The diffusion of LED lamps on the market is becoming increasingly wide and it is expected that, in a few years, they become a sort of standard de facto for lighting of houses as well as offices. As a consequence, they can be considered for replacing the incandescent bulb in the international standard for flicker measurement given that, as it is well known, this last lamp is banned from the market and hence the measurement of flicker severity is no more related with the actual annoyance caused by the light fluctuation. In this connection, this paper will investigate the behavior of several same-power LED bulbs under non-sinusoidal voltage conditions to verify if it is possible to choose a specific LED source as a reference for flicker evaluation.

The big changes in indoor illumination caused by the introduction of LED-based devices may have effects on the health and well-being of the persons that are still under study. From the point of view of flicker, these changes further highlight the inadequacy of the current international standard. With the aim of providing a contribution to a matter that involves several scientific disciplines, new results on pupil responses induced by RGB flickering stimuli are presentedin this paper. Tests on volunteers have been performed to evaluate the inter- and intra-subject variability of pupil responses induced by the above stimuli.An instrument formerly developed (and described in previous paper) has been usedto investigate the pupil response. The results of this extensive measurement campaign are presented and discussed.

We present results from a combined experimental and numerical investigation of trap-assisted tunneling contributions to subthreshold forward current in InGaN/GaN light-emitting diodes. We show that the excess forward leakage current in single-quantum-well InGaN/GaN light-emitting diodes can be explained by non-local tunneling-into-traps processes and subsequent non-radiative recombination with free carriers.

The Standards EN 61000-4-15 which has been adopted by the IEEE as IEEE std 1453, gives functional and design specifications about the actual Flickermeter based on the analysis of the voltage supplying a specified light source. Such incandescent light source based instrument is obsolete nowadays, with the advent of new light sources, such as halogen, fluorescent, and especially solid state sources; a different and appropriate tools is mandatory to investigate the effects on the human eye of these sources. This paper describes an improved version of the instrument presented in our previous articles. Thanks to a microcontroller, the new system allows controlling all the characteristics of the flicker stimulus, i.e. amplitude, mean value, modulation, frequency and color. Moreover, the optical head has been revised in order to improve the alignment repeatability.

A simple measuring system for early detection of haemolysis during haemodialysis is proposed. The developed measuring system performs an optical absorption spectroscopy analysis of the dialysis fluid in order to estimate the free haemoglobin concentration in the blood returned to the patient-the potential cause of injury for the patient. The integration of the developed measuring system into hemodialyzers results simple and relatively inexpensive (overall system cost is about few hundred dollars). Preliminary results confirm the applicability of the proposed measuring system.

A portable pupillometer has been developed which is capable of performing accurate measurements of the pupil diameter during chromatic flicker stimulations. The handheld measuring system records the near-infrared image of the pupil at the rate of 25 fps and simultaneously stimulates the eye using a diffused flicker light generated by light emitting diodes (LEDs). Intensity, frequency and chromatic coordinates of the stimulus can be easily adjusted using a user-friendly graphical interface. Thanks to a chromatic monitoring of the stimulus close to the plane of the eye, photopically matched conditions can be easily achieved. The pupil diameter/area can be measured during flickering stimuli that are generated with frequency in a range of 0.1-20 Hz. The electronic unit, properly connected to the personal computer through a USB port, drives the optical unit, which can be easily held in a hand. The software interface controlling the system was developed in LabVIEW. This paper describes the instrument optical setup, front-end electronics and data processing. Moreover preliminary results obtained on a voluntary are reported.