Optical design and fabrication of zinc selenide microlens array with extended depth of focus for biomedical imaging

Optical coherence tomography is a well-known technique for the optical imaging biological tissues. However, depth scanning range of high-resolution restricted by its focus. In this study, Zinc Selenide (ZnSe) Microlens Array (MLA) employed to overcome depth-of-focus limitation tomography. The ZnSe material with low Abbe number and high chromatic dispersion extends focus transverse resolution. MLA focused incident light (from visible near-infrared (NIR) region) on multiple focal planes uniform distribution over tissue. designed using Zemax OpticStudio software fabricated via single-point diamond-turning based Slow Tool Servo (STS) configuration. STS machining has unique advantage offering larger degrees freedom no additional baggage, thereby reducing setup time. experimental results show effectiveness process in fabricating desired accuracies. characterization Coherence Correlation Interferometry (CCI) depicts lenslets structural positional distortion, total error 32 nm within tolerance limit.