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Abstract We are presenting a compact radar range system with a scale factor of 10⁵. Replacing the radio frequency (RF) by optical wavelength (300 THz), the system easily fit on a tabletop. We used interferometric time-of-flight to reproduce radar ranging measurements. Sub-micron range accuracy was achieved with a 100 fs laser pulse, which correspond to 3 cm for a s-band (3 GHz) radar. We demonstrated the system potential on a simple target, and compared the results with radio frequency measurement using a vector network analyzer. We also present measurement with a more realistic model, a 3D printed reproduction of the USS Arizona battleship, for which a 3D model is extracted from the ranging data. Together with our previous demonstration of radar cross section measurement with a similar system, this report further validates our proposal to use optics to simulate radar properties of complex radio frequency systems. 

We present a two-dimensional ultra large aperture optical phase array (OPA) with 160×160 elements enabled with optical microelectromechanical system (MEMS). The random access beamsteering up to 4.4°×4.6° scanning range at 1550nm is demonstrated. 

Optical phased arrays (OPAs) are key enabling elements for solid-state LiDAR (light detection and ranging) and three-dimensional (3-D) imaging without bulk mechanical moving parts [1]. Solid state LiDARs are highly sought after for self-driving cars and autonomous vehicles [2,]. OPA's are also instrumental for free-space communications [3], optical switches [4], and holographic displays [5]. OPAs are capable of sophisticated beamforming such as scanning and simultaneous pointing/tracking of multiple objects. Narrow beam divergence and large field of views (FOVs) are desirable for these applications. 

Holography can offer unique solutions to the specific problems faced by automotive optical systems. Frequently, when possibilities have been exhausted using refractive and refractive designs, diffraction can come to the rescue by opening a new dimension to explore. Holographic optical elements (HOEs), for example, are thin film optics that can advantageously replace lenses, prisms, or mirrors. Head up display (HUD) and LIDAR for autonomous vehicles are two of the systems where our group have used HOEs to provide original answers to the limitations of classical optic. With HUD, HOEs address the problems of the limited field of view, and small eye box usually found in projection systems. Our approach is to recycle the light multiple times inside a waveguide so the combiner can be as large as the entire windshield. In this system, a hologram is used to inject a small image at one end of a waveguide, and another hologram is used to extract the image several times, providing an expanded eye box. In the case of LIDAR systems, non-mechanical beam scanning based on diffractive spatial light modulator (SLM), are only able to achieve an angular range of few degrees. We used multiplexed volume holograms (VH) to amplify the initial diffraction angle from the SLM to achieve up to 4π steradian coverage in a compact form factor. 

Optical phased array (OPA) is a key enabling element for solid state LIDAR (light detection and ranging). In this paper, we demonstrate a novel MEMS micromirror array OPA. Vertical combdrive actuators are integrated underneath the mirrors to achieve a small pitch (2.4μm) and a large field of view (22° at 905nm wavelength and 40° at 1550nm). The OPA has 2μs response time, and 10V actuation voltage.