Observation instrument and video imager arrangement therefor

1. An observation instrument comprising a shaft and an imaging unit, the imaging unit comprising an objective lens system and an electronic image sensor arranged for picking up an image generated by the objective lens system, the imaging unit being pivotably arranged about a pivot axis in a distal end section of the shaft, the pivot axis of the imaging unit being transverse to a longitudinal axis of the distal end section of the shaft and essentially parallel to a pick-up surface of the image sensor; wherein the image sensor is arranged substantially parallel to an optical axis of the objective lens system; wherein the objective lens system comprises a plurality of optical elements, the optical elements of the objective lens system being fixedly positioned relative to each other within a sleeve; wherein the imaging unit comprises a deflection element comprising a deflection prism for deflecting light exiting from an image end of the objective lens system to an image pick-up surface of the image sensor, wherein the imaging unit is pivotable between a first end position, in which the optical axis of the objective lens system is approximately parallel to a longitudinal axis of the distal end section of the shaft, and a second end position, in which the optical axis of the objective lens system forms a maximal angle to the longitudinal axis of the distal end section of the shaft, and wherein the objective lens system and the electronic image sensor are pivotable as a unit with respect to the shaft, wherein a length, L, of the objective lens system is

L≤h /sin α− d /tan α

wherein h is an inner diameter of the distal end section of the shaft and d is a diameter of the objective lens system.

2. The observation instrument of claim 1 , wherein the deflection prism fixed to the image pick-up surface or a coverglass of the image sensor.

3. The observation instrument of claim 2 , wherein the deflection prism is fixed to an image end of the sleeve.

4. The observation instrument of claim 2 , wherein the pivot axis is arranged at a distal edge of the image sensor.

5. The observation instrument of claim 3 , wherein the pivot axis is arranged at a distal edge of the image sensor.

6. The observation instrument of claim 2 , wherein the pivot axis is arranged at the image end of the objective lens system.

7. The observation instrument of claim 3 , wherein the pivot axis is arranged at the image end of the objective lens system.

8. The observation instrument of claim 2 , wherein the image sensor has a diagonal having a length exceeding an inner diameter h of the distal end section of the shaft.

9. The observation instrument of claim 3 , wherein the image sensor has a diagonal having a length exceeding an inner diameter h of the distal end section of the shaft.

10. The observation instrument of claim 1 , wherein the optical axis of the objective lens system is offset to the image pick-up surface of the image sensor.

11. The observation instrument of claim 1 , wherein the maximal angle, α, is between approximately 25° and approximately 75°.

12. The observation instrument of claim 1 , wherein the image sensor has a diagonal having a length exceeding an inner diameter h of the distal end section of the shaft.

13. The observation instrument of claim 1 , wherein the shaft is distally closed by a curved cover glass.

14. The observation instrument of claim 1 , wherein the observation instrument is an endoscope, an exoscope or an endoscopic capsule.

15. The observation instrument of claim 1 , wherein the objective lens system comprises a negative front lens and two further optical elements, wherein the negative front lens is the optical element of the objective lens system positioned most distally from the image sensor.