Can light be split by colour accurately?

[cwinhall]

Dear Physicists,

My understanding of physics is at the utmost basic level. Let me apologise in advance for what is probably a dumb question.

What I do know (I think):
When white light hits a prism, it comes through the other side, showing the colours of the rainbow. It is my udnerstand that this is based off several laws of physics depending on the material and the refractive index.

What I want to know:
Can you accurately separate colours out and what are the effects on the "quality" of the output of that separated light?

Example:
If I shine white light through a prism/material (or multiple prisms/materials), can I separate all colours and only let red shine through?

 

[jbriggs444]

Are you thinking of measuring the "quality" of a light source using a spectrometer?

 

[CWatters]

The spectrum of light is continuous so if you define one frequency as "red" there is another frequency infinitely close either side that you want to define as "not red" and to be blocked. Does that help you answer your question?

 

[cwinhall]

Are you thinking of measuring the "quality" of a light source using a spectrometer?

After typing out a long explanation of my idea I suddenly came to the embarassing realisation of what I was "inventing". A projector.

 

[sophiecentaur]

After typing out a long explanation of my idea I suddenly came to the embarassing realisation of what I was "inventing". A projector.

Actually, the design of a "Projector" attempts to eliminate the 'splitting' of light forming an image into it's different wavelengths. That would give all the images fuzzy / coloured edges. It's called Chromatic Aberration. To do what you are asking for requires loads of chromatic separation - such as with a prism.

 

[cwinhall]

Actually, the design of a "Projector" attempts to eliminate the 'splitting' of light forming an image into it's different wavelengths. That would give all the images fuzzy / coloured edges. It's called Chromatic Aberration. To do what you are asking for requires loads of chromatic separation - such as with a prism.

Can the same separation of light occur as effectively with a prism/ multiple prisms?

 

[sophiecentaur]

Can the same separation of light occur as effectively with a prism/ multiple prisms?

I'm not sure what you mean by "effectively" when the purpose of a 'projector' is to restrict the direction of light from each point on an object (slide) to a specific point on the screen. If it happens, the lens is not good enough - but there will always be some aberration at some wavelengths. If you want to split light into its spectrum then you use an appropriate device - prism or diffraction grating (best).

Can the same separation of light occur as effectively with a prism/ multiple prisms?

 

[Drakkith]

What I want to know:
Can you accurately separate colours out and what are the effects on the "quality" of the output of that separated light?

Example:
If I shine white light through a prism/material (or multiple prisms/materials), can I separate all colours and only let red shine through?

Yes, absolutely. Though, instead of using colors, you'd instead choose a range of wavelengths you want to end up with.

 

[sophiecentaur]

If I shine white light through a prism/material (or multiple prisms/materials), can I separate all colours and only let red shine through?

A spectrometer produces a band of light with the spectral colours spread out over it. If you use a narrow slit, a narrow band of wavelengths can be selected. Would that be what you wanted?