Apparatus and methods for anchoring and orienting equipment in a well provide enhanced economy, convenience and utility. The probe for the scanning tunneling microscope is formed of an Ag2S crystal having both ion conductivity and electron conductivity. A test surface is provided on the aperture screen, so that the test surface receives a part of the beam that is not passed along the remainder of the beam path. The reinforcement casing is made of a brittle material and has a predetermined breaking point at a longitudinal position between the connecting elements.