对633nm波长下湿空气折射率计算公式的精确修正

Correction to the Calculation Equations of Moist Air Refractive Index at the Wavelength of 633nm

目前公式法测量空气折射率大多采用Boensch等于1998年提出的改进Edlen公式，其对湿空气的修正系数是基于4个波长（644．0、508．7、480．1、467．9nm）并在19．6℃～20．1℃范围内测得的数据，这与当前光学精密测量多采用633nm He-Ne激光波长且环境温度范围更大的实际情况存在矛盾，从而导致其应用时产生的误差较大。为此，提出了以相移干涉光路为基础的折射率测量实验光路，在较大温度范围内（14．6℃～24．0℃）测得了在633nm波长下对湿空气折射率的修正系数并得到其修正公式。与文献结果比对表明其精度高于Boensch公式。该修正公式可广泛应用于633nm激光精密测量中的空气折射率补偿。

Revised Edlen＇s equations by Boensch and Potulski in 1998 are mostly used to calculate air refractive index at present. Since the correction coefficient of water vapour influence on refractive index is performed with four wavelengths （644.0 nm, 508. 7nm, 480.1 nm, and 467.9 nm） and the temperature between 19.6 ℃ and 20.1 ℃, the accuracy will be influenced when the laser wavelength is 633 nm, which is mostly applied in optical precision measurement, and the environmental temperature is far away from 20 ℃. To solve this problem, a refractive index measurement system based on phase step interferometry is presented. The correction coefficient of water vapour influence on refractive index is measured and the revised equations are acquired with the wavelength of 633 nm and the larger temperature range （14.6℃ - 24.0℃ ）. The comparison results show that the accuracy by presented equations is better than that by Boensch＇s equations.