Weird experience with perception of light

[Blazenarrow]

So, yesterday I was listening to a presentation given by a graduate student in a lab I work at. She was giving the presentation using power point and a projector. The lights were off, and I noticed something I have never noticed. When I would quickly glance at the beam of light being emitted from the projector, and glance away just as quickly, I would see the individual colors of light, almost in a rainbow pattern.

 

The key is, this would only happen when I would look at the light for just a split second. It would also work if I looked at the beam of light and closed my eyes, and then open and shut my eyes as fast as I could. It was like when light travels through a prism, and then you can see the individual color spectrum's of light.

 

Has anyone experienced this? The only thing I can think of is somehow in that millisecond of perceiving the light, you're brain is able to separate the frequencies of light into distinguishable colors.

 

Any thoughts?

[insane_alien]

this is because the projector projects the colours seperately. there will be the blue fram the green frame and the red frame (not necessarily in that order though) when you blink really fast what your doing is creating a strobe effect which can allow you to see things that are too quick for you to see if you keep your eyes open as it gets mixed in with what is happening next.

[Flashman]

If all colors were being projected together, it could have been a result of how the eye and brain dark adapt and adjust to intensity. This may have been due to the lights being dimmed. The light from the projector scattering off random dust may not have been very intense, and in the darkened surroundings your eyes switched from cones to rods. The cones perceive color, the rods mostly intensity. So for an instant when you opened your eyes, the individual colors of the image were noticable in the projector beam, but your eyes/brain in adjusting to the overall illumination level switched to processing info mostly from the cones, whereupon it appeared white.

 

I think I've got the basic outline right there but I'm fuzzy on the exact details.

 

Cones can work in low light situations but take a long time to get dark adapted, for example, go outside, look at the night sky and you see a lot of white stars, keep looking for ten minutes and you see yellow, red and blue tints to them.

[Blazenarrow]

If all colors were being projected together, it could have been a result of how the eye and brain dark adapt and adjust to intensity. This may have been due to the lights being dimmed. The light from the projector scattering off random dust may not have been very intense, and in the darkened surroundings your eyes switched from cones to rods. The cones perceive color, the rods mostly intensity. So for an instant when you opened your eyes, the individual colors of the image were noticable in the projector beam, but your eyes/brain in adjusting to the overall illumination level switched to processing info mostly from the cones, whereupon it appeared white.

 

I think I've got the basic outline right there but I'm fuzzy on the exact details.

 

Cones can work in low light situations but take a long time to get dark adapted, for example, go outside, look at the night sky and you see a lot of white stars, keep looking for ten minutes and you see yellow, red and blue tints to them.

 

I see your reasoning, but let me make another point clear. I was looking right at the projector, and the rainbow image I saw expanded out only about 9-12 inches form the lens of the projector. Thus it seems that this phenomena is more along the lines of what 'insane alien' mentioned. But I still don't think this explains it all.

 

So, the projector projects different colors simply because that's how all of our digital images work, they simply have 'pixels' of color, specifically green red and blue. However, I still don't see hot it can be explained just by saying the strobe effect. For one, you cant say that by me blinking really quick that i'm able to see distinct frequencies of light. Billions and billions of photons are being emitted from the projector, and the separate colors are emitted in a pattern representing the visual image for which they are projecting. What I saw looked looked like this in the instant I blinked:

 

 

This happened every time I tried it too. So how can it be explained that you actually SEE that spectrum of light, in individual bands when billions of photons of light at different frequencies are being emitted at a constant rate?

[Flashman]

I think I'm understanding you better but not quite. Was the spectrum on axis or off axis? Was the banding parallel or perpendicular to the axis?

 

A further thought, eyelashes tend to give some refraction of light, not a lot, I think this is because they can be thought of as sort of like glass tubes with pigment stuffed up the middle, this is noticable due to the eye being so close to them, as they flicked up and down as you blinked your eyes open, they'd "sweep" through the spectrum as the angle to the light changed. The outer "tube" of the hair not being very transparent, more translucent, means this effect is somewhat weak.

[Blazenarrow]

I think I'm understanding you better but not quite. Was the spectrum on axis or off axis? Was the banding parallel or perpendicular to the axis?

 

A further thought, eyelashes tend to give some refraction of light, not a lot, I think this is because they can be thought of as sort of like glass tubes with pigment stuffed up the middle, this is noticable due to the eye being so close to them, as they flicked up and down as you blinked your eyes open, they'd "sweep" through the spectrum as the angle to the light changed. The outer "tube" of the hair not being very transparent, more translucent, means this effect is somewhat weak.

 

Good questions....

 

Here is another picture. I was looking at the projector from the side, in a dark room. I was in the room for about 30 minutes, and the same phenomenon was experienced every time I tried it.

 

 

No, let me try to explain a little more. I don't think it has anything to do with the eye lashes. Why? Well because it didn't ONLY happen when I would blink. If I was looking at something else, then really quick glanced at the beam of light, and then glance away, the spectrum would appear. If my eyes stayed fixed on the beam of light after first glancing at it, the spectrum disappears instantly. I would then do this over an over. My head was faced away, and I would move my eyes to the beam of light, and away at very fast speeds. Doing this allowed the image to come into perception each time my eyes looked at it.

 

Now another note, the spectrum I saw wasn't a perfect rectangle. However the spectrum was vertically aligned, as shown in the picture. So the banding, to answer your question, was perpendicular to the axes of light travel.