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.
Spatial frequency response of color image sensors: Bayer color filters and Foveon X3
We compared the Spatial Frequency Response (SFR) of image sensors that use the Bayer color filter pattern and Foveon X3 technology for color image capture. Sensors for both consumer and professional cameras were tested. The results show that the SFR for Foveon X3 sensors is up to 2.4x better. In addition to the standard SFR method, we also applied the SFR method using a red/blue edge. In this case, the X3 SFR was 3-5x higher than that for Bayer filter pattern devices.
Effect of numerical aperture on interference fringe spacing.
The effect of numerical aperture on the fringe spacing in interferometry is analyzed by the use of wave optics. The results are compared with published experimental results, and the influence of apodization of the wave front is discussed. The effects of central obscuration and surface tilt are also considered.