Laser scanning based on Micro-Electro-Mechanical Systems (MEMS) scanners has become very attractive for biomedical endoscopic imaging, such as confocal microscopy or Optical Coherence Tomography (OCT). These scanners are required to be fast to achieve real-time image reconstruction while working at low actuation voltage to comply with medical standards. In this context, we report a 2-axis Micro-Electro-Mechanical Systems (MEMS) electrothermal micro-scannercapable of imaging large fields of view at high frame rates, e.g. from 10 to 80 frames per second. For this purpose, Lissajous scan parameters are chosen to provide the optimal image quality within the scanner capabilities and the sampling rate limit, resulting from the limited A-scan rate of typical swept-sources used for OCT. Images of 233 px × 203 px and 53 px × 53 px at 10 fps and 61 fps, respectively, are experimentally obtained and demonstrate the potential of this micro-scannerfor high definition and high frame rate endoscopic Lissajous imaging.

Flat optics have been proposed as an attractive approach for the implementation of new imaging and sensing modalities to replace and augment refractive optics. However, chromatic aberrations impose fundamental limitations on diffractive flat optics. As such, true broadband high-quality imaging has thus far been out of reach for fast f-numbers, large aperture, flat optics. In this work, we overcome intrinsic spectral bandwidth limitations, achieving broadband imaging in the visible wavelength range with a flat meta-optic, co-designed with computational reconstruction. We derive the necessary conditions for a broadband, 1 cm aperture, f/2 flat optic, with a diagonal field of view of 30° and average system MTF contrast of 20% or larger for a spatial frequency of 100 lp/mm in the visible band (>30% for <70 lp/mm). Finally, we use a coaxial, dual-aperture system to train the broadband imaging meta-optic with a learned reconstruction method operating on pair-wise captured imaging data. Fundamentally, our work challenges the entrenched belief of the inability of capturing high-quality, full-color images using a single large aperture meta-optic.

Light’s ability to perform massive linear operations in parallel has recently inspired numerous demonstrations of optics‐assisted artificial neural networks (ANN). However, a clear system‐level advantage of optics over purely digital ANN has not yet been established. While linear operations can indeed be optically performed very efficiently, the lack of nonlinearity and signal regeneration require high‐power, low‐latency signal transduction between optics and electronics. Additionally, a large power is needed for lasers and photodetectors, which are often neglected in the calculation of the total energy consumption. Here, instead of mapping traditional digital operations to optics, we co‐designed a hybrid optical‐digital ANN, that operates on incoherent light, and is thus amenable to operations under ambient light. Keeping the latency and power constant between a purely digital ANN and a hybrid optical‐digital ANN, we identified a low‐power/latency regime, where an optical encoder provides higher classification accuracy than a purely digital ANN. We estimate our optical encoder enables ∼10 kHz rate operation of a hybrid ANN with a power of only 23 mW. However, in that regime, the overall classification accuracy is lower than what is achievable with higher power and latency. Our results indicate that optics can be advantageous over digital ANN in applications, where the overall performance of the ANN can be relaxed to prioritize lower power and latency.

Wide field of view and light weight optics are critical for advanced eyewear, with applications in augmented/virtual reality and night vision. Conventional refractive lenses are often stacked to correct aberrations at a wide field of view, leading to limited performance and increased size and weight. In particular, simultaneously achieving a wide field of view and large aperture for light collection is desirable but challenging to realize in a compact form-factor. Here, we demonstrate a wide field of view (greater than 60^∘) meta-optic doublet eyepiece with an entrance aperture of 2.1 cm. At the design wavelength of 633 nm, the meta-optic doublet achieves comparable performance to a refractive lens-based eyepiece system. This meta-doublet eyepiece illustrates the potential for meta-optics to play an important role in the development of high-quality monochrome near-eye displays and night vision systems.

This paper reports a compact microendoscopic OCT probe with an outer diameter of only 2.7 mm. The small diameter is enabled by a novel 2-axis scanning MEMS mirror with a preset 45° tilted angle. The tilted MEMS mirror is directly integrated on a silicon optical bench (SiOB). The SiOB provides mechanical support and electrical wiring to the mirror plate via a set of bimorph flexure, enabling a compact probe mount design without the requirement of a 45° slope, which is capable to dramatically reduce the probe size and ease the assembly process. Additionally, the SiOB also provides trenches with properly-designed opening widths for automatic alignment of the MEMS mirror, GRIN lens and optical fiber. The 45°-tilted MEMS mirror plate is actuated by four electrothermal bimorph actuators. The packaged 2.7 mm-diameter probe offers 2-axis side-view optical scanning with a large optical scan range of 40° at a low drive voltage of 5.5 Vdc in both axes, allowing a lateral scan area of 2.2 mm × 2.2 mm at a 3 mm working distance. High-resolution 2D and 3D OCT images of the IR card, ex vivo imaging of meniscus specimens and rat brain slices, in vivo imaging of the human finger and nail have been obtained with a TDOCT system.

This paper introduces an optical 2-axis Micro Electro-Mechanical System (MEMS) micromirror actuated by a pair of electrothermal actuators and a set of passive torsion bars. The actuated element is a dual-reflective circular mirror plate of 1 $\mathrm{m}\mathrm{m}$ in diameter. This inner mirror plate is connected to a rigid frame via a pair of torsion bars in two diametrically opposite ends located on the rotation axis. A pair of electrothermal bimorphs generates a force onto the perpendicular free ends of the mirror plate in the same angular direction. An array of electrothermal bimorph cantilevers deflects the rigid frame around a working angle of 45 ${}^{\circ }$ for side-view scan. The performed scans reach large mechanical angles of 32 ${}^{\circ }$ for the frame and 22 ${}^{\circ }$ for the in-frame mirror. We denote three resonant main modes, pure flexion of the frame at 205 $\mathrm{Hz}$ , a pure torsion of the mirror plate at 1.286 $\mathrm{kHz}$ and coupled mode of combined flexion and torsion at 1.588 $\mathrm{kHz}$ . The micro device was fabricated through successive stacks of materials onto a silicon-on-insulator wafer and the patterned deposition on the back-side of the dual-reflective mirror is achieved through a dry film photoresist photolithography process.