Patent ID: 7384193

Claim:
A method of selecting the location of the range of focus z 0 −qΔz to z 0 +pΔz in a line scan camera having time domain integration imaging sensors, the method comprising the steps of: (a) selecting as the height of a plane of least blur a height z 0 along a z axis that is generally normal to an x-y plane in which is disposed at least one time domain integration imaging sensor whose length in pixel locations is parallel to x, whose direction of time domain integration is a width in pixel locations parallel to y and whose time domain integration is performed in response to cycles in a shift clock signal; (b) continuously moving a workpiece interposed between the x-y plane and a source of actinic radiation centered on the z axis and illuminating the at least one time domain integration imaging sensor in the x-y plane, the motion of the workpiece being in a plane parallel to the x-y plane and in a direction parallel to y; (c) selecting a value physical Δy, such that for a ray leaving the source of actinic radiation and passing through some imaged location of the workpiece and intersecting a first pixel cell within the at least one time domain integration imaging sensor, when the workpiece is displaced by step (b) in the amount of physical Δy another ray passing through the same imaged location intersects a second pixel cell within the at least one time domain integration imaging sensor and adjacent to the first pixel cell in the y direction; (d) detecting the y position of the workpiece; (e) issuing the shift clock signal each time the y position detected in step (d) changes by the value of physical Δy selected in step (c); and (f) storing in a memory a collection of x direction output values shifted out from the time domain integration sensor each time the shift clock signal is issued by step (e).