Patent ID: 8508849
Filing Date: 2013-08-13
Classification: G02B

Abstract:
1. An optical filter, comprising: a substrate; a first plurality of hard-coating layers provided on the substrate and including alternating first and second layers, each first layer having a first refractive index with at least a real first refractive index and each second layer having a second refractive index with at least a real second refractive index, the real second refractive index being greater than the real first refractive index over a wavelength range; a second plurality of hard-coating layers provided on the substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of: a first instance of a third layer, a first instance of a first group layer, a fourth layer, a second instance of the first group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each first group layer selected from one of a first intermediate index layer and a first Herpin equivalent layer, each first group layer having a first group refractive index with at least a real first group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real first group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the wavelength range; and a third plurality of hard-coating layers provided on the substrate, the third plurality of hard-coating layers including at least one repeated sequence consisting of: a first instance of a fifth layer, a first instance of a second group layer, a sixth layer, a second instance of the second group layer, and a second instance of the fifth layer, each fifth layer having a fifth refractive index with at least a real fifth refractive index, each second group layer selected from one of a second intermediate index layer and a second Herpin equivalent layer, each second group layer having a second group refractive index with at least a real second group refractive index, and each sixth layer having a sixth refractive index with at least a real sixth refractive index, the real second group refractive index being greater than the real fifth refractive index and less than the real sixth refractive index over the wavelength range; wherein the optical filter has a transmission characteristic as a function of wavelength, the transmission characteristic having an average transmission greater than or equal to 80% over a first band of wavelengths, the transmission characteristic having a first blocking level over a second band of wavelengths, a second blocking level over a third band of wavelengths, and a third blocking level over a fourth band of wavelengths, each of the first, second, and third blocking levels having an average optical density (OD) greater than or equal to 6, the second, third, and fourth bands of wavelengths being associated with the first plurality of hard-coating layers, the second plurality of hard-coating layers, and the third plurality of hard-coating layers, respectively, and each of the first plurality of hard-coating layers, the second plurality of hard-coating layers, and the third plurality of hard-coating layers being associated, respectively, with a first transmission characteristic, a second transmission characteristic, and a third transmission characteristic, each of the first, second and third transmission characteristics having an average transmission greater than or equal to 80% over the first band of wavelengths.