US Patent 7495839 - Lens IR filter using oxide nanoparticles

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In order to reduce the sensitivity of imaging sensors to infrared radiation dielectric multilayer films are often integrated into the lens. This patent from Hon Hai Precision teaches an easier fabrication procedure to achieve equivalent results by using nanoparticles. Claim 1 reads:

1. A lens, comprising:

a base; and

a plurality of nano-particles distributed in the base,

the nano-particles being configured for filtering infrared rays from incoming light,

the nano-particles consisting one of upconversion fluorescence material and absorption material selected from the group consisting of silicon oxide and titanium oxide.