Automated compensation of fringe pattern in digital holography and TV holography

摘要

Digital holography and TV holography is the most promising tool for industrial applications. For a successful industrialmeasuring system automated evaluation is necessary. To develop this kind of measuring system the fringe compensationprinciple can be used. Because both digital holography and TV-holography operate with images recorded with a digitalcamera, several computer based compensation methods can be applied. In our investigations automated compensationtechniques were investigated to develop industrial measuring systems.In digital holography the compensation method can be easier, using digital compensation, performing the compensationprocess in the computer using the recorded complex amplitude of the scattered light from the investigated object. In thiscase the compensation is based on the phase manipulation of the reconstructed waves.Digital compensation method was chosen for TV holography too. Previously developed fringe synthesizing method wasapplied in Tv holographic measurements. In this method a set of phase shifted fringe patterns of the investigated object isrecorded. Using the recorded fringe systems new contour fringe pattern can be generated.Based on these methods, the evaluation program in digital holography or in TV holography can set the sensitivity of themeasurement, can separate different deformation components (e.g. rotation, local deformation) after the measurementwas performed. Measuring the separated deformation components new alternative output of the measurement can begenerated: a list of the deformation components with its features.