Holtmann, F., Oevermann, M. & Denz, C. Appl. Phys. B (2009) 95: 633. doi:10.1007/s00340-009-3500-5
A nonlinear dynamic phase-contrast stereoscope has been developed for the measurement of all three velocity components of a microfluidic flow field. The stereoscope system captures simultaneously two images of different off-axis views of the same region of interest in a microflow, seeded with tracer particles. Two independent photorefractive two-beam coupling novelty filters, one in each stereoscope channel, are employed to enhance the contrast of tracer particle images. A subsequently applied particle tracking algorithm extracts the velocity information from the images, and in first experiments the axial velocity components could be determined with an error of less than 5%. Finally we report on the determination of the velocity field in a rectangular microchannel with a 170 μm high microstep with the dynamic phase-contrast stereoscope.