lensometry
Lensometry is the practice of determining the optical properties and power of lenses, especially ophthalmic spectacles, by means of specialized instruments. It is used to verify prescriptions, check quality, and assist in dispensing eyewear, as well as in optical laboratories and manufacturing.
Most common instrument is the lensometer (also called a focimeter). The lens is mounted in a holder,
Measurements rely on the thin-lens approximation and proper alignment; accuracy depends on instrument calibration and lens
In research and industry, focimeters or lensometers are used to characterize lenses, test optical materials, and