Mid-infrared imaging with a solid immersion lens and broadband laser source

The application of hemispherical solid immersion lenses (SILs) is an approach to increasing the spatial resolution attainable with infrared (IR) microscopy. A hemispherical SIL forms an image for which the effective numerical aperture and magnification are increased by a factor of the SIL material index of refraction. A microscope designed for exploration of IR SIL imaging based on a hemispherical ZnSe SIL, an InSb focal plane array detector, and a broadband IR laser source is described. The imaging characteristics of this system are reported, including the spatial resolution improvement achieved in the imaging of organic test samples.