WHAT IS MAGNIFICATION?
Magnification is the increase in the apparent size of an object or surface feature. In microscopy and optical metrology, it allows small details to be observed and measured more easily.
However, magnification should not be confused with resolution. Higher magnification makes the image appear larger, but it does not automatically mean the system can resolve finer details or provide more accurate measurements.
KEY ASPECTS OF MAGNIFICATION IN OPTICAL METROLOGY
From a surface metrology perspective, magnification is closely related to:
Field of view (FOV): as magnification increases, the measured area usually becomes smaller.
Lateral sampling: the physical size represented by each pixel on the sample surface.
Numerical aperture (NA): a key factor influencing lateral resolution and the ability to capture fine details.
Optical resolution: the minimum distance between two features that can be distinguished.
Measurement technique: different optical technologies, such as confocal, interferometry, or focus variation, may perform differently at the same magnification.
In 3D optical metrology, increasing magnification does not automatically lead to higher resolution, better accuracy, or more reliable measurements. Two systems with the same magnification can deliver different results depending on numerical aperture, detector characteristics, optical design, system noise, calibration, and the measurement technique used.
Magnification should therefore be selected to balance measurement area, lateral resolution, vertical performance, sample geometry, and measurement reliability.
