Structured illumination microscopy (SIM) is a broadly applicable super-resolution microscopy technique which does not impose photophysics requirements on fluorescent samples. Multicolor SIM implementations typically rely on liquid crystal on silicon (LCoS) spatial light modulators (SLM's) for precise patterning of the excitation light, but digital micromirror devices (DMD's) are a promising alternative, owing to their lower cost, increased imaging rate, and simplified experimental timings. Given these advantages, why do existing DMD SIM implementations either rely on incoherent projection, resulting in an order of magnitude lower signal-to-noise, or utilize coherent light at only a single wavelength? The primary obstacle to realizing a multicolor coherent DMD SIM microscope is the lack of an efficient approach for dealing with the blazed grating effect. To address this challenge, we developed quantitative tools applicable to a single DMD acting as a polychromatic diffractive optic. These include a closed form solution of the blaze and diffraction conditions, a forward model of DMD diffraction, and a forward model of coherent pattern projection. We applied these to identify experimentally feasible configurations using a single DMD as a polychromatic diffractive optic for combinations of three and four common fluorophore wavelengths. Based on these advances, we constructed a DMD SIM microscope for coherent light which we used to validate these models, develop a high-resolution optical transfer function measurement technique, and demonstrate SIM resolution enhancement for calibration samples, fixed cells, and live cells. This low-cost setup opens the door to applying DMD's in polychromatic applications which were previously restricted to LCoS SLM's.

中文翻译：

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数字微镜装置的多色结构照明显微镜和多色相干光的定量控制

结构照明显微镜（SIM）是一种广泛适用的超分辨率显微镜技术，它不对荧光样品提出光物理要求。多色SIM的实现通常依赖于硅上液晶（LCoS）空间光调制器（SLM）来对激发光进行精确的图案化，但是数字微镜设备（DMD）由于其成本更低，成像速度更高以及简化的实验时间。鉴于这些优势，为什么现有DMD SIM实施方案要么依赖于非相干投影，从而导致信噪比降低了一个数量级，或仅使用单个波长的相干光？实现多色相干DMD SIM显微镜的主要障碍是缺乏一种有效的方法来应对炽烈的光栅效应。为了解决这一挑战，我们开发了适用于充当多色衍射光学器件的单个DMD的定量工具。这些包括闪耀和衍射条件的封闭形式解，DMD衍射的正向模型和相干图案投影的正向模型。我们将其应用于使用单个DMD作为三种和四种常见荧光团波长组合的多色衍射光学器件来确定实验可行的配置。基于这些进展，我们构造了用于相干光的DMD SIM显微镜，并用于验证这些模型，开发一种高分辨率的光学传递函数测量技术，并演示了用于校准样品，固定细胞和活细胞的SIM分辨率增强。这种低成本的设置为在以前仅限于LCoS SLM的多色应用中使用DMD开辟了大门。