In order to improve the correction accuracy of liquid crystal adaptive optical system(LCAOS)

a new method of measuring the response matrix for the purpose of getting accurate control matrix by changing the modulated wavelength is proposed. First

the actual phase modulation lines of first 35 Zernike modes are measured under a series of modulated wavelengths. Then

the phase modulation lines of each modulated wavelength referenced to the origin point are calculated

and one of the phase modulation line can be found whose slope is closest to the actual phase modulation line and whose corresponding modulated wavelength is the one that must be applied on the liquid crystal wavefront corrector when measuring response matrix. With this method

35 modulated wavelengths can be gained corresponding to 35 Zernike modes. Finally

the normalization of each column of response matrix by modulated wavelength is conducted

and the accurate control matrix is obtained. Experimental results indicate that，with the new method

the correction accuracy of the system improved from 73% to 95%. The residual compensated error is only 1/5 of that with the normal method

and the coefficient is not related to the maximum compensated phase. It is shown that the new method greatly improves the correction accuracy of the LCAOS.