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Shack-Hartmann wavefront sensor (SHWFS) is considered as an efficient and complementary tool in the field of optics metrology. It is widely used for evaluating and characterizing rigid glass and soft eye contact lenses. However, the presence of any type of aberrations will cause measurement errors decreasing the precision of the sensor. Therefore, in the current study an experimental configuration based on an active adaptive SHWFS was presented for optical testing of circular optical elements such as thin and soft eye contact lenses. As an adaptive element, deformable mirror (DM), was integrated to the SHWFS setup to dynamically compensate for the wavefront aberrations of the illumination laser beam to provide an ideal plane. The concept was firstly verified by measuring standard thin lenses then applied to measure soft eye contact lenses. For the quantitative evaluation, Zernike polynomials was used to accurately define the dominant modes of wavefront aberrations and thus to calculate the wavefront to be written on the DM. Based on the standard deviation (1σ) between the given and the measured focal lengths of the tested thin glass lenses, the measurements show an improvement of the measurement error from 15.18% difference of the uncompensated wavefront and 3.90% of the referencebased method to only 2.11% after aberration compensation of the illumination beam. While for the contact lenses, the measurement error was 22.93% for uncompensated aberrations, 51% for the reference-based method, and 1.75% after aberrations compensation. The results reveal that the aberrations of the illumination laser beam and the wet cell induced aberrations affect the accuracy of the measurements which can be drastically improved by compensating the existing aberrations utilizing the active adaptive SHWFS setup. In conclusion, adaptive-SHWFS can be considered as an in-production, accurate and complementary tool for testing of optical components.
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