Metrology & Interferometry
High-precision metrology (i.e., laser distance measurement) is a challenging application for semiconductor laser diodes due to the extreme wavelength stability requirements. Often these applications have utilized gas-source lasers the precisely emit on an atomic transition line.
IPS single-mode single-frequency lasers have been utilized for these applications, but further require high precision temperature control to minimize frequency variation of the source and frequency calibration routines to account for these small frequency variations.
Often further temperature stability techniques such as enclosing the laser inside a temperature-controlled chamber is necessary to obtain the required stability; see for example US Patent 9,059,555.