Optical measurement plays an important role in non-contact strategies for 3D visualization and quantification of surface topography. The dominant techniques today involve imaging microscopy combined with confocal, focus-variation, quantitative phase imaging, digital holographic or interferometric principles to achieve sensitivity to height variations in the object surface. In this tutorial, we will review the fundamentals of these advanced techniques, including principles, implementation and best practice examples of applications and data interpretation. We will then move on to interference microscopy as an illustrative example of the current state of the art. Hot topics include performance enhancements, new objective designs for wide-field imaging, vibration robustness, accommodation of highly sloped surfaces, correlation to contact methods, metrology for additive manufacturing, and transparent surface films characterization. We will also consider the impact and importance of calibration, surface texture parameters, and standardization. Finally, a gallery of applications illustrates the current state of the art as well as the future potential for optical methods of surface structure analysis.
- describe the principles of confocal, focus-variation, digital holographic and interferometric microscopy for surface topography measurement
- identify, name and describe the optical, mechanical and electrical components of generic instrument configurations, including the types of objectives, types of light sources, scanners, filters and cameras
- summarize the most common data analysis methods, as well as the signal modeling techniques that are increasingly common in advanced processing
- explain the meaning and importance of relevant performance specifications, as well as potential sources of uncertainty and error
- explain the meaning of calibration, verification and adjustment
- provide and define the most common ISO surface texture parameters