Source of aberration concept
In an actual optical system, there is a practical image generated by the remote shaft zone and the ideal image generated by the near-axis region. Deviate. At this time, the beam emitted from the object from the object cannot be gathered by the optical system, but forms a dispersive spot, which is like the shape of the original object, which is aberration.
When imaged with white light, in addition to each monochromatic light still produces five monochromatic aberrations, there is a dispersion caused by different refractive indices due to different color light. Further, different color light has a different propagation optical path, thereby exhibiting aberrations caused by the difference between the optical path differences of different color light, referred to as a chromaticity (referred to as chromatic aberration). The color difference between the color difference is divided into position color difference and the magnification color difference.
Position color difference
The color difference is a color difference that describes the difference in imaging position of the two types of color light on the axis.
positive lens position color difference diagram:
negative lens position color difference diagram;
color difference seriously affects optical system imaging properties The general optical system must correct color difference. Position color difference can be corrected with a positive and negative lens.
The main factor affecting the color difference
(1) increases with the increase of hole diameter;
(2) and the refractive index of the optical material and The dispersion rate is related;
(3) is related to the focal length of the lens.
magnalte color difference
magnification color difference is a color difference due to differences due to different color light imaging.
It is a difference in the difference between the intersection height of the main light of the main light of the two color light (which is F-light and C light), indicated by the symbol.
The magnification color difference graphic:
The color difference increases with the increase in the field of view, due to the existence of the magnification, make the object edge color Thus, the image caused by white light is color spots.
For the general optical system, the three pairs of ball, the wisdom, and the positional color difference have a large impact on the imaging properties, so the first consideration is eliminated, because the human eye has automatic correction color difference function, so affecting the imaging The quality is mainly the ball difference and the wisdom.
The main factor affecting the color difference
(1) increases with the increase in the field of field;
(2) is related to the position of the diaphragm; < / p>
(3) related to the refractive index and dispersion of the optical material
ball difference - shaft Low wide light beam fault;
coma - axis outlet width beam fault;
Like - axis point fine beam fault;< P> Image bend (referred to as field music);
1. Ball poor:
shaft site is generated by wide beam imaging Aberration.
The image of the light formed by the light of different aperture angles is deviated with respect to the position of the ideal image point.
Since this ball is measured along the optical axis direction, it is also referred to as an axial ball.
The positive lens ball difference is shown:
The presence of the ball is existed, so that a dispersion is formed on the image plane, and the radius is a vertical axis ball.
The main factor affecting the ball:
(1) increases with the increase in the angle of the fifth;
(2) related to the lens shape
(3) is related to the focal length, the longer the focal length, the smaller the ball difference.
coma - axial point wide light beam;
Like - axis spot fine beam fault; < / p>
image bend (referred to as the field song);
1. Hui Para:
moon: Symmetry of the axis outer substance b and the optical axis.
arc pavement: The face is perpendicular to the main light and the mob.
Main Light: Send and pass the light of the center of the center of the center.
(1) Submur rat: The intersection BT 'of the lower light in the moon is from the deviation of the main light in the vertical optical axis direction, referred to as the meridiance, and symbol KT'.
(2) arc vector coma: Before the arc cavity, the intersection BS 'to the main light in the vertical optical axis direction is referred to as the arcing coma, and is represented by the symbol KS'.
The production of distortion
For a general actual optical system, only the vertical axis amplification rate in the near-axis region is constant. When the field of view increases, the varying magnification of the like varies depending on the field of view, which will make similarity relative to the original. This imaging defect such as a deformation is referred to as distortion.
If the optical system is orthodontically distortion, the actual image is higher than the ideal image, the resulting image is a pillow shape, and the negative variable is a barrel.
The distortion only causes deformation, and does not affect the sharpness of the image of the image. The optical system is distorted from different heights of the conjugate surface.
Like distortion, but does not affect the clarity of the image (it is different due to the difference between the vertical axis magnification).
The meaning of optical design
Although the optical system has a series of aberrations, it is generally not fully corrected and eliminated. However, due to the human eye and all other light energy receivers, there must be certain sensitive defects, as long as the value of various aberrations is less than one allowable limit, the human eye and other light receivers or awareness or reflecting the imperfectness of its imaging . Such optical systems can be considered ideal from practical meaning.