There are relevant similarities and differences in the HACR and LOCR instrumentation and measurement protocols.
Additionally, LOCR is on a translation stage so the trap detector can move into the laser beam in the same optical plane, allowing both devices to be exposed to the same beam profile.
While LOCR uses ac bridge electronics located directly under the cryostat, HACR uses a dc measurement of the temperature.
HACR and LOCR measured the two trap detectors, labeled TSO2 and NIST 6 using the optical setups, protocols, and uncertainties described in their respective papers [1, 2].
Therefore, the LOCR can measure the absolute optical power relatively quickly.