Optical microendoscopy enabled by a microelectromechanical system (MEMS) scanning mirror offers great potential for in vivo diagnosis of early cancer inside the human body. However, an additional beam folding mirror is needed for a MEMS mirror to perform forward-view scanning, which drastically increases the diameter of the resultant MEMS endoscopic probe. This paper presents a new monolithic two-axis forward-view optical scanner that is composed of an electrothermally driven MEMS mirror and a beam folding mirror both vertically standing and integrated on a silicon substrate. The mirror plates of the two mirrors are parallel to each other with a small distance of 0.6 mm. The laser beam can be incident first on the MEMS mirror and then on the beam folding mirror, both at 45°. The MEMS scanner has been successfully fabricated. The measured optical scan angles of the MEMS mirror were 10.3° for the x axis and 10.2° for the y axis operated under only 3 V. The measured tip-tilt resonant frequencies of the MEMS mirror were 1590 Hz and 1850 Hz, respectively. With this compact MEMS design, a forward-view scanning endoscopic probe with an outer diameter as small as 2.5 mm can be made, which will enable such imaging probes to enter the subsegmental bronchi of an adult patient.

中文翻译：

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基于硅光学台式的前视两轴扫描仪，用于微内窥镜应用

由微机电系统（MEMS）扫描镜实现的光学显微内窥镜在体内诊断人体内的早期癌症方面具有巨大潜力。然而，MEMS反射镜需要额外的光束折叠镜来执行前视扫描，这会大大增加所得MEMS内窥镜探头的直径。本文提出了一种新型的单片式两轴前视光学扫描仪，它由电热驱动的MEMS反射镜和垂直折叠并集成在硅基板上的光束折叠镜组成。两个镜的镜板彼此平行，间距为0.6 mm。激光束可以先以45°入射到MEMS反射镜上，然后入射到光束折叠镜上。MEMS扫描仪已成功制造。在仅在3 V下工作的MEMS反射镜的测得的光学扫描角度为x轴为10.3°，y轴的测得的扫描角为10.2°。MEMS反射镜的测得的尖端倾斜共振频率分别为1590 Hz和1850 Hz。通过这种紧凑的MEMS设计，可以制造外径小至2.5 mm的前视扫描内窥镜探头，这将使此类成像探头能够进入成年患者的节段性支气管。