[Introduction]LiDAR (Laser Detection and Ranging, LiDAR) has become a key technology in ranging applications. As the technology becomes more mature and product prices become more reasonable, its applications are becoming more and more extensive. This article will introduce you to the development of LiDAR technology, as well as laser diode solutions from ROHM.
LiDAR technology that can accurately sense the distance between objects
LiDAR is an application that consists of ToF (time-of-flight) systems (light source and ToF sensor or image sensor, etc.), etc., used to sense the surrounding situation, usually through a beam of pulsed lasers to measure parameters such as the distance of the target. Lidar has applications in surveying and mapping, archaeology, geography, geomorphology, seismology, forestry, remote sensing, and atmospheric physics. In addition, this technology is also used in specific applications such as airborne laser mapping, laser altimetry, and lidar contour mapping.
The most basic working principle of lidar is no different from that of radio radar, that is, a signal is sent by the radar transmitting system, reflected by the target and collected by the receiving system, and the distance to the target is determined by measuring the running time of the reflected light. Because the speed of light is known, the distance between the laser and the object can be calculated according to the time difference between the time when the emitted light is emitted and the time when the backscattered light is received. This is the principle of LiDAR ranging.
Laser diode (LD) is one of the key devices of lidar. It is a kind of laser generator. Its working material is semiconductor, which belongs to solid-state laser generator. Most laser diodes are similar in structure to general diodes. This kind of Electronic device appeared as early as 1962. In the early days, it could only emit low-brightness red light. Later, other monochromatic versions were developed. Today, the light that can be emitted has spread to visible light, infrared light and ultraviolet light, and the brightness has also improved. To a considerable degree, laser diodes have the advantages of high efficiency, small size, and long life.
Farther, more accurate and lower power laser diodes
In recent years, LiDAR, which can accurately measure distances and recognize spaces, has become increasingly popular in a wide range of applications that require automated work, such as robot vacuums, AGVs (autonomous vehicles for industrial use), and autonomous vehicles. In this context, in order to be able to detect information farther, more accurately, and with lower power consumption, there is a higher requirement to improve the performance of laser diodes as light sources.
ROHM, a world-renowned semiconductor manufacturer, has been developing and supplying FP laser diodes including LEDs and VCSEL (Vertical Cavity Surface Emitting Laser) products, which have recently been used in applications such as ToF sensor light sources in cleaning robots and surveillance cameras. increasingly popular.
At the same time, ROHM continues to promote the development of optical components to maximize the performance of components and further improve the output power using the development experience and technology of optical components accumulated in the process of launching various products. Through the development of components and their application in modules, ROHM has also developed a number of sensor light source products with their own advantages, which have contributed to improving the accuracy of distance measurement and space recognition systems.
75W high output power laser diode
A few days ago, ROHM has developed a high output power semiconductor laser diode – RLD90QZW3, which is very suitable for AGVs and service robots in the field of industrial equipment equipped with LiDAR for ranging and space recognition, and sweeping robots in the field of consumer electronic equipment and other applications.
ROHM already has its own patented technology that enables narrower laser linewidths, helping LiDAR support longer distances and achieve higher accuracy. The 25W high output power laser diode RLD90QZW5 has been mass-produced since 2019 and is increasingly used in applications mainly in the field of consumer electronics. This time, ROHM has developed a 75W high-output laser diode RLD90QZW3 in order to expand its application to the growing market of industrial equipment.
The RLD90QZW3 is an infrared 75W high output power laser diode developed for LiDAR using 3D ToF systems for ranging and spatial recognition. Utilizing ROHM’s own component development technology, an ultra-narrow line width of 225µm has been achieved among laser diodes with the same output power in the industry. Compared with ordinary products with a line width of 290µm and a temperature dependence of 0.25nm/℃, the line width is narrowed by 22%. %, achieving high beam performance.
At the same time, by making the luminous intensity more uniform and utilizing the low temperature dependence of the laser wavelength, the temperature dependence of the laser wavelength is as low as 0.15nm/℃, which can be reduced by 40% compared with ordinary products, and is not easily affected by temperature changes. As a result, high performance can be achieved stably, thus helping LiDAR to achieve long-distance applications in various environments, and in the case of equal measurement distances, it also contributes to achieving and higher accuracy. In addition, the photoelectric conversion efficiency (PCE), which has a trade-off relationship with the narrow line width, has also reached 21% of that of ordinary products (when the forward current is 24A and 75W output), so there is no need to worry about the increase when using the RLD90QZW3. power consumption. For more information, please visit the RLD90QZW3 product page: https://www.rohm.com.cn/products/laser-diodes/high-power-lasers/rld90qzw3-product.
Currently, ROHM is developing laser diode products with high output power of 120W and automotive grade (qualified to AEC-Q102). In the future, ROHM will continue to contribute to the development of safe and convenient LiDAR application products including in the automotive field.
Diverse support tools accelerate product development
In order to assist customers in the development of new products and support the rapid introduction of products into the market, ROHM provides a wealth of design data for evaluating and importing new products on its official website free of charge, including application guides containing driving circuit design methods, data for circuit board development and Models for simulation (SPICE model, Ray data), etc.
In addition, ROHM has also introduced a single-channel LiDAR (REFLD001) reference design, a single-channel LiDAR demonstration board that allows you to check the operation of high-speed optical front-ends using LiDAR ToF range technology, measuring distances up to 50m.
The REFLD001 reference design is based on LiDAR ToF technology and is easy to use for further development by customers. In addition, low-power long-distance measurements can be achieved through high-speed switching. REFLD001 adopts ROHM 905nm 75W RLD90QZW3 invisible laser diode, which can support long-distance measurement, provide more power-saving 15nsec pulsed laser under the same LD power condition, and all systems are powered by a single power supply. The LiDAR ToF architecture can be applied to automotive and consumer and industrial machinery fields, and can be widely used in LiDAR lidar, distance measurement tools, security sensors/proximity sensors, BIM (Building Information Modeling), parking assistance systems, robotic vacuum cleaners, AGVs and other products.
With the introduction of high-power laser diodes, the performance of LiDAR applications has become better and better, and the market acceptance has gradually increased. The infrared 75W high output power laser diode launched by ROHM has higher precision and lower power consumption, and provides complete technical support, which will be a better device choice for LiDAR applications.
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