B&W Glass Filter: Does it Exist?

[eyedreamer]

Hi to all!

I have a little question for you. Does a b&w glass filter exist?
I now there are all kind of color glass filters, but I want to know if there are any possibilities to generate a b&w image without using your camera or your computer.
I know about the monochromator device, but it acts on a single ray. I'm not sure if I could get an image using a monochromator.

Any help would be appreciated!

 

[eyedreamer]

I forgot to give the link for the monochromator: http://en.wikipedia.org/wiki/Monochromator

 

[chroot]

Not that I know of, no.

- Warren

 

[Danger]

The problem that I can see here is that white light is composed of all wavelengths. As soon as you start filtering out colours, it can't exist.

 

[eyedreamer]

What if it is somehow possible to get equal value for R, G and B? I'm not sure whether this works in the real physical world, but I know that a color with a value RGB 50/50/50 (or simply said x/x/x) is a greyish color.

 

[chroot]

Well, a "black-and-white filter" maps a color (R, G, B) to a colorless triple like (R+G+B, R+G+B, R+G+B). This filter involves adding frequencies together, which physical filters cannot do. All that a physical filter can do is remove frequencies from its input.

- Warren

 

[Danger]

I just had me a thought here, but I don't know if it would work.
Take one R filter, one G, and one B. Mount them side-by-side, then use lenses to correct for parallax and focus them all on one viewing area.
Chroot...?

 

[eyedreamer]

Danger, I had a similar idea, too. But chroot said that a physical filter only removes frequencies from its input. I think that this will produce a totally white image. Am I right or...?
I was actually imagining as if the picture passing thorugh a monochromator, it separates the different colors, and then they're somehow equalized to the same value, thus producing a b&w image. Correct me if this doesn't make any sense :)

 

[Danger]

I'm going to wait for Chroot or someone else about this. I'm over my head.

 

[Mech_Engineer]

I think the 3-color filters method is how they capture images on spacecraft and the Mars rovers... Combined they give you a full color picture.

You can capture a black & white picture on B&W film, btw.

 

[eyedreamer]

Mech_Engineer, a b&w film works different. The film has some kind of grains on it, which are light-sensitive. As soon as the lighting strikes over them, they can't "reset" anymore. I want to be able to see through those filters or whatever it is, and see a b&w representation. I don't need a still image. Hope you understood me. Thanx for the tip, btw.

 

[eyedreamer]

Chroot, What do you think about Danger's preposition?

 

[chroot]

Danger's idea would not work.

Imagine that the image you want to pass through your filter has only the color red in it. Your desire a filter that produces a grayscaleB] output. In other words, dim red light would appear on the output screen as dim white light; bright red light would appear on the output screen as bright white light.

Assume that you pass your red image through Danger's three-filter system. The red light would go through the red filter, but will be blocked by the green and blue filters next to it. The final image formed will be... red. Not white.

- Warren

 

[Danger]

Warren, I think that I might not have expressed my intention properly, given your response. The filters that I proposed are beside each other, not in line. Lenses compensate for the parallax difference, so that each one 'sees' the same image despite their spatial orientation. You then have one red image, one green image, and one blue image all coinciding at the same viewing pane. It still might not work, but not for the reason that you cited.

 

[chroot]

Danger,

I understood your proposal perfectly well. You didn't understand my response.

For example, the desired "black and white filter" would convert an image containing nothing but shades of red into shades of gray, based on their intensity. Your filter setup could not do this. If you pass red light through your side-by-side red, green, and blue filters, you will get a red image on the other end.

- Warren

 

[lightarrow]

Indeed, what it would need here is the opposite of a filter: a device that trasforms the energy of a specific frequency into the same energy equally distributed on the entire visible spectrum; instead of a "monochromator", a "multichromator"!
Are there optical crystals which can have a similar property or, at least, which can broden the spectrum's range of a light source?

 

[lightarrow]

Mech_Engineer, a b&w film works different. The film has some kind of grains on it, which are light-sensitive. As soon as the lighting strikes over them, they can't "reset" anymore. I want to be able to see through those filters or whatever it is, and see a b&w representation. I don't need a still image. Hope you understood me. Thanx for the tip, btw.

So, you mean that you could simply need a B&W videocamera?

 

[Danger]

I'm going to have to bail out of this one, guys. It seems to be something that I know so little about that I can't even quite follow the explanations. I'll keep reading to learn more, though.
Meanwhile, how about a night-vision device or a simple B&W TV camera?

 

[eyedreamer]

Chroot, you said that the filter should be able to add frequencies together. Is there any physical way to accomplish this? For example to separate the image on 3 channels and then add their frequencies together?

 

[eyedreamer]

Danger: My initial plan was to create a mirror which will reflect a B&W image, instead of color. But I would be happy ig I could make a simple B&W image without using any electrical stuff.

 

[chroot]

eyedreamer:

There is absolutely no way to do this with passive optics. If you pass in an image with nothing but shades of red, you want to get out an image with nothing but shades of gray. To convert red into gray, you have to add additional blue and green light. No mirror or lens can do this. You're stuck with some kind of active solution.

- Warren

 

[NoTime]

Certain types of material can up convert or down convert the frequency of the incident light.
Theoretically, if the right materials were actually available, you should be able to create a solid state device to do this.

I would consider this to be an active solution, just as chroot says.

 

[eyedreamer]

Certain types of material can up convert or down convert the frequency of the incident light.
Theoretically, if the right materials were actually available, you should be able to create a solid state device to do this.

I would consider this to be an active solution, just as chroot says.

Any idea what kind of materials should I use?

 

[chroot]

I would consider this to be an active solution, just as chroot says.

Once you bring in power supplies, there are about a million ways you could accomplish this B&W "filter" -- but there's no way to make it using nothing but passive glass and mirrors.

- Warren

 

[NoTime]

Any idea what kind of materials should I use?

Gonna have to wait for nanotech to get a bit farther along

In the meantime, you can use your computer to recolor video anyway you want.