The C01 is the standard sensor head type for the PICOSCALE Interferometer. Due to its collimated output beam, the compact form factor and the various customization options, it is appropriate for most common applications. Each sensor head (see figure 1) is based on two main components: the lens system, collimating the fiber output beam and the beam splitter, which splits the beam into a reference and probe beam. The reference beam is reflected off an internal reference mirror, coated to one side of the beam splitter cube. The probe beam exits the head and is reflected off the target surface in order to track its relative displacement. The front surface of the beam splitter marks the absolute zero position of every PICOSCALE measurement as here the probe and reference beam are of equal length.