Overview of Phase-contrast microscope

The attached video contains a precise overview of the phase-contrast microscope. It is a type of light microscopy and converts phase shifts in the light passing through a transparent specimen to change brightness in the image TIMELINE: 0:00 Introduction 0:10 why phase-contrast microscope was invented? 0:23 Phase shift 0:52 Definition of phase-contrast microscopy 1:04 How phase microscope works 2:25 Difference between histological slide made from brightfield microscope and phase-contrast microscope