Any optical imaging instrument with a spherical lens combination has aberration, which affects the imaging quality. The role of high-precision optical imaging instruments is to improve the quality of imaging by using techniques that correct for aberrations. The eye is a sophisticated and complex optical instrument, and also has aberrations. Among the aberrations of the normal human eye, such as spherical aberration, coma aberration, image dispersion, image plane bending, aberration, chromatic aberration, etc., chromatic aberration is the most influential to vision.
I. Chromatic aberration of the eye
Any optical medium, for different wavelengths of monochromatic light in the transparent band, has a different refractive index. The optical system mainly with white imaging, white light incident on any shape of the media partition interface, as long as the angle of incidence is not zero, a variety of color light will have a different propagation path due to dispersion, resulting in a variety of color light has a different imaging position. This difference in imaging is called chromatic aberration. The human eye also exists chromatic aberration. We use the optical focal length of the human eye visual system to represent the chromatic aberration of the human eye. For the convenience of calculation, the standard eye can be reduced to a refractive spherical model called the parsimonious eye.
II. Chromatic aberration and visual fatigue
The refractive index of the cornea and crystal of the human eye is basically between 1.31-1.33, which is higher than the refractive index of air, which determines that the dispersion of the human eye is objective, and the existence of this dispersion has a great impact on the visual quality. Due to the existence of dispersion, for a certain image to point into the eye because of the wavelength of radiation, according to the principle of geometric optics should only a certain wavelength of light produce a true conjugate, the rest of the wavelength of light will form a concentric circle with the conjugate point as the center.
1. The presence of chromatic aberration causes blur in the retina after the image enters the eye, which is more obvious in close vision.
2. blurring inevitably causes ciliary muscle regulation, and excessive ciliary muscle regulation is one of the causes of eye deformation; excessive ciliary muscle regulation is one of the causes of visual fatigue.
3. blurring of the image quality in the retina generates invalid and harmful visual signals, which increases the brain imaging processing burden, which is an important cause of visual fatigue. This is an important cause of visual fatigue.