Characterization and performance improvement of a pupillometer prototype for flicker annoyance measurement.

LED-based devices are becoming more widespread day-by-day with the inner expectation that solid-state lighting will become a sort of standard de facto for indoor illumination, considering the technology promise of dramatic lighting energy reductions for the future to come. The claimed scenario that should arise from the adoption of LEDs in our daily lives is a 46% reduction, in terms of electricity, by 2030, as explained in the IEEE 1789 standard, with consequent societal benefits, in the form of reduced greenhouse gas emissions, and large savings for building owners and operators. However, the introduction of a new technology requires an adequate investigation of its associated health risks; in the case of LEDs, its introduction in our daily lives may have consequences that are still under study. Since these light sources have demonstrated to be extremely more sensible to peak voltage variations than traditional incandescent bulbs, the human eye flicker annoyance becomes a first-order problem that demands further discussion. For this purpose, different tests have been performed on volunteers in order to estimate human pupillary reflex induced by RGB flickering stimuli: the obtained results are presented and discussed in this thesis, along with different improvements and characterization measurements performed on the device that has permitted these experimental sessions. The prototype instrument that has been used is a highly versatile binocular pupillometer, capable of stimulating different human retinal areas with heterogeneous stimuli, due to the use and control of RGB LEDs with different parameters, such as frequency, peak intensity and duty cycle. Moreover, the device offers the possibility of performing a real-time monitoring of the human pupil, thus permitting direct access to information that could contribute to the understanding of the issue of flicker annoyance, identifying, at the same time, a measurable quantity which could describe it: the pupillary area.