位相シフトディジタルホログラフィーを用いた管内表面形状計測における円錐鏡の軸ずれによる誤差の補正

Phase-shifting digital holography is applied to a surface profilometry of an inner surface of a pipe. For the surface contouring of the inner wall, two wavelength method using an injection-current induced wavelength change of a laser diode is used. To illuminate the inner wall of the pipe, a cone-shaped mirror is set inside the pipe. A compensation method using a calculated optical path length in the experimental alignment is used to evaluate the inner shape of the pipe. The effectiveness of the compensation method has been experimentally investigated by shifting the cone-shaped mirror from the center of the pipe. To demonstrate an inspection of the pipe inner wall, the proposed method has been applied to detection of two seals pasted on the inner wall. Three-dimensional profile of the seals on the inner wall of the pipe can be evaluated using a simple image processing.