Height measurement method and height measurement device
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.
1. A height measurement method by using an image detection device,
the image detection device comprising:
a lens system of a liquid resonant type whose focus position is varied in response to a drive signal to be inputted;
a lens controller configured to output the drive signal to the lens system;
a continuous illuminator configured to continuously illuminate a workpiece; and
an image detector configured to detect an image of the workpiece through the lens system,
the height measurement method comprising:
calculating an EDOF image on a basis of a detected image that is detected by the image detector;
causing an extended focal depth of the EDOF image to be increased or decreased by increasing or decreasing an amplitude of the drive signal;
determining a focus state of a portion of interest of the workpiece included in the EDOF image; and
measuring, as a height of the portion of interest, 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 in association with the increase or the decrease of the extended focal depth.
2. A height measurement device comprising:
a lens system of a liquid resonant type whose focus position is varied in response to a drive signal to be inputted;
a lens controller configured to output the drive signal to the lens system;
a continuous illuminator configured to continuously illuminate a workpiece;
an image detector configured to detect an image of the workpiece through the lens system;
an image calculation unit configured to calculate an EDOF image on a basis of a detected image that is detected by the image detector;
a focal depth adjustment unit configured 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 configured to determine a focus state of a portion of interest of the workpiece included in the EDOF image; and
a height measurement unit configured to measure, as a height of the portion of interest, 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 in association with the increase or the decrease of the extended focal depth.