Improved Fractographic Strength Estimates Based on Surface Profilometry

Self-referenced Surface Profilometry

INTRODUCTION In optical surface metrology the reference surface is usually self-calibrated against the part under test because the errors in the reference are of the same order as those in the part under test. The self-calibration, or “absolute test”, is typically done by making three interferometric measurements, an initial measurement and then two more with the part under test shifted lateral...

Heterodyne moiré surface profilometry.

In this study, a novel moiré fringe analysis technique is proposed for measuring the surface profile of an object. After applying a relative displacement between two gratings at a constant velocity, every pixel of CMOS camera can capture a heterodyne moiré signal. The precise phase distribution of the moiré fringes can be extracted using a one-dimensional fast Fourier transform (FFT) analysis o...

Improved geometrical model of fringe projection profilometry.

The accuracy performance of fringe projection profilometry (FPP) depends on accurate phase-to-height (PTH) mapping and system calibration. The existing PTH mapping is derived based on the condition that the plane formed by axes of camera and projector is perpendicular to the reference plane, and measurement error occurs when the condition is not met. In this paper, a new geometric model for FPP...

O-ring Surface Inspection With 3D Profilometry

Longitudinal spatial coherence applied for surface profilometry.

A method of optical coherence profilometry, believed to be new, is demonstrated. This method is based on the spatial, rather than the temporal, coherence phenomenon. Therefore the proposed interferometric system is illuminated by a quasi-monochromatic spatial incoherent source instead of a broadband light source. The surface profile is measured by means of shifting the spatial degree of coheren...