Patent ID: 7773302

Claim:
An optical device, comprising: a substrate having a surface; and a plurality of layers provided on the surface of the substrate, the plurality of layers including alternating first and second layers, the first layers having a first refractive index, n L , and the second layers having a second refractive index, n H , greater than the first refractive index, wherein the plurality of layers has a spectral characteristic, the spectral characteristic having a passband, which is defined by a first passband wavelength λ 1passband and a second passband wavelength λ 2passband , the spectral characteristic having a center wavelength between λ 1passband and λ 2passband and having an average transmissivity at least equal to 80% over the passband, the spectral characteristic having an average optical density greater than 4 over at least one of first and second blocking bands of wavelengths, wherein the first blocking band of wavelengths extends from a first blocking wavelength, λ 1block , having an associated optical density equal to 4 to a second blocking wavelength, λ 2block , the second blocking wavelength satisfying: λ 2block <0.9*((1− x )/(1+ x ))*λ 1block , wherein the second blocking band of wavelengths extends from a third blocking wavelength, λ 3block , having an associated optical density equal to 4 to a fourth blocking wavelength, λ 4block , the fourth blocking wavelength satisfying: λ 4block >1.1*((1+ x )/(1− x ))*λ 3block , where x = 2 π ⁢ arc ⁢ ⁢ sin ⁡ ( n H - n L n H + n L ) , wherein a first edge band of wavelengths is associated with a first edge portion of the spectral characteristic adjacent the passband, the first edge band of wavelengths extending from λ 1passband to λ 1block , such that, at a first transmission wavelength, λ 1-50% , within the first edge band of wavelengths, the coating has a transmissivity of 50%, λ 1passband , λ 1block , and λ 1-50% , satisfy: (λ 1passband −λ 1block )/λ 1-50% <2%, and wherein a second edge band of wavelengths is associated with a second edge portion of the spectral characteristic adjacent the passband, the second edge band of wavelengths extending from λ 2passband to λ 3block , such that, at a second transmission wavelength, λ 2-50% , within the second edge band of wavelengths, the plurality of layers has a transmissivity of 50%, λ 2passband , λ 3block , and λ 2-50% , satisfy: (λ 3block −λ 2passband )/λ 2-50% <2%, and a minimum spectral distance between λ 1block and λ 3block is greater than 2% of the center wavelength.