Digital Processing and Evaluation of Fringe Patterns in Optical Metrology and Non-Destructive Testing

Rapid optical inspection of micro deep drawing parts by means of digital holography

“…This has the effect of low-pass filtering and therefore reduces the probability for black and changes the statistics for small intensities as seen from the measured density distribution in Fig. 5 [12]. The results show that the speckle field is fully developed; hence we conclude that digital holographic contouring is applicable to typical micro deep drawing parts such as the presented bowl-like structure.…”

“…Probability density function of the detected speckle field[12] The real amplitude of one reconstruction E O,1 (j) (x, y) for example and the phase difference between the two phase distributions examplarily b Duð1Þ O ðx; yÞ in the top and c Du ð4Þ O ðx; yÞ in the lower observation plane. The white box in a marks the corresponding cutting areas in b and c, which are sampled by 690 9 540 pixels.…”

Full-field measurement of the phase retardation for birefringent elements by using common path heterodyne interferometry

“…(7). If c is not within the range (Àp, p), it should be modified by using the similar operation in the phase unwrapping process [18]. That is, À2p and 2p are added to c, respectively; only one result is within the range (Àp, p).…”

Study of the performance of 84 phase-shifting algorithms for interferometry

“…These small errors were detected in the case of • 4-α-Juptner et al [15] psas with α = 2π 3 , π 2 , π 3 , π 6 but with α = π 4 the method does work perfectly. And, though Osten [18] suggested that the 4-α-Juptner et al [15] is an improved version of 4-α-Carré [7], we found the derived algorithms to perform slightly worse and prone to errors (originating in the denominator calculation of the phase-shift α, cf. (30)).…”

“…According to Osten [18] an improved version of the 4-α-Carré [7] algorithm was made by Juptner et al [15], and is defined by:…”