Interferometric microscope with true color imaging
Optical 3D profilers based on Coherence Scanning Interferometry (CSI) provide high-resolution non-contact metrology for a broad range of applications. Capture of true color information together with 3D topography enables the detection of defects, blemishes or discolorations that are not as easily identified in topography data alone. Uses for true color 3D imaging include image segmentation, detection of dissimilar materials and edge enhancement. This paper discusses the pros and cons of color capture using standard color detectors and presents an alternative solution that does not rely on color filters at the camera, thus preserving the high lateral and vertical resolution of CSI instruments.
3D interferometric microscope: color visualization of engineered surfaces for industrial applications
3D microscopes based on white light interference (WLI) provide precise measurement for the topography of engineering surfaces. However, the display of an object in its true colors as observed under white illumination is often desired; this traditionally has presented a challenge for WLI-based microscopes. Such 3D color display is appealing to the eye and great for presentations, and also provides fast evaluation of certain characteristics like defects, delamination, or deposition of different materials. Determination of color as observed by interferometric objectives is not straightforward; we will present how color imaging capabilities similar to an ordinary microscope can be obtained in interference microscopes based on WLI and we will give measurement and imaging examples of a few industrial samples.
Real-time color holographic interferometry.
A new optical technique based on real-time color holographic interferometry has been developed for analyzing unsteady aerodynamic wakes in fluid mechanics or for measuring displacements and deformations in solid mechanics. The technique's feasibility is demonstrated here. It uses three coherent wavelengths produced simultaneously by a cw laser (mixed argon and krypton). Holograms are recorded on single-layer panchromatic silver halide (Slavich PFG 03C) plates. Results show the optical setup can be adjusted to obtain a uniform background color. The interference fringe pattern visualized is large and colored and exhibits a single central white fringe, which makes the zero order of the interferogram easy to identify. An application in a subsonic wind tunnel is presented, in which the unsteady wake past a cylinder is recorded at high rate.