A semi-submersible microscope objective includes a microscope objective having a protective barrel with an optical inlet and optical outlet, and a protective element affixed to the microscope objective, sealing the optical exit but not the optical inlet. A transparent portion of the protective element is aligned with the optical exit. The protective element is separable from the microscope objective without damaging the microscope objective. Use of the semi-submersible microscope objective in a multiphoton imaging method is also disclosed.