A THERMODIFFUSION DYEING METHOD AND AN OPTICAL ELEMENT PREPARED WITH THE METHOD

摘要

The present invention deals with a thermodiffusion dyeing method for preparing a transparent substrate having a spectral transmittivity which fits to a predetermined target spectrum and an optical element prepared with the method. The thermodiffusion dyeing method is fulfilled with dyestuffs, one at a time, chosen in advance based on special features thereof in a ground dyeing. During the dyeing, the current transmission spectrum of the substrate under colouring is compared to the predetermined target spectrum. In case of a deviation, depending on the nature of the deviation, the substrate is either placed back into the heated dye solution for increasing its dyestuff content or placed into a heated clean solvent for decreasing its dyestuff content. Then the current transmission spectrum of the substrate and the target spectrum are compared again. This iterative process is continued in gradually refining steps until the current deviation becomes smaller than a predetermined threshold.