How does light split into colors?

[YeeHaa]

Hi all

Today I came home to find very discrete lines of colored light on my living room floor. Can anyone help me to explain this phenomena? I am familiar with dispersion but am wondering how the combination of glass and blinds is creating this effect.
When I rotate the shutters as you can see from the pictures, the colors changed.

Regards

 

[pinball1970]

Hi all

Today I came home to find very discrete lines of colored light on my living room floor. Can anyone help me to explain this phenonoma? I am familiair with dispersion but am wondering how the combination of glass and blinds is creating this effect.
When I rotate the shutters as you can see from the pictures, the colors changed.

Regards

that's very nice!

Do you gave any glass ornaments on your sill?
[quote fixed by mod]

 

[pinball1970]

My parter had something similar that was the result of hanging glass beads

 

[nabil23]

when the white sun light enters through a glass leaf at a specific angle, the light decomposing to the original color according to it wave length, the red color has a longer wave is angled at a lower angle, the yellow at a larger angle , then the green color , then the blue . so the the white sun light decomposes into spectrum colors like the rainbow.

 

[LURCH]

Just a visual impression; this spectrum appears to be too spread out to be coming from the glass in your window. Is there any glass or reflective objects out in the yard? Or as has been suggested above, maybe a glass ornament, but rather than on the sill, perhaps hanging from the eve, or a branch a few feet away?

 

[Tom.G]

If you look out that window you will see a transparent object. That object is wedge shaped and its distance from the door is about 2.8 times the short dimension of the floor tiles. If the photo was taken about 1.5 hours before sunset, the object is probably about 1.8 floor-tiles above the floor, also assuming that there is no obstruction between the object and the window.

Notes: since there were no dimensions given, the floor tiles were used as the 'master yardstick'. using rather simple geometry, the optical distortion of the floor tiles to find the angle between the color rays. knowing the ray angles and the dimensions in units of 'floor tiles', the point of convergence was found to be 4.04 tiles from the start of the rays. subtracting the distance to the door gave the distance to the point of convergence. the height of the prism-like item was estimated from the assumed solar elevation of 22.5° at 1.5 hours before sunset and the distance to the start of the rays.

Cheers,
Tom

 

[pinball1970]

If you look out that window you will see a transparent object. That object is wedge shaped and its distance from the door is about 2.8 times the short dimension of the floor tiles. If the photo was taken about 1.5 hours before sunset, the object is probably about 1.8 floor-tiles above the floor, also assuming that there is no obstruction between the object and the window.

Notes: since there were no dimensions given, the floor tiles were used as the 'master yardstick'. using rather simple geometry, the optical distortion of the floor tiles to find the angle between the color rays. knowing the ray angles and the dimensions in units of 'floor tiles', the point of convergence was found to be 4.04 tiles from the start of the rays. subtracting the distance to the door gave the distance to the point of convergence. the height of the prism-like item was estimated from the assumed solar elevation of 22.5° at 1.5 hours before sunset and the distance to the start of the rays.

Cheers,
Tom

I am now very curious to see what is outside his window!

 

[YeeHaa]

Thank you for the replies everyone!

Some more details and pictures:

• No glass beads. However there is "light dome" which is above our bycicle shed. If you look in a straight line from where the lines originated you do not see the dome. It is slightly to the left (see second picture and sketch).
• The blinds are plane white blinds with a fine vertical structure going over the entire height of the blind (barely feel the structure when touching).
• The picture was taken at 12:38, 27th of October (before winter time, 28th of October time was adjusted).
• I live in Neerpelt area, Belgium.
• I included a sketch of the situation with some reference measurement (tile).

If any other info is needed feel free to ask.
Even if it is the dome causing this, I would still love to know how to lines became this discrete/high intensity.

Regards

 

[DrStupid]

Even if it is the dome causing this, I would still love to know how to lines became this discrete/high intensity.

The lines are most probably caused by the vertical blinds. It would have been a good idea to remove them and see if you get a continuous spectra.
The intensity is relative The light from the external source (whaterver it is) was just brighter than everything else. It wouldn't appear that bright compared to direct sunlight.

 

[gmax137]

I don't have anything to add to the discussion, but those pictures in the OP are very cool! I have never seen anything quite like that. Thanks for sharing them!

 

[LURCH]

I think the dome shape of the skylight cover explains how the light came in during the middle of the day. Apparently, even though the sunlight was coming nearly straight down, somewhere along that curve was a spot with just the right angle to send the light into your window. Was it raining just before you saw this?

A very cool effect. Thanks for the pics!

 

[lightarrow]

What I don't understand is this: if a light source (Sun or whatever it is) is refracted from matter, it comes out at an angle different from zero, even if the incoming beams were parallel. Then, how can the colured beams in the OP's photo be so parallel and not diverge at all?

--
lightarrow

 

[phinds]

What I don't understand is this: if a light source (Sun or whatever it is) is refracted from matter, it comes out at an angle different from zero, even if the incoming beams were parallel. Then, how can the colured beams in the OP's photo be so parallel and not diverge at all?

--
lightarrow

Odd, I see them a CLEARLY not parallel.

 

[LURCH]

As Tom mentioned in Post #6, th lines are not exactly parallel. That is how he calculated a point of origin.

 

[lightarrow]

Odd, I see them a CLEARLY not parallel.

I mean, *every* single beam doesn't seem to diverge appreciably, it seems a laser beam.

--
lightarrow

 

[OmCheeto]

...using rather simple geometry...

Do not ever let me know where you live, as I will find you, and I will kill you...

My answer is: The source is somewhere between what you said, and infinity.

Just a visual impression; this spectrum appears to be too spread out to be coming from the glass in your window.

I think it was the spacing of the colors that didn't seem right to me, based on my observations.

 

[Tom.G]

Odd, I see them a CLEARLY not parallel.

That's mostly because of the wide-angle camera lens.
If you assume that the floor tiles are rectangles, from the OPs photo you can measure the spacing between the Red and Green light beams as a percentage of the tile size (tile width in the photos). Do this for the near edge and the far edge of a tile. This essentially gives you the divergence (relative horizontal 'slope') of the light beams across the tile.

I mean, *every* single beam doesn't seem to diverge appreciably, it seems a laser beam.

The spacing of the individual lines of color was because the continuous spectrum was blocked by the vertical window blinds. The angle of the blinds was such that there was visually enough space between them to let slivers of light thru. Or to put it another way, the space between the blinds acted as slits for the spectrum to get thru and shine on the floor. The individual beams did not disperse much because the source of light, the 'light dome', was much further away than the slits in the blinds. (Besides any beam divergence is difficult to spot because of the wide-angle camera lens.)

Do not ever let me know where you live, as I will find you, and...

Aww, I'd rather be friends (or frenemys if you insist )

Cheers,
Tom

 

[phinds]

What is it that makes you think it was a "wide angle" camera lens? Seems like very normal pics to me.

 

[pinball1970]

What is it that makes you think it was a "wide angle" camera lens? Seems like very normal pics to me.

Quite a few comments since I last looked.Consensus is :Light Source (sun), prism like object, dispersion, then the blinds prevent all the colours coming through hence the dark bands?The blinds also have a mirror effect “straightening” out the angles as it were projecting the remaining colours on to the floor? Is that possible?Those rays do look straight and the blinds seem uniform angle wise.I also would like to see what the dispersion object is, you can get this with objects other than a prism apparently but not as pronounced (quick google)

 

[OmCheeto]

...
Aww, I'd rather be friends (or frenemys if you insist )
...

I was just amazed at how quickly you solved that.
It took me a week to solve a similar* problem, back in April.

----------
*Similar, as in, basic geometry, that is.
Dreading spending another week working through this one...

ps. Fun problem! Thanks, @YeeHaa !

 

[lightarrow]

. . .
The individual beams did not disperse much because the source of light, the 'light dome', was much further away than the slits in the blinds. (Besides any beam divergence is difficult to spot because of the wide-angle camera lens.)

The dispersing object doesn't seem to me so much further away, based on the OP' sketch in post #8; maybe such dispersing object also focuses light a little, acting as converging lens.
Edit: Think of a prism the second face of which is not plane but convex: the different colour beams, already separated inside the main part of the prisms, are focalized in the last part and when they come out of the object they are less diverging one to the other and even every one of them it is.
--
lightarrow

 

[davenn]

maybe such dispersing object also focuses light a little, acting as converging lens.

well it can't do that as the dome is convex in shape as far as the light source
is concerned, so it cannot produce convergence

 

[Dadface]

The lines resemble projected laser lines.

 

[Tom.G]

What is it that makes you think it was a "wide angle" camera lens? Seems like very normal pics to me.

I was using the the first of the OPs photos, the one that shows where the rays start. Perhaps it was just the closeup perspective that gave that floor tile such an odd shape. Would you accept 'distortion' as better word choice?

Cheers,
Tom

 

[phinds]

I was using the the first of the OPs photos, the one that shows where the rays start. Perhaps it was just the closeup perspective that gave that floor tile such an odd shape. Would you accept 'distortion' as better word choice?

Well, I guess if that's what you see. I'm just not seeing it. Looks normal to me.

 

[lightarrow]

well it can't do that as the dome is convex in shape as far as the light source
is concerned, so it cannot produce convergence

Don't understand this, can you expand? Doesn't a convex lens focuses light beams? My interpretation is the following. Let's outline the convex dome as a (thin) convex-plane lens, a prism and a (thin) plane-convex lens: the first lens just deviate a white beam; the prism deviate and disperse it in all the colours, each deviated (refracted) with a different angle; the last lens reduces the divergence of the beams of different colours, making them more parallel.
It's not so?

--
lightarrow

 

[davenn]

Doesn't a convex lens focuses light beams?

yes, but when the light is going through the lens. in the OP's case the light is being refracted/reflected off the surface of a curved dome that is not a lens

 

[lightarrow]

yes, but when the light is going through the lens. in the OP's case the light is being refracted/reflected off the surface of a curved dome that is not a lens

Can you make a simple drawing of the light's beam optical path in the dome? (it's likely I haven't understood it). Later with more time I'll post my idea of it.
Thanks.
--
lightarrow

 

[Nik_2213]

Fascinating !

MIL's Siamese kitten used to chase the dancing multicoloured twinkles from their 'garden room' sun-catcher, was much more fun than day-time TV...

OT: Very, very late one evening, I glanced out of our kitchen window, was astonished to see the Full Moon, enlarged but *almost square*...

Took me a few moments to realize this bizarre apparition was below the roof-line of neighbour's darkened house. I was seeing the reflection in an upstairs double-glazed window which must have been slightly dished...

Sadly, by the time I thought to grab a camera, clouds had rolled in...
;-((

 

[Jonathan Scott]

As far as I can tell, those lines are indistinguishable from parallel, so the source was not close. This suggests that sunlight was being temporarily redirected and refracted through some distant object, perhaps across the road, producing a continuous spectrum, which was split into lines by the blind. Of course, looking through the blind from low down would have revealed the source.

 

[OmCheeto]

As far as I can tell, those lines are indistinguishable from parallel, so the source was not close. This suggests that sunlight was being temporarily redirected and refracted through some distant object, perhaps across the road, producing a continuous spectrum, which was split into lines by the blind. Of course, looking through the blind from low down would have revealed the source.

I don't think the rays are from refraction. One thing I missed up until now, is that the OP said:

When I rotate the shutters as you can see from the pictures, the colors changed.

Which is indeed true:

I was working with image #2, and completely ignored image #1.
The spacing of the colors, along with the anomalous white ray(s, and pinkish one that I didn't include), indicates to me that the rays are not the product of refraction, nor diffraction, but could only be the result of light reflecting off of a multicolored surface.

ps. I suspect the entire problem is photo-shopped*, but given that this is a delightful test of math skills, I really don't mind.

*The orange line is a bit too "crisp", IMHO.

 

[DrStupid]

Of course, looking through the blind from low down would have revealed the source.

The location of the source could also be identified with another picture taken from the same position as the first one but with the window open.

 

[mfb]

Is it repeatable? If yes:

What happens if you cover the dome?
As asked already: What happens if you open the blinds more?
Can you put an object close to the blinds to see where its shadow appears? This gives an estimate for the vertical angle of the light.

 

[RPinPA]

I don't think the rays are from refraction. One thing I missed up until now, is that the OP said:View attachment 233320

I was working with image #2, and completely ignored image #1.
The spacing of the colors, along with the anomalous white ray(s, and pinkish one that I didn't include), indicates to me that the rays are not the product of refraction, nor diffraction, but could only be the result of light reflecting off of a multicolored surface.

This image says to me that the beams are arriving at different vertical angles, that there is refraction happening in both the horizontal and vertical planes.

I love this entire discussion and think it would make a good exercise for a physics class.

 

[DaveC426913]

Man! That is one cool effect!

 

[lightarrow]

yes, but when the light is going through the lens. in the OP's case the light is being refracted/reflected off the surface of a curved dome that is not a lens

Light doesn't go through the dome? Then it's not the dome which generates the colours and even mention it in the discussion would be misleading.

--
lightarrow

 

[DAH]

Great pics
I'm no expert on light but it looks like the effects of light passing through a diffraction grating. Maybe the material of the blinds itself are acting like the small spacing of diffraction grating, if so there would probably be 1st and 2nd orders of diffraction somewhere else in the room.
Just a thought but I'm probably wrong.

 

[Jonathan Scott]

I don't think the rays are from refraction.

It's certainly not something simple like a prism. I agree that the strength of the effect suggests an alternative of something like reflecting from a brightly coloured surface, or from a reflective surface with a "holographic" type finish which gives a rainbow effect. However, I've seen a striking display of rainbow colours from sunlight striking old glass objects in a shop window, where the colour wasn't just a simple spectrum but rather a series of coloured curves, presumably caused by a combination of refraction and reflection, and that might just about account for it. The sharpness of the lines certainly suggests a small distant source.

 

[davenn]

Light doesn't go through the dome? Then it's not the dome which generates the colours and even mention it in the discussion would be misleading.

--
lightarrow

unfortunately, it's become obvious that you are missing the point of the whole discussion

you need to go back to the beginning of the thread and catch up on the bits you have missed
particularly the post #8 by the OP. Then you will understand why the discussion of the dome was involved

 

[Dadface]

To me those lines don't resemble anything that you would expect to see due to reflection, refraction or diffraction due to the combined optical arrangement of the systems outside and inside the house. They do look like projected lines, very similar to laser lines. Laser line marking seems to be a growing technology. There is one photo I find a little bit puzzling and that is picture one in post eight where there is a squiggly white line which seems to be obscuring the top of the table on the right side of the picture.

 

[davenn]

There is one photo I find a little bit puzzling and that is picture one in post eight where there is a squiggly white line which seems to be obscuring the top of the table on the right side of the picture.

seriously ?

tis obvious he has probably erased some personal stuff on the table rather than having that info spread across the internet

 

[Dadface]

seriously ?

tis obvious he has probably erased some personal stuff on the table rather than having that info spread across the internet

I suppose that is a possibility but note that something black is projecting from the edge of the table. Now try googling laser line markers. I think it's possible that YeeHaa is having a joke and obscured most of the table top as a clue.

 

[Tom.G]

Naah. Peeking out from the left edge of the table is what looks like the handle of a skillet complete with the nicely shaped hole for hanging it on a hook. Way back on the table top near the chair is something that looks like the edge of a dinner plate with perhaps a place mat under it.
(inspection done at 350% magnification)

 

[Dadface]

Naah. Peeking out from the left edge of the table is what looks like the handle of a skillet complete with the nicely shaped hole for hanging it on a hook. Way back on the table top near the chair is something that looks like the edge of a dinner plate with perhaps a place mat under it.
(inspection done at 350% magnification)

Could well be but if that's all there is why did YeeHaa want to obscure it? Why not just move it out of the way? Anyway, whatever is on the table may well be irrelevant. But those lines lines still look like projected lines.

 

[lightarrow]

unfortunately, it's become obvious that you are missing the point of the whole discussion

I have a bit of suspect that many of us, here, are missing the hole point, since:
1. we don't know if the OP is cheating us or not ,
2. we still don't know which is the source of the coloured lines,
3. in post #8 the OP wrote: "Even if it is the dome causing this, I would still love to know how to lines became this discrete/high intensity" so he didn't exclude this possibility,
4. we don't know how that "dome" is made (maybe this kind of structures is common where you live but it's not usual for me)
5. in post #15 I expose a doubt on the single coloured beams because they seemed too much collimated to me, like laser beams and I haven't received a clear answer to it.
But if you have more clear ideas you can write them.

--
lightarrow

 

[YeeHaa]

Hello all,

Wow! thank you for the huge amount of replies.
In a lot of replies I read some doubt about my sincerity but believe me (on my pretty blue eyes): no photoshop, no cheating. The pictures were taken with my Galaxy S8 phone and were uploaded straight to this forum (shared via mail).
I will make some more overview pictures when I get the chance.

There were also comments as to why I blanked out the table. Simply because it was not relevant and I considered that as my own private (mess) ;-).

I had some discussion at work (I am an opto-mechanical engineer) and were also on the path of "the blinds are shading part of the coloured spectrum"... But no solutions (yet).

Just for the fun of it, I uploaded the third picture I took that day so you can see I am not cheating ;-)

 

[Tom.G]

Using the most recent photo that @YeeHaa posted:
Using the much lower distortion of that photo, I get the parallelism of the color rays as within 2.3°, well within the measurement error of being parallel. Even if the 2.3° is accurate, that puts the source distance at 25 tiles away (50ft. or 15m.).

Question for YeeHaa: Is that effect reproducible enough that you can visually sight along one of those rays to determine the source?
I hope so. You have a whole bunch of us VERY curious as to the cause.

Cheers,
Tom

 

[DennisN]

Hi Yeehaa,

I will make some more overview pictures when I get the chance. [...] I had some discussion at work (I am an opto-mechanical engineer) and were also on the path of "the blinds are shading part of the coloured spectrum"... But no solutions (yet).

I think mfb gave some good suggestions:

Is it repeatable? If yes:

What happens if you cover the dome?
As asked already: What happens if you open the blinds more?
Can you put an object close to the blinds to see where its shadow appears? This gives an estimate for the vertical angle of the light.

Also, you could try the following:
Ask another person, perhaps a friend, walk outside the blinds while you observe the lines to see if and when they disappear depending on where the person is. That can give you (and us!) a clue from where the light originates.

 

[Herman Trivilino]

How often are these lines seen?

When they are seen, is it during some circumstance that is not routine?

 

[YeeHaa]

I have never seen these lines, the blinds are installed for approx. 4 years now. It is the only time I saw this.
I will get back to sending more pictures!

"Question for YeeHaa: Is that effect reproducible enough that you can visually sight along one of those rays to determine the source? I hope so. You have a whole bunch of us VERY curious as to the cause"
I have not tried this at that moment...

Can I make the summary that this is dispersion of light caused by an accidental position of the light source due to the time of day & object which is refleting the light (dome?), where the blinds are causing the dispersion and at the same time are shadowing part of the color gradient? Hard to de-duct from all responses what the general consensus is!