LiDAR

From ancient times to the present day, mankind has continuously invented new technologies & tools for their comfort and progression. Be it fire, be it a wheel, be it electricity, be it a computer, be it internet, be it a mobile or the latest LiDAR laser technology.

InPhenix offers a broad range of products and services for Light Detection and Ranging (LiDAR) systems.

Autonomous Vehicles is a field where new companies and systems are emerging every month. Wind Turbines are now a major growth area in the Energy sector. And 3D Scanning systems are changing the way factories operate.

In such rapidly evolving markets, it is vital for your business to acquire distinct technological advantages over your rivals to survive and excel.

InPhenix offers High Power VCSELs, fast SOA switches and Narrow Linewidth DFB lasers in key wavelengths such as 850nm, 905nm, 940nm, 1310nm and 1550nm for a wide variety of Time of Flight (TOF), Frequency-Modulated Continuous Wave (FMCW), Flash and Doppler LiDAR systems.

Our strong customization capabilities and flexible manufacturing processes allow you to quickly design and build unique LiDAR systems which will outperform your competitors.

Lidar Laser

 

 

 

 

What is LIDAR?

LiDAR stands for Light Detection and Ranging. LiDAR devices accurately measure distances to a target(s) and its speed by illuminating this target with a laser beam and then processing information from the reflected light. These reflection measurements can be used for many applications such as scanning objects, measuring speed, mapping large expanses of terrain, as well as providing data on a car’s surroundings for autonomous navigation (Advanced Driver Assistant Systems (ADAS), and much more. How does this terrific technology work?

Distance measurements

1. Amplitude modulation method (Time of Flight)

LiDAR relies on a highly directed laser beam. In air-light travels at a practically constant speed of light. This is basically the universal speed limit, and clocks in at about 3×108 m/s. This can be used to determine the distance of objects in a method called a time of flight (TOF). When a LiDAR system emits light, typically from a pulsed (Amplitude Modulated) laser diode, it will start an internal clock. This pulse of light will travel the distance to an object and then some of the light will scatter on and reflect from the object, and travel back towards the LIDAR system, where it will be registered by a photo-detector. When the light hits the photodetector, it tells the clock and hence the total amount of time is accurately measured. Because we know how fast the light traveled, and the time it took to travel the distance between the system and the object twice, we can calculate the distance to the object. In order for distance to be precisely measured, the timing mechanism should be really fast. For example, if there were an object 100 meters away, it would take about 0.7 microseconds for the light to get there and back.

Typical time-of-flight LiDARs using 905nm lasers are limited to a range of 100 meters due to eye-safety acceptable emission limits (AEL) of International Electrotechnical Commission (IEC) regulations, thus limiting their use.

2. LIDAR MAPPING

The mapping strategy in most current LiDAR systems uses TOF imaging where the relative proximity of an object is determined by how fast the photodetector receives an optical signal reflected from its surface.  However, one of the underlying limitations of TOF is a limited field of view even if an array of lasers is used instead of a single laser. Therefore, a scanning mechanism is required in order to reproduce a 3D image that, in the case of ADAS Lidar, depicts the roads, pedestrians and other stationery or moving objects.

The first generation of automotive LiDAR systems used mechanical scanning systems to achieve 360o view coverage at distances up to 300 m. Alternatively, a galvanometric system can be used to shift mirrors that quickly scan a static laser beam both horizontally and vertically. Mechanical scanning systems have a proven track record and their sensors performs better when placed higher on the vehicle. However, because they are bulky, they are not aesthetically pleasing and are challenging to integrate into a car’s design.

The bulky architecture of mechanical scanning can be scaled down using micro-electro-mechanical systems (MEMS) that employ laser beam scanning at the micro-level inside of the microchip.

Many experts see mechanical and micromechanical LiDAR systems as a transitional technology before more reliable solid-state LiDAR systems become widely available.  The potential advantages of fewer moving parts, better reliability and lower power consumption are clear.

Flash LiDAR is currently one of the most advanced solid-state technology. In this approach, the laser beam is spread out to illuminate an entire scene in a single burst, similar to a camera flash, and the reflected signal is then collected and processed to recreate a complete 3D scene. Such systems are fast and durable against shock and vibration, but they require more sensitive detectors to capture the lower amount of reflected light compared to mechanical scanning systems making them vulnerable to confounding background noise.

Another approach within the solid-state LiDAR technology is to use vertical-cavity surface emitting lasers (VCSELs) for more efficient scene illumination with each burst. These very compact light sources irradiate perpendicular to the substrate rather than laterally like traditional edge-emitting lasers do. Coupled with arrays of ultrasensitive single-photon avalanche diodes, VCSEL-based Lidars enable solid-state systems with extremely compact form factors.

On the laser front, LiDAR companies are also exploring other refinements including longer-wavelength light sources. Traditionally the standard wavelength for LiDARs is 905 nm because of laser diode technology developed for the telecommunication industry. This wavelength has an excellent response from silicon-based photo detectors. However, this wavelength can be also damaging to the human eye, limiting the output power the laser can safely emitand as a result limiting range detection and resolution.

Coherent light at near-infrared (NIR), 1310 nm and 1550 nm, is much safer even when pumped out at high energy levels. Although, NIRdiode lasers are more expensive than 905 nm sources and require costly specialized photodetectors based on InGaAs rather than silicon, NIR diode lasers provide longer detection ranges and higher resolution.

NIR diode lasers are also a critical building block for frequency-modulated continuous-wave (FMCW) LiDAR, an emerging alternative to TOF-based LiDAR. FMCW LiDAR uses tunable lasers that continuously project a laser beam while incrementally shifting the frequency of illumination. By analyzing the frequency of reflected signals, FMCW LiDARS can determine the presence of obstacles at much longer ranges due to the higher power permitted given the eye safety of 1550 nm lasers. Moreover, FMCW LiDARS can also calculate the speed at which those objects are moving relative to the vehicle.

APPLICATIONS OF LIDARS

Our presentation so far has been focused on LiDARs applications for autonomous vehicles. However, LiDAR applications are not limited only to the automotive industry.

Military:

The military uses LiDAR technology for automated target identification, Airborne Laser Mine Detection System and stand-off detection for biological warfare agents. With LiDAR, the military has the option to use longer wavelengths so their equipment is undetectable to night vision goggles. LiDAR also plays a large role in the military’s autonomous vehicles. The military takes advantage of autonomous off-road vehicles to scout and carry supplies.

Oceanography:

When scientists want to know the exact depth of the ocean’s surface to locate any object in the case of a maritime accident or for research purposes, they use LiDAR technology to accomplish their mission. In addition, LiDAR is also used for calculating phytoplankton fluorescence and biomass in the oceansurface (a challenging task without LiDAR).

Digital Elevation or Terrain Model:

Terrain elevations play a crucial role during the construction of roads, large buildings and bridges. LiDAR technology provides x, y and z coordinates, which makes it incredibly easy to produce 3D representations of elevations.

Agriculture & Archaeology:

Typical applications of LiDAR technology in the agriculture sector include analysis of yield rates, crop scouting and seed dispersions. Besides this, it is also used for campaign planning, mapping under the forest canopy, and much, much more.