Final answer:
The condenser lens is the microscope component that focuses light onto the specimen for optimal illumination, which is essential for viewing under higher magnifications.
Step-by-step explanation:
The part of a microscope responsible for gathering diffuse rays from the light source and illuminating the specimen with a concentrated, bright light is known as the condenser lens. The condenser is strategically positioned below the microscope stage to focus light through the specimen, thereby matching the aperture of the objective lens located above the specimen. To maximize illumination and enhance visibility of details at higher magnification levels, the condenser collects and directs light toward the specimen. The amount of light delivered can be further controlled by adjusting the diaphragm or using the rheostat to illuminate the specimen effectively without causing damage.