Office of Technology Transfer – University of Michigan

Angle-Insensitive Spectrum Filters

Technology #5810

Researchers at the University of Michigan have developed a set of spectrum filters that produce a filtered spectrum independent of, or insensitive to, varied incident angle. Angle insensitive spectrum filters are often used in display and imaging systems, but current nanostructure-based spectrum filters typically suffer from intolerance to incident angle variations. The proposed spectrum filters can be used in any flat panel display, either transmission or reflection type, and especially in high-input-power applications, e.g., in 3D projection displays

Design Details

The angle insensitive spectrum filters developed at the University of Michigan overcome the drawbacks of extant nanostructure-based spectrum filters. The proposed designs exploit the optical phase in metal-dielectric-metal type resonators, thereby making the resonance phase insensitive to the angle of incidence. The designs, which simplify color filter fabrication, are based on a dielectric (TiO2) sandwiched between silver (Ag) mirrors, a top functional layer of TiO2, all mounted on fused silica. Additionally, the filters can recycle reflected light for higher overall transmission efficiency


  • LCD and 3D projection displays
  • Colored e-books
  • Long lasting pigment-less and chemical-less colored prints
  • Anti-counterfeiting and cryptographic applications


  • Angle-insensitive spectrum filtering
  • Simplified color filter fabrication
  • High transmission efficiency