Phase error correction by π-shift odd-step fringe projection and speckle filtering in phase measuring profilometry

摘要

Abstract. Phase measuring profilometry based on structured illumina-ntion with a digital projector has great flexibility. However, the phase errornintroduced by the gamma nonlinearity of the projector and the presencenof speckle noise inevitably decreases the accuracy and resolution of thenmeasurement. This paper presents a new phase error correction algo-nrithm by which the odd-step fringe projection is done twice with an initialnphase shift of u0001 between, and the two captured deformed fringe imagesnare then digitally subtracted. The speckle noise is further suppressed bynapplying a sine-cosine median filter. Both theoretical analysis and experi-nmental results showed that this algorithm is effective and fast. © 2010nSociety of Photo-Optical Instrumentation Engineers. u0001DOI: 10.1117/1.3407430