Answer:
The answer is Dark-field microscope.
Step-by-step explanation:
Dark-field microscope is a microscope that uses a focused beam of very intense light in the form of a hollow cone concentrated on the sample, where the illuminated object disperses the light and thus becomes visible against the dark background behind it, making the transparent portions of the Specimen remain dark, while surfaces and particles look bright. This form of illumination is used to analyze transparent and unpigmented biological elements, invisible with normal illumination, without killing the specimen.