In discrete applications, repeatability and Minimum Object separation are two specifications used to describe sensor capabilities.
But not all specifications are equal indicators of real-world performance; let's break it down.
Repeatability is the measurement of how reliably a sensor can repeat the same measurement in the same conditions. Repeatability is calculated by having a sensor detect a motionless, single-color target multiple times in a laboratory setting. For that reason, repeatability is a useful specification to use when comparing products, but it is not the best indicator of real-world performance.
Minimum Object Separation.
Minimum Object Separation, or M.O.S., refers to the minimum distance a target must be from the background to be reliably detected by the sensor.
M.O.S. is the more valuable specification for discrete applications because it captures dynamic repeatability by measuring different points on the same target at the same distance, giving you a much better idea of how the sensor will perform in the real world.