| 摘要 |
<p>The disclosed diffractive subtractive filter provides a high contrast between black and white together with a substantially neutral black. Neutral black is achieved when two superimposed, crossed, sine-wave gratings embossed in plastic have different depths which are selected to provide a zero-diffraction-order-light transmittance wavelength selectivity characteristic for any one of the phase gratings which exhibits a minimum zerodiffraction-order-light transmittance at desired different wavelengths in the visible spectrum.</p> |
