What is a dark field microscope?

The bright field of metallographic microscope is illuminated by the coaxial light of microscope, which shines on the surface of the object, then reflects back to the objective lens and is observed by our naked eyes through the eyepiece. Under the eyepiece, the reflective part of the sample is bright, and other scattered or non-reflective parts are black or dark.

The difference between dark field and bright field is mainly the light path distribution and lighting effect. The parallel light of the dark field light source is blocked by the annular diaphragm, and the central light cannot pass through, so a hollow annular light beam enters the vertical illuminator, making the light pass through the periphery of the objective lens, transmit to the special reflective condenser, and reflect the light to the ground surface of the metallographic sample. Because of the large inclination of reflected light, if the sample is a polishing mirror, the light on the sample still reflects in the opposite direction with a large inclination and cannot enter the objective lens, so the field of view is dark.

Leica metallographic microscope DM2700M has a switching device, which can switch between bright field and dark field freely.

The above answers are provided by the collar instrument ~