The TeraSpike Defender is an optional housing protecting the sensitive tip of the probe against accidential mechanical impact. The exposure of the tip can be manually adjusted from -1mm to +1mm. In the negative exposure range a direct contact of the probe-tip to a flat surface is prevented by the TeraSpike Defender housing. Optical excitation as well as visual monitoring of the tip region is not impaired by the protective structure thanks to vertically placed openings. The TeraSpike Defender can be applied to any existing or new TeraSpike probe.