Characterising tissue stiffness and fiber alignment of Anterior Cruciate Ligament (ACL) with Atomic Force Microscopy Infrared Spectroscopy (AFM-IR) and confocal endoscopy = Karakterisasi kekakuan jaringan dan penjajaran serat ligamen lutut anterior menggunakan spektroskopi infrared berbasis Atomic Force Microscope (AFM-IR) dan endoskopi konfokal