DISPLACEMENT MEASURING DEVICE, DISPLACEMENT MEASURING METHOD, AND PROGRAM THEREOF

PROBLEM TO BE SOLVED: To maintain a measuring accuracy of the displacement of a subject without depending on the setting conditions of an imaging part.SOLUTION: A displacement measuring device acquires more than two images of which a pattern having a fixed pitch is spatially repeated. A phase computing part calculates a phase of the moire image acquired by interpolating a thinning-out image generated by being thinned-out at a predetermined thinning-out interval. A displacement amount computing part calculates a displacement amount of the thinning-out pattern based on a difference between the phase at one point and the phase at the other point. A correction arithmetic processing unit subtracts the displacement amount of the other repeating pattern multiplying a ratio of one repeating pattern of the pitch of the other repeating pattern to the repeating pattern by the displacement amount of the other repeating pattern as a correction amount from the displacement amount of one repeating pattern.SELECTED DRAWING: Figure 5 【課題】撮像部の設置条件によらず被写体の変位の測定精度を維持する。【解決手段】一定のピッチを有する模様が空間的に繰り返される２つ以上の繰り返し模様の画像を取得し、位相演算部は、繰り返し模様について、所定の間引き間隔で間引きして生成される間引き画像を補間して得られるモアレ画像の位相を算出する。変位量演算部は、一時点における位相から他の時点における位相との差に基づいて繰り返し模様の変位量を算出する。補正演算処理部は一つの繰り返し模様の変位量から、他の繰り返し模様のピッチの一つの繰り返し模様のピッチに対するピッチ比を乗じた他の繰り返し模様の変位量を補正量として差し引く。【選択図】図５