Department of Optoelectronic Engineering, Jinan University, Guangzhou 510632, China.
Department of Optoelectronic Engineering, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Jinan University, Guangzhou 510632, China.
Ultramicroscopy. 2018 Dec;195:74-84. doi: 10.1016/j.ultramic.2018.08.016. Epub 2018 Aug 27.
Numerous advanced microscopic imaging techniques have been proposed for optical sectioning, but they generally employ a complex and costly optical system. Here we report a microscopy termed spatially-incoherent annular illumination microscopy (SAIM). It allows for simple, effective, non-fluorescence, and bright-field optical sectioning. The proposed technique is implemented by installing an annular array of light emitting diodes (LEDs) on a standard bright-field microscope for illumination. The LED array produces distinctive illumination, that is, each LED provides coherent, large-angle oblique illumination while all LEDs generate spatially-incoherent annular illumination. Such a distinctive illumination can improve both lateral resolution and axial resolution. The improvement of lateral resolution is due to the coherent and large-angle oblique illumination. The spatially-incoherent annular illumination can improve the axial resolution. It is because, for defocused structures, each LED results in a blurred image with a different lateral shift and all LEDs result in an incoherent stagger superposition of the defocused images. The superposition looks much more blurred, which improves the contrast of the in-focus image remarkably. We experimentally demonstrate that SAIM is able to provide bright-field optical sections with 600-nm axial resolution and 150-nm lateral half-pitch resolution by using a 525-nm wavelength LED array and an objective with 100X, numerical aperture (NA) 1.25.
已经提出了许多用于光学切片的先进微观成像技术，但它们通常采用复杂且昂贵的光学系统。在这里，我们报告了一种称为空间非相干环形照明显微镜（SAIM）的显微镜。它允许进行简单、有效、非荧光和明场光学切片。所提出的技术是通过在标准明场显微镜上安装环形发光二极管（LED）阵列来实现照明。LED 阵列产生独特的照明，即每个 LED 提供相干、大角度斜角照明，而所有 LED 产生空间非相干环形照明。这种独特的照明可以提高横向分辨率和轴向分辨率。横向分辨率的提高是由于相干和大角度斜角照明。空间非相干环形照明可以提高轴向分辨率。这是因为对于离焦结构，每个 LED 会导致具有不同横向位移的模糊图像，并且所有 LED 会导致离焦图像的非相干交错叠加。叠加看起来更加模糊，从而显著提高了聚焦图像的对比度。我们通过使用 525nm 波长的 LED 阵列和 100X、数值孔径（NA）为 1.25 的物镜，实验证明了 SAIM 能够提供具有 600nm 轴向分辨率和 150nm 横向半节距分辨率的明场光学切片。
