Introduction to the magnification of continuous zoom stereomicroscope
1、 Overview
Continuous zoom stereoscopic microscope is a Khan's instrument instrument stereoscopic microscope with continuous zoom function in the optical system, and its magnification can continuously change within the calibration range. Due to the fixed field of view diameter of the eyepiece of the Mac Audi stereo microscope (such as a 10X eyepiece with a field of view diameter of 22mm), the field of view diameter of the object side (observed object side) changes with the magnification and is inversely proportional to the magnification: object side field of view diameter=nominal field of view diameter of the eyepiece/magnification value on the objective zoom handwheel display ring
2、 Detection of Microscopic Objective Magnification and National Standards
1. Detection of objective magnification
(1) Objective lens scale (1/100, total length 2mm, each small grid=0.01mm), dividing eyepiece (equipped with a 5/100 straight line dividing plate, each small grid=0.05mm)
Preparation Procedure
Firstly, adjust the microscope according to conventional usage requirements; Change the reticle eyepiece and adjust the reticle image to the clearest visual state for the measurer; Place the objective ruler on the microscope stage, adjust the focusing mechanism of the Hanmeng Purple Star microscope, find the ruler image of the objective ruler in the eyepiece, and further adjust it to high and low magnification confocal; Move the objective stage ruler under the mirror to align it with the dividing edge ruler of the eyepiece; You can start by measuring the actual magnification of each nominal magnification of the objective lens from the high to the low magnification.
⑶ Measurement Procedure
After completing the above preparation work, start the measurement: align the magnification of the objective lens to be measured with the "line of sight" on the mirror body using the hand wheel magnification number; Observing through an eyepiece and measuring the length of the 2mm ruler on the eyepiece differentiation plate, dividing the length value by the actual length of the object by 2mm, is the measured magnification of the microscope objective at the indicated magnification; The difference between the measured magnification and the indicated magnification is the amplification error of the indicated magnification.
The magnification of the left and right optical paths of a stereoscopic microscope can be measured separately using the above measurement methods.
2. Regulations of National Standards
According to GB/T 19864.2-2005 (Quality Standard for High Performance Stereoscopic Microscopes), the total magnification error of stereomicroscopes should not exceed ± 7.5%; The magnification difference between the left and right optical systems should not exceed 1.5%.
Continuous zoom stereoscopic microscope and magnification related issues
1. In terms of performance development direction, continuous zoom stereoscopic microscopes should pursue both "high magnification" and "large field of view", which is a contradiction. Especially in terms of "large field of view", when the diameter of the eyepiece field of view is determined (such as 24mm), according to the above formula, the diameter of the object field of view will reach 36.36mm when the objective magnification is 0.66X, fully meeting the high-end performance requirements of "wide angle, large field of view" for stereo microscopes at low magnification! This data is indeed a technical challenge and a very high technical difficulty for existing stereomicroscopes. Because the determined structural data and optical system conditions (material performance, imaging quality, cost, etc.) from various aspects all constrain its implementation. On the other hand, for stereoscopic microscopes, the requirement of "high magnification" is relatively easy to achieve, because the higher the magnification and the smaller the field of view, the better the technical solution (within the roughly corresponding magnification range of the stereoscopic microscope). Therefore, some manufacturers choose to "reduce the magnification range and increase the magnification" in the continuous zoom mirror, reducing the difficulty of designing and manufacturing optical systems; Moreover, by increasing the upper deviation of the labeling magnification, the difficulty of design and manufacturing can be reduced and users can be deceived.
2. In addition to observation and under the microscope operation, continuous zoom stereoscopic microscopes are often also used for measurement purposes, especially when equipped with photography and imaging functions. They have high requirements for the accuracy of various magnification factors (especially integer magnification) and require the installation of a "magnification positioning" device. Therefore, high magnification accuracy is an important indicator of the quality of continuously variable magnification stereoscopic microscopes.
Stereoscopic microscopes are not simply optical instruments that pursue high magnification. In order to facilitate and efficiently operate under the microscope, the diameter of the object's field of view at low magnification is also a necessary performance parameter! If we are pursuing high magnification, we can suggest that users purchase more suitable biological microscopes or metallographic microscopes!
