Chromatic aberration can be corrected in two different ways in the eyeglass. The first and least common method is to use a doublet. A doublet is the use of a strong positive lens made from a low dispersion glass like crown glass coupled with a weaker high dispersion glass like flint glass. This will allow the focal point of the two wavelengths (red and blue) to become the same and allow for a clearer image.
Yea so I've run out of things to send and that was a paragraph from my 24k word assignment on eyes and glasses in year 12 for physics
There are two types of chromatic aberration:
axial (
longitudinal), and
transverse (
lateral). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens, i.e., different points on the optical
axis (focus
shift). Longitudinal aberration is typical at long focal lengths. Transverse aberration occurs when different wavelengths are focused at different positions in the
focal plane (because the
magnification and/or
distortion of the lens also varies with wavelength; indicated in graphs as (change in) focus
length). Lateral aberration is typical at short focal lengths. The acronym LCA is used, but ambiguous, and may refer to either longitudinal or lateral CA; for clarity, this article uses "axial" (shift in the direction of the optical axis) and "transverse" (shift perpendicular to the optical axis, in the plane of the sensor or film).
[2]
These two types have different characteristics, and may occur together. Axial CA occurs throughout the image and is specified by optical engineers, optometrists, and vision scientists in the unit of focus known widely as
diopters,
[4] and is reduced by
stopping down. (This increases
depth of field, so though the different wavelengths focus at different distances, they are still in acceptable focus.) Transverse CA does not occur in the center, and increases towards the edge, but is not affected by stopping down.
In digital sensors, axial CA results in the red and blue planes being defocused (assuming that the green plane is in focus), which is relatively difficult to remedy in post-processing, while transverse CA results in the red, green, and blue planes being at different magnifications (magnification changing along radii, as in
geometric distortion), and can be corrected by radially scaling the planes appropriately so they line up.