Laser sensors detect targets or objects and produce an electronic output signal, usually a pulse. They are used to detect distances, particularly when things cannot be seen by any other means; they can also detect rare events, such as leaks from pipelines or water pipes. Lasers can also be used for purposes other than distance measurement, such as controlling actuators and/or detecting hazardous material.
Many applications of laser sensors exist today but can be classified into different groups. This article will introduce each group’s laser sensors and how it works in various environments.
Industrial lasers are widely used as material-processing tools. They are used to harden, weld, and cut materials, including steel, glass, and plastic. Lasers can also be used to detect flaws in materials and workpieces. The reflection of a laser beam can detect metal defects such as grain distortion or skin contaminants; the absorption of the laser signal can see glass grinder burns. Laser sensors are also frequently used for inventory control, especially for parts that require high precision in their dimensions.
Laser sensor technology is often used to detect defects in nuts and bolts. Lasers can see flaws, such as thread voids and threaded parts damaged by their threads breaking or by the bolt head breaking during assembly. Laser sensors also allow the machining of alloys in which the laser beam is absorbed, eliminating the need to grind alloys with a particular grain structure, thus producing better alloys with more yield strength.
Industrial lasers are very powerful tools; they are usually fed by high-voltage power supplies (such as transformers), making them sensitive to voltage fluctuations on the supply lines. These laser products are often very large and heavy; therefore, they must be installed on dedicated machines.
Medical laser technology primarily produces light-induced effects, including coagulation for controlling bleeding, cutting for removing skin or other tissue, and vaporization for destroying diseased tissue or tumors. Medical lasers also remove tattoos, causing the tattoo ink to collapse into an insoluble crystalline form.
Medical laser products are typically high-voltage devices but usually medium-energy ones with smaller spot sizes and wavelengths. Medical lasers should be installed in an area that is well-ventilated because of their intense power output.
Civil engineering applications
Civil engineering applications include several types of laser sensors. The two primary types of civil engineering lasers are the ranging and tracking devices that measure the distances to humans, buildings, or other stationary targets. Other civil engineering laser products, such as water leak detectors, detect hazardous liquids and gas leaks.
Civil engineers also use high-powered lasers to heat targets, such as soils, to improve their ability to support foundations. Various sensors can be used simultaneously: ranging and tracking laser sensors can be used simultaneously with radar systems for locating artificial objects; only a few miles may be covered by using both methods together.
Environmental and scientific applications
Environmental and scientific laser sensors are used to observe, measure and record the many natural factors contributing to various conditions on Earth. These include: detecting the presence of chemical materials, measuring the speed of particles in gases and liquids, lighting up subjects for detailed observation, calculating surface temperature, and determining wind speed.
The chief use of lasers in these applications is detecting or analyzing chemicals. A laser can be used to measure the concentration of a chemical in gaseous or liquid phases by using both absorption and emission spectroscopy methods. The laser is used as a sampling probe for drawing samples into its beam for analysis. The chemical is then identified using the wavelength or wavelength combinations of the sample’s characteristic peaks in the laser light.
Emerging laser applications have yet to be used widely but have shown considerable promise. Laser-based range finders are being used for several emerging applications. One is monitoring atmospheric greenhouse gases to ensure compliance with the Kyoto Protocol and to watch for any changes in concentration. Another application is monitoring dust and ash particles in volcanic eruptions so that an early warning might be given if new storms or tsunamis are on the horizon.
Another emerging use of lasers is in laser printing/writing technology, where a powerful laser beam is directed into a photoresist material; it then erases or changes areas on a surface by liquefying those areas of the photoresist. This process is extremely slow to change large surfaces.
A laser generates a beam consisting of an oscillation or radiation of light at one frequency (wavelength). The most common optical frequencies used are near-infrared and visible light. Lasers are used in a variety of applications. They can be either continuous waves or pulsed; endless waves emit light constantly, while pulsed lasers emit short pulses of light on and off.
Laser beams are generally focused on an area by mirrors or lenses, but they may also be created in free space with the help of optical cavities.
Advantages and limitations of laser sensors
The advantages and particularities of laser sensors can be summarized as follows:
Besides the advantages of lasers in industrial, medical, and scientific applications, their applications in civil engineering and environmental science are gaining importance. This is because of the unique characteristics of these fields (high sensitivity to distance and light intensity) that make laser sensors very useful.
Also, another limitation of laser sensors is that they often rely on external power supplies or vacuum pumps to generate the high voltages required for operation. For example, a typical measurement will need a current input equal to 10 or 15 mA; this value may be several orders of magnitude greater than the current value provided by a standard 1.
With the growing importance of applications in environmental science and civil engineering, there is also an increasing demand for high-performance laser sensors to be used in these fields. As shown above, various types of lasers are available for use in multiple applications. Lasers are becoming popular instruments because they provide reliable measurements within minutes at high levels of accuracy, with low noise and no need to contact the objects being measured.
There are numerous advantages of using lasers in various fields; the main benefits include the following.