Analysis of the use of a good microscope objective lens and focussing
In the use of microscopes, take the first low-power and then high-power focusing principle, low-power objective lens focusing is equivalent to the high power objective lens to do the initial focusing, turn the high power objective lens only need to turn the lens directly to (that is, does not change through the low-power lens operation and the initial adjusted focus), in the high power microscope as long as the slight adjustment or even do not need to be adjusted to the tissues can be observed. However, many operating instructions avoid the specific reference to the "low-power objective".
In microscope use, the 10x objective is the standard and commonly used objective for focusing work. The reason for this is that there is no drastic change when changing from a 10x objective lens to a lower objective lens, or from a 10x objective lens to a higher objective lens. Another reason is that the longer focal depth of the lower objective lens makes it difficult for the observer's naked eye to focus properly, and the sample is likely to come into contact with the lens during the subsequent changeover directly to the higher objective lens.
At the same time, the 10x objective lens is not only the standard common objective lens in focusing work, but also involved in the actual work is very much. For example, in many metallographic inspection of the relevant national standards, in 100 times the observation conditions against the standard reference chart is * common, and 100 times the acquisition is 10 times the objective lens with 10 times the eyepiece. From a practical point of view, as long as it is not arbitrary, malicious, the front of the operation behaviour should be to make the objective lens is in the vicinity of the focal plane, under the conditions of 10 times the objective lens, the sample is placed correctly, there should be a fuzzy image, or even clearer, slightly adjusted fine-tuning can be.
(2) Relevant discrepancies
In the low-magnification objective lens to high-magnification objective lens after the conversion of the focusing problem, our experience and the introduction of other literature has a relatively large discrepancy. As a result of the improvement of the microscope production process, microscopes, different objectives of the focus is relatively good, especially foreign products, so that the low-focus clear, to high-focus observation, sometimes do not have to focus again the image is already very clear; or, slightly increase the object distance can be adjusted to the extent of the concept of 1 to 3 turns, that is, 1 to 3 degrees (angle) of the concept of the amount of extremely small adjustments.
(3) About the objective lens converter
When converting the objective lens, you should not push the objective lens directly by hand, otherwise it is easy to cause the fixed objective lens wire buckle to slip, so that the optical axis is skewed. The objective lens of the microscope and the micro digital camera system are screwed onto the objective lens converter. In the change of different objectives, rotating the objective converter, to hear a slight "click" sound and feel the resistance steeply for the end, at this time, the objective lens is in a normal working position: perpendicular to the plane of the carrier platform.
(4) "Shun, reverse" and "object distance" relationship
Microscope coarse adjustment, fine-tuning knob rotation direction, and the object distance is closely related to increase and decrease. The so-called clockwise, counterclockwise, but also relative, generally from the right side of the microscope to see the effect of the past; different types of microscopes, in the object distance reduction, increase the problem of the direction of rotation of the focusing knob needs to be different, need to be clear in the process of teacher guidance. In the case of ambiguity, the formal operation of the microscope must be clear in advance the relationship between the focus knob and the object distance; never blindly based on some of the instructions of the clockwise, anti-clockwise special occasions.
