Project Title:

AlyGa1-yN/InxGa1-xN Short-pass Optical Filters for Electronic Imaging Systems

94-1	12.09	6000		

AlyGa1-yN/InxGa1-xN Short-pass Optical Filters for Electronic 
Imaging Systems  

Abstract:

Spire Corporation proposes to develop thin film optical filters 
for electronic imaging systems that will pass light with 
wavelengths shorter than a specific, controllable cut-off while 
reflecting longer wavelengths. These "short-pass" interference 
filters will be fabricated from highly transparent nitrides of 
aluminum, gallium, and indium. Direct-bandgap, thin-film nitrides 
feature very sharp cut-off wavelengths and opacities 
beyond cutoff that greatly exceed the specifications of simple glass 
filters. A newly established plasma-assisted metalorganic chemical vapor 
deposition system allows us to deposit multiple layers of these nitride 
alloys at relatively low temperature (~350@C). The nitrides are physically 
hard, chemically inert, and can be applied to most substrate materials, 
including glass and silicon; thus they could be applied directly to charge-
coupled devices in electronic cameras. Development of the AlyGa1-yN/ 
InxGa1-x~N filters can improve efflciency of electronic color photography 
for a broad range of applications, from spectral imaging from aircraft and 
spacecraft to consumer photographic products. 

In addition to applications in conventional and electronic photography, 
optically efficient, stable, mechanically robust thin film filters could be 
applied to television projection systems and transparent packaging 
materials such as glass and plastic. 

electronic imaging, short-pass optical filters, interference filters, thin 
films, nitrides, plasma-assisted deposition 

Spire Corporation
One Patriots Park
Bedford, MA 01730-2396