A Spherically Mounted Retroreflector (SMR) is a special type of reflector prism used in surveying and metrology to measure the position of objects with high accuracy. The SMR consists of a spherical reflector mounted on a specially designed holder.
The principle of measurement with an SMR is based on the reflection of light from a laser rangefinder. The rangefinder sends a laser beam to the SMR, which reflects the light back to the rangefinder. The distance is calculated from the time it takes for the light to travel from the rangefinder to the SMR and back.
The SMR provides high accuracy in distance and position measurements because it has a very small reflecting surface and reflects the light directly back to the rangefinder without any scattering or other errors. The holder of the SMR is designed to position and fix the reflector with high precision.
SMRs are commonly used in geodesy and construction to measure the position of buildings, bridges, tunnels, and other objects. They can also be used in the automotive industry to determine the position of vehicles, especially in robotics and autonomous vehicle navigation.
There are various types of SMRs that are optimized for different applications. Some have additional features, such as a built-in laser target point, which helps the user to locate and align the SMR from a distance. Others have a particularly robust construction to protect them against vibration or environmental influences.