Mehta Dalip Singh, Hinosugi Hideki, Saito Shohei, Takeda Mitsuo, Kurokawa Takashi, Takahashi Hideki, Ando Masahito, Shishido Masataka, Yoshizawa Tetsuo
The University of ElectroCommunications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan.
Appl Opt. 2003 Feb 1;42(4):682-90. doi: 10.1364/ao.42.000682.
The maximum measurable range of a spectral interference microscope depends on the coherence length of the light transmitted by its tunable spectral filter. To achieve a large range in step-height measurement we have developed a new tunable spectral filter that uses tandem liquid-crystal Fabry-Perot interferometers (LC-FPIs), which can simultaneously attain both a high spectral resolution and a large tuning range. Fringe visibility measurements were carried out, and it was found that the coherence length of the light transmitted through tandem LC-FPIs is two times larger than that transmitted through a single LC-FPI. Using this novel tunable spectral filter, we developed a new spectral interference microscope for the measurement of three-dimensional shapes of discontinuous objects. Experimental results of step-height measurements both with a single LC-FPI and with tandem LC-FPIs are presented for a combination of standard steel gauge block sets with 1-, 99-, and 100-microm steps. A large range (1-100 microm) of measurement with submicrometer resolution was achieved with tandem LC-FPIs that was not possible with our previous system in which a single LC-FPI was used.
光谱干涉显微镜的最大可测范围取决于其可调谐光谱滤波器所透射光的相干长度。为了在台阶高度测量中实现大范围测量，我们开发了一种新型可调谐光谱滤波器，它采用串联液晶法布里 - 珀罗干涉仪（LC - FPI），能够同时实现高光谱分辨率和大的调谐范围。进行了条纹可见度测量，结果发现通过串联LC - FPI透射的光的相干长度比通过单个LC - FPI透射的光的相干长度大两倍。利用这种新型可调谐光谱滤波器，我们开发了一种用于测量不连续物体三维形状的新型光谱干涉显微镜。给出了使用单个LC - FPI和串联LC - FPI对具有1微米、99微米和100微米台阶的标准钢量块组进行台阶高度测量的实验结果。使用串联LC - FPI实现了1 - 100微米的大范围测量且具有亚微米分辨率，这在我们之前使用单个LC - FPI的系统中是不可能实现的。
