Five common observation methods of microscope
1. Bright field method
A method of observing light reflected directly from a sample. Light from the illuminator is incident on the sample through a vertically aligned objective, and direct reflected light from the sample is observed through the objective.
2. Dark field method
Observe sample drying methods involving diffracted light. The illumination light is obliquely incident on the sample through the periphery of the objective lens, and the dry light from the sample is observed while the diffracted light is observed.
Ideal for detecting small scratches or cracks on samples and inspecting mirror-like surfaces of samples such as wafers.
3. Polarized light method
This is a microscopic observation technique that uses polarized light formed by two sets of color filters (detection polarizer and polarizer). These polarization axes are always perpendicular to each other. Some samples show a sharp contrast between the two filters. Or express color based on birefringence properties and orientation (i.e. polished samples of zinc structures). When the analyzer is inserted in the observation light path in front of the eyepiece, the polarizer is in the light path in front of the vertical illuminator.
It is suitable for observing metallographic structure (ie graphite growth mode of ductile iron), minerals and liquid crystal (LCD) and semiconductor materials.
4. Differential interference contrast method
This is a microscopic observation technique that changes the contrast height into a stereoscopic or three-dimensional image by using the bright field method that may not be observed by the bright field method. The illumination light is changed from the differential interference contrast prism to two diffracted lights. The difference in sample height caused by the two diffracted lights creates a small difference in the light path, and the difference in light path becomes the contrast between the contrast prism and the analyzer using differential interferometry.
Sensitive samples are reused to enhance highly variable chromatic aberrations.
It is suitable for testing samples with extremely high-precision height differences, including metallographic structures, minerals, magnetic heads, hard disk surfaces and wafer refined surfaces.
5. Fluorescence method
This technique is used for samples that fluoresce.
It is suitable for detecting wafer contamination, residual photosensitive resin, and detecting cracks by fluorescence method.
