Phosphor-Converted LED for Iris Acquisition Based on Visible and Near-Infrared Phosphors

Capturing both structural and pigmented iris textures is essential for accurate identity authentication and medical testing, particularly for heavily pigmented irises. Traditional near-infrared (NIR) lighting captures only structural details, while multiwavelength LEDs capture both but hinder device miniaturization. We present a solution using a phosphor-converted LED (pc-LED) that emits both visible and NIR light, combining commercial CaAlSiN3:Eu2+ and Ca3LuAlGe3O12:Cr3+ phosphors. This compact lighting source improves the emission efficiency and thermal stability through Lu3+ substitution with Al3+, allowing for the capture of clear iris images that reveal both structural and pigmented textures. Our results highlight the potential of visible and NIR pc-LEDs to enhance iris biometrics for portable devices and reduce the cost of iris medical testing equipment.