A simple method to unwrap the geometrically discontinuous phase map and its application in the measurement of IC package

Research on the techniques to unwrap the geometrically discontinuous phase map is an active area during the past decade, various algorithm are developed. Basically, these algorithms need a prior knowledge about the spatial extension of the discontinuity area in the sample for correct phase unwrapping, manual mask is often involved and negate the sense of automatic processing to fringe patterns. More ever, current phase unwrapping algorithms are either computationally complex or highly time consuming. In this paper, a refined method is proposed to deal with the geometrical discontinuity problem in an improved automation sense: suppression of background noise and recognition of discontinuity area in the phase map can be finished in the same time, and discontinuous phase map can be unwrapped in a simple way to avoid the effect of discontinuity area. An example of electronic package with complex shape and structure is used to verify the efficiency of this method. (C) 2002 Elsevier Science Ltd. All rights reserved.