Do eyeballs exhibit chromatic aberration?

Question

Fairly straightforward question. If not, why not?

I suspect that if they do, it is not perceived due to the regions of highest dispersion being in one's region of lowest visual acuity.

Answer 1

Yes, they do. We don't see it because our brain automagically 'corrects it' because it always sees the same aberration since childhood.

Our eye focuses on 'green' wavelengths as that's its peak sensitivity, so red and especially violet lines are usually slightly out of focus.

All conventional refractive optical elements (i.e. lenses from various transparent materials) exhibit chromatic aberration. Reflective optics is the only straight forward way to avoid chromatic aberration - but clearly our eyes use refractive optical elements.

Answer 2

Here is an interesting webpage on the aberrations of the eye: http://www.telescope-optics.net/eye_chromatism.htm

According to http://kaschke-medtec.de/SS10/Exercise5.pdf the eye has quite a large chromatic aberration of 2 dptr across the visible range.

I heard (the rumor?) that for this reason the color bands in the french flag don't have the same width.

I also read of the interesting (and probably true) theory that the colour bands around edges actually help you to focus while you reading text. I think that explains why I find reading quite hard with LED illumination of small (non-overlapping) spectral bandwidth.

One could think it would be useful to wear color corrected glasses but I don't think that would help in any way (the aberrations due to the glasses will be small compared to the aberrations in the eye).

Answer 3

Because refractive index is a function of wavelenght, every lens experiences chromatic aberration, and so does a human eye.

This could have severe effect on human vision. However, eye has tuned spectral bandwidth - it is well known eye is most sensible to visible light which has wavelenght of 550 nm. Relative luminosity is also a function of wavelenght (in which more than 70% of the luminous energy is confined to a defocus range of less than 0.25 D defocus on either side of focus (if eye is optimally focused at 550 nm)). The exact spectrum to which we are sensitive, depends on light levels. Rods saturate at moderate and high light levels, so in this region spectral sensitivity is governed by cones. At lower light levels cones are no longer as sensitive and rods dominate the response. All this results in different spectral sensitivity for various luminosity and in this way eye is able to filter out some effects of chromatic aberration.

Answer 4

I have a 405nm laser pointer, which emits light right on the edge of the visible spectrum. It is easy to see that this wavelength of light appears out of focus through the eye likely due to chromatic aberration. I would imagine this is because our eyes are not made to see that kind of light. I've also noticed that mercury vapor streetlights have a faint violet halo around them due to what I believe is chromatic aberration, since the violet light on the edge of the spectrum is refracted the most through our eyes.