LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser is a powerful source of light with properties that are not found in normal light sources. Laser sensors offer long ranges of detections and high resolutions. They are good at accuracy, speed and reliability. They work at temperatures irrespective of variations. Lasers occur in various mediums such as solid, liquid, gas and semiconductor.
Laser is an electronic diode that converts an energy source into a thin and concentrated beam of light, which is used to detect very small objects or to reach very high distances. The laser sends a beam of light from the transmitter to the target. A receiver has a photoelectric sensor and collecting lens that detects the reflected light from the target at an angle without the use of a reflecting surface such as a triangular prism. Laser sensors are coherent which makes the beam of light narrow and easy to focus on the target object.
Simple geometric relationship is the theory behind laser sensors. It is calculated using trigonometric formulae. The distance can be evaluated accurately using simple mathematic calculations. The resolution of the laser beam depends on the design of the sensor. The laser beam emitted by the diode is aimed at the target and reflected on a CMOS array. Point type laser sensors are popular in the market as they are simple to use. They operate at high temperatures and harsh environments. They are known to accurately detect minute objects in the size of the mounting clip.
Laser sensors are non-contact by design which prevents the target object from damage or distortion. The range depends on the angle at which the transmitter projects to the receiver. The accuracy of the range depends on the divergence of the beam. Hence, accuracy can be obtained by considering the average of various divergence of the beam and determine the angle which is suitable to project the laser beam. Light beams travel long distances with a little convergence. This is one of the unique properties of laser sensors. Laser sensors produce radiation depending upon the wavelength at which the light beam travels. This radiation is produced in a particular direction. Lack of awareness of laser sensors can lead to dangerous eye hazards and skin infections due to the high intensity of laser beams. The intensity is so high that it can even melt diamond in a few seconds. Hence precautions must be taken while using laser beams.
One of the major limitations of laser sensors is that they consume a very large amount of energy to reach minor distances. Each sensor technology works differently and influences which type of objects the sensor is capable to detect. Laser sensors are suitable for reflective surfaces in a particular alignment only. The environment in the path through which the beam travels should always be clean as the dust particles and foreign bodies can influence the measurement of the laser beam. The sensor head should be oriented properly and mounted firmly in order to avoid expansion and contraction due to changes in temperature.
The cost of laser sensors depends upon many factors. The quality of the lens, design of the laser sensor and the purpose of use are a few factors. The cost of laser sensors might range from a few hundred dollars to thousand dollars. Laser sensors are used for space research, military systems, astronomy, communications, engineering, technolody, medicine and so on. These high-end lasers are very costly when compared to low-end laser sensors. In military, laser sensors are used to increase the length of the projection of missiles. Scientists are still investigating the alternate methods to prevent the dangerous effects of lasers.
Kasuya, T., and Tsukakoshi, M., Handbook of Laser Science and Technology (1988)
Meyers,Robert, ed., Encyclopedia of Lasers, 3d ed. (1989)
Steen, W. M., ed. Lasers: Invention to Application (1987)