Based on laser radar equations, a Doppler shift model of a laser pulse beam scattered by a rotating arbitrary convex target is reported in this paper. The boundary relations between an incident pulse beam and the dete...Based on laser radar equations, a Doppler shift model of a laser pulse beam scattered by a rotating arbitrary convex target is reported in this paper. The boundary relations between an incident pulse beam and the detected area elements are analyzed by geometric methods. The Doppler shift characteristics of the rotating cone and cylinder are discussed and the difference between the laser pulse beam and the plane wave scattered from the same rotating target is compared accordingly. Numerical simulations show that the Doppler shift is tightly relevant to their dimensions, speeds, and so on. In the same incidence conditions, the pulse beam and plane wave have difference peak values and the same Doppler shift bandwidth. If the waist radius of the pulse beam is larger, the peak value is higher, and the Doppler shifts are proportional to the speed of the rotating target. By virtue of our theoretical model, we probe into the scattered characteristics of the Doppler shifts of a laser pulse beam, which would benefit target identification in national defense.展开更多
Stimulated Raman-scattering-based lasers provide an effective way to achieve wavelength conversion.However,thermally induced beam degradation is a notorious obstacle to power scaling and it also limits the applicable ...Stimulated Raman-scattering-based lasers provide an effective way to achieve wavelength conversion.However,thermally induced beam degradation is a notorious obstacle to power scaling and it also limits the applicable range where high output beam quality is needed.Considerable research efforts have been devoted to developing Raman materials,with diamond being a promising candidate to acquire wavelength-versatile,high-power,and high-quality output beam owing to its excellent thermal properties,high Raman gain coefficient,and wide transmission range.The diamond Raman resonator is usually designed as an external-cavity pumped structure,which can easily eliminate the negative thermal effects of intracavity laser crystals.Diamond Raman converters also provide an approach to improve the beam quality owing to the Raman cleanup effect.This review outlines the research status of diamond Raman lasers,including beam quality optimization,Raman conversion,thermal effects,and prospects for future development directions.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61271110,60801047,and 61073106)the New Scientific and TechnologicalStar Project of Shaanxi Province,China(Grant No.2011KJXX39)+1 种基金the Aviation Science Foundation(Grant No.2011ZC53042)the Natural ScienceFoundation of Shaanxi Province,China(Grant Nos.12Jk0955 and 2014JQ0816)
文摘Based on laser radar equations, a Doppler shift model of a laser pulse beam scattered by a rotating arbitrary convex target is reported in this paper. The boundary relations between an incident pulse beam and the detected area elements are analyzed by geometric methods. The Doppler shift characteristics of the rotating cone and cylinder are discussed and the difference between the laser pulse beam and the plane wave scattered from the same rotating target is compared accordingly. Numerical simulations show that the Doppler shift is tightly relevant to their dimensions, speeds, and so on. In the same incidence conditions, the pulse beam and plane wave have difference peak values and the same Doppler shift bandwidth. If the waist radius of the pulse beam is larger, the peak value is higher, and the Doppler shifts are proportional to the speed of the rotating target. By virtue of our theoretical model, we probe into the scattered characteristics of the Doppler shifts of a laser pulse beam, which would benefit target identification in national defense.
基金supported by the National Natural Science Foundation of China(Nos.62005075,61927815,and 61905061)Hebei Science and Technology Research Project(No.QN2020182)Hebei Natural Science Foundation(Nos.F2020202029 and F2020202026)。
文摘Stimulated Raman-scattering-based lasers provide an effective way to achieve wavelength conversion.However,thermally induced beam degradation is a notorious obstacle to power scaling and it also limits the applicable range where high output beam quality is needed.Considerable research efforts have been devoted to developing Raman materials,with diamond being a promising candidate to acquire wavelength-versatile,high-power,and high-quality output beam owing to its excellent thermal properties,high Raman gain coefficient,and wide transmission range.The diamond Raman resonator is usually designed as an external-cavity pumped structure,which can easily eliminate the negative thermal effects of intracavity laser crystals.Diamond Raman converters also provide an approach to improve the beam quality owing to the Raman cleanup effect.This review outlines the research status of diamond Raman lasers,including beam quality optimization,Raman conversion,thermal effects,and prospects for future development directions.
