In this work, we review the viability and precision of the photon-momentum-based optical power measurement method that employs an amplification effect caused by a multi-reflected laser beam trapped in an optical cavity. Measuring the total momentum transfer of the absorbed and re-emitted photons from a highly reflective surface (reflection of the laser beam from an optical mirror) as a force provides the possibility of measuring the optical power with direct traceability to SI units. Trial measurements were performed at two different metrology laboratories: the laboratory for mass/force at the Technical University of Ilmenau, and the clean room laser radiometry laboratory at PTB, with a portable force measurement setup consisting of two electromagnetic force compensation balances. We compared the results of the optical power measurements performed with the force measurement setup, via the photon-momentum-based method, with those performed using a calibrated reference standard detector traceable to PTB’s primary standard for optical power, the cryogenic radiometer. The comparison was carried out for an optical power range between 1W and 10W at a wavelength of 532nm, which corresponds to a force of approximately 2000 nN at the upper limit, yielding approximately 2.3% relative standard uncertainty in the case of 33 reflections. Thus, conflating the high-precision force metrology technique at μN to nN levels with the optical setup required to achieve specular multi-reflection configuration of the laser beam, where a macroscopic optical cavity with ultra-high reflective mirrors (>99.995%) can adjustably be suspended from the force sensors, depending on required geometry of reflections, we show that the uncertainty of the optical power measurements upon further increase of the nominally applied optical power, the number of laser beam reflections, or the reflectivity coefficient of the mirrors can be markedly reduced.

在这项工作中，我们回顾了基于光子动量的光功率测量方法的可行性和精度，该方法采用了由捕获在光腔中的多反射激光束引起的放大效应。通过力测量来自高反射表面的吸收和再发射光子的总动量传递（来自光学镜的激光束的反射），可以测量具有直接溯源至SI单位的光功率。试验测量是在两个不同的计量实验室进行的：伊尔默瑙工业大学的质量/力实验室和PTB的洁净室激光辐射实验室，其便携式力测量装置包括两个电磁力补偿天平。我们将通过基于光子动量的方法用力测量设置进行的光功率测量结果与使用可追溯至PTB低温功率的主要标准即低温辐射计的校准参考标准检测器进行了比较。比较是在波长为532nm的1W到10W之间的光功率范围内进行的，这对应于上限处大约2000 nN的力，在33次反射的情况下，产生大约2.3％的相对标准不确定性。因此，将μN到nN级别的高精度力计量技术与实现激光束的镜面多反射配置所需的光学设置相结合，其中宏观光学腔具有超高反射镜（> 99）。