Objective lens unit and liquid immersion microscope

1. An objective lens unit for a liquid immersion microscope, the objective lens unit comprising:

a lens;

a cover that houses the lens and comprises a groove therein;

a first liquid passage in a pipe shape including an opening disposed at a lens surface end on a lens surface of the lens at a closest side to an observing object, the first liquid passage being coupled through the groove to an outside of the objective lens unit;

a second liquid passage in a pipe shape disposed independently from the first liquid passage, the second liquid passage including an opening disposed at a position adjacent to the opening of the first liquid passage on the lens surface end, the second liquid passage being coupled through the groove to the outside of the objective lens unit; and

a depression formed in the lens on the lens surface end to dispose the opening of the first liquid passage and the opening of the second liquid passage,

wherein the groove houses the first and second liquid passages together therein and has an opening at a distal end thereof, and the depression is formed in the lens at a position opposed to the opening of the groove such that the opening of the first liquid passage and the opening of the second liquid passage face a side surface of the lens.

2. The objective lens unit according to claim 1 , wherein

the first liquid passage is a flow passage to supply an immersion liquid to the lens surface end, and

the second liquid passage is a flow passage to suction and discharge the immersion liquid that flows out of the opening of the first liquid passage.

3. The objective lens unit according to claim 1 , wherein

the lens at the closest side to the observing object is a cemented lens including a meniscus lens having a depression in a center of a surface on an observing object side and a small-sized plano-convex lens fitted in the depression in the center of the meniscus lens, and

the opening of the first liquid passage and the opening of the second liquid passage are disposed at a position avoiding overlapping the plano-convex lens.

4. The objective lens unit according to claim 1 , wherein

the first liquid passage and the second liquid passage are disposed so as to avoid projecting to the observing object side with respect to the lens surface end.

5. The objective lens unit according to claim 1 , further comprising

a cover that houses the lens at the closest side to the observing object, wherein

the cover includes a groove to house the first liquid passage and the second liquid passage.

6. A liquid immersion microscope comprising:

the objective lens unit according to claim 1 ;

a supply mechanism that supplies an immersion liquid to the lens surface end via the first liquid passage;

a discharge mechanism that discharges the immersion liquid via the second liquid passage; and

a controller that controls operations of the supply mechanism and the discharge mechanism, wherein

the controller causes a supplying operation of the immersion liquid and a discharging operation of the immersion liquid to be simultaneously performed at a start of supplying the immersion liquid and causes the discharging operation of the immersion liquid to be precedingly terminated.

7. The liquid immersion microscope according to claim 6 , wherein

the liquid immersion microscope is an inverted liquid immersion microscope.

8. The objective lens unit according to claim 1 , wherein the first liquid passage is disposed on a same side of the lens as the second liquid passage.

9. The objective lens unit according to claim 1 , wherein the depression is configured so as to avoid overlapping an optical range of the lens surface so that both a supply port and a suction port are disposed at a position that avoids overlapping the optical range.