The LISA Technology Package reference laser unit (RLU) is a 35 mW Nd:YAG non-planar ring oscillator of the same design commonly used in metrology labs around the world and in space applications. This laser design is ideal for space applications due to its small size, high electrical to optical efficiency and inherent low noise operation.
The laser beam output of the RLU is through the green connector (in the foreground, on the left). The output passes along fibre optical cable to the laser modulator unit (LMU).