| 摘要 |
<p>An optical element is disclosed comprising an upper portion (9) and a lower portion (8) defined in opposite parts with respect to a median line (x-x) passing through the geometric center (C1, C2) of the optical element, wherein the factor of luminous transmittance is between 30% and 80% in the lower portion (8) and between 3% and 40% in the upper portion (9). Advantageously, furthermore, the curve of spectral transmittance as a function of the wavelength in the lower portion (8) and at a distance of at least 10 mm from the median line (x-x) is such as to show: a minimum in a wavelength range of from 495 to 510 nm, ii) an increase in spectral transmittance at wavelengths lower than 495 nm and higher than 510 nm, iii) a maximum at a wavelength lower than 440 nm, iv) a reduction in the spectral transmittance as the wavelength decreases starting from said maximum. <IMAGE></p> |
