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High Precision Single Surveying Reflector Prism Total Station Accessory

Model: AK16

Item Overview:

Plastic frame.

Leica type of connector (no threads).

Does not have a 5/8 x11 thread.

Single tilt prism with soft bag

Circular prism sealed in red polymer holder. Large integrated target plate provides good visibility.

Specifications

Lifetime
High quality prisms have longer lifetime. In contrast to many conventional prisms, the reflective copper coating on the reverse side of high quality prisms consists of a support coating, a vacuum-metallised copper coating, a protective coating and an overlying coat of lacquer. The special adhesive lacquer protects the underlying layers from corrosion and detachment. Working together, the copper coating and the lacquer increase the life of the prism significantly. An additional anti-reflex coating on the sensitive front surface of the prism provides a tough resistance to scratches. The production process of these coatings is so complex that only a very few manufacturers worldwide meet the requirements of high standard prisms.
 

Survey Prism Offsets

Retro-reflectors (or corner cube prisms) used with electronic distance measuring (EDM) instruments have an offset because the transmitted light beam from the EDM takes longer to enter and exit the prism. This longer time translates to a longer distance measured. This distance is corrected by using an 'offset' and positioning the prism in relationship to the plumb line of the prism holder. The offset is determined by multiplying the height of the prism by the refractive index of the glass used. Common offsets are 0, -17.5 mm, -30 mm, -34 mm, and -40 mm.

A nodal offset on a surveying prism 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 surveying prism has a nodal offset. Surveying 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.

For high accuracy surveying it is recommended to use a round prism instead of a 360o prism if you are using a robotic total station. A Nodal Point prism should be used for high accuracy traversing and layout work.

Optical Surveying Reflector Prism Applications

Surveying reflector prisms are used by surveyors and engineers to measure the change in position of a target that is assumed to be moving. Survey prisms are used for a wide range of monitoring applications including:

1. Rail Monitoring
2. Settlement Monitoring
3. Displacement Monitoring
4. Deformation Monitoring
5. Convergence Monitoring

Packing and Details