Height measurement method and height measurement device

    公开(公告)号:US11644304B2

    公开(公告)日:2023-05-09

    申请号:US17106638

    申请日:2020-11-30

    发明人: Masafumi Yamanaka

    摘要: A height measurement device includes: a lens system; a lens controller to output a drive signal to the lens system; a continuous illuminator to continuously illuminate a workpiece; an image detector to detect an image of the workpiece; an image calculation unit to calculate an EDOF image on a basis of a detected image; a focal depth adjustment unit to cause an extended focal depth of the EDOF image to be increased or decreased by increasing or decreasing an amplitude of the drive signal; a focus determination unit to determine a focus state of a portion of interest of the workpiece included in the EDOF image; and a height measurement unit to measure an upper limit or a lower limit of the extended focal depth, the upper limit or the lower limit being based on a timing at which the focus state of the portion of interest has changed.