Abstract
Modern LiDAR systems offer operation with two wavelengths: 905 nm and 1550 nm. The 905 nm wavelength is optimal for cost-effective solutions due to the availability of silicon detectors, making it ideal for compact and mass-produced applications. At the same time, 1550 nm provides greater range, accuracy, and eye safety, which is especially important for demanding applications in challenging environments. Utilizing both wavelengths allows for versatile and adaptive solutions suitable for mapping, construction, inspection, and other industries. The choice of wavelength becomes a key factor in achieving the best results and maximizing operational efficiency.
The following sections will be covered: “Introduction to infrared radiation,” “Features of 905 nm and 1550 nm infrared radiation”, and “The future of LiDAR and new technologies from Inertial Labs.” The conclusion will summarize the benefits of using 905 and 1550 nm LiDARs.
Section 1. Introduction to infrared radiation
Infrared (IR) radiation was discovered in 1800 by the English astronomer W. Herschel [1]. While studying the Sun, he sought to reduce the heating of the observation instrument. Determining with thermometers the effect of different parts of the visible spectrum, Herschel found that the “maximum of heat” lies behind the saturated red color and, perhaps, “behind the visible refraction.” This study marked the beginning of the study of infrared radiation.
Previously, laboratory sources of infrared radiation exclusively consisted of glowing bodies or electrical discharges in gases. Modern sources of infrared radiation with adjustable or fixed frequency have been created based on solid-state and molecular gas lasers. Infrared radiation is used in industrial, scientific, military, commercial, and medical applications.
Modern LiDAR systems are based on such sources, mainly in the IR spectrum. IR light is invisible to the human eye, typically detecting wavelengths between 380 and 700 nm. The IR range is from 750 nm to 1000 µm. The general classification is that near-infrared (NIR) is from 750 nm to 1400 nm, Figure 1. Shortwave infrared (SWIR) ranges from 1400 nm to 3000 nm, mediumwave infrared (MWIR) ranges from 3000 nm to 8000 nm, and longwave infrared (LWIR) extends from 8000 nm to 15000 nm (15 µm) [2].
Figure 1. Radiation spectrum.
The choice of a particular wavelength depends on the application and operating conditions. Below, we will examine the differences and features between today’s most popular wavelengths.
Section 2. Features of 905 nm and 1550 nm infrared radiation
Modern LiDARs can operate at one of the two most common wavelength ranges today to avoid the risk of damage to human vision. These are 905 nm and 1550 nm [3]. It is also worth noting that some lidars can use wavelengths other than those listed here, such as 903 nm. But there is no significant difference at such a slight difference.
So, let us consider the key features and differences of two different wavelengths:
The range is around 905 nm.
– Silicon detectors are suitable for this wavelength. They are widely available, low cost, and have been used in industry for a long time.
– Such lidar is cheaper to manufacture, making it a popular choice for many applications.
The range is around 1550 nm.
– Silicon is not sensitive to this wavelength, so Ge or InGaAs detectors are used, which are more expensive but are actively being improved. With technological advances, the cost difference between silicon and InGaAs is rapidly narrowing.
– At the same power, 1550 nm lasers are 40 times safer for the eye, allowing for more powerful emitters and longer detection ranges.
– Better collimation and less beam divergence.
– The size of the light spot at a distance of 100 meters is 4 times smaller than that of 905 nm. This increases the accuracy of object recognition.
– 1550 nm resists atmospheric influences (e.g., dust and fog) better, but worse in rainy and snowy weather.
– 1550 nm requires more power, which causes heat dissipation and autonomy issues if such a solution is used for aerial scanning with a drone.
Thus, LiDARs at 1550 nm are superior to 905 nm in terms of safety, detection range, and accuracy. However, they require more sophisticated technology and are higher in cost. The choice of wavelength depends on the specific task and application.
In conclusion, here is a table comparing the two different wavelength ranges, Table 1.
Table 1. Key comparison of two different wavelength ranges.
Therefore, despite its higher cost, 905 nm is chosen for low-cost solutions and moderate requirements—1550 nm – for applications with high range, accuracy, and safety.
Section 3. The future of LiDAR and new technologies from Inertial Labs
Suppose you are looking for a cheap, reliable, and versatile solution that can be mounted on drone vehicles and allow manual scanning. In that case, RESEPI (Remote Sensing Payload Instrument) with RTK and PPK support is your key to precise positioning and unrivaled data quality! The equipment has advanced NovAtel OEM7720 GNSS receivers, working with GPS, GLONASS, Galileo, and BeiDou systems, which provide stable signal reception regardless of conditions [4].
Figure 2. RESEPI Models.
Why choose RESEPI?
- Maximum accuracy. Equipped with LiDAR and RTK/PPK GNSS technology leader to create detailed 3D maps.
- Compact design. Lightweight and can integrate with many different drones.
- Ready for any task. Support 905nm or 1550nm LiDARs, adaptable to your environment and requirements.
- Full automation. Intuitive software simplifies data acquisition and post-processing.
Conclusion
Your specific applications and conditions determine the choice of lidar wavelength, 905 nm or 1550 nm. For compact, cost-effective solutions such as drones, 905 nm provides the best combination of cost and performance. When you need high accuracy, long-range, or challenging environments, 1550 nm lidars are the best choice due to their eye safety, resistance to atmospheric interference, and ability to work with high-power lasers.
RESEPI GEN II epitomizes versatility by supporting both wavelengths to meet various needs. This platform is ideal for mapping, surveying, construction, infrastructure inspection, and other industries. With its lightweight design, accurate GNSS RTK/PPK integration, and intuitive software, RESEPI GEN II allows users to maximize using advanced lidar technology.
With RESEPI GEN II, you get the flexibility to choose the optimal wavelength, access to state-of-the-art LiDAR solutions, and the ability to tackle any complexity with maximum accuracy. This versatile solution is your reliable partner for future projects!
References
[1] “Herschel Discovers Infrared Light.” Web.archive.org, 25 Feb. 2012, web.archive.org/web/20120225094516/coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities/herschel_bio.html.
[2] Wikipedia Contributors. “Infrared.” Wikipedia, Wikimedia Foundation, 23 May 2019, en.wikipedia.org/wiki/Infrared.
[3] Mendez, Maria. “What Is LiDAR? Transforming Industries with Precision Mapping.” Inertial Labs, 10 Sept. 2024, inertiallabs.com/what-is-lidar-transforming-industries-with-precision-mapping/. Accessed 2 Dec. 2024.
[4] “RESEPI – LiDAR Remote Sensing Payload Instruments.” Inertial Labs, inertiallabs.com/products/resepi-lidar-remote-sensing-payload-instruments/.
