Transmittance Analisys System for Solar Lenses

• Grant number: 12/03565-6
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2012
• End date: February 28, 2014
• Field of knowledge: Engineering - Biomedical Engineering - Medical Engineering
• Principal Investigator: Liliane Ventura Schiabel
• Grantee: Marcio Makiyama Mello
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The Brazilian standard NBR15111/2004 (sunglasses protection, sun protection filters for general use and filters for direct observation of the sun), currently prevailing states that in the region of 280 - 380 nm the filter should block certain percentage of this radiation, for categories 0 - 4 of sunglass lenses. The categories refer to the degree of darkening of lenses and they are calculated as a function of the visible light transmission (380-780 nm).In 2010, while upgrading of the cited standard, where Prof. Liliane is part of the committee CB49 ABNT and petit committee for reviewing and drafting of the standard, it was noted that some parameters should be best suited so that they become in agreement with the type of solar radiation (UV index) that reaches Brazil, a country of continental dimensions. The NBR15111 is based on European standard EN1836/2005, and the Laboratory of Ophthalmic Instrumentation (LIO) is studying some items, more specifically related to UV protection, to protect our population properly against the radiation conditions that we have in our country. Among these items, FAPESP is supporting a research project to obtain the frequency range of UV light protection for ocular health in Brazil according to the UV index, where Professor Liliane is the coordinator. In this context, it was observed that there is no system, in our country, where the user can position its own glasses, without help from others, and get information about UV, category and traffic light protection over its glasses. Recently, it was developed by LIO a unit of self-service to the community, which measures the transmission of UVA through sunglasses, with no degree, as well as the category to which they belong. The student Marcio took part in the development of this equipment and was responsible for measuring the category of lenses (scientific initiation - FAPESP proc. In: 2009/14775-9). However, this first prototype has two fundamental flaws: 1. The spectrum used to determine the category is not fully covered, and the intersection between the categories as provided in the standard was not implemented; 2. The range of the UV protection was 315 - 380 nm when it should be 280 - 380 nm in accordance with the weighting function in NBR15111, which corresponds to the curve of the human eye response. In detail, the device must measure the transmission in the UV range between 280 - 400 nm (the current system measures up to 380nm), with accuracy provided by the standard; the category of the tested lenses; the transmission of the traffic light (check if the sunglasses are able to be used while driving); and the light transmittance, itens that the current system does not perform, or performs improperly. We aim in this project to develop a system with modules for UVA and UVB, Visible and Signal Light test for public use, here on the campus of USP in São Carlos according to NBR15111 that was revised by the committee in this year of 2012 and its waiting for ABNT approval, and solve the problems of the former project about the UV protection that must be extended to 280 - 400 nm; and also the problem with thresholds in category measurements. These imply some changes in systems electronics, where sensors must answer for this new range of wavelengths, and in software. All light transmittance testing will be compared with the measured spectra of the lens in the spectrophotometer CARY-5000, at the LIO. This system provides an improve in our studies relative to sunglasses, contributing more effectively to the population, with a self-service totem, which provides the non-trained person to measure its sunglasses, with a smart interface to give directions on performing these measurements, and having the means to understand the results presented. The system will be able to measure the sunglasses before and after being subjected to a stress test by irradiation, which is being implemented in the LIO. This research is sponsored by FAPESP (Proc. 2011/06079-2).

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

MELLO, Marcio Makiyama. Transmittance analysis system for solar lenses. 2014. Master's Dissertation - Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) São Carlos.