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Dimensional measurements

Power and radius of reference lenses

Spherical, cylindrical and prismatic lenses in the range ± 0.05 dioptres to ± 25 dioptres

Measurement of spherical surfaces by interferometry

An important factor in achieving accurate production of spectacle lenses is the maintenance of consistent standards of lens power in the ophthalmic examination, lens manufacture and subsequent spectacle fitting. Consistent measurements of power may be assessed in all these stages by using focimeters and spherometers which have been calibrated with suitable reference lenses.

NPL offers a range of services in support of accurate ophthalmic measurements including the calibration of customer supplied reference lenses, the provision of boxed sets of calibrated ophthalmic reference lenses, and the calibration of focimeters.

Key features

  • Calibrations traceable to national standards
  • Calibration of the power of reference lenses in the range ± 1 dioptre to ± 25 dioptres. Measurement uncertainty ± 0.005 dioptres to ± 0.02 dioptres
  • Calibration of the power of weak lenses in the range ± 0.05 dioptres to ± 1 dioptre. Measurement uncertainty ± 0.002 dioptres
  • Power measurements of spherical, cylindrical and prismatic lenses
  • NPL certificate of calibration issued

Associated services

  • Supply of boxed sets of calibrated ophthalmic reference lenses
  • Calibration of focimeters on and off site
  • Calibration of the optical properties of a Gaugemaster
  • Power measurement of contact lenses
  • Assessment of ophthalmic equipment and measuring processes

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Contact our Customer Services team on +44 20 8943 7070