自适应光学中的大气色散效应

ATMOSPHERIC DISPERSION IN ADAPTIVE OPTICS

用Zernike多项式展开的方法讨论了双波长自适应光学系统中的大气色散效应。根据位相展开系数的双频相关求得了大气色散产生的剩余位相误差。结果表明:虽然大气色散会使位相补偿不完全,但用比发射激光波长更短的光源为信标,并将信标位相畸变量与比值λ_2/λ_1(信标波长/发射波长)的乘积作为位相预畸变,能较好地校正发射光束的位相畸变。

The atmospheric dispersion in a two-wavelength adaptive system is discussed by Zernike's polynomial expansion. The bifrequency correlation function of the expansion coefficients is presented and used to derive the residual phase error due to dispersion. It is shown that the compensation will not be exact because there will be phase difference between the transmitted beam and the beacon's beam when the wavelengths are different. By using shorter wavelength beacon as well as multiplying the beacon's signal by λ_2/λ_1 (the ratio of beacon's wavelength to transmitted wavelength), the phase difference variance will be considerably reduced.