From barcode scanners in supermarkets to cameras in new smart phones, laser scanners are an indispensable part of our daily lives. It relies on lasers and detectors for precise positioning.
The use of LiDAR (a combination of light and radar) for distance and object recognition is becoming more and more common: the reflected laser beam records the surrounding environment and provides key data for autonomous vehicles, agricultural machinery and factory robots.
Current technology reflects the laser beam from a moving mirror. This is a mechanical method that causes slower and inaccurate scanning, not to mention the huge physical size and complexity of the equipment that houses the laser and mirror.
posted on Nature CommunicationsA research team from the Graduate School of Engineering at Kyoto University introduced a new type of beam scanning device that uses “photonic crystals”
Researchers have found that changing the shape and position of the lattice points causes the laser beam to be emitted in a specific direction, rather than arranging the crystal lattice points into an ordered array.
Team leader Susumu Noda explained: “The result is a photonic crystal lattice that looks like a piece of Swiss cheese, where each crystal is calculated to emit a light beam in a specific direction.”
“By eliminating the mechanical mirror, we have made a faster and more reliable beam scanning device.”
The photonic crystal laser is a “semiconductor laser” whose lattice points can be regarded as nano-scale antennas, which can be arranged so that the laser beam is emitted vertically from the surface. But initially, the beam will only travel in a single direction on a two-dimensional plane; the team needs to cover more areas.
Arranging the antenna positions periodically can successfully change the direction, but the reduction in power output and the deformation of the shape make this solution infeasible.
Noda continued: “Modulating the antenna position will cause the light emitted by adjacent antennas to cancel each other, which leads us to try to change the antenna size.”
“In the end, we found that adjusting the position and size at the same time will produce a seemingly random photonic crystal, producing an accurate beam without power loss. We call it a’dual modulation photonic crystal’.”
By organizing these crystals in a matrix (each crystal is designed to emit a beam in a unique direction), the team was able to build a compact, switchable two-dimensional beam scanner without any mechanical parts.
Scientists have successfully constructed a scanner that can generate beams in one hundred different directions: a resolution of 10×10. It is also combined with the divergent laser beam to form a new type of LiDAR with a larger detection range.
The research team estimates that through further improvement, the resolution can be increased by 900 times: the resolution range reaches 300×300.
Noda concluded: “At first, people were interested in whether a seemingly random structure could really work.” “We now believe that eventually we will be able to develop a sufficiently lightweight LiDAR system.”
Slow lighting speeds up the development of LiDAR sensors
Ryoichi Sakata et al., “Dual Modulation Photonic Crystal” realizes a two-dimensional beam scanning laser with high power and high beam quality. Nature Communications (2020). DOI: 10.1038 / s41467-020-17092-w
Provided by Kyoto University
Citation: Researchers describe a new beam scanning device using photonic crystals (November 13, 2020). The technology was launched from https://phys.org/news/2020-11- on November 13, 2020. scanning-device-photonic-crystals.html
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