Different methods to determine the group index by measuring the material dispersion in spectrally resolved white-light interferometry were analysed. Four methods were investigated: computing the phase derivative directly, using the group index definition to calculate it from the refractive index derivative, locating the equalisation wavelength, and locally evaluating the fringe periodicity. For each method, different paths or variants were investigated to evaluate their efficacy and determine their advantages and drawbacks. We considered the measurement range of a typical CCD camera, from 400 to 1000 nm, and tested every method with two different samples: a 1-mm thick BK7 plate and an optical cell filled with deionised water; obtaining similar results in both cases. Only methods requiring the acquisition of a few frames were considered.

分析了在光谱分辨白光干涉法中通过测量材料色散来确定组指数的不同方法。研究了四种方法：直接计算相位导数，使用组指数定义从折射率导数计算相位导数，确定均衡波长，并局部评估条纹周期。对于每种方法，都研究了不同的路径或变体，以评估其功效并确定其优缺点。我们考虑了典型CCD相机的测量范围，从400到1000 nm，并用两种不同的样品测试了每种方法：一个1毫米厚的BK7平板和一个装有去离子水的光学元件；在两种情况下都获得相似的结果。仅考虑需要获取几帧的方法。