Patent ID: 11900591
Assignee: CANON KABUSHIKI KAISHA
Field: Audio-visual technology (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A displacement meter comprising:
an incoherent light source configured to illuminate an object to be measured;
a double telecentric optical system configured to receive diffused-reflected light generated on a surface of the object that has been illuminated by the incoherent light source;
an image pickup unit configured to receive diffused-reflected light through the double telecentric optical system to output an image; and
at least one processor or circuit configured to function as:
a calculation unit configured to calculate the displacement of the object to be measured,
wherein the calculation unit calculates a displacement amount of the object to be measured by using sub-pixel estimation and using a cross-correlation function between reference image data and measurement image data, in which an image acquired during a predetermined timing from an imaging unit serves as the reference image data and an image acquired after the predetermined timing serves as the measurement image data,
generates a value obtained by subtracting a correction value from the displacement amount to serve as a correction displacement amount,
sets the most recent measurement image data as the reference image data and sets a predetermined initial value as the correction value in a case where the displacement amount meets a predetermined condition, and
sets the displacement amount obtained most recently as the correction value in a case where the displacement amount does not meet the predetermined condition.