Culture observation apparatus

1. A culture observation apparatus, which is used for observing a cultured cell while culturing the cell, comprising:

a culture device that cultures the cultured cell, the culture device including a first space that is controlled to an environment suitable for culture of the cell, and a second space that is controlled to a lower humidity condition than the first space; and

a microscope which is used for observing the cultured cell, and which includes an objective optical unit including an objective lens;

wherein the objective lens comprises a plurality of lenses, a plurality of lens frames that hold the lenses and that have at least one through hole, and a cylinder member that houses the lens frames to be held therein;

wherein the cylinder member extends into the first space through an opening formed in a partition wall that separates the first space and the second space, with a gap between the cylinder member and the partition wall being sealed by a sealing member;

wherein a first part of the cylinder member is exposed in the first space and a second part of the cylinder member is exposed in the second space;

wherein the objective lens includes a flow path which makes a space formed by the lenses and the lens frames to be vented with the second space; and

wherein the cylinder member has a flow path that connects the through hole of the lens frames to the second space.

2. The culture observation apparatus according to claim 1 , wherein the flow path of the cylinder member extends through the cylinder member.

3. The culture observation apparatus according to claim 1 , wherein the flow path of the cylinder member extends toward a rear end of the cylinder member.

4. The culture observation apparatus according to claim 1 , further comprising a circulating device that circulates or diffuses a dry gas in the space formed by the lenses and the lens frames.

5. The culture observation apparatus according to claim 4 , wherein the circulating device includes:

a dry gas supplying unit, and

a supplying flow path used for supplying the dry gas supplied from the dry gas supplying unit to the space formed by the lenses and the lens frames.

6. The culture observation apparatus according to claim 5 , wherein:

at least one of the plurality of lens frames has a through hole; and

the cylinder member has at least two flow paths that connect the through holes of the lens frames to the second space, with the supplying flow path of the circulating device being connected to one of the flow paths of the cylinder member.

7. The culture observation apparatus according to claim 6 , wherein the flow path of the cylinder member extends through the cylinder member.

8. The culture observation apparatus according to claim 6 , wherein:

the flow path of the cylinder member extends toward a rear end of the cylinder member;

the objective optical unit has an objective lens supporting member that supports the objective lens; and

the supplying flow path of the circulating device extends in a manner so as to penetrate the objective lens supporting member.

9. The culture observation apparatus according to claim 5 , wherein the supplying flow path of the circulating device is connected to the second space of the culture device.

10. The culture observation apparatus according to claim 1 , further comprising a drying unit used for removing moisture in the space formed by the lenses and the lens frames.

11. The culture observation apparatus according to claim 10 , wherein the drying unit includes:

a desiccant housing unit that houses a desiccant for absorbing moisture, and

a communicating flow path that allows an inner space of the desiccant housing unit to communicate with the space formed by the lenses and the lens frames.

12. The culture observation apparatus according to claim 11 , wherein:

at least one of the plurality of lens frames has a through hole;

the cylinder member has a flow path that connects the through hole of the lens frame to the second space; and

the communicating flow path of the drying unit is connected to the flow path of the cylinder member.

13. The culture observation apparatus according to claim 12 , wherein the flow path of the cylinder member extends through the cylinder member.

14. The culture observation apparatus according to claim 12 , wherein:

the flow path of the cylinder member extends toward a rear end of the cylinder member;

the objective optical unit has an objective lens supporting member that supports the objective lens; and

the communicating flow path of the drying unit extends in a manner so as to penetrate the objective lens supporting member.

15. The culture observation apparatus according to claim 10 , wherein the drying unit comprises a desiccant that is put in the second space of the culture device.

16. The culture observation apparatus according to claim 10 , wherein the drying unit includes:

a liquefying unit that changes moisture inside the second space of the culture device into a liquid, and

a discharging flow path used for discharging the liquid generated in the liquefying unit out of the second space.

17. A culture observation apparatus, which is used for observing a cultured cell while culturing the cell, comprising:

a first space that is controlled to an environment suitable for culture of the cell;

a second space that is controlled to a lower humidity condition than the first space, for observation of the cultured cell;

a partition wall that separates the first space and the second space;

an objective optical unit including an objective lens for observation of the cultured cell, wherein the objective lens is held in the second space and extends into the first space through an opening formed in the partition wall, and wherein the objective lens includes a plurality of lenses, a plurality of lens frames that hold the lenses, and a cylinder member that houses the lens frames to be held therein;

a sealing member that seals a gap between the cylinder member and the partition wall; and

a flow path that makes a space formed by the lenses and the lens frames to be vented with the second space so as to prevent dew condensation on the surface of the objective lens and inside of the objective lens;

wherein a first part of the cylinder member is exposed in the first space and a second part of the cylinder member is exposed in the second space.

18. A culture observation apparatus, which is used for observing a cultured cell while culturing the cell, comprising:

a first space that is controlled to an environment suitable for culture of the cell;

a second space that is controlled to a lower humidity condition than the first space, for observation of the cultured cell;

a partition wall that separates the first space and the second space;

an objective optical unit that is held in the second space and extends into the first space through an opening formed in the partition wall, the objective optical unit including an objective lens for observation of the cultured cell, wherein the objective lens includes a plurality of lenses, a plurality of lens frames that hold the lenses, and a cylinder member that houses the lens frames to be held therein;

a cap that is detachably attached to an outer face of the cylinder member at a front end of the objective lens;

at least one transparent, parallel flat plate that is held by the cap and arranged between the cultured cell and the objective lens;

a sealing member that seals a gap between the cap and the partition wall; and

a through hole that is provided in the cap and that communicates a space between the cap and the cylinder member of the objective lens with the second space so as to prevent dew condensation on the surface of the objective lens and inside of the objective lens.