physical property. Wavelength is not a description of a color you perceive/see. So asking about a combined red/green that makes 589nm is an imaginary question--there can be no such thing.
A wavelength is term independent of human observation -- a description of electromagnetic radiation.
You can't make a 589nm wavelength by combining red and green--all you get if do that is a visual illusion of the color yellow that is still just red and green wavelengths. You don't get any new wavelengths. Colors created by combining wavelengths still remain the wavelengths used-- if you split the created "yellow" apart with a prism you get the wavelengths used to create the illusion of yellow. It is not a single pure wave, and as such, it does not have a well defined `wavelength' like 589nm for example.

Yessir, that's what I was attempting to convey in the OP, although I did not do a very good job explaining upon a re-reading of my post... I am very familiar with the etymological differences between wavelength and colour... and how one is a spatial period of an EM wave, in metric units... Compared with a "colour" which is the physiological manifestation of how that λ is perceived by human optical cone cells. I appreciate the "who knows what this guy knows" grounds up explanation of the differences between the two, btw. I always treat everyone on a forum like they're starting from scratch in their understanding.

While I understand that overlapping two different λ, to a (as congruently as possible) similar focal point, will produce a different "colour" of light, when perceived by the human eye... I understand I'm not creating a Yellow wavelength by, say, combining "green" and "red" beams, but I'm attempting to approximate the perceived "colour" of a 589nm light source by combining the correct variants of red (638nm, 650nm, 660nm etc) and green (505-532nm) in the appropriate power ranges. At least, to the best of my ability using all the solid state green/red diodes available.

My question is as such, does anyone know the math, have a formula, or calculator, of how humans perceive different combinations of mixed light, from different wavelengths. I understand the perceived brightness curves as we approach our optimal perception wavelength of 550-560nm, and I therefore know that altering the input λ of the combined beams will change the perceived "colour" attained. But I'm just concerned with how the input wavelengths will affect output colour perception... And to a lesser degree... if this even makes a difference, compared to changes in input amplitude.

You can buy a cheap RGB laser module for about $50 and experiment with creating the illusion of many other colors by varying the amouns of each. R. G. and B.
If you want a cheap imaginary "yellow" get your feet wet creating the limited illusion of white laser and many other colors as well, one of the RGB modules module on eBay for around $50 are a good starting place. See: https://www.ebay.com/sch/i.html?_from=R40&_nkw=RGB+white+laser+module&_sacat=0&LH_TitleDesc=0&_sop=15

I think I might do this, actually, as an exercise in optics anyways... However, these cheap RGB modules aren't typically analog (nor do I know how to fully control an analog light source, only have experience with TTL) nor are the input wavelengths tunable (obviously...) so this helps me deal with output power differences in perception... But I'm trying to investigate how changes in λ affect colour perception... I'd love to avoid buying all those diodes and swapping them out.

O-like makes a low cost lab type red/green combiner at $89.99 see: http://www.o-like.com/index.php?main_page=product_info&cPath=72&products_id=385

This is the combining crystal I will be attempting to use.

BTW, Aliexpress does sell some pretty decent RGB combiners. I have one, and I can produce a white beam (using 3 pointers, so the dot characteristic, even at 10ft are terrible - I need isolation tables and mounts to really get a good beam) for around 12$ shipped for a cubic 12.7 mm combiner. It handles 3 100w input (638nm, 488nm, 515nm) just fine, using a 3D printed M6 mount.

Replied in Quote. Thank you for the discourse. I always appreciate a good hypothetical dicussion about light, especially when I'm only starting to wrap my head around the intricacies of it.

I have done a couple of RGB projects. While I do not have any formula for you, I can say that the red ratio must be much higher than the green.

This makes obvious sense. As we approach a central wavelength of 550-560nm (depending on the study/human/Individual eyeball sensitivity) the same amount of optical output is perceived as more and more visible, at least during photopic. The curve is quite brutal as well, I believe it's like... 45nm makes up 1 standard deviation on the curve or something approximating that...

I do plan on buying an analog RGB unit, perhaps with a 500mw output (combined) to see the effects of perceived colour on beam output... But, again, I'm more concerned with input wavelengths, and how, when combined, they affect perceived colour.

I could be entirely missing the point here.... Assuming 532nm is more visible than 520nm, by the same laws of perception... Do we get a different perceived colour with 520nm + 638nm, than we would 532nm + 638nm, when the greens are corrected for perceived brightness.

 

[ArcticDude]

Look at this:

Chroma - a laser color blender

Having put a few more hours into this little project I feel it has reached a point where it might be worthy of its own thread. What is Chroma? Well, it is a tool for calculating the chromatic coordinates of mixtures of monochromatic light and displaying them in a CIE xy chromaticity diagram...

photonlexicon.com

If you find that program, please let me know how well it works out for you. Of course, what you will probably want to do is find two laser devices with similar red and green beam characteristics to combine that way and what you get, is what you get for an approximate color hue.



CDBEAM777 built a pointer using dichros for green and blue diodes to produce the perception of a cyan wavelength, search the forum for "cyan cannon" for more info on that.

Here is awesome example of "RGB color combining" at Berlin photo week: there was three spot lights (R/G/B) pointed at the wall making white light, until you walked front of those light they made your "shadow" of those color combinations (7 colours)

 

[CDBEAM777]

First.....Of course yes....You will only perceive the color that the 589 line makes....

Second, My build...the Chartreuse Coruscation is almost complete...and it is a Red+Green combiner hand held....which can generate a color seen at the 560 ~570 line....but not 589.....my goal was Green yellow....which this unit achieves nicely !

See the link in my description. I will note that I found that mixing 520 nm + 638 nm was not satisfactory for generating the Chartreuse color.....approx. 560 ~ 570 nm. I do not know why.....but I do know I tried....and was very disappointed !. SO....I switched to 532 nm + 638 nm.....and got the color I was after.

The commercial RGB module sold by Opt Laser....is a real beauty....and I hope to purchase one....someday !!!

I must note that beam combining with different wavelength is not perfect. There is some slight overlap....one color ( 532 nm ) not perfectly aligned with another color ( 638 nm )…...but....the beam in mid air.....and at the Farfield target looks acceptable....for my build anyway.

Good luck.....and enjoy the ride !!!

CDBEAM

 

[Arcygenical]

Chroma looks great, but for the life of me I can't get it to run under x64 windows 10... Even with the proper Mathlab compiler (7.11) and environment variables set. Bah.


On an unrelated note... Mathlab is a terrible runtime. My god. I thought JRE had that award. Real PITA without backward compatible runtime libraries... This program was written in 2009. Good luck finding runtime environments from 2009.

 

[Alien Laser]

Remember back 2/3years ago 488nm was $$$$ i wonder when the 589nm direct diode will hit the market !!
at a resemble price just like 488nm today

 

[Encap]

Remember back 2/3years ago 488nm was $$$$ i wonder when the 589nm direct diode will hit the market !!
at a resemble price just like 488nm today

Probably never as been discussed many times on LPF --there has always existed a spectral gap in the yellow-orange region where room-temperature LD semiconductor materials can't be made to emit however some European researchers made one in a lab that worked at room temp in the 599-605nm range back in early2018---I assume nothing ever came of it. see thread: https://laserpointerforums.com/threads/directly-injected-orange-yellow-diode-lasers-soon.103306/

Not a big enough market for any diode maker to waste the time and money necessary to develop technology needed for a commercial low cost 589nm diode would be my guess. For now and the foreseeable future DPSS is the only commercially available yellow.

 

[Alien Laser]

The only problem with DPSS the can fail easy this is why i dont have a 589nm i wonder if the are reliable

 

[hakzaw1]

There is a real yellow--but it is a HeNe-- mine came from Sam at a SELEM event--only 6mW but like green it is quite bright.
I had to find my own PS-- & still paid Sam $350 for the HeNe. Its one of my favs.
I doubt that any SS yellows will ever be made & if they are expect a very very high pricetag.
good luck=-----methinks you will need lots of it...

Interesting note-- the 'yellow' we see at most (if not ALL) laser shows is combined R & G.. Sadly the 'trip glasses' you get (also called rainbow glasses) 'undo' all the alignment work AND pretty much the same thing if you use R+G for Lumia.

hk

 

[Alien Laser]

I need to get one HeNe laser the lock so nice when activated