Abstract: The application discloses an apparatus for measuring interfacial properties of a fiber-matrix composite material, such as a ceramic-matrix, metal-matrix or continuous fiber metal-matrix composite; or a support material, such as a fiber-optic fiber support medium. The apparatus includes a linear motion feedthrough having an indentor for pushing a fiber end, a load cell for sensing debonding and frictional sliding loads, and a scanning electron microscope (SEM) for magnifying the material in order to align the indentor with the fiber end. The feedthrough may push the fiber at a predetermined velocity with up to about a 20 pound load force. The SEM may include a vacuum chamber for housing the material, the indentor, the load cell, and a hot stage module. The hot stage module may increase the temperature of the material to about 1500.degree. C.