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LiDAR glass for the mass market

The development of LiDAR systems is paving the way for driverless cars, robotics and many other applications related to geological and industrial uses. However, in order to reach the mass market, manufacturers will need components that meet exact performance standards at reasonable cost. BOROFLOAT®33, a technical float glass made by SCHOTT, is gaining traction in LiDAR applications because of its excellent material properties at agreeable prices.

LiDAR works much like radar, but it uses light instead of sound. That makes LiDAR faster, more accurate, and able to interpret surroundings in much finer detail.

In forestry, LiDAR can assess the density of the tree canopy. After a storm, LiDAR can measure coastal erosion. Researchers used LiDAR to map an ancient Mayan megalopolis hidden by the jungle in Guatemala. It’s also used to map the Great Pacific Garbage Patch, a massive accumulation of floating plastic littering the world’s largest ocean.

And those are just the airborne applications.

Car manufacturers are spending millions of dollars to test and evaluate LiDAR for autonomous driving vehicles. These LiDAR units need to collect and process an enormous amount of data, with minimal signal interference, in harsh situations that require thermal stability and mechanical strength.

The component quality has a tremendous impact on system performance. Glass plays a major role, as it is used as entrance window and in optical elements such as filters and mirrors, which directly influence signal strength.

Standing up to real world conditions

Used as an entrance window, BOROFLOAT® provides extremely high light transmission while remaining strong, lightweight, and resistant to potential corrosive environments or thermal changes. High transmission at the relevant laser wavelength is especially important as it ensures that light passes unimpeded through the entrance window, which serves as a protective cover for the components inside. If the entrance window impairs the LiDAR signal, it will not see its surroundings accurately.

BOROFLOAT® glass also has a very strong microstructure, resulting in high material hardness, excellent abrasion resistance, and low degradation behavior during high-intensity radiation exposure.

A noisy world of light

Many LiDAR systems use lasers of a specific wavelength, some of the most common of which are 532nm, 905nm, and 1550nm. BOROFLOAT® has a long history as a substrate for narrow bandpass filters that reduce signal-to-noise ratio, allowing only the wavelength of interest to be transmitted or received. BOROFLOAT® glass is often the substrate of choice for such coatings, as a high material transmission is key for exceptional filter properties.

BOROFLOAT® glass’ high transmission properties stem from the use of extremely pure raw materials. It features high UV transparency down to 300 nm, greater than 92 percent light transmittance in the visible and near IR wavelength range, outstanding colorless visual appearance, low auto-fluorescence, high resistance to solarization, and a low refractive index.

SCHOTT’s BOROFLOAT glass has been identified as a suitable substrate for various components in LiDAR systems as it has an exceptional high transmission across the entire laser wavelength range - from visible to near-infrared.
Three components of a traditional LiDAR unit could be made of BOROFLOAT® 33 borosilicate glass.

The perfect mirror

Mirrors are a third essential component of LiDAR systems, and BOROFLOAT’s thermal stability and resistance to thermal shock equates to a highly accurate imaging system.

LiDAR systems, attached to airplanes and drones that fly at high altitude or cars that speed down highways or climb up mountains, are subject to pressure or temperature fluctuations. Many materials change shape, when the temperature changes. This presents special challenges for LiDAR systems, because expansion or contraction of optical materials can lead to light distortion, which in turn leads to reduced data collection quality and increased interference.

BOROFLOAT® glass has excellent thermal stability over a wide range of temperatures due to the high boron content, which lowers the thermal expansion coefficient to 3.25 10-6 K-1. The end result is a narrower and more stable signal transmission.

Creating cost-effective LiDAR

Many LiDAR developers design their systems with optical glass, which is valued for its high transmission rates, transparency, and well-defined wavelength filtering. Yet they continue to search for materials that offer the high performance at a cost that is much more reasonable to mass production.

While it is priced as an industrial glass, BOROFLOAT® has been widely used in optical applications for decades.

As a specialty float glass, BOROFLOAT® is also extremely flat. The fabrication method, in which liquid glass flows over a layer of molten tin, creates a panel with a highly consistent, ultra-flat surface.

Designers around the world have enjoyed BOROFLOAT® glass as an optical substrate for many different uses that require more than just excellent optical characteristics.

With its high optical transmission, material hardness, thermal stability, and industrial-scale fabrication, BOROFLOAT® glass could be the material that brings the many applications of LiDAR to the masses.

April 15, 2019

Contact

Tina Gallo
Technical Glass Solutions
SCHOTT North America, Inc.

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