3D microscopy based on optical frequency comb by RF control

在我们以前的报告中，我们使用的光学频率梳发生器由两个相位调制器串联组成，产生的梳状谱的带宽很窄，只有2 nm，并导致有限的分辨率高达300μm。由于矩形梳状谱的存在，在干涉峰的周围出现了许多旁瓣的噪声。另外，由于光纤干涉仪采用点到点扫描的方式，数据采集时间较长，为了改善原有系统的性能，我们引入了宽带频率梳和线型图像传感器的新功能，实现了基于频率梳的干涉显微镜。该系统的改进之一是通过将由安装在法布里-珀罗腔中的相位调制器和随后的波长均衡器组成的波导型频率梳发生器^<6-8）>组合在一起，获得了超过10 nm的宽带频率梳谱。深度分辨率 ...更多信息 最后，在35 μm处，干涉信号的旁瓣也消失了。另一个重要的改进是利用线型图像传感器在水平方向上一次捕获一条线的图像，实现了三维图像的高速观测，通过引入波导型频率梳发生器和波长均衡器，测量分辨率最终缩小到35 μm。此外，引入线阵图像传感器可以实现对干涉信号的整个水平截面图像的同时测量。我们成功地证明了三维表面轮廓术的日本10日元硬币和观察的透明薄膜的横截面层析成像图像，通过改变梳频率间隔没有机械移位。深度方向的动态范围约为1.1mm，测量分辨率为35μm。七次厚度测量的标准偏差为5μm。少

In our previous report, the optical frequency comb generator consisting of two phase modulators in tandem we used generated the narrow bandwidth of the comb spectrum, only 2 nm, and resulted in the limited resolution up to 300μm. And some noises of many side-lobes appeared around the interferometric peaks due to a rectangular frequency comb spectrum. Furthermore, it took a long time for the data acquisition because the point-to-point scanning was used in a fiber-optic interferometer.To improve the performance of our previous system, we introduced new functions of a broad band frequency comb and a line-type image sensor to realize a frequency comb-based interferometric microscope. One of the improvements in the proposed system is that a broadband frequency comb spectrum of over 10 nm was obtained by combining a waveguide type-frequency comb generator^<6-8)> consisting of the phase modulator installed in the Fabry-Perot cavity and a subsequent wavelength equalizer^<9)>. The depth resolut … More ion is finally improved up to 35 μm, and the side-lobes in the interferometric signals also disappeared. Another important improvement is to realize a high-speed observation of three-dimensional images by the use of a line type-image sensor for capturing a line image in a horizontal direction at a time.The measurement resolution narrowed finally to 35 μm by introducing the waveguide-type frequency comb generator and the wavelength equalizer. Furthermore, introducing the line image sensor can obtain the simultaneous measurement of the whole horizontal cross sectional image of the interferometric signal. We successfully demonstrated the 3 dimensional surface profilometry of a Japanese 10-yen coin and observation of a cross sectional tomography image of transparent thin films by varying the comb frequency interval without mechanical shift. The dynamic range in the depth direction was about 1.1 mm and the measurement resolution was 35μm. The standard deviation of seven times thickness measurements was 5μm. Less