Photochromic glass with sharp cutoff

A photochromic glass comprising:

• a base glass, said base glass including 19 wt %-39 wt % B2O3, 0.5 wt %-15 wt % Al2O3, 46 wt %-65 wt % SiO2, 3.5 wt %-12.5 wt % alkali metal oxide, and 0.005 wt %-0.40 wt % SnO2;
• and
• 0.64 wt %-1.12 wt % copper;
• and
• 0.1 wt %-0.7 wt % halide;
• and
• a photochromic agent, said photochromic agent including a nanocrystalline cuprous halide phase within said base glass, said nanocrystalline cuprous halide phase including a copper component and a halide component, said copper component including at least a portion of said copper, said at least portion of said copper including Cu+ and Cu2+, said halide component including at least a portion of said halide;
• and
• 0.005 wt %-0.05 wt % Ag;
• and
• 0.05 wt %-0.50 wt % WO3.

A photochromic glass comprising:

• a base glass, said base glass including 19 wt %-39 wt % B2O3, 0.5 wt %-15 wt % Al2O3, 46 wt %-65 wt % SiO2, 3.5 wt %-12.5 wt % alkali metal oxide, and 0.005 wt %-0.40 wt % SnO2;
• and
• 0.64 wt %-1.12 wt % copper;
• and
• 0.1 wt %-0.7 wt % halide;
• and
• a photochromic agent, said photochromic agent including a nanocrystalline cuprous halide phase within said base glass, said nanocrystalline cuprous halide phase including a copper component and a halide component, said copper component including at least a portion of said copper, said at least portion of said copper including Cu+ and Cu2+, said halide component including at least a portion of said halide;
• and
• 0.005 wt %-0.05 wt % Ag;
• and
• 0.05 wt %-0.50 wt % MoO3.