Lunar Laser Ranging with High-Power CW Lasers

We present a comprehensive analysis of high-power continuous-wave (CW) lunar laser ranging (LLR) systems designed to achieve sub-millimeter Earth-Moon range precision. Using a 1 kW laser at 1064nm paired with a 1m-aperture telescope, we construct a detailed link budget that ac- counts for beam divergence, atmospheric transmission, retroreflector efficiency, and high-sensitivity single-photon detection. Key challenges include shot-noise limitations under multi-second coherent integration, atmospheric turbulence introducing path fluctuations of 300–500 μm, mechanical and thermal drifts in the optical system, and oscillator stability at the 10^−13–10^−14 level. By maintaining sub-0.01◦C thermal stability and leveraging ultra-stable frequency references, photon fluxes of ∼ 10^4 s−1 are achievable, reducing statistical noise to sub-millimeter levels. We further explore differential LLR, alternating between retroreflectors separated by ∼ 1000 km to suppress common- mode station errors. Under favorable turbulence conditions (r0 ∼ 20 cm), differential ranging precision at the tens-of-μm level is feasible. This “photon-rich” approach—combining high-power CW lasers, dual-wavelength ranging, narrowband filtering, and turbulence averaging—provides a scalable and precise alternative to pulsed-laser systems. Our findings establish high-power CW LLR as a transformative tool for advancing lunar geodesy, refining the lunar reference frame, and enabling next-generation tests of gravitational theories and low-frequency gravitational-wave detection.

本研究针对旨在实现亚毫米级地月距离测量精度的高功率连续波（continuous-wave，CW）月球激光测距（lunar laser ranging，LLR）系统开展了全面分析。本研究采用1千瓦、波长1064纳米的激光器搭配1米口径望远镜，构建了涵盖光束发散角、大气透过率、后向反射器效率及高灵敏度单光子探测的详细链路预算模型。核心挑战包括多秒相干积分下的散粒噪声限制、大气湍流引发的300至500微米级路径波动、光学系统的机械与热漂移，以及10^−13至10^−14量级的振荡器稳定度要求。通过维持低于0.01摄氏度的热稳定性并采用超稳频率参考源，可实现约10^4每秒的光子通量，将统计噪声降至亚毫米级水平。本研究进一步探索了差分月球激光测距方案：通过在间距约1000千米的后向反射器之间切换，以抑制共模站误差。在有利湍流条件（大气相干长度r0约20厘米）下，可实现数十微米级的差分测距精度。这种“富光子”方案——融合高功率连续波激光器、双波长测距、窄带滤波与湍流平均技术——为脉冲激光系统提供了一种可扩展且高精度的替代方案。本研究成果证实，高功率连续波月球激光测距可作为变革性工具，用于推动月球大地测量研究、优化月球参考框架，并支撑引力理论的下一代检验以及低频引力波探测。

搜集汇总

背景与挑战

背景概述

该数据集分析了高功率连续波激光在月球激光测距中的应用，旨在实现亚毫米级的地球-月球距离测量精度。它详细探讨了技术挑战，如大气湍流和系统稳定性，并提出通过差分测距方法在有利条件下达到数十微米级精度，为推进月球大地测量和引力理论测试提供了新工具。