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Transmittance analysis system for solar lenses

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Marcio Makiyama Mello
Total Authors: 1
Document type: Master's Dissertation
Press: São Carlos.
Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
Defense date:
Examining board members:
Liliane Ventura; Lino Misoguti; Lígia de Oliveira Ruggiero
Advisor: Liliane Ventura

Transmittance measurements in sunglasses are a part of the standard tests proposed by NBR15111, however, it was observed that there is no accurate system for measuring transmittance different than using spectrophotometers and skilled practitioner to manage the equipment, apply the weighting functions and provide technical reports on the lens tested. Therefore, this study proposes methodologies using simple components and that can result a device that can provide information about sunglass filters automatically, according to NBR15111. Spectrophotometry was calculated in 45 lenses of sunglasses for general use, and their respective transmittance (visible, ultraviolet, traffic light), used as samples for testing the methodologies. The tests included lamps and LEDs as light sources for the visible region spectrum and fluorescent lamps for ultraviolet region, specific sensors for each spectral region, and electronic for control and signal acquisition. Statistical analysis tools were used, such as RMS error, goodness-of-fit coefficient (GFC) and the Bland - Altman analysis. Approximately 62% of the tested lenses failed in the test for signal light recognition and none has failed for UV protection. The RMS and GFC methods indicated combinations between source and sensor that calculated transmittance with the lowest standard deviations of the spectrometric measurements. The system for testing UV showed improvement compared to other previously equipment, with a standard deviation of 4.45 and the system for testing the visible region used the TCS sensor, in which the polynomial regression showed better results than artificial neural networks. A larger number of samples can improve the methods in order to obtain an optimal calibration that includes all sunglasses. LEDs seem to be a good alternative in terms of cost, size and low power consumption for portable transmittance meters. We developed a system with modules for testing UV, Visible and Traffic Light transmittance for public use on the USP São Carlos campus, providing awareness and extent of studies about the sunglasses, in order to contribute more effectively to the Brazilian population. (AU)