Patent ID: 8199407

Claim:
An immersion objective for microscopic investigation of a specimen, the objective comprising: an objective body; an outer lens disposed in the objective body; a delivery device including a cap disposed over the objective body so as to form an annular space delimited by an inner wall of the cap and an outer wall of the objective body and adapted to receive an immersion liquid, the cap being open in a region of the outer lens so as to form a gap with the outer lens, the cap including at least one connector configured to provide a continuous supply of the immersion liquid to the space so that the immersion liquid emerges through the gap to a region between the outer lens and at least one of the specimen and a specimen slide; a sensor device adapted to detect a condition of an immersion film of the immersion liquid in an immersion film region thereof, the sensor device being configured to detect the condition of the immersion film based on at least one of an electrical conductivity of the immersion film, an inductive effect of the immersion film in an alternating electromagnetic field and a capacitive effect of the immersion film in an alternating electromagnetic field; and a control device configured to control delivery of the immersion liquid based on the condition of the immersion film.