System for Evaluating UV Radiation in Ophthalmic Lenses

Abstract

The aim of this work is the development of a prototype for measuring the ocular protection of the UVA and UVB radiations offered by ophthalmic lenses. The prototype is an optoelectronic device, composed by ultraviolet radiation sources and detectors, having electronic components for the digital processing and results visualization. The UV source is a Sankyo Denki BLB 6W light. A PIN type silicon photodiode was selected to detect the transmitted radiation through the lenses. In order to display the percentage of transmitted radiation by the lenses in a graphic display, the analog/digital electronic circuit has been projected in accordance with the sensor electrical signal features. The prototype projects the ultraviolet beams within the range of 280nm-410nm through the tested lenses and the transmitted light is observed in a amplified photodiode sensor. Tests on several lenses and polarizers were performed and the results have been compared to measurements on commercial spectrophotometer.

The precision of the prototype is 0,3%, which is the precision required for these kind of measurements and the correlation factor between the system and the spectrophotometer is 0.95.