Kuang Cuifang, Ma Ye, Zhou Renjie, Lee Justin, Barbastathis George, Dasari Ramachandra R, Yaqoob Zahid, So Peter T C
Opt Express. 2015 Oct 19;23(21):26999-7010. doi: 10.1364/OE.23.026999.
We report a novel approach to Fourier ptychographic microscopy (FPM) by using a digital micromirror device (DMD) and a coherent laser source (532 nm) for generating spatially modulated sample illumination. Previously demonstrated FPM systems are all based on partially-coherent illumination, which offers limited throughput due to insufficient brightness. Our FPM employs a high power coherent laser source to enable shot-noise limited high-speed imaging. For the first time, a digital micromirror device (DMD), imaged onto the back focal plane of the illumination objective, is used to generate spatially modulated sample illumination field for ptychography. By coding the on/off states of the micromirrors, the illumination plane wave angle can be varied at speeds more than 4 kHz. A set of intensity images, resulting from different oblique illuminations, are used to numerically reconstruct one high-resolution image without obvious laser speckle. Experiments were conducted using a USAF resolution target and a fiber sample, demonstrating high-resolution imaging capability of our system. We envision that our approach, if combined with a coded-aperture compressive-sensing algorithm, will further improve the imaging speed in DMD-based FPM systems.
我们报告了一种傅里叶叠层显微镜术（FPM）的新方法，通过使用数字微镜器件（DMD）和相干激光源（532纳米）来产生空间调制的样品照明。先前展示的FPM系统均基于部分相干照明，由于亮度不足，其通量有限。我们的FPM采用高功率相干激光源以实现散粒噪声受限的高速成像。首次将成像在照明物镜后焦平面上的数字微镜器件（DMD）用于为叠层成像产生空间调制的样品照明场。通过对微镜的开/关状态进行编码，照明平面波角度可以以超过4千赫兹的速度变化。由不同倾斜照明产生的一组强度图像用于数值重建一幅无明显激光散斑的高分辨率图像。使用美国空军分辨率靶标和光纤样品进行了实验，证明了我们系统的高分辨率成像能力。我们设想，如果将我们的方法与编码孔径压缩感知算法相结合，将进一步提高基于DMD的FPM系统的成像速度。
