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Primary Calibration

Special applications require unique solutions:
Primary calibration services by SPEKTRA

Primary calibration is used for calibrations with the smallest possible measurement uncertainty. This procedure is typically used to calibrate reference standards and reference transducers. These are later used as standards for secondary calibration.

In primary calibration, the measurand is traced back to a natural constant or to other physical measurands, up to the SI base units.

Unlike secondary calibration, in which a comparison is made with a reference standard of the same measurand, the measurand in primary calibration is traced back to another base unit. During primary calibration of accelerometers, a laser interferometer is used as a reference.  The measured dynamic vibration is compared to the wavelength of the laser light used. In primary calibration, the measuring instrument thus defines an absolute measurand, without the need for prior calibration by means of other instruments.


  • Calibration in a laboratory accredited by DAkkS* (for vibrations)
  • Lowest measurement uncertainty
  • Highest level of traceability

*the German national accreditation body

»As a primary calibration laboratory, SPEKTRA works with standards of the highest quality and the lowest measurement uncertainty.«

For vibration, SPEKTRA offers a calibration service also for primary systems.

Primary calibration: Vibration

Sinusoidal primary calibration according to ISO 16063 part 11: Primary vibration calibration by laser interferometry

The following items can  undergo primary calibration:

  • Vibration sensors
  • Vibration calibrators
  • Vibration measuring instruments and laser vibrometers

Vibration measuring instruments only  undergo primary calibration if they measure the vibration amplitude by interferometry (laser vibrometers) or if the associated vibration sensor allows an adaptation for a primary procedure that is compliant with the calibration.

Our experts calibrate primary systems for acoustics.

Primary calibration of acoustic measuring equipment

Primary reciprocity calibration (factory calibration certificate indicating ISO calibration)

  • B&K 4180 and GRAS 40AU-1 reference microphones

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What is a typical setup for primary calibration?

© SPEKTRA 2021

Why do I need a primary calibration?

A primary calibration (as defined in ISO16063-11) is the standardized means of obtaining the absolute minimum of measurement uncertainty. But to answer the question ‘why primary calibration?’ completely, the reasons for the calibration must first be examined.

Why is a primary calibration necessary?

A primary calibration normally requires a laser interferometer which enables an absolute calibration by comparing the dynamic vibration with the wavelength of the laser light. This high-precision method of vibration measurement comparison results in a very low level of measurement uncertainty.

For whom is a primary calibration necessary?

The high level of precision is required in national primary laboratories or elsewhere where accelerometer transfer standards (also known as reference standards) are manufactured.

The low level of inaccuracy of the reference sensor is decisive for the accuracy of the comparison calibration (secondary calibration). Transfer standards are often used in primary laboratories of the government, the defense industry and major industrial users.