IR GRIN optics: design and fabrication

Diffusion-based gradient index optics for infrared imaging

“…To date, design exercises with these materials have suggested that the primary virtue of IR-GRIN elements in imager design is the ability to partially correct for chromatic aberration. 39 To demonstrate, the design and performance of 25-mm focal length, f∕1.0 homogeneous, and GRIN singlet lenses for LWIR (8 to 12 μm) are considered here. An IR-GRIN lens with an axial GRIN profile and aspheric surfaces is shown in Fig.…”

Advances in infrared GRIN: a review of novel materials towards components and devices

“…Arbitrary 3-D profiles may not be possible due to intrinsic shape of diffusion profiles; stacking (for axial GRIN) is much easier than rod-in-tube for radial GRIN designs; post-diffusion molding (slumping) could be used to further change the bulk optic's shape and performance. [35][36][37][38] B: Thermally Poleddiffractive or refractive optics Mobile ion-containing bulk glass is subjected to a thermal poling process (applied electric field and temperatures near Tg) to create a composition gradient between electrodes; electrode patterning imparts gradient to composition profile with arbitrary shape (grating, micro-lens, etc) without transmission degradation. Index changes (∆n) to +0.05 in ChG shown with long-lived (>1.5 year) stability.…”

Infrared GRIN GeS2–Sb2S3–CsCl chalcogenide glass–ceramics

“…In particular, ChGs are of the unique compositional and microstructural flexibility to produce GRIN profiles in them. Multiple ways for creating GRIN in ChGs had been developed, including precision glass molding, 9 laser‐induced vitrification, 10 ionic exchange, 11 and spatially gradient glass crystallization (SGGC) 12 . The former three methods required expensive experimental equipment or complex sample processing, whereas the SGGC could create the GRIN profile simply through thermal treatment under spatially gradient temperature field.…”