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In recent years, Light Detection and Ranging (LiDAR) has been drawing extensive attention both in academia and industry because of the increasing demand for autonomous vehicles. LiDAR is believed to be the crucial sensor for autonomous driving and flying, as it can provide high-density point clouds with accurate three-dimensional information. This review presents an extensive overview of Microelectronechanical Systems (MEMS) scanning mirrors specifically for applications in LiDAR systems. MEMS mirror-based laser scanners have unrivalled advantages in terms of size, speed and cost over other types of laser scanners, making them ideal for LiDAR in a wide range of applications. A figure of merit (FoM) is defined for MEMS mirrors in LiDAR scanners in terms of aperture size, field of view (FoV) and resonant frequency. Various MEMS mirrors based on different actuation mechanisms are compared using the FoM. Finally, a preliminary assessment of off-the-shelf MEMS scanned LiDAR systems is given.

An endoscopic optical coherence tomography (OCT) system based on a microelectromechanical mirror to facilitate lateral light scanning is described. The front-view OCT scope, adapted to the instrument channel of a commercial endoscopic sheath, allows real-time cross-sectional imaging of living biological tissue via direct endoscopic visual guidance. The transverse and axial resolutions of the OCT scope are roughly 20 and 10.2mum, respectively. Cross-sectional images of 500x1000 pixels covering an area of 2.9 mmx2.8 mm can be acquired at ~5 frames/s and with nearly 100-dB dynamic range. Applications in thickness measurement and bladder tissue imaging are demonstrated.

In this paper we report the design, testing and use of a scannerless probe specifically for minimally invasive imaging of deep tissue in vivo with an epi-fluorescence modality. The probe images a 500 µm diameter field of view through a 710 µm outer diameter probe with a maximum tissue penetration depth of 15 mm specifically configured for eGFP imaging. Example results are given from imaging the pituitary gland of rats and zebrafish hearts with lateral resolution of 2.5 µm., "Real-time visualization of human prolactin alternate promoter usage in vivo using a double-transgenic rat model," Mol. Endocrinol.Fast handheld two-photon fluorescence microendoscope with a 475 μm × 475 μm field of view for in vivo imaging," Opt.

Two-photon fluorescence and second harmonic generation microscopy have enabled functional and morphological in vivo imaging. However, in vivo applications of those techniques to living animals are limited by bulk optics on a bench top. Fortunately, growing functionality of fiber-optic devices and miniaturization of scanning mirrors stimulate the race to develop nonlinear optical endoscopy. In this paper, we report on a prototype of a nonlinear optical endoscope based on a double-clad photonic crystal fiber to improve the detection efficiency and a MEMS mirror to steer the light at the fiber tip. The miniaturized fiber-optic nonlinear microscope is characterized by rat esophagus imaging. Line profiles from the rat tail tendon and esophagus prove the potential of the technology in in vivo applications.