Naked Science Forum

Non Life Sciences => Technology => Topic started by: Ricardo Hernandez Lopez on 09/11/2008 22:55:22

Title: Are some colours due to structure rather than pigment?
Post by: Ricardo Hernandez Lopez on 09/11/2008 22:55:22

Ricardo Hernandez Lopez asked the Naked Scientists:

Hi,

Is it true that the colour of feathers of parrots are due to the structure of the feathers and not the pigments??

What about the colour of butterflies or those blue/green flies??

Can we use those colours for TV screens or fancy cars?

Thanks,
Ricardo

What do you think?

Title: Are some colours due to structure rather than pigment?
Post by: Soul Surfer on 10/11/2008 19:39:03

Yes that is true a restricted range of spectacular colours can be produced by regular structures of reflectors on the feathers and scales of birds and butterflies these cause certain frequencies in the incident light to be reflected strongly while others are not reflected well and absorbed.  Interference fringe colours have a special iridescent quality.

Title: Are some colours due to structure rather than pigment?
Post by: RD on 10/11/2008 22:21:37

Quote from: Ricardo Hernandez Lopez on 09/11/2008 22:55:22

Can we use those colours for TV screens or fancy cars?

Quote

Coolest new car colors
A car that changes from pink to white as it drives by?
The latest developments in manufacturing make fancy paint colors mainstream...

At the extreme of color shifting paints are the ChromaFlair colors created by JDS Uniphase.
These pigments use colorless flakes which refract light creating colors in the same way that butterfly wings and bird feathers do.

http://edition.cnn.com/2007/AUTOS/04/09/car_colors/index.html

Very "pimp-my-ride".

Title: Are some colours due to structure rather than pigment?
Post by: lyner on 10/11/2008 22:28:46

This is the same phenomenon as you see in thin oil films on water. You can get any colour you want using 'dichroic' filters. They work by interference rather than absorption. Hence they seem much brighter because there is none of the overall loss which you get with pigments.
Furthermore, the birds and butterflies don't need a load of fancy chemical elements to produce the pigments. They just need to produce layers of keratin(?) of the appropriate thickness.

Title: Are some colours due to structure rather than pigment?
Post by: nicephotog on 23/11/2008 11:34:55

Wavelength splitting(e.g. prisms Pink Floyd)
Soul Surfer: ..."reflectors on the feathers"...
Refraction..............

Title: Are some colours due to structure rather than pigment?
Post by: lyner on 23/11/2008 15:59:49

Quote from: nicephotog on 23/11/2008 11:34:55

Wavelength splitting(e.g. prisms Pink Floyd)
Soul Surfer: ..."reflectors on the feathers"...
Refraction..............

No - not refraction / dispersion: interference filters.

Title: Are some colours due to structure rather than pigment?
Post by: nicephotog on 24/11/2008 05:54:10

...Can we use those colours for TV screens or fancy cars?...
I'm reasonably sure even LCD is an electronic fluorescency of the chemical by ground state.
Try Fire-flies, min mins e.t.c.
I thought birds feathers were by refraction? Not that it matters here finally.
Electric eels and chameleons may be a place to look.

Title: Are some colours due to structure rather than pigment?
Post by: lyner on 24/11/2008 09:46:21

colour LCD screens use a White backlight and colour filters in all pixels with LCD modulators in front.
Birds feathers: interference filters, with a big range of colours.
Fireflies: chemical luminescence, with a limited set of colours but works at night!