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Optical Metrology

Definition: the science and technology of performing measurements with light

More specific term: frequency metrology

German: optische Metrologie

Category: optical metrology


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Optical metrology is the science and technology concerning measurements with light. Such measurements can either target properties of light and light sources or properties of objects such as dimensions, distances and temperatures. There is no strict boundary between those fields because often one uses measured properties of light not just to characterize a light source, but for other purposes – for example, optical frequency metrology is used for ultraprecise optical clocks.

Some examples of optical metrology are:

Optical metrology uses a wide range of measurement instruments. For calibrating those, special calibration light sources are required, providing light with well-defined properties like optical power, luminance or wavelength, for example. For example, there are certain spectral lamps providing quasi-monochromatic light with a precisely defined wavelength.

Typical Qualities of Optical Metrology

In many cases, optical metrology can be extremely precise and is ultimately limited by laser noise or quantum noise in detection.

Optical measurements are usually quite fast and suitable e.g. for in-process metrology, i.e., for monitoring industrial production processes.

Generally, optical measurements are non-destructive. Even very sensitive parts can be checked without touching them (non-contact methods), i.e., without a risk of damage.

Special Challenges

Obviously, optical metrology becomes particularly challenging when extremely high precision is required. However, the magnitude of that challenge also depends on the circumstances. For example, particularly sophisticated metrology is required for characterizing very large optics. Some traditional techniques can they not be used or need to be specially adapted.


The RP Photonics Buyer's Guide contains 52 suppliers for optical metrology equipment. Among them:

See also: light, frequency metrology, optical clocks, interferometers, distance measurements with lasers, reflectometers, optical profilometers, laser noise, spectrometers, wavemeters, radiometry, photometry

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