Calibration tool for rotating endoscope

A method for calibrating a rotating SEE, the method comprising:

• providing a calibration apparatus comprising:
• a body configured to encompass at least a portion of a SEE;
• a bottomed surface affixed to a distal end of the body;
• and
• a calibration chart configured on an inside wall portion of the apparatus,
• wherein the apparatus has an open end, opposite the bottomed surface, wherein the open end is configured to receive the at least a portion of the SEE, and the SEE is a rotating SEE,
• scanning the calibration chart with a SEE spectral line to obtain an image;
• determining a sign of a tangential shift of the spectral line based on a slope of at least one of the radial lines of the first image in a polar coordinate;
• computing a magnitude of the tangential shift based on at least one of the radial lines of the first image in either a polar coordinate or a Cartesian coordinate;
• determining a sign of a radial shift of the spectral line based on whether the slope has a turning point or not;
• computing a magnitude of the radial shift by measuring a location of the turning point if the radial shift is determined to be negative;
• scanning the calibration chart with the SEE spectral line to obtain a second image if the radial shift is determined to be positive;
• computing the magnitude of the radial shift based on the magnitude of the tangential shift and a radius of the circle;
• and
• applying the tangential shift and the radial shift for a corrected calibration.