Heat - sink and Package datum , Pad Spacing, Gap , Length, Width, Spread, Tweeze , Missing, Broken or Un - plated Pad.

Analyzing the experimental datum by regression, it draws the different influences of the modification of the weights of two kinds of control points on length of NURBS curve.

In this paper the distortion of image collimating system is analyzed, and then an on-line self-calibration method with double-frequency laser length measuring result as length datum is presented.