is that the center and edge of the spherical monolithic lens have different thickness, even if monochromatic light passes through it, it will produce different refraction. After passing through the lens, it will not focus on one point, and the image point on the axis will be replaced by a diffuse light spot, which is spherical aberration.
metallographic microscope is affected by many factors. Today, what is the biggest aberration that affects the imaging effect of metallographic microscope?
1. Spherical aberration
is that the center and edge of the spherical monolithic lens have different thickness, even if monochromatic light passes through it, it will produce different refraction. After passing through the lens, it will not focus on one point, and the image point on the axis will be replaced by a diffuse light spot, which is spherical aberration. In order to improve the spherical aberration, a compound lens is now used, that is, a divergent concave lens is added in front of the main lens. Nevertheless, it cannot be completely eliminated, so the use of the microscope can be improved by appropriately adjusting the size of the aperture stop.
2, image domain bending
upright object passes through the lens is called the image field curvature. The reason for its formation is caused by the tilt of the off-axis beamlet into the lens. This aberration is particularly detrimental to metallographic microphotography, so in metallographic photography; planar achromatic and planar apochromatic objectives should be selected because they correct for chromatic aberration at the edge of the field of view.
3, multi-color aberration
polychromatic aberration refers to a series of color group phenomena caused by the decomposition (dispersion) of light due to refraction after the white light passes through the lens. Which is divided into longitudinal chromatic aberration and lateral chromatic aberration. Longitudinal chromatic aberration refers to the non-monochromatic light beam emitted from a certain point on the axis. Due to the different (& lambda;) light waves included in the composition, dispersion will occur, causing these light rays to intersect different points on the axis, forming a series of chromatic aberration phenomena of group images. Lateral chromatic aberration. Because the refractive index of light of various colors is different, the focal length is also different, but because the magnification is related to the focal length, the points on the target that are not on the axis are imaged at different distances from the axis, which then produces lateral chromatic aberration, also known as magnification chromatic aberration.
the above is the aberrations that affect the lens of the metallographic microscope summarized by the small editor of Deep Vision Optical Valley. In fact, when the metallographic microscope is observed, there are many factors that are affected, and it is not enough to solve a certain problem. I hope the above introduction can help everyone.
