Chapter 7  Squareness Measurements in a Vertical Plane
Aligning the Laser Beam to the Machine’s Travel Path for the Second 
Axis Measurement
7-22 Measurements Reference Guide
17 If you cannot get the return beam to enter the upper port using step 16, 
follow these steps:
a. Repeat steps 8 through 10 in the last section, “Mounting the optics.”
b. Repeat steps 1 through 15 in this section.
When the beam enters the upper port of the laser head, you are ready to 
align the laser beam to the machine’s travel path.
Aligning the Laser Beam to the Machine’s 
Travel Path for the Second Axis Measurement 
Before using the following instructions, make sure that the turret ring on 
the laser head is set to STRAIGHT and the large opening is in place over 
the upper aperture.
To align the laser beam to the machine’s travel path, follow these steps:
1 While watching the two dots on the optical square’s surface, move the 
interferometer away from its start position.
As you move the optic, the two dots in the optical square’s slot separate 
(Figure 7-12). Your goal is to make sure that (1) they remain in the plane 
of the midpoint notches on the optical square and (2) both dots remain at 
an equal distance from the center of the slot.
• If the two dots on the optical square’s surface begin to move out of this 
pattern, tilt the laser head vertically or rotate it left and right to 
adjust the dots to their correct position.
• If the beam from the turning mirror moves out of the alignment ring 
on the retroreflector, translate the laser head vertically or horizontally 
until the beam reenters the ring.