0mm Prism Total Station Machine AK10 Total Station Survey Equipment

Reflector Prisma Topcon Type Prism Assembly Black and White Color Total Station Prisms

Model: AK10

Specifications:

Prism Constant: 0mm/-30mm

Type: Single Prism

Color: Black and White

Prism Size: 64mm

Weight: 1Kg

For: Total Station (Sokkia, Nikon, Trimble, Pentax, Topcon etc.)

Package: Soft Yellow Carrying Bag

Target Plate: Metal

Thread Type: 5/8x11 female thread

Features:

1. This complete tilting prism assembly comes with a 64mm prism mounted in a sealed canister.
2. The prism can either be mounted in a -30mm or zero offset position.
3. Tilting knob can fix the prism angle.
4. High reflection rate by aluminum coated prism
5. Un-foggy by aluminum coating on prism and sealed structure
6. Prism Comes with a protective padded nylon carrying case.
7. 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.

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. Unfortunately, ideal alignment is not always achieved in the field.