A polarizing microscope is equipped with two polarizers. The polarizer installed under the stage is called the lower polarizer (polarizer), and the polarizer installed in the barrel above the objective lens is called the upper polarizer (analyzer).
Normally, the vibration planes (vibration directions) of the polarized light transmitted from both are perpendicular to each other.
Ⅰ. Structural components of polarizing microscope
1. Mechanical system components
Mirror base, mirror arm, stage, lens tube.
2. Optical system components
The light source, lower polarizer, locking aperture, condenser, objective lens, upper polarizer, eyepiece, Bertrand lens.
3. Accessories
①Quartz wedge, gypsum test board, mica test board, etc.;
② Mechanical table, object table, micro ruler, etc.
Ⅱ. Adjustment of polarizing microscope
1. Attaching and unloading the lens
- ① Loading and unloading the eyepiece: Insert the selected eyepiece into the lens barrel, and make the eyepiece crosshairs located in the east-west, north-south direction. The binocular tube also needs to adjust the distance between the two eyepieces so that the distance between the eyes is consistent with the binocular field of view.
- ② Loading and unloading the objective lens (turntable type): Install the objective lens on the objective lens rotating disc at the lower end of the lens barrel, and then rotate the required objective lens directly below the lens barrel until the spring is stuck.
2. Adjust lighting (aiming)
In the process of adjusting the lighting, first put the voltage adjustment knob in the low voltage direction, then turn on the power switch, and then adjust the voltage knob to increase the brightness of the field of view to the appropriate brightness.
3. Adjust focus (accurate focus)
- ① Place a thin slice on the stage (note that the cover glass must face upward).
- ②Look at the objective lens from the side, turn the coarse screw to raise the stage to the highest position (be careful not to crush the sheet).
- ③ Observe through the eyepiece and turn the coarse screw at the same time to lower the stage. When an object just appears in the field of view, use the fine screw for fine adjustment.
- ④Switch to a high-magnification objective lens and adjust the focus in the same way.
Ⅲ. Calibration of polarizing microscope
1. Calibration center
2. Correction of polarizer
(1) Determination and correction of the vibration direction of the lower polarizer
- ① Select a biotite with a set of extremely complete cleavage seams in a thin slice and place it in the center of the field of view.
- ② The rotating object stage makes the biotite color the deepest. At this time, the direction of the biotite cleavage seam represents the vibration direction of the lower polarizer.
- ③ If the direction of the biotite cleavage seam is parallel to the cross wire, the lower polarizer is in the correct position;
- ④ If it is not parallel, rotate the animal stage so that the direction of the biotite cleavage seams is parallel to the cross hairs, and rotate the lower polarizer until the color of the biotite becomes the deepest. At this time, the vibration direction of the lower polarizer is in the east-west direction.
(2) Check whether the vibration directions of the upper and lower polarizers are orthogonal
- ① Use a medium magnification objective lens and adjust the lighting to make the field of view the brightest. Push in the upper polarizer. If the field of view is dark, it proves that the vibration directions of the upper and lower polarizers are perpendicular to each other (orthogonal).
- ② If the field of view is not dark, it means that the vibration directions of the upper and lower polarizers are not orthogonal.
- ③ If the vibration direction of the lower polarizer has been corrected to the east-west direction, you need to correct the vibration direction of the upper polarizer. At this time, you need to rotate the upper polarizer until the field of view is dark.
(3) Check whether the eyepiece crosshairs are strictly consistent with the vibration direction of the upper and lower polarizers.