High Refractive Index GRIN Lens for IR Optics

Infrared gradient refractive index (GRIN) material lenses have attracted much attention due to their continuously varying refractive index as a function of spatial coordinates in the medium. Herein, a glass accumulation thermal diffusion method was used to fabricate a high refractive index GRIN lens. Six Ge17.2As17.2SexTe(65-x) (x = 10.5-16) glasses with good thermal stability and high refractive index (n(@10) mu(m) > 3.1) were selected for thermal diffusion. The refractive index span (increment n) of 0.12 was achieved in this GRIN lens. After thermal diffusion, the lens still had good transmittance (45%) in the range of 8-12 mu m. Thermal imaging confirmed that this lens can be molded into the designed shape. The refractive index profile was indirectly characterized by the structure and composition changes. The structure and composition variation became linear with the increase in temperature from 260 degrees C to 270 degrees C for 12 h, indicating that the refractive index changed linearly along the axis. The GRIN lens with a high refractive index could find applications in infrared optical systems and infrared lenses for thermal imaging.

Automated summary

This study fabricated a high refractive index gradient refractive index (GRIN) lens using a glass accumulation thermal diffusion method. A refractive index profile with a span of 0.12 was achieved, and the lens exhibited good transmittance in the range of 8-12 μm. The structure and composition changes indicated a linear variation of refractive index along the axis. This high refractive index GRIN lens has potential applications in infrared optical systems and lenses for thermal imaging.