Fig. 1. Cs133 DBT experimental setup.

Fig. 2. Cs D1 absorption line and fitted residuals near the probe power of 110μW at a verification temperature point of 301.526 K.

Fig. 3. Error of measurement as a function of probe power.

Fig. 4. Results of sixty measurements with the probe power of 110μW at the reference temperature of 301.526 K. The blue straight line shows the relative error of the averaged results. The shade depicts the relative standard deviation of the measurements, and the red line shows the reference value.

Fig. 5. Verification of reproducibility by comparing the results of two independent measurements within the linear region.