Six aberrations common to industrial lenses

Aberration is an important factor affecting image quality, and the image quality of different industrial lenses is not the same. Even if the same type of industrial lens is used, the image quality is changed due to the relationship of processing fineness, lens structure and material. Because of this, the price of industrial lens is also from a hundred yuan to ten thousand yuan gap. When we choose industrial lenses, the first thing to consider is aberration, which is an important factor affecting the imaging quality. There are six common industrial lens aberrations as follows:

1, the spherical aberration: from a physical point on the spindle to monochrome cone beam from the optical system, after the refraction optical series, if the original beam different aperture Angle of the light, not to the same location on the main shaft, so that an ideal image plane on the spindle, forming a dispersion spot (commonly known as blur), then this optical system imaging error is called the spherical aberration.

2. Comet: a monochrome conical light beam sent from an extraxial point outside the principal axis to an optical system. If, after refraction by the optical series, a clear point is not formed at the imaginary plane, but a comet with a bright tail is formed, the imaging error of the optical system is called the comet.

3. Astigmatism: the oblique monochrome conical light beam sent to the optical system by an off-axis object point located outside the main axis. After refraction of the optical series, it can not form a clear image point, but can only form a diffuse light spot.

4. Field curvature: a clear image formed by an optical system of a plane object perpendicular to the principal axis is not in an image plane perpendicular to the principal axis, but on a curved surface with the principal axis as symmetry, that is, the optimal image surface is a curved surface, then the imaging error of the optical system is called field curvature. When the focus to the center of the image is clear, the image around the screen blurred; When the images around the screen are clear, the images in the center of the screen begin to blur.

5. Distortion: the straight line outside the main axis in the plane of the object being photographed becomes a curve after imaging by the optical system, then the imaging error of the optical system is called distortion. Distorted aberration only affects the geometry of the image, not the sharpness of the image. This is the fundamental difference between distortion and spherical aberration, comet, astigmatism and field curvature.

6, chromatic aberration: by the white object to the optical system emits a white light, refracted by the optical system, the color light can not converge on a point, and form a color spot, known as chromatic aberration. The reason of chromatic aberration is that the refractive index of the same optical glass is different to the light of different wavelength, the refractive index of short wave light is large, and the refractive index of long wave light is small.