Measurement of parallelism is based on two sets of straightness measurements. The first straightness is measured, then the laser beam is bent by two optical squares exactly by 180 degrees and the second straightness is measured. The parallelism error is calculated.

Parallelism set LS 132

Both the LS 12 and LS 10.1 lasers can be used. The LS 130 straightness set and LS 131 squareness set are used.