Metalenz is commercializing metasurfaces – a new optical element that allows complete control over all aspects of light (phase, wavelength, intensity, and polarization) with a single, planar semiconductor layer. Comprised of subwavelength nanostructures, a single metasurface can carry out optical functions typically requiring four or more conventional refractive and/or diffractive optics. This document will explore the different scenarios in automotive sensing systems – both external lidar and in-cabin driver monitoring – where a solution with Metalenz’s innovative optical metasurfaces (meta-optics) can provide cost and performance improvements over traditional optics and whole new insights into the environment that current cameras and machine vision systems cannot capture.
While lidar systems contain various high-level tradeoffs, certain component-level choices can provide distinct advantages. The optics of many lidar systems use a combination of traditional refractive lenses and a diffractive optical element (DOE) for the transmitting (Tx) optics and refractive lenses for receiving (Rx) optics. As mentioned previously, automotive requirements dictate that optical systems operate across a very large temperature range and collect as much light as possible. Since the optical properties of traditional lenses vary with temperature, a complex optical assembly requiring many elements is typically required to athermalize the system. These additional system complexities and added costs can be overcome by using metasurface optics to replace refractive lenses and DOEs on the Tx and Rx sides of an automotive lidar system.
Meta-optics can combine the optical functions typically found in multiple refractive or diffractive optics into a single planar optical element.
For example, a single Tx metasurface optic can simultaneously perform the collimating functions of a refractive lens stack and the pattern metalenz.com generation function of a DOE and achieve similar or better optical performance. Alternatively, a single Rx metasurface optic can simultaneously perform the collimating and focusing functions of a refractive lens stack, again with similar performance. These meta optics can improve optical performance by improving light collection and contrast, reducing noise, and allowing wider field of illumination (FOI) and field of view (FOV) using single optical elements. In addition to their multifunctional design and performance enhancing capabilities, meta-optics have higher thermal stability than conventional optics, enabling them to maintain performance in the demanding automotive environment. Meta-optics also benefit from the proven semiconductor industry processes which are used to fabricate them, ensuring high part-to-part repeatability and reasonable scale- up to automotive quantities. These advantages make metasurface optics an attractive solution for automakers and tier-1 suppliers.
There are additional benefits to using a metasurface optic in an automotive lidar system, particularly on the Tx side. For line scanning applications, a single meta-optic can generate many (greater than one hundred)
lines without a complex optical system and with a wide FOI (>150°). For diffuse patterns where a metasurface optic would replace a DOE and a refractive stack, precise control over the intensity throughout the FOI is possible in a single optic. In dot pattern applications for direct time-of-flight lidar systems, a meta- optic from Metalenz can generate highly uniform spots with high contrast ratio throughout the relevant FOI. As demonstrated by these examples, a key advantage of metasurface optics is their design flexibility due to their precise control over the characteristics and properties of the incoming light. Meta-optics from Metalenz have a particular design advantage for short- to midrange lidar systems for autonomous vehicles. Wide FOI optics are particularly desirable for peripheral sensing applications such as metalenz.com blind spot detection or lane assist, where shorter range lidar systems excel. Additionally, transmitting patterns rather than flood illumination can improve signal-to-noise ratio for these short-range applications. Metasurface optics from Metalenz can combine these desirable functions in a single optical element, saving cost while not compromising on performance. Metalenz’s optics are fabricated in state-of-the-art semiconductor foundries using well-established production techniques perfected over decades.
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Whereas automotive optical systems must operate reliably across a wide temperature range, traditional lenses exhibit temperature-dependent optical properties, necessitating complex assemblies to maintain performance. Meta-optics, with their inherent thermal stability, can replace efficiently refractive lenses and diffractive optical elements (DOEs) in lidar systems, simplifying design and reducing costs.
