Endoscope with illumination window and observation window facing different angles

An endoscope comprising:

• a distal end part body that is provided on a distal end side of an insertion part;
• a treatment tool delivery port that is formed in the distal end part body and delivers a treatment tool inserted into the insertion part;
• an elevator that is rotatably supported in the treatment tool delivery port of the distal end part body and controls a delivery direction of the treatment tool delivered from the treatment tool delivery port and is capable of being elevated in a normal direction;
• an ultrasonic transducer including a distal end side provided on an end of the distal end part body and a proximal end side opposite to the distal end side, wherein the distal end side and the proximal end side extend along a longitudinal direction which is perpendicular to the normal direction;
• an observation window positioned on the proximate end side of the ultrasonic transducer and has a full viewing angle range of θc which is an angle less than 180 degrees when viewed from a width direction which is perpendicular to the longitudinal direction and the normal direction and a part of the ultrasonic transducer is visible within the full viewing angle;
• and
• a first illumination window positioned on the proximate end side of the ultrasonic transducer and has a full irradiation angle range of θL which is an angle less than 180 degrees when viewed from a width direction which is perpendicular to the longitudinal direction and the normal direction, wherein:
• the distal end part body comprises:
• a first inclined surface facing an observation axis which is normal to the first inclined surface and having the observation window disposed on the first inclined surface as the observation axis extends from the observation window in a normal direction,
• a second inclined surface facing a first illumination axis which is normal to the second inclined surface and having the first illumination window disposed on the second inclined surface as the first illumination axis extends from the first illumination window in a normal direction, and
• the first inclined surface and the second inclined surface have different inclination angles, and
• a first illumination axis angle is between the first illumination axis and a reference axis from a perspective of the latitudinal direction, the reference axis is parallel to the longitudinal direction, and an observation axis angle is between the observation axis and the reference axis from the perspective of the latitudinal direction,
• the observation axis angle and the first illumination axis angle are more than 0 degree inclined relative to the reference axis, and
• as Δθ is a difference between the first illumination axis angle and the observation axis angle, Δθ satisfies Δθ<((θL/2)−(θc/2)).