Darkfield microscopy

    Darkfield microscopy is based on the light scattering by the microscopic objects, including those that are smaller than the resolution limit of a light microscope.

    Light from an illuminator and a mirror passes through a special darkfield condenser which forms the light beam in the shape of a hollow cone and directs it onto the specimen. In the reflected light the role of the darkfield condenser is played by an elliptical mirror, fastened to the objective mount. Upon leaving the condenser the main part of the rays passes by the objective (which is inside this cone). The image in the microscope is formed by only a small portion of the rays scattered by the microparticles of the specimen inside the cone and passed through the objective.

    Thus, light images of the structural elements of the specimen that differ from the surroundings in refractive index can be seen in the field of view against a dark background.

    Reflected darkfield observation mode is often used for the study of opaque samples, which are invisible with brightfield microscopy, such as thin sections of metals. Furthermore, the method is ideal for the observation of small defects on semiconductor wafers that appear in the image in the form of bright ‘flashes’.

     Microscopes:

∙   MICRO 200 (T) - 01

∙   MA 300 AUTOMATED STATION

∙   MI - 1 (T) 

     Transmitted darkfield observation is used to study transparent non-absorptive objects that are invisible with brightfield microscopy. Biological specimens are frequently of this type