Liquid-crystal light valve in combination with a cathode ray tube containing a far-red emitting phosphor

DETAILED DESCRIPTION In accordance with the invention, LiAlO.
sub.
2 and LiGaO.
sub.
2 doped with Fe are phosphors which exhibit faster decay and increased light output under cathode ray excitation, compared with commercially available far-red phosphors.
The decay time of this material has been determined by the inventors to be dependent upon activator concentrations.
A 50% improvement of the phosphor efficiency and reduced decay time of 19 msec is achieved when the iron concentration is increased to at least about 0.
015 mole.
Reducing the particle size to an average of about 4 .
mu.
m provides a desired high resolution.