Analysis on the Differences of Aspherical Lens and Spherical Lens of Optical Lenschancctv
First of all, the first analysis of aspherical lens and spherical lens professional English how to express: aspherical lens (Aspherical Lens), spherical lens (Spherical Lens)
Aspherical lens: Aspherical lens It is different from the spherical surface of the lens, an optical lens or a composite lens with a combination of lenses, at least one surface on different parts of the point there is no common core. A composite lens containing at least one lens is called an aspherical lens.
Spherical lenses: Most lenses are spherical, so the distance between the points on a particular surface and the center of the sphere (radius or center point) is equal, and the front and back surfaces of a lens are always at different radii Spherical. The biggest drawback of this design principle is that the spherical aberration can not be avoided and is corrected only by passing aspherical lenses.
Spherical aberration is caused by the spherical surface of the lens is caused by the spherical surface. The light emitted by the same point on the optical axis converges through different points in the field space through the lens, resulting in an offset of the image position.
Aspherical lenses are not as simple as the ordinary convex surface of the spherical, aspheric mirror in the lens edge of the larger thickness, mirror as non-spherical shape. The role of the aspherical lens is by modifying the curvature of the lens surface, so that the near axis of light and the distance formed by the axis of light coincides with the location. When the paraxial light and the long axis of light are on the same focal plane, the spot will disappear, the imaging sharpness will increase.
There are three main methods of making aspherical lenses:
1, polished aspherical lenses: direct grinding on the whole piece of glass, this manufacturing process costs are relatively high;
2, molded aspherical lens: the use of metal casting technology will melt the optical glass / optical resin directly from the suppression of this manufacturing process cost is relatively low;
3, composite aspherical lens: polished in the spherical surface of the glass lens covered with a layer of special optical resin, and then part of the optical resin grinding into aspheric surface. The cost of this manufacturing process is between the two processes described above.
As the light into the wide-angle lens of the incident angle is relatively large, so the performance of the spherical aberration in the wide-angle lens is particularly evident, so in the wide-angle lens using aspherical lens is an effective way to eliminate aberrations. The following sections of the wide-angle lens structure are used aspherical lenses.
The usual aspherical lens is a non-spherical surface, the other side is spherical, in recent years there have been double-sided aspherical lens, using such a lens, you can make the number of lenses to reduce the number of lenses can also be greater magnification zoom lens.