|
Fiber-optic microendoscopy imaging systems are actively being researched. They are interesting as they can be designed with a single fiber in conjunction with gradient refractive index (GRIN) micro-lenses. However, these systems face a significant limitation in the form of optical aberrations caused by beam scanning, resulting in reduced resolution at the edges of the imaging field. The current solutions involve bulky refractive optics, combining micro-optics with an aspherical lens that present challenges in fabrication and alignment. To overcome these limitations, we propose the design of a compact metasurface correction element (diameter = 1 mm) that can be seamlessly integrated into the existing optical system alongside the 1 mm diameter GRIN lens. Accurately modeling such a complex system involving nanoscale metasurface and macroscale optics is challenging. We present the interconnection of ray tracing and electromagnetic simulations to simultaneously achieve the desired optical system performance and the required phase profile. In our imaging probe design, the target phase profile of the correction element is optimized using Zemax Optic Studio for multiple beam scan angles to achieve a minimal and uniform spot of 1 μm across the imaging field, which spans approximately 100 μm. The target phase mask obtained from ray tracing simulation and the phase-look-up table obtained from electromagnetic simulation of the unit cell are used to create the metasurface. The simulation of the metasurface of 1mm diameter is performed in Lumerical and the solved near field is propagated in Zemax to assess the imaging system through physical optics propagation and diffraction analysis.
|
