A turbine engine includes a target structure, for example, a rotating turbine blade. A probe is arranged near the target structure for communicating a detection frequency relative to the target structure for gathering information such as tip clearance. A housing is arranged adjacent to the target structure. In one example, the housing is a blade outer air seal. The housing includes a structural material that supports a window material. The window material is arranged between the probe and the target structure. The window material is transparent to the detection frequency permitting the detection frequency to pass through the window to the target structure for measurement of its position relative to the housing. The window material prevents probe contamination and provides a seal between the cooling path and turbine gas flow path.