Classification of Special Objective Lenses for Metallurgical Microscopes
1. Correction collaborative objective: A ring-shaped adjustment ring is installed in the middle of the objective lens. When the adjustment ring is rotated, the distance between the lens groups inside the objective lens can be adjusted to correct the coverage difference caused by non-standard cover glass thickness. The scale on the adjustment ring can range from 0.11 to. 023, and this number is also marked on the outer shell of the objective lens, indicating that the error of the cover glass can be corrected from 0.11 to 0.23mm thickness.
2. Iris diaphragm objective: The upper part of the objective lens barrel is equipped with an iris diaphragm, and the outer side can also rotate an adjustment ring to adjust the size of the diaphragm aperture. This type of objective is an oil immersed objective, which is used to reduce the quality of inspection when the background of the field of view is not dark enough during dark field inspection. At this point, adjust the size of the aperture to darken the background, make the object being inspected brighter, and enhance the mirror inspection effect.
3. Phase contrast objective: This type of objective is a specialized objective used for phase contrast microscopy, characterized by the presence of a phase plate at the back focal plane of the objective.
4. Uncover objective: Some objects cannot be covered with a cover glass, so an uncover objective should be used during microscopy, otherwise the image quality will significantly decrease, especially during high-power microscopy. The outer shell of this objective lens is often marked with NC, and there is no letter 0.17 at the position of the cover glass thickness, but marked with "0".
5. Long working distance objective lens: This type of objective lens has a focal length greater than ordinary objectives and is designed to meet the inspection needs of liquid materials (high-temperature metallography), liquid crystals, tissue culture, suspensions, and other materials.
