为了准确地测量透射平行平板,提出了基于最小二乘迭代的多表面干涉条纹分析方法。依据波长调谐相移的原理,通过最小二乘迭代准确地求得每组双表面干涉条纹的实际相移值,从而准确地提取平板前后表面面形及厚度变化等信息。模拟计算结果表明,当相移值有微小偏差(小于0.2 rad)时,通过10次迭代后求得相位的峰值(PV)误差为0.005 rad,均方根（RMS）误差为0.002 rad,而相应Okada算法的PV误差为0.512 rad,RMS误差为0.103 rad。实验结果验证了该算法的有效性。

To accurately profile transparent elements with parallel surfaces, a method based on least-squares iteration is presented to extract the phase information from multiple-surface interference fringes. According to the principle of wavelength-tuned phase shifting, the least-squares iteration is applied to obtain the actual phase shifts of the different two-beam interference fringes in each frame. Therefore, it allows extraction of front surface, back surface and thickness variation from multiple-surface interference fringes with high precision. The simulation results show that when the phase-shifting error is less than 0.2 rad, the proposed algorithm needs only 10 iterations and reduces the residual phase errors from 0.512 rad (peak value, PV) and 0.103 rad (root-mean-square, RMS) obtained by Okada's algorithm to 0.005 rad (PV) and 0.002 rad (RMS). Its validation is also demonstrated by the experiment of three-surface fringes analysis.