Commonly used flatness measurement methods are wired laser, two-dimensional laser and 2D laser scanning sensor. When measuring with two-dimensional laser, the high-end sensors will give the measured values in the width and height direction (for example, the Iridium scanCONTROL series of Inter Milan, Germany, and many other brands of sensors do not give the original data). These measured values are matched with the motion information in the front and back direction, and are usually input by an encoder, so that three-dimensional data can be obtained.

Generally, the highest value on the whole surface minus the lowest value is considered as flatness. Of course, there are also algorithms such as average and variance. Verify that the line laser is also reciprocating, and calculate the repeatability of each measurement position. If the repeatability is good, the laser sensor is stable. The specific requirements are still required by the customer, and whether it can be realized can be negotiated with the sensor manufacturer. I hope it helps!