Optical time of flight position sensors and instruments determine displacement and distance by measuring the time it takes light to travel from the instrument to a target and back. These sensors can use either lasers or LEDs as light sources. LEDs are often less powerful than lasers, limiting their effective distance. However, because LEDs are relatively weak sources of light, they do not have safety classifications and can be used in different applications than lasers can. The lasers in these sensors can be safety class I, II or III devices.
Some measurement methods analyze a single trip or a pulse of light while others calculate the measured range over a number of trips, using a continuous wave. For very long-range distance measurements (up to many miles) time of flight laser rangefinders with pulsed laser beams are used. The laser emits very brief, very intense pulses of light. The amount of time the pulse takes to reach the target and return is measured and converted to a distance measurement. The scan field for optical time of flight sensors can use a single point of light or a line, depending on the needs of the application.
Optical time of flight position sensors and instruments determine displacement and distance by measuring the time it takes light to travel from the instrument to a target and back. These sensors can use either lasers or LEDs as light sources. LEDs are often less powerful than lasers, limiting their effective distance. However, because LEDs are relatively weak sources of light, they do not have safety classifications and can be used in different applications than lasers can. The lasers in these sensors can be safety class I, II or III devices.
Some measurement methods analyze a single trip or a pulse of light while others calculate the measured range over a number of trips, using a continuous wave. For very long-range distance measurements (up to many miles) time of flight laser rangefinders with pulsed laser beams are used. The laser emits very brief, very intense pulses of light. The amount of time the pulse takes to reach the target and return is measured and converted to a distance measurement. The scan field for optical time of flight sensors can use a single point of light or a line, depending on the needs of the application.
Optical time of flight position sensors can have either visible or invisible light beams. Sometimes a visible beam can make the sensors easy to mount and aim at a target. Occasionally a visible beam can be undesirable. For instance, in a factory or processing center where a number of humans are working, a visible beam can be distracting and lead to accidents.
Some critical specifications for time of flight position sensors are measuring range and accuracy. Range resolution is also important, as is sampling rate. Resolution is the smallest change in distance that the sensors can detect. Outputs for optical time of flight position sensors can be analog voltage, current or frequency; digital TTL, serial or parallel signals; or even a switch or an alarm.
