What are Laser Headlights?

The next generation of automotive lighting technology could be laser headlights. Some major automakers are already using them. Laser headlights (or laser headlamps) are part of an advanced headlight system, which are brighter, more energy efficient, and allow drivers to see much further in the dark (so any oncoming cars can be spotted much sooner).

Laser headlights are the latest in headlight technology, which has continued to advance significantly from halogen lights and xenon bulbs to light-emitting diodes (LEDs). LED lights have been adopted for all the interior and exterior lighting for some vehicles.

Laser headlights are an advanced headlight system that uses simple blue laser diodes focused from the laser light source onto a lens with a yellow phosphorus surface to produce bright light.

For some lighting devices, a red phosphor can be used, but a yellow phosphor is used for headlights. The blue lasers are positioned to focus on a mirror system, with all the laser energy then focused on the yellow phosphor surface.

The process works based on the principle of stimulated emission, with the combination of the blue light beam and yellow phosphor on the lens producing an intense white light. The brightness and specific color of the white light is governed by the ratio of the blue laser beam and yellow phosphor. This light is then shone backwards onto a reflector, which then reflects white light out to the road in front of the headlight. The high power of laser headlights means that they help to make night driving safer for drivers because they reduce the reaction times required for any oncoming traffic.

Laser headlights have not gained the momentum that was expected by car manufacturers, but they still have some use cases already. In fact, they are already being used by some major automakers such as BMW and Audi.

Beyond economic barriers to large-scale adoption, there are two main reasons for lower than anticipated momentum. The first reason is the introduction of the U.S. Federal Motor Vehicle Safety Standard rule 108. This rule introduced a limit on the headlight power on vehicles sold in the U.S. to only 150,000 total candela. In Europe, up to 430,000 total candela is permitted, stunting the adoption in the U.S. market.

The second reason is the introduction of Adaptive Driving Beam (ADB) headlights in 2022 to the U.S., which offered a simpler alternative option using existing LED technology that can control the light beam from the headlight with a lot higher accuracy than standard LED headlights.

Adaptive LED headlights require more complexity than LED lights — as they require micro-mirrors or microelectromechanical systems (MEMS) — but are more versatile and safer to operate with existing LED headlights. While laser headlights offer brighter lights, a lot of the focus in new headlight designs has centered around controlling light beams, rather than making them as bright as possible.

However, laser headlights are being integrated into high-end vehicles because they are currently too expensive to use in all vehicles that might benefit from the improved performance.

Today, laser headlights are being used as the high beam only, while conventional LED lights are used as the low beam. Laser headlights will only come on when there are no cars within a certain distance and speed thresholds have been reached (about 45 mph or 72 kph). So, laser headlights are currently used in a hybrid format with LED lights, but it might be possible in the future to create headlights where the low and high beams both use lasers — though the low beam would have to be a low-power laser.

Aside from headlights, lasers have the potential to be used in many different automotive lighting applications inside and outside of the vehicle, just like LED lights are today, including in near-field projectors, glass displays, and aesthetic lighting. This lighting is slightly different in that the blue laser light passes along an optical fiber with a yellow phosphor jacket. So, as the laser passes along the fiber, it creates white light along the fiber.

There have been concept vehicles developed, such as the Lotus Theory 1 electric vehicle (EV), which use laser lighting for multiple functions. The car was developed alongside Kyocera who used their superluminescent diode (SLD) lasers as part of both the internal and external lighting. In addition to the white headlights, signature lighting inside the vehicles was created using lasers coupled to an optical fiber, and the car also featured red laser taillights on the back of the car.

Laser headlights are a more advanced automotive lighting system than others that have come before it. However, while there are a number of advantages to their use, there are still some limitations that have hindered their widespread adoption in the automotive industry.

Advantages of Laser Headlights:

• Increase visibility up to a half a mile (800 meters) ahead of the vehicle to improve reaction times for the driver
• Use less energy than other car headlights, making it a more energy efficient headlight system
• Reach much higher lumen levels with fewer watts of power than other headlight technologies, reducing energy consumption
• Versatile in design and can be used for a lot of different types of automotive lighting, much like LED technology today
• Deliver good longevity, lasting for around 10,000 hours
• Can be integrated into existing LED-based headlight systems
• Compact size of 1/100 of an LED element enables designers to provide better aesthetics for higher end cars by offering flexibility for compact designs

Limitations of Laser Headlights:

• High costs compared to LEDs and other automotive lighting technology — currently 3-4 times the cost of LED technology
• Require advanced safety features to protect people from being blinded by laser light. This is for both operations on the road and in manufacturing environments where the headlights are handled by different personnel
• Require advanced sensors for ensuring safe operation on the road, further increasing costs
• Select number of manufacturers that supply laser headlights
• More parts are required because headlights with over 2000 lumens need a washer for the headlights (although this is true for all high-power headlights, not just laser headlights, but lasers are more likely to reach higher levels more frequently)
• Could be limited by how much brightness is required from vehicles, so the additional costs may not be justified for many automakers, leading to LED technology continuing to be the preferred option
• More complex technology incorporated than other headlights
• Compete against more conventional LED technology that continues to be developed and innovated in different ways — such as adaptive headlights that have become the preferred option
• Unable to be activated unless the vehicle is traveling above a certain speed threshold or in certain driving conditions
• Slow adoption of laser headlights predicted based on regulatory requirements 

While a number of the advantages and limitations of laser headlights are in direct response to LED headlights — as they are the current gold standard being implemented into new cars — the table below shows the main differences between the two lighting technologies.

Lasers are a complex light source, and multiple tools need to be combined to simulate the laser, its properties, its propagation from the diode, and the use of the laser in the vehicle environment. This is because it is a coherent light source with specific properties that need to be simulated as a complete system. Ansys has a range of optical and non-optical simulation tools to look at the behavior and performance of laser headlights as noted below.

Ansys Lumerical FDTD advanced 3D electromagnetic FDTD simulation software: Used to characterize the laser beam itself and model the optical properties of the beam before considering its properties at a component and wider system level.

Ansys Zemax OpticStudio optical system design and analysis software: Takes the laser beams developed in Ansys Lumerical software and assesses how the diodes and headlights work and behave at a component level to ensure that they have the right performance and projection into the road, and the light from the headlights is behaving as expected.

Ansys Speos CAD integrated optical and lighting simulation software: Integrates data from Ansys Lumerical and Ansys Zemax OpticStudio software to simulate how the laser headlights behave on a system level, taking into account many different driving scenarios to ensure that they pass regulations.

Ansys Mechanical structural finite element analysis software and Ansys Icepak electronics cooling simulation software: Used to measure the heat given off by the lasers during normal operation to ensure that it will not be high enough to cause any operational issues or damage to the components.

Ansys AVxcelerate Headlamp automotive headlamp testing software: Used to simulate and test how headlamps perform in different real-time driving scenarios.

Even though laser headlights have not been as widely adopted as first thought, there is still a lot of interest in developing them further in the future. If you’d like to discover how you can use simulation to develop cheaper and higher performing laser headlights, then get in touch with our technical team today.

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