30.1.2.3 Endoscope specification

Source:  Leiner

• Field of view: maximum angle that can be viewed  Leiner

  • Generally constructed so that the FOV is wide enough so that the ‘head on’ view is visible even when the DOV is not zero.  Leiner
  • This is to reduce the chances of bumping the instrument into anatomy right in front of the shaft.  Leiner

• Direction of view: angular offset of the optical axis from the longitudinal axis of the endoscope shaft

  • Realised by adding a reflecting prism at the endoscope tip, which inclines the direction of view  Leiner
  • Enables the surgeon to be able to look to the side or even to the back, by only rotating the scope along its longitudinal axis—useful for cases where range of motion is very limited due to anatomical restrictions   Leiner

• Diameter: the smaller the better, to reduce trauma to patient

• Image resolution

• f-number: ratio of the optical system’s focal length to aperture

  • Higher f-number: higher resolution
  • Lower f-number: increases brightness, decreases depth of field