Endoscope apparatus and measuring method

1. An endoscope apparatus that measures a subject using a pattern projection image of the subject on which a light and dark pattern of light is projected, the endoscope apparatus comprising:

an insertion tube having a central axis;

an image sensor configured to acquire an image of the subject;

an objective optical system configured to form the image of the subject on the image sensor;

an illumination light source configured to emit illumination light to illuminate the subject;

a pattern projector configured to project the light and dark pattern onto the subject;

a projection window for the pattern projector; and

an observation window for the objective optical system,

wherein the objective optical system has a prism configured to direct light incident through the observation window to a direction toward the image sensor,

wherein the objective optical system is disposed such that an optical axis of the light directed by the prism and incident on the image sensor is offset relative to the central axis of the insertion tube,

wherein a plane is formed on part of an outer circumferential surface of a distal end portion of the insertion tube, the plane having a normal line perpendicular to the central axis of the insertion tube,

wherein an illumination window through which the illumination light emitted from the illumination light source is transmitted is disposed on the plane, and

wherein when viewed in a direction perpendicular to the plane, the illumination window is disposed on the central axis of the insertion tube.

2. The endoscope apparatus according to claim 1 ,

wherein when viewed in the direction perpendicular to the plane, the observation window and the projection window are disposed on the plane so as to be visible,

wherein an optical center of the observation window is offset relative to the central axis of the insertion tube so as to be at one side of the central axis of the insertion tube, and

wherein an optical center of the projection window is offset relative to the central axis of the insertion tube so as to be at the other side of the central axis of the insertion tube.

3. The endoscope apparatus according to claim 2 , wherein when viewed in the direction perpendicular to the plane, the illumination window is spaced from an imaginary plane that extends along a direction perpendicular to the central axis of the insertion tube and that passes through a center of the observation window.

4. An endoscope apparatus that measures a subject using a pattern projection image of the subject on which a light and dark pattern of light is projected, the endoscope apparatus comprising:

an insertion tube having a central axis;

an image sensor configured to acquire an image of the subject;

an objective optical system configured to form the image of the subject on the image sensor;

an illumination light source configured to emit illumination light to illuminate the subject;

a pattern projector configured to project the light and dark pattern onto the subject;

a projection window for the pattern projector; and

an observation window for the objective optical system,

wherein the objective optical system has a prism configured to direct light incident through the observation window to a direction toward the image sensor,

wherein the objective optical system is disposed such that an optical axis of the light directed by the prism and incident on the image sensor is offset relative to the central axis of the insertion tube,

wherein a plane is formed on part of an outer circumferential surface of a distal end portion of the insertion tube, the plane having a normal line perpendicular to the central axis of the insertion tube,

wherein when viewed in a direction perpendicular to the plane, the observation window and the projection window are disposed on the plane so as to be visible,

wherein when viewed in the direction perpendicular to the plane, the observation window and the projection window are disposed along the central axis of the insertion tube, and

wherein when viewed in a front view of the insertion tube, the plane and an optical axis of the light incident on the image sensor are both offset relative to the central axis of the insertion tube such that the plane and the optical axis of the light incident on the image sensor are on respective opposite sides of the central axis of the insertion tube.

5. The endoscope apparatus according to claim 4 , wherein an illumination window through which the illumination light emitted from the illumination light source is transmitted is disposed on the plane, and

wherein when viewed in the direction perpendicular to the plane, the illumination window is spaced from the central axis of the insertion tube at a position not overlapping with the observation window.

6. The endoscope apparatus according to claim 5 , wherein when viewed in the direction perpendicular to the plane:

an optical center of the observation window is disposed on the central axis of the insertion tube, and

a center of the projection window is disposed on the central axis of the insertion tube.

7. The endoscope apparatus according to claim 5 , wherein the illumination window comprises a first illumination window and a second illumination window,

wherein the first illumination window is provided on a first side of the observation window, and

wherein the second illumination window is provided on a second side of the observation window different from the first side of the observation window.

8. The endoscope apparatus according to claim 4 , wherein a center of the projection window is disposed on the central axis of the insertion tube.

9. An endoscope apparatus that measures a subject using a pattern projection image of the subject on which a light and dark pattern of light is projected, the endoscope apparatus comprising:

an insertion tube having a central axis;

an image sensor configured to acquire an image of the subject;

an objective optical system configured to form the image of the subject on the image sensor;

an illumination light source configured to emit illumination light to illuminate the subject;

a pattern projector configured to project the light and dark pattern onto the subject;

a projection window for the pattern projector; and

an observation window for the objective optical system,

wherein the objective optical system has a prism configured to direct light incident through the observation window to a direction toward the image sensor,

wherein the objective optical system is disposed such that an optical axis of the light directed by the prism and incident on the image sensor is offset relative to the central axis of the insertion tube, and

wherein when viewing a distal end of the insertion tube from a position in front of the insertion tube, the projection window is offset laterally with respect to the prism.

10. The endoscope apparatus according to claim 9 , wherein a plane is formed on part of an outer circumferential surface of a distal end portion of the insertion tube, the plane having a normal line perpendicular to the central axis of the insertion tube,

wherein when viewed in a direction perpendicular to the plane, the observation window and the projection window are disposed on the plane so as to be visible,

wherein an optical center of the observation window is offset relative to the central axis of the insertion tube so as to be at one side of the central axis of the insertion tube, and

wherein an optical center of the projection window is offset relative to the central axis of the insertion tube so as to be at the other side of the central axis of the insertion tube.

11. The endoscope apparatus according to claim 9 , wherein an illumination window through which the illumination light emitted from the illumination light source is transmitted is disposed on the plane, and

wherein when viewed in a direction perpendicular to the plane, the illumination window is disposed on the central axis of the insertion tube.

12. The endoscope apparatus according to claim 11 , wherein when viewed in the direction perpendicular to the plane, a center of the illumination window is disposed on the central axis of the insertion tube.

13. The endoscope apparatus according to claim 9 , wherein an illumination window through which the illumination light emitted from the illumination light source is transmitted is disposed on the plane, and

wherein when viewed in a direction perpendicular to the plane, the illumination window is disposed between the distal end of the insertion tube and the observation window in a direction along the central axis of the insertion tube.

14. The endoscope apparatus according to claim 9 , wherein a position of a center of the observation window coincides with a position of a center of the projection window in a direction along the central axis of the insertion tube.