Endoscope apparatus

A method for operating an endoscope apparatus comprising:

• an insertion portion;
• a light source configured to radiate a pulsed light beam onto an imaging subject;
• an imaging optical system disposed at a distal end of the insertion portion and configured to form an image of the imaging subject based on a reflected light beam of the pulsed light beam coming from the imaging subject;
• an image transmission optical system disposed along a longitudinal direction of the insertion portion and configured to transmit the image of the imaging subject;
• and
• an optical sensor comprising a plurality of pixels arrayed on a light receiving surface, the optical sensor being configured to detect a first light level of a first reflected light beam accumulated during a first period and a second light level of a second reflected light beam accumulated during a second period,
• wherein the method comprises:
• calculating a distance based on the first light level and the second light level;
• and
• subtracting a correction value from the calculated distance, the correction value being set on a basis of the depth to which the pulsed light beam is transmitted into the imaging subject.

An endoscope main body comprising:

• an optical sensor comprising a plurality of pixels arrayed on a light receiving surface, the optical sensor being configured to detect a first light level of a first reflected light beam accumulated during a first period and a second light level of a second reflected light beam accumulated during a second period,
• one or more processors comprising hardware configured to:
• calculate a distance based on the first light level and the second light level;
• and
• subtract a correction value from the calculated distance, the correction value being set on a basis of the depth to which a pulsed light beam is transmitted into an imaging subject.