Leica GPR1 Single Circular Prism Precision Round Reflector Survey
Prism
Model: GPR1
Introduction:
The GPR1 is Leica’s standard round prism, and is arguably the
finest surveying prism made today.
The Leica GPR1 Single Circular Prism is a precision round prism
that easily snaps on to prism poles. It features a centering
accuracy of 2.0 millimeters with zero millimeter offset. The GPR1
is manufactured from high-quality optical glass for increased range
and accuracy.
This Leica round prism’s surface is coated with anti-reflection
copper which also improves reflectivity and prevents adverse dirt
or condensation.
It is compatible with Leica GLS111 reflector poles and perfectly
fits the Leica GPH1 and GPH3 round prism holders.
Features:
- 62 mm diameter
- 0 mm offset
- 2.0 mm centering accuracy
- Anti-reflection copper coating
- High-quality optical glass
- Compatible with Leica GLS111 reflector poles
- Fits Leica GPH1 and GPH3 round prism holders
Nodal Offsets
A nodal offset is defined by the relationship of the prism holder
and prism that places the optical center of the prism on the plumb
line of the holder. This offset is the most advantageous at close
range work when the apex or center of the prism is used as a
pointing target for vertical and horizontal angle measurement.
Every prism has a nodal offset. Prisms and holders that are not in
the nodal position, however, can cause angular errors when using
the prism apex as a target if it is not perfectly pointed toward
the measuring instrument.
To reduce pointing errors, several prism assemblies are designed
with a nodal point alignment at -17.5 (for 25 mm prisms) or -40 mm
offset (for 62 mm prisms).
Commonly, the best reading of the beam is achieved when the prism
face is perpendicular to the incoming beam for a parallel return.
To compensate for pointing errors, nodal point alignment minimizes
the error associated with misalignments
