Sokkia AK17 Survey Accessory Reflection Big Single Prism for
Surveying Total Station
Model: AK17
Specifications:
A.Prism Constant: 0mm/-30mm
B.Type: Single Prism
C.Effective Diameter: 64mm
D.Weight: 1Kg
E.For: Total Station (Sokkia, Nikon, Trimble, Pentax, Topcon etc.)
F.Package: Soft Carrying Bag
G.Target Plate: Metal
H.Category: Optics Instruments Accessory
Features:
The single prism with target assembly allows the user to quickly
adjust the tilting target from behind the prism as it is pointing
at the instrument to allow accurate sighting.
The prism can be either mounted in a 0 or -30mm offset position.
Prism Range
Surveying Prisms, also known as retro-reflectors, redirect a
measuring beam back to the EDM (Electronic Distance Measurement)
for processing distance. There are two main factors for good range
measurement: prism diameter and beam deviation. If the beam
deviation is not accurate then the returned beam will miss the EDM
completely. This occurs mainly near the maximum range of the EDM.
Prism Holder Accuracy
Prism accuracy is determined by the physical location of the prism
in its canister and then to the prism holder. Certificates of
compliance are available upon request.
Survey Prism Offsets
Some Surveying Prisms have an offset due to the fact that the
transmitted beam from the EDM takes longer to enter and exit the
prism. The longer time translates to a longer distance measured.
The distance is corrected by using an 'offset' and/or positioning
the prism in relationship to the plumb line of the prism holder.
Common offsets are 0, -17.5 mm, -30 mm, -34 mm, and -40 mm. The
offset is determined by multiplying the height of the prism against
the refractive index of the glass used.
