There are two types of calibration methods for the flatness of assembly platforms: direct measurement method and indirect measurement method.

The direct measurement method of assembly platform is to directly obtain the deviation value of each point on the plane or directly evaluate the flatness error value.

This measurement method can directly obtain line value results, so it is also called line difference method.

There are various measurement methods that belong to this category, such as the padding method with a straight edge or flat edge, the marking method with a standard assembly platform, and the laser collimator measurement method.

The indirect measurement method for assembly platform flatness is to use a level or self aligning instrument to measure several measurement sections on the measured plane using the pitch method;

Obtain the inclination degree of each measured point relative to the measurement reference (horizontal plane or optical axis line);

When obtaining the final result, convert the quantity value represented by the angular value to the quantity value represented by the line value.

The value read from the instrument by this method is the angle value, so it is also called the angle difference method.

There are two methods that belong to this category: the level method and the autocollimator method.