Development of geometric parameters metrology system for contact lens based on spectral-domain OCT

In this paper, a set of geometric parameters metrology system for contact lens based on SD-OCT (Spectral domain-optical coherence tomography) is developed and optimized, which can dealing with difficulties in measuring geometric parameters of contact lens, especially those with complex structures and surface shapes. Dispersion compensation, SNR(Signal-to-noise ratio) improvement and error compensation are introduced to improve the measurement accuracy. What’s more, the developed system is calibrated according to JJF 1148-2006. After calibration, the system meets the following indicators: test range of diameter: 8 mm-16 mm, indication error: ±50 μm; test range of center thickness: 0mm-1 mm, indication error: ±5 μm; test range of curvature radius: 6.5 mm-9.5 mm, indication error: ±20μm, repeatability of measurement: 10 μm. In addition, key parameters of a rigid contact lens with complex structure are measured, including diameter, vector height and center thickness, which can be recognized and measured automatically.