The Flat Plane - Penta Prism

The geometry laser generates a flat plane, which is accomplished by using a device called the Penta Prism. The penta prism acts as a deflector to the incoming laser beam through a precise 90° angle. If the penta prism is mounted on a set of precision bearings and rotated, it generates a very flat laser plane. In a 50-foot radius .001" accuracy can be obtained, in a shorter radius, or if the laser is set in one corner and the sweep plane is limited to 90 degrees .0001 accuracy's can be possible over the entire area.

The L-723/L-743 has a penta prism in each turret to generate a flat plane in relationship to the axis being measured. Models P-403 & P-405 optical squares also utilize the penta prism to create a 90 degree angle.

This style of prism is referred to as a compensating prism. If the prism is rotated or shifted the right angle that is generated by the laser beam will not change as it enters and exits the penta-prism. The accuracy of the 90 degree angle is built into the prism and will not change.

As the illustration shows the laser beam is still produced at 90 degrees even though the penta prism is tilted.