Establishment of calibration projects for metallographic microscopes
(1) Install an objective lens, place a 0.01mm standard micrometer on the workbench, and press it tightly; Rotate the focus knob to adjust the focus to the middle of the micrometer, with clear imaging at the center of the field of view. At this time, contact the dial gauge head with the surface of the workbench and align it with the zero position of the meter;
Rotate again to focus and adjust the focus to the edge of the micrometer, making the field of view edge imaging clear.
Observing the dial gauge, its maximum offset is the field curvature error of the objective lens, and other objectives are calibrated accordingly. The indicators for the field curvature error of the objective lens are as follows: 10X<0.2mm, 25X<0.1mm, 40X<0.07mm, 63X<0.065mm, 100X<0.04mm
(2) Correctness of objective magnification: Install a 10X standard eyepiece and the tested objective, place a 0.01mm standard micrometer on the workbench and press it tightly. When observing, the micrometer should match the reticle in the eyepiece, and its offset measurement is the error in magnification. Other objective lenses are calibrated using this method, with an error not exceeding 5%
(3) The accuracy of the eyepiece reticle: Rotate the lens of the eyepiece with a reticle, place the reticle on the worktable of the universal display, and adjust the focal length; Adjust the workbench so that the horizontal line of the dividing plate is parallel to the longitudinal guide rail stroke of the universal display and aligned with the zero position. Measure every 20 grids until the 100th grid, and the error should not exceed 5um
(4) The clear imaging range of the objective lens is achieved by focusing the micrometer or metallographic sample with the tested objective lens and 10X eyepiece to ensure clear imaging. When the center image of the field of view is clear, the error in the measured imaging clarity range within the field of view shall not be less than 60%
(5) Install the 10X eyepiece of the tested instrument on the grid value of each objective lens relative to the eyepiece, and place a 0.01mm standard micrometer (it is recommended to use a random 0.01mm micrometer) on the workbench and press it tightly;
Adjust the axis of the micrometer scale to be parallel to the axis of the instrument's eyepiece reticle, and read out the number of n micrometer scale lines included in the i reticle lines of the eyepiece reticle. The relative grid value of the objective lens to the eyepiece is C=n/i * 0.01mm. The grid values of other objectives are calibrated accordingly.
