Luo Songjie, Suzuki Takamasa, Sasaki Osami, Choi Samuel, Chen Ziyang, Pu Jixiong
Appl Opt. 2019 May 1;58(13):3548-3554. doi: 10.1364/AO.58.003548.
In order to perform an exact surface profile measurement with a white-light scanning interferometer (WLSI), an actual optical path difference (OPD) changing with time is detected with an additional interferometer in which the light source of the WLSI and an optical band-pass filter are used. This interferometer is simply equipped in the WLSI and does not negatively influence the WLSI. The real OPD is easily calculated from an interference signal with the same signal processing as that in the WLSI. The interference signal of the WLSI is corrected with the real OPD values or the real scanning position values. The corrected interference signal with a constant sampling interval is obtained with an interpolation method. With this correction method, a surface profile with a step shape of 3-μm height is measured accurately with an error less than 2 nm.
为了使用白光扫描干涉仪（WLSI）进行精确的表面轮廓测量，利用一个额外的干涉仪检测随时间变化的实际光程差（OPD），该干涉仪使用WLSI的光源和一个光学带通滤波器。这个干涉仪简单地安装在WLSI中，并且不会对WLSI产生负面影响。通过与WLSI中相同的信号处理，很容易从干涉信号中计算出实际的OPD。WLSI的干涉信号用实际的OPD值或实际的扫描位置值进行校正。通过插值方法获得具有恒定采样间隔的校正干涉信号。采用这种校正方法，可以精确测量高度为3μm的台阶形状的表面轮廓，误差小于2nm。
