Fluorescence microscopy and derived techniques are continuously looking for photodetectors able to guarantee increased sensitivity, high spatial and temporal resolution, and ease of integration into modern microscopy architectures. Recent advances in single-photon avalanche diodes (SPADs) fabricated with industry-standard microelectronic processes allow the development of new detection systems tailored to address the requirements of advanced imaging techniques (such as image-scanning microscopy). To this aim, we present the complete design and characterization of two bidimensional SPAD arrays composed of 25 fully independent and asynchronously operated pixels, both having fill factor of about 50% and specifically designed for being integrated into existing laser scanning microscopes. We used two different microelectronics technologies to fabricate our detectors: the first technology exhibiting very low noise (roughly 200 dark counts per second at room temperature) and the second one showing enhanced detection efficiency (more than 60% at a wavelength of 500 nm). Starting from the silicon-level device structures and moving towards the in-pixel and readout electronics description, we present performance assessments and comparisons between the two detectors. Images of a biological sample acquired after their integration into our custom image-scanning microscope finally demonstrate their exquisite on-field performance in terms of spatial resolution and contrast enhancement. We envisage that this work can trigger the development of a new class of SPAD-based detector arrays able to substitute the typical single-element sensor used in fluorescence laser scanning microscopy.

中文翻译：

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用于图像扫描显微镜的基于SPAD的异步读出阵列检测器

荧光显微镜和衍生技术一直在寻找能够保证提高灵敏度，高空间和时间分辨率以及易于集成到现代显微镜架构中的光电探测器。利用行业标准微电子工艺制造的单光子雪崩二极管（SPAD）的最新进展，可以开发出专门为满足先进成像技术（例如图像扫描显微镜）要求而量身定制的新检测系统。为此，我们介绍了由25个完全独立且异步操作的像素组成的二维SPAD阵列的完整设计和特性，这两个像素的填充系数均为50％，并且专门设计为集成到现有的激光扫描显微镜中。我们使用了两种不同的微电子技术来制造探测器：第一种技术显示出非常低的噪声（室温下每秒大约200个暗计数），第二种显示出更高的检测效率（在500 nm波长下超过60％）。从硅级器件结构开始，朝着像素内和读出电子器件的描述发展，我们介绍了两个探测器之间的性能评估和比较。将其整合到我们的自定义图像扫描显微镜中后获得的生物样品的图像最终展示了其在空间分辨率和对比度增强方面的出色现场性能。