FM-to-AM(frequency modulation-to-amplitude modulation)conversion caused by nonuniform spectral transmission of broadband beam is harmful to high-power laser facility.Smoothing by spectral dispersion(SSD)beam is a spec...FM-to-AM(frequency modulation-to-amplitude modulation)conversion caused by nonuniform spectral transmission of broadband beam is harmful to high-power laser facility.Smoothing by spectral dispersion(SSD)beam is a special broadband beam for its monochromatic feature at the given time and space on the near field.The traditional method which uses the optical spectral transfer function as filters cannot accurately describe its AM characteristics.This paper presents the theoretical analysis of the etalon effect for SSD beam.With a low-order approximation,the analytic model of the temporal shape of SSD beam is obtained for the first time,which gives the detailed AM characteristics at local and integral aspects,such as the variation of ripples width and amplitude in general situation.We also analyze the FM-to-AM conversion on the focal plane;in the focusing process,the lens simply acts as an integrator to smooth the AM of SSD beam.Because AM control is necessary for the near field to avoid optics damage and for the far field to ensure an optimal interaction of laser-target,our investigations could provide some important phenomena and rules for pulse shape control.展开更多
The accuracy of solid density primary standard is decided mainly by the accuracy of the diameter measurement of silicon sphere. With traditional five-interferogram algorithm to unwrap phase for di- ameter measurement,...The accuracy of solid density primary standard is decided mainly by the accuracy of the diameter measurement of silicon sphere. With traditional five-interferogram algorithm to unwrap phase for di- ameter measurement, the phase steps should be equal to π/2 exactly, but this is almost impossible to achieve in nanometer positioning technique. In order to overcome this defect, we have derived an im- proved five-interferogram algorithm, which not only keeps the high accuracy of traditional five-inter- ferogram algorithm, but also does not require absolute equal step to unwrap phase. Instead, the im- proved five-interferogram algorithm only needs measuring phase shifting. Based on the improved al- gorithm, we have developed a novel interferometer with special etalon, and the cavity length of this etalon can be changed by pressure from vertical direction to realize phase shifting. The accuracy of this interferometer is better than 3 nm and can be improved in future research.展开更多
基金supported by the National Natural Science Foundation of China(No.11404306)the Presidential Foundation of the China Academy of Engineering Physics(No.YZJJLX2016008)
文摘FM-to-AM(frequency modulation-to-amplitude modulation)conversion caused by nonuniform spectral transmission of broadband beam is harmful to high-power laser facility.Smoothing by spectral dispersion(SSD)beam is a special broadband beam for its monochromatic feature at the given time and space on the near field.The traditional method which uses the optical spectral transfer function as filters cannot accurately describe its AM characteristics.This paper presents the theoretical analysis of the etalon effect for SSD beam.With a low-order approximation,the analytic model of the temporal shape of SSD beam is obtained for the first time,which gives the detailed AM characteristics at local and integral aspects,such as the variation of ripples width and amplitude in general situation.We also analyze the FM-to-AM conversion on the focal plane;in the focusing process,the lens simply acts as an integrator to smooth the AM of SSD beam.Because AM control is necessary for the near field to avoid optics damage and for the far field to ensure an optimal interaction of laser-target,our investigations could provide some important phenomena and rules for pulse shape control.
文摘The accuracy of solid density primary standard is decided mainly by the accuracy of the diameter measurement of silicon sphere. With traditional five-interferogram algorithm to unwrap phase for di- ameter measurement, the phase steps should be equal to π/2 exactly, but this is almost impossible to achieve in nanometer positioning technique. In order to overcome this defect, we have derived an im- proved five-interferogram algorithm, which not only keeps the high accuracy of traditional five-inter- ferogram algorithm, but also does not require absolute equal step to unwrap phase. Instead, the im- proved five-interferogram algorithm only needs measuring phase shifting. Based on the improved al- gorithm, we have developed a novel interferometer with special etalon, and the cavity length of this etalon can be changed by pressure from vertical direction to realize phase shifting. The accuracy of this interferometer is better than 3 nm and can be improved in future research.
