The aim of this study was to examine the effect of exposure to different types of television displays at habitual bedtime on human melatonin and cortisol secretion. Thirteen male participants (mean age: 22.7 ± 0.85 years) were tested over three nights in one baseline and two experimental sessions. Participants were instructed to watch a movie on four different luminance-and wavelengthcontrolled television displays: normal luminance (450 candela [cd]/m 2 ) or high luminance (1200 cd/ m 2 ) and normal blue light or half blue light. Salivary melatonin and cortisol levels were measured at two time points before and after television viewing. There was no significant difference in cortisol secretion due to the different displays. Melatonin suppression was significantly lower following the exposure to the half-blue light display compared with the normal blue light display. These results suggest that the use of half-blue light displays during night time may prevent circadian rhythm dysfunction.

A local-dimming control is one of the advanced ways for backlighting an LCD. It balances less power consumption with higher contrast than other ordinary backlighting systems by independently controlling each luminance of backlights according to pictures. On the other hand, a new defect arises; that is, all the backlight units are not completely uniform and luminance of each backlight varies as an input signal changes. We define this defect as "Halo". There have not been presented any particular methods to evaluate "Halo" so far. In this paper, we propose a new method on how to evaluate Halo defect in local-dimming backlight systems with explaining the mechanism why Halo defect arises.

Second-harmonic generation (SHG) was investigated for 48 tetrazole compounds. Nine tetrazole compounds were found to generate second harmonic light upon irradiation with Nd:YAG laser light and to have an absorption edge of short wavelength below 350 nm.